BIOLOGY 12
Mamaril
Notes
Animal Reproduction and Development:
Features
of living organisms:
- Metabolism
- Growth
and development
- Biological
organization
- Responsiveness
to stimuli
o Homeostasis,
irritability
- Reproduction
o To
maintain species
o Different
from the other currencies because it is done at certain stages in the life
cycle
Increase
in population = depletion of resources
-
↑ competition
-
↑ diseases
-
↑ pollution
-
↓ food
-
↓ water
Biodiversity crisis – many species are on the verge of
becoming extinct
__________________________________
Figure
52.21 – Human population growth
|
Year
|
Population
|
|
1650
|
0.5
billion
|
|
1850
|
1 billion
|
|
1930
|
2 billion
|
|
1975
|
4 billion
|
|
1987
|
5 billion
|
|
1999
|
6 billion
(reached
on October 12, 1999)
|
Figure 45.12
9000
BC – domestication of plants, animals (11k years ago)
5200
BC (est.) – agriculturally based urban societies
1600
AD – beginning of industrial, scientific revolutions
Projected
population for 2050: 9 B or 11
B
Only our species has that kind of
population growth!
|
|
Edward
O. Wilson – naturalist
-
Entomologist – studied ants
-
Evolutionary and conservatory biologist
-
The Future of Life
Population of the
world
|
Continent
|
Current Population
|
Projected Population
for 2025
|
|
Asia
|
3.7
billion
|
4.7
billion
|
|
Europe
|
727
million
|
717
million
|
|
Africa
|
818
million
|
1.3
billion
|
|
South
America
|
525
million
|
700
million
|
|
North
America
|
316
million
|
382
million
|
|
Oceania
|
30
million
|
40
million
|
Population of the
Philippines
|
Year
|
Population
|
|
2001
|
76.4
million
|
|
2002
|
80
million
|
|
2005
|
85.2
million
|
|
2008
|
88
million
|
-
In 2002, the Philippines was the 14th most populous
country among 243 countries
-
2.37% growth
rate from 1995 – 2000
-
2001 – we are the only Catholic country in
Asia but we have the biggest growth rate
2002 statistics
-
Germany has a negative population growth
o
Population: 81.947
-
Vietnam has a positive population growth
o
Population: 80.305
o
1.7%
-
Brazil
– 1.9
-
Mexico – 1.3
Demography
-
Population studies
-
Age-structure “pyramids”
Fig 52.23 – Age Structures
of 3 Nations
-
Sweden – decreasing
-
US – many were born after World War II
o
Baby boom generation
o
Has a steady growth
-
Mexico – comparable to the Philippines or
Afghanistan
Youth Bulge:
-
Youth: 15 years old – 24 years old
-
1980’s: youth bulge occurred in Hong Kong,
Taiwan, and Singapore
-
Indonesia and Thailand’s youth bulge occurred
in 2000s
-
Philippines:
o
Youth: 16 million (versus the 5 million in 1965)
o
It will peak at 2025 if present trends continue
o
23.8% of youth
are having premarital sex
§ 11% of them are having sex with the same sex
|
|
Diliman Sex Study
-
1/3 do it
o
126 respondents had sex
-
Use of protection:
o
40% - sometimes
o
36% - always
o
24% - never
-
Kinds of protections used:
o
88% condom
o
10% birth control pills
o
12% rhythm
Several thousand years ago, the
population growth was slow, but it increased rapidly in the latter part
Population Models:
1. J-shaped
o
Exponential
o
Populations that are in ideal environments
o
Unlimited resources, no competition, no
diseases
§ Resources: space,
food, water, nutrients, light, humidity
Examples of species
with a J shaped pop’n:
-
Human population*
-
Bacterial culture
o
Artificial population
-
Cyanobacterium (blue green algae)*
o
Laguna de Bay
has Microcystis aeruginosa
o
Algal blooms can cause chronic damage to
environment
§ Causes
depletion of dissolved oxygen, so env becomes hypotoxic (low O2)
· It may lead
to death in some species (fish)
-
Insect pests*
o
Forests – budworm
o
Locust infestations
§ Can cause
damage to crops
-
Mammals*
o
If hunting becomes illegal
o
Elephants, deer
*
populations in the wild
The population can’t increase
indefinitely because there is no such thing as unlimited resources
2. Logistic Model
o
S-shaped/Sigmoidal growth
o Carrying capacity (K)
§ Maximum
number of individuals that can be supported by the environment without hurting
the environment
§ Leads to a
population crash
· They will
only stay at K or a little lower
|
|
Figure 52.15 – Lab
population
-
Paramecium – K = 900
-
Daphnia – K = 135
o
Population crashed because it exceeded K
__________________________________
The human population
increases rapidly in spite of:
1. Humans
have low fecundity
-
Fecundity – condition of the number of eggs
that the species produces
-
400
oocytes
produced in a woman’s reproductive life
o Average: 6 offspring
o Maximum: 12 dozen
o
Women: least fecund
-
In contrast to:
o
Common toad – 7,000 eggs per spawning
o
Herring (fish) – 50,000 EPS
o
Sturgeon (fish) – 6,000,000 EPS
§ In danger
of becoming extinct because Europeans are hunting sturgeons to make caviar
· Caviar: $200
per kilo
§ Pre-historic
fish
§ Russian
males eat caviar with vodka
§ The Russian
population is declining because the
husbands get too drunk to have sex
o
Tapeworm – 6,000,000 eggs every year for 35 years
§ Intestinal
parasite
o
Queen termite – 11,000,000 eggs/year for 15
years
2. Humans have one of the longest generation
times:
-
Generation
time
– time (units) from the time an organism is born/hatched until they are able to
have their first offspring
-
Generation time and body size are inversely
proportional
-
Escherichia coli
–
one of the deadliest and most famous
o
for further breakdown of food in the large
intestine
o
also make certain vitamins (Vit K) that the
human body cannot produce through their metabolism
o
takes only 20 minutes for one to
become two
|
|
Generation times of
some species:
-
Protozoans – more or less a day
-
Arthropods – 1 week to a month
-
Small mammals – months to five years
-
Big mammals – 5 years to 10 years+
3. Humans engage in sex
-
Our species is the only one that does things
differently
In what ways are we
weird?
a. Ovulation is concealed
-
Vs ape relatives – advertised
o
Brightly colored genitals and swollen lips
|
|
Fig 15.12b: Our
relatives: chimpanzees, gorillas, orangutans
-
2 species of chimpanzee:
o
Pan troglodytes
–
common chimp
o
Pan paniscus
– pygmy
chimp
-
Similarity between chimps and humans in DNA: 98.4%
|
|
-
Jared Diamond – Why is Sex Fun? The Evolution
of Human Sexuality
o
The Third Chimpanzee
o
Procreation à Recreation
b. We have sex even when the woman is not ready
to be pregnant
-
Menstruation
-
Menopause
c. Copulation occurs in private
d. Women undergo menopause (end of
fertility)
__________________________________
Modes of Reproduction:
-
Asexual
Reproduction
o
Reproduction of an individual without gametes
(eggs/sperm). (Hickman, 1995)
o
Formation of an individual whose genes all
come from one parent, without fusion of sperm and oocyte (egg)
o
Asexuals –
organisms that reproduce asexually
-
Sexual
reproduction
o
Reproduction with gametes
Asexual
Reproduction
-
Almost always relies on mitotic cell division
Advantages:
o
Animals in isolation need not find mates
o
Numerous offspring formed in little time
§ Ideal for
colonizing a habitat rapidly
o
Little energy expenditure
-
Beneficial in stable, favorable habitats,
perpetuates successful genotypes precisely
-
Disadvantages:
o
Does not promote genetic variability
o
Offspring are clones
§ Genetically
identical copies of a single parent
Cloning is
advantageous only so long as:
-
The parents are highly adapted to the env
-
The env stays stable and favorable
Mechanisms of Asexual
Reproduction:
1. Fission
-
Splitting
-
Sea anemones, Planaria (flatworms)
2. Budding
-
Parent produces a small copy at first
-
Cnidarians (hydra, hydrozoans), Annelids
(freshwater oligochaetes, polychaetes)
-
Figure
33.6: The life cycle of the hydozoan Obelia
o
Buds appear as branches
-
Oligochaeta (Aolosoma
hemprichii)
o
Aquatic
o
Buds appear at posterior end
3. Fragmentation, then
regeneration
o
Sponges, cnidarians, turnicates, echinoderms
(especially sea stars)
4. Gemmulation (formation of gemmules)
-
Unique to freshwater sponges (and a few
marine sponges)
-
Gemmule – tiny
ball but can be seen
-
Formed when the sponge senses that their
spongeworld is becoming bad (unfavorable conditions)
-
It’s the quickest way to save themselves
-
Covering: spicules
o
For protection
Parthenogenesis
-
Development of the egg without fertilization
-
Sexual reproduction
-
In rotifers, cladocerans (Crustacea), aphids,
honeybees, frogs, whiptail lizards, turkey
-
Only when conditions are just right
-
No mammals
1. Rotifers
-
Mainly freshwater, free-living, pseudocoelomates
Groups of Rotifers:
a. Bdelloid rotifers (Philodina)
-
Only have ovaries (paired)
-
They form eggs that pass through the colaca
and anus in order to be deposited in the water
-
All of them are females
-
They have been here for 40 million years
|
|
“No
sex for 40 days and 40 nights? I’ll go crazy!”
b. Monogonot rotifers (Brachionus)
-
Amictic females,
amictic eggs
o
Amictic: no meiosis
-
Every egg becomes a new being
-
One ovary rotifer
-
Diploid parthenogenesis (2N)
-
Can do this process for as long as 40
generations, only if conditions are favorable
-
Mictic females,
mictic eggs, unfertilized mictic egg à male!
o
Mictic: they make 2 kinds of eggs
§ Unfertilized
haploid egg that becomes the male
o
The zygote produced will remain dormant until
favorable conditions come. Then they will become female rotifers capable of
parthenogenesis.
|
|
The male monogonot
rotifer:
-
Smaller than the female because it has very
little life and no digestive system.
-
It only has:
o
Cilia
o
Plenty sperm
o
One mission: to fertilize eggs of the female
§
|
|
· He pricks
the female’s skin with his tiny penis
-
Lives for only 2-3 days
|
|
Mamaril’s QOTD!
Mamaril:
“When there is trouble in paradise, who are
you going to call?”
Class:
“…..”
Mamaril:
“Of course, the usual answer is
Ghostbuster, but perhaps I am asking the wrong generation”
2.
Cladocera
(Crustaceans) - Daphnia
-
Almost all are females
-
Freshwater, found in temperate areas
-
Most studied (guinea pig of freshwater
organisms)
-
Asexual eggs (parthenogenetic eggs) are
produced during good times:
o
Favorable conditions (spring)
o
Brood pouch – 6 eggs
o
Viviparous young (live birth)
§ Come out
like mother
-
Sexual eggs (ephippium, ephippia) are produced during bad times:
o
Fewer in number (3 eggs)
o
Need to be fertilized
o
Covered with chitin
o
Dropped in the lake à dormant
o
They hatch in favorable conditions (spring)
3. Desert whiptail lizards – Cnemidophorus
uniparens
-
Unisexual (all females)
|
|
Figure 46.3: Sexual
behavior in parthenogenic lizards
-
“He”
uses his tongue to flick at female to see if she is ready
-
“He” mounts “himself” on top of her and bites
the skin of “her” neck
-
“He” bends “his” body until cloacal
apposition (“cloacal kiss”) is possible
o
Doughnut position
o
Nothing is transferred; it only stimulates
the female to release more eggs
§ Pseudocopulation
-
The second time around, they will reverse
roles
o
Explanation: hormones!
-
The eggs develop through parthenogenesis
Quick
notes about the lizards:
-
A lizard may still reproduce by
parthenogenesis by herself
o
They only go through pseudocopulation in
order to release more eggs
-
These lizards are doing it in this manner,
yet their ancestors are bisexual (C. inornatus)
Sexual
Reproduction
-
Mode of reproduction of majority
-
Formation of new individuals by fusion of
haploid gametes to form a zygote
-
Gametes arise by meiosis
o
Female gamete (egg, ovum, oocyte)
§ Large and
stationary
o
Male gamete (sperm, spermatozoon, sperm
cells)
§ Much
smaller and motile
§ Almost
always has a flagellum (others are amoeboid)
§ Numerous
-
Advantage: promotes
genetic variability
o
Generates unique combinations of genes
inherited from 2 parents
o
Offspring have a variety of phenotypes
o
Enhances the reproductive success of the
parents when environmental conditions change rapidly and adversely
-
Disadvantage:
biologically expensive (bioenergetically costly/large energy outlay)
Why is sex expensive?
Full
separation into male and female imposes biologically expensive demands
1.
All kinds of structural and behavioral
adaptations to get sperm to the egg
a.
Behavioral
terms
o
Male
and female reproductive cycles must be synchronous (gametes released at the
same time)
o
Complex hormonal control mechanisms and
sensory receptors that detect such stimuli as longer days and other environmental
cues (water, rain)
o
Means by which males and females recognize
each other; energy outlays needed for coming up with structural signals as
bright feathers and for performing courtship routines
§ The male is
almost always the prettier of the two
|
|
“Girls, no need! Wag na kayo
magpaganda… no hope rin naman!”
b. Structural terms (fertilization is
less complicated among aquatic animals)
i. External fertilization – large
number of sperm and eggs
ii. Internal fertilization – all-land dwelling animals
and some aquatic forms
§ Fewer sperm
are transferred
2.
Another requirement: nourishment of
fertilized egg and protection of embryo
a.
Yolk
–
food for the embryo
i. No yolk
§ Mammals,
except for egg bearing ones
§ Alecithal
§ Sea urchin
egg – after 40 hours of fertilization, it reaches the larval stage and it is
able to feed itself
ii. Moderate
yolk
§ Mesolecithal
§ Frog eggs
iii. Much yolk
§ Telolecithal
§ Bird eggs
b. Parental care
i. Oviparous – eggs released
outside
ii. Ovoviviparous
–
eggs develop within (usually in the oviduct) and hatched life from the mother’s
body
§ Feeds on
the yolk; the embryo has no connection to the mother’s tissue
§ Various
annelids, some fishes (sharks), few snakes (copperhead), lizards, some
brachiopods, gastropods
iii. Viviparous – egg is
nourished directly from maternal tissues
§ Mammals
Sharks are oviparous, ovoviparous, and
viviparous
|
|
Figure 6.2, Hickman
Whales
-
The male has a penis that is 3 m long
o
When the female is around, the penis takes a
life of its own
o
After sex, he pulls it out and puts it inside
his body
§ To avoid
being damaged
§ And for
hydrodynamics
-
Fertilization is internal
Figure 46.8: Insect
Reproductive Anatomy
Male:
-
Testis
(where
sperm is formed) Ã vas deferens
à receives
mat’l from seminal
vesicle à penis
-
Note: the penis is any structure as long as
it can convey the sperm to the female.
Female:
-
Must be structurally adapted to receive sperm
-
Ovary à oviduct (fertilization) à spermatheca à vagina
Bees can’t stay long mating because
they need to avoid predators
-
The male stores a lot of sperm in the spermatheca
|
|
How do animals find
each other?
-
Male – rounded posterior end
-
Female – pointed posterior end
Pheromones – chemical compounds
(metabolites)
-
Chemical signatures of animals
-
Airborne/waterborne
-
Catch attention of the opposite sex
Ex.
Lepidoptera
(butterflies and moths)
-
Female releases sex pheromones to the air.
-
The male flies to the female
What might smell good for one animal
might be toxic to others
Do humans have
pheromones?
-
Yes and No!
-
Before: Our ancestors had pheromones because
they had no chance to look good
-
Now: modern humans do things that wash away
sex pheromones
o
Bath products, esp. feminine wash (douching)
|
|
Mamaril’s QOTD!
Mamaril
“Girls, what do you do every day?
It’s personal.”
Girl
“Wash my…”
Mamaril, scandalized:
“Don’t make it too personal!”
Girl
“Feminine wash”
German
Shepherd - 225,000 olfactory
cells
Humans
– 5,000 olfactory cells
Separate
sexes:
-
Dioecious
= gonochoristic
United
sexes:
-
Monoecious
= hermaphroditism
-
They have difficulties finding suitable
partners
|
|
Figure 46.6:
Reproductive Anatomy of a Parasitic Flatworm
-
Chinese liver fluke (Clonorchis sinesis)
o
Oriental liver fluke
o
Found in bile ducts
o
Waits for another Oriental liver fluke and
they exchange sperm
§ As a rule,
cross-fertilization must be practiced
Figure 19-18:
Earthworm Reproduction
-
External fertilization
Simultaneous
hermaphroditism
Sequential
hermaphroditism
-
Marine gastropod: Slipper shell limpet (Crepidula fornicata)
o
Larva of gastropods – veliger (free swimming)
-
Gonads are not present at the same time
-
Male before – intersex
-
Protandry – male à female
o
May return to being a male after
-
Protogyny – female à male
o
Ex. coral reef wrasse
What makes the veliger
larvae always turn out into males?
-
The female releases sex pheromones to the
water
|
|
Figure 51.19:
Courtship behavior in the three-spined stickleback
-
Freshwater fish
-
Male: the belly is red and shimmery
1.
F appears
2.
M swims zigzag to the F
3.
M swims toward nest
4.
F follows
5.
M shows entrance to nest
6.
F enters nest
7.
M prods F’s tale with trembling movements
8.
F spawns and leaves
9.
M enters the nest and fertilizes the eggs
|
|
-
Oncorhynchus tshawytscha
-
They only enter a certain river to reproduce
-
They swim upstream (this is difficult and
dangerous because of the predators, rapids, waterfalls, etc)
-
Once in the head waters, the male builds the
nest immediately
-
The young go back downstream until they reach
the Pacific Ocean. They will grow and live there until it’s time to breed
again.
-
After they breed, they stay in the head
waters and die
-
Head waters – cradle and grave
-
Semelparity (semelparous) – Condition in which organisms take a long time before
they breed;
o
They breed only once, then they die
o
Pacific Salmons are the only animals known to
do this
o
Other examples of plants: agave, bamboo
(takes a century)
-
Iteroparity
(iteroparous)
– repeated reproduction
|
|
Figure 29-26: Life
cycle of a leopard frog
1.
It takes 3 years to become sexually mature
o
They do it at night, in water
o
The males croak
o
They only breed with the same species
§ They are
able to distinguish other species through the sound the male makes (“frog
call”)
2.
Male clasps female (amplexus), eggs are
fertilized as they are shed
o
Male is smaller, on top
§ Inner
digits are swollen
· To assist
him in amplexus
3.
Eggs – surrounded by jelly coats
o
Can float, sticky (can attach to plants)
o
Jelly coat – for insulation
4.
Cleavage
5.
Embryo nourished by yolk
o
tail bud stage
6.
Tadpole begins feeding on algae after he
wiggles himself out of the jelly
o
external gills
o
Herbivore!
7.
Skin fold grows over external gill, water
exits through spiracle
8.
Hindlimbs, then forelimbs emerge
9.
The tail shortens by reabsorption,
metamorphosis nearing completion
-
Froglet – young of
frog
o
Becomes a carnivore/insectivore
-
The leopard frog does not take care of its
eggs
Maternal Care for
Frogs:
Figure 29-4:
Reproductive Strategies of Anurans
1. Pygmy marsupial frogs
o Flectonotus
pygmaeus
o
Live in trees, their only access to water is
rain
o
Females have a dorsal brood chamber where
eggs develop
2. Surinam frogs
o
Females have holes (concavities) on their
backs
§ Where eggs
develop until they become froglets
3. Poison arrow frogs
o
Tadpoles cling to the back of the male
(paternal care)
o Phyllobates
bicolor
4. Darwin’s frog
o Rhinoderma
darwinii
o
No access to water, so the inside of the
male’s body is the only moist environment.
o
The male keeps the eggs in his vocal pouch until
they become froglets
__________________________________
Human Reproduction
Figure 46.8:
Reproductive anatomy of human male
-
Testis
-
Epididymis
o
Where sperm mature
o
If stretched, it goes as long as 5 m
-
Floats in luminal fluid up the vas deferens
o 74 days until it reaches the ejaculatory duct
-
Ejaculatory
duct
o
receives secretions from:
§ Bulbourethral glands
· Mucus-like
substance - lubrication
§ Seminal vesicles
· Fructose – energy source of
sperm
· Prostaglandins – have no function
while inside male
o
Cause contractions of the uterus
§ Prostate gland
· Alkaline – neutralize pH of the
vagina (pH 3.8 – 4.2)
o
Masturbation: sperm die immediately
-
Urethra, if sexually active
Sperm can
stay in the vagina for 72
hours/3 days
-
Scrotum – outside
the abdominal cavity
o
Evolutionary reason:
§ To help
maintain the temperature suitable for sperm formation
§ 34 oC
o
Sometimes, the testes don’t descend from
inside the abdominal cavity
§ Temperature
inside the abdominal cavity: 38
oC
· Inhibitory
for sperm formation
§ Cryptorchidism
· Infertile
man!
· He does not
have the right number, nor the right kind of sperm
-
Seminiferous
tubules
– where spermatogenesis occurs
o
Leads to a network called the rete testis
Sperm
+ Secretions = SEMEN
Semen:
-
Body fluid (just like tears and saliva)
-
Colorless, tasteless, nutritious
o
Rich in protein – 30% more than cow milk
o
Low in calories – 1/9 of sugar and fat in cow
milk
|
|
Mamaril’s QOTD!
“Class, I am not encouraging you to engage
in activities that involve eating semen. I don’t want you running to your
mothers saying, ‘Mommy! Mommy! Semen pala, according to our Bio 12 lecture, is
yummy yummy!”
Stratified
epithelial tissue
-
Basement membrane
o
Spermatogonia lie here
§ When born,
this is what males have
o
Sexual maturity à 1o spermatocytes
§ Beginning
of spermatogenesis
o
2o spermatocytes à meiosis II
o
Stem cells: starting cells
o
End: 4 haploid sperm
Non Spermatogenic Cells:
1. Sertoli Cells
-
Nurse cells, sustentacular cells
-
Provide nourishment to spermatids until they
become sperm
-
Believed to release inhibin
(exerts negative feedback on anterior pituitary and hypothalamus)
|
|
Figure 27.9B:
Structure of a Human Sperm Cell
-
Sperm – result
of spermatid losing its cytoplasm
o
Head:
§ Nucleus – most important part
§ Acrosome – cap that contains
minute amounts of digestive enzymes
· Used to
gain entry to the egg cell – nuclear warhead
o
Neck
§ Mitochondrion
– supplies energy
§ Centriole
o
Flagellum
§ Have
microtubules made of protein tubulin (similar
to actin)
· Provides
strength to sperm
2. Interstitial Cells
-
Interstitial endocrinocytes, Leydig cells
-
Found in interstices between adjacent
seminiferous tubules
-
Synthesize the male sex hormones
o
Androgens – testosterone
|
|
-
Male lion – symbol of male sex
o
Testosterone : O, CH3, CH3, OH (mandatory fxnl groups)
o
Gives all the male characteristics
§ Mane –
attractive to lioness
-
Female lion
o
Estradiol: HO, CH3,
OH
-
Lifestyle:
o
The lion stays at home while the lioness
hunts. The food is offered first to the lion and the leftovers are given to the
cubs.
Figure
26.3: The Major Endocrine Glands in Humans
-
Ovary – where
sex hormones for females are made
-
Adrenal
cortex
– other source of sex hormones
Estradiol
and testosterone can be synthesized from cholesterol à Steroids!
All of us
have testosterone and estradiol
The
reproductive system takes orders from the hypothalamus
-
Does its regulation via pituitary
gland/hypophysis
Figure 26.4A: Location
of the Hypothalamus and Pituitary
-
Anterior
pituitary gland (APG)
o
Infundibulum – links APG to hypophysis
o
Releases FSH and LH
Process:
-
Nerve cells in hypothalamus release
gonadotropin releasing hormones
-
Stimulates APG to release FSH and LH
-
Blood stream
-
Target organs
Figure 46.14: Hormonal
Control of the Testes
-
Refer to book
-
FSH – works through Sertoli cells to promote
spermatogenesis
-
LH – ICSH (Interstitial cell stimulating
hormone)
o
Works through Leydig cells
o
Testosterone:
§ Spermatogenesis
§ 1o and
2o sex characteristics
-
Testosterone sends message to APG and
hypothalamus to slow down to prevent overproduction of sperm and over secretion
of testosterone.
_________________________________
Testes
Ã
ejaculatory duct (74 days)
Spermatogonium
à sperm (65-75 days)
Sperm
produced: 300 M daily
What is happening to
sperm in men?
-
1996,
Brit Med J
o
Men born after 1970 had a sperm count 25% lower than those born
before 1959
-
1995, Study
of men in Paris, France
o
2.1%
annual decline
over the past 20 years
-
1992, Skakkebaek
et al
o
Covered 15,000 men from 21 countries
combining results of 61 separate studies over the past 50 years: decline from
about 113 M per mL in 1938
to 66 M in 1990 – a
plunge of nearly 50%
-
Decline of quality of sperm
-
Increase of incidence of testicular cancer
and undescended testes
What may be causing
oligospermy?
-
Stress, smoking, drug use
-
Men having children later in life
-
Increase in STDs
-
Shift from boxer shorts (gives ventilation)
to briefs
-
Environmental pollutants such as DDT
(insecticide that combats malaria and insect pests especially after WWII), some
forms of dioxins (dirty dozen), PCBs (used in computers) and a number of
synthetic substances – environmental estrogens or xenoestrogens
(POPS)
o
Concern: they bind with receptors that normally
recognize estrogens and other natural hormones, fooling the body into thinking
that they are natural estrogens
o
For men: natural estrogens work in testes
(rete testis)
§ Reabsorb
the components of luminal fluid: ions, proteins, water
§ Make the
sperm more concentrated
|
|
Lab
tests: small amounts of industrial chemicals, delivered at a crucial stage of
fetal development, can “feminize” a male embryo
-
Smaller testicles, low sperm output,
miniscule penis
-
For extreme cases, some don’t have a penis at
all
How many sperm must a
man house to be considered fertile?
-
48 million
mL,
where > 63% are
motile sperm
-
Infertile man:
o
< 13.5
million mL-1, where < 32% are motile sperm
|
|
Mamaril’s take home
messages!
-
Check the equipment (testes should have
descended)
-
He should have the right number of sperm
|
|
Mamaril’s QOTD!
“When I got married to my wife, we
signed a contract stating that I will always have the last word, and my last
words are always ‘yes, I’ll do it.”
Figure 27. 2C:
Sideview of the female reproductive anatomy
-
Ovaries – where part of oogenesis takes place
o
Every 20 days a 2o oocyte is
released and goes to the fallopian tube where it could be fertilized
o
Lifespan of oocyte: 48 hours
o
Release oocyte alternately
-
Vagina
o
Passage of baby during delivery
o
Where sperm are deposited
o
Where sperm die
o
Passage of menstrual flow
What makes the vagina
acidic?
-
Bacterium: Lactobacillus
acidophilus
o
As they metabolize, they produce lactic acid
o
Same bacterium used in yogurt
Why do we need an
acidic vagina?
-
Kills the pathogenic bacteria that enters the
vagina
-
Kills sperm
-
The egg is held along the ciliated cells of
the fallopian tube
-
When no fertilization occurs, the endometrium
is sloughed off
-
Sometimes the blastula is implanted in the
oviduct or abdominal cavity
o
Ectopic
pregnancy
– must have embryo taken out by surgery
Figure 44.6a: The
position of the female reproductive system relative to the pelvic girdle and
urinary bladder
-
The reproductive system is protected by the
pelvic girdle
Figure 46.16:
Formation of the zygote and early post-fertilization events
1.
Fertilization
o
Conception, act of conceiving
2.
Cleavage
3.
Blastocyst implants
o
Start of pregnancy
Figure 27.4 B: Meiosis
in Oogenesis
-
Embryos: oogonia
-
Birth: 1o oocyte, no oogonia
anymore
o
Arrested in prophase of meiosis I
o 400,000
-
Sexual maturity/puberty: one 1o
oocyte starts to develop (released)
-
Ovulation: 2o oocyte (N) – 400 only
o
Remain as such until there is sperm
-
Menopause: no more ovulation
Differences between
oogenesis and spermatogenesis:
-
Both start with stem cells
-
One 2o oocyte is produced
o
For boys, two 2o spermatocytes are
formed
-
Only 1 egg is formed
-
Males do it for life
Figure 46.11: Human
Oogenesis
-
Follicle
cells
– make estrogen and progesterone
-
Ovary – can be
considered an endocrine gland
-
14th
day
of menstruation – fully mature follicle – triggers the release of the 2o
oocyte
o The
follicle becomes the corpus luteum.
§ Continues
to release the same hormones, but produces larger quantities of progesterone
and less quantities of estrogen
o
Not pregnant: after 10 days, the corpus luteum shrivels until it
sinks into the substance of the ovary
o
Pregnant: the corpus luteum stays until the 1st trimester,
then it shrinks
Female
reproductive cycles in mammals:
|
Estrous
cycle
|
Menstrual
cycle
|
|
Non-primate
mammals and a few primates
|
Mainly
in women and few primates
|
|
Advertised
ovulation
Estrus phase – only
when mammals engage in sex. When the female is sexually receptive
“in
heat”
|
Concealed
ovulation
|
|
Endometrium
is not sloughed off
|
Endometrium
is shed (menstrual flow)
|
|
|
Figure 46.15: The
reproductive cycle of the human female
-
28 days
-
Primary follicle
- Growing
follicle Follicular
phase
-
Graafian follicle
-
Ovulation
-
Corpus
luteum Luteal
-
Disintegrating corpus luteum phase
Hormones:
-
Estrogen – high
amounts before ovulation
o
To prepare the uterus for possible
implantation
o
Builds endometrium and connective tissues
-
Progesterone
o
Brings about growth of blood vessels
§ Increases
after ovulation
o
Brings about accumulation of glycogen and
enzymes
-
Follicle-stimulating
hormone
(FSH)
o
Development of follicle (keeps oocyte)
o
Present until LH peaks
o
Low estrogen à prevent other follicles from developing
-
Luteinizing
hormone
(LH)
o
High LH + high estrogen = ovulation
o
Functions:
§ Triggers
ovulation
§ Brings
about change from residual follicle to corpus luteum
§ Drives
corpus luteum to stay for a while for progesterone
When
should a woman have sex?
- Days 13-17
__________________________________
See
table 27.7: STDS common in the US
-
Trichomoniasis
|
|
Fact of life #4589439:
Without contraception 85 pregnancies would
occur
How would the woman
know that she is ovulating?
-
Ovulation predictor test kits
How do men have sex?
-
Erectile tissue – virtually empty spaces
o
Corpora
cavernosa
o
A cascade of chemical events trigger erection
-
Process of erection:
o
Arousal Ã
o
Parasympathetic nerves Ã
o
release L-arginine Ã
o
Enzyme 1 Ã
o
Nitric Oxide (NO) Ã
o
Guanylate cyclase Ã
o
cGMP (cyclic guanosine monophosphate
§ relaxes and
dilates blood vessels in the penis. Blood remains here longer
-
Process of ejaculation
o 400 M sperm in 3.5 mL
-
Enzyme 2 – breaks down nitric oxide
Erectile
dysfunction
-
Failure to release semen
-
Solution: Viagra (1998)
o
Has Sildenafil citrate
o
Works by preventing enzyme 2
o
Pfizer (earns 1 B a year because of this!)
Difficulties of a
sperm’s life:
1.
Sperm have to survive the journey to the
urethra
o
Subject to intense shearing forces
o
Travel 5 m/s
o
Have a flagellum that keeps them intact
2.
Acidic vagina
3.
Cervical mucus
o
Prostaglandins
4.
Hostile environment of the uterus
o
Sperm capacitation:
§ Gives a
bath of glucose to sperm
§ Proteins
o
WBC see sperm as foreign bodies
o
There are only a few hundred thousand sperm
left at this point
5.
Fallopian tube
o
only 200 at this point
|
|
Mamaril’s take home
message!
-
Getting pregnant is not that simple
|
|
Fact of life
#82947329:
30% of pregnancies end up in spontaneous
abortion/miscarriage
Life lessons from
Professor Mamaril:
How
to Make Babies
Problems:
-
Man infertile; oligospermy; sperm not motile
enough
-
Female infertile; failure to ovulate;
blockage in oviducts
-
Sexually transmissible diseases – often
produce scar tissue that blocks the oviducs
-
Antibodies produced in uterus immobilize
sperm
Solutions:
reproductive technology
1.
Hormone therapy – to increase production of
sperm or oocyte
2.
Surgery – correct disorders like blocked
oviducts
3.
Cryoperservation – sperm banks; oocyte
storage
o
Stored in liquid nitrogen
4.
Assisted reproductive technology (ART)
a.
In vitro
fertilization (IVF)
§ Culture
dish; up to 8 cells
§ Taken from
gonads
§ When in the
8 cell stage, the secondary oocyte is brought to the oviduct
b.
Zygote
intrafallopian transfer (ZIFT)
§ Zygote
placed in oviduct
c.
Gamete
intrafallopian transfer (GIFT)
§ Oocyte and
sperm are placed in the oviduct
d.
Surrogate
motherhood
§ Has ethical
and legal problems
|
|
November
13, 2004
-
Frances
Harris
(Georgia, USA)
o
5 children, pregnant with twins
o
59 y/o, menopausal
o
Had tubal ligation
o
Divorced from Raymond
January
18, 2005
-
Romania
o
World’s oldest mom – 66 y/o
o
Triplets, but only 1 survived
|
|
Mamaril’s QOTD:
Mamaril:
“Why shouldn’t old women have
babies?”
Migs:
“Because they won’t be able to take
care of the kids”
Mamaril:
“That’s the serious answer. I’m not
looking for the serious answer. The less serious answer is: the women might
forget where they left their babies.”
Cloning 101: How to make your own clone
1. Remove nucleus from the egg cell
o Secondary oocyte, haploid
2. Add the nucleus from a somate cell from adult donor
3. Grow in culture to produce an early embryo (Blastocyst)
4. Blastula implanted in another female
|
|
Roslin Institute (Edinburgh, Scotland)
- Dr. Ian Wilmot
- Successful cloning – July 1996
o Announcement: Feb 1997
- Dolly
o
|
|
o 3 ewes involved
§ Source of secondary oocyte
§ Source of nucleus
§ Surrogate mother
o Died February
2003. Got a viral infection and lung disease.
o 6 y/o
Figure 43.4: Overview of the stages of animal development
1. Gamete formation
2. Fertilization
3. Cleavage
4. Gastrulation
*** Neurolation – development of the nervous
system
o First organ system to develop because it regulates
everything else
5. Organogenesis
6. Growth, tissue specialization
External fertilization of sea urchins:
- They release gametes to water
How do these sperm and eggs find each other?
Problems:
1. Water movements
a. Waves
b. Current
c. Tide
2. Big sea
3. Simultaneous spawning
Solution:
- Oocytes have chemotactic
factors
o Dispersed and picked up by the sperm
o Species-specific
o Lock and key principle
|
|
Phylum Protozoa
Class 1: Mastigophora
o
Move and fed by means of flagellum
Class 2:
Sporoza
o
Spore-formers
Class
3: Sarcodina
o
By pseudopodia
Class 4:
Ciliophora
Plant
Kingdom
Bacteria
Algae
Fungi
Bryophytes
Tracheophytes
Sarcomastigophora – super
class, combination of sarcodina and mastigophora because they are super similar
Protozoa – phylum of single-celled
animals (before)
-
Botany wanted Mastigophora and Algae
(flagellated and photosynthetic)
3
Kingdom Scheme:
-
Protozoa à Kingdom Protista
o
Included algae at that time
o
Monera:
§ Bacteria
§ 1 group of
algae
o
Fungi had its own kingdom
o
What was left: bryophytes, tracheophytes
Figure 28.3 Semantics
and Phylogeny of Eukaryotes
-
Ernst Haeckel
a.
Five Kingdom System
Monera Protista Plantae Fungi Animalia
b.
Eight Kingdom System
Bacteria Archaea
Archaezoa Protista (Protozoa) Chromista Plantae Fungi Animalia
c.
Three Domain System
o
Domain Bacteria
o
Domain Archaea
o
Domain Eukarya
PROTISTS
-
1674 – Antoni Van Leeuwenhoek
-
37,000-38,000
species
(+44,000 fossil species) of protozoan protists
-
Even a low-power microscope can reveal a
great variety of organisms in a drop of pond water
-
Protist – informal name of the kingdom of
mostly 1-cell eukaryotes
-
Advances in eukaryotic systematic have caused
the classification of protists to change significantly
-
Protists constitute a polyphyletic group, and Protista is no longer valid as a kingdom
Figure 26.2: Kingdom
Protista Problem
-
Choanoflagellates – protists but related to
animals
-
Fungi are closer to animals
Structural and
Functional Diversity in Protists
-
Protists exhibit more structural and
functional diversity than any other group of eukaryotes
-
Single-celled protists can be very complex,
and all biological forms are carried by organelles in each individual cell
-
The most nutritionally diverse of all
eukaryotes
o
Photoautotrophs –
chloroplasts
o
Heterotrophs
–
absorb organic molecules or ingest larger food particles
o
Mixotrophs – combine
photosynthesis and heterotrophic nutrition
o
Can be exclusively photosynthetic, but under
certain conditions, this is impossible so they resort to heterotrophy. They can
switch back to photosynthesis after.
-
Can reproduce asexually/sexually or by sexual
processes of meiosis and syngamy
Endosymbiosis in
Eukaryotic Evolution
-
Endosymbiosis – process
in which certain unicellular organisms engulf other cells, which become
endosymbiotic and ultimately organelles in the host cell
-
There is now considerable evidence that much
protist diversity has its origins in endosymbiosis
o
We are all descendants of bacteria
-
Mitochondria evolved by endosymbiosis if an
aerobic prokaryote
-
Plastids evolved by endosymbiosis by means of
a photosynthetic cyanobacterium
o
Gave rise to red algae and green algae
-
Green algae underwent secondary endosymbiosis
o
They were ingested in the food vacuole of
heterotrophic eukaryotes and became endosymbiotic themselves
§ Ex.
Chlorarachniophytes
The Five Supergroups
of Eukaryotes
-
No longer thought that amitochondriates are
the oldest lineage of eukaryotes
-
Our understanding of the relationships among
protist groups continues to change rapidly
-
One hypothesis divides all eukaryotes into 5
supergroups:
o
Excarta, Chromalveolata, Archaeplastids,
Rhizaria, Unikonta
1.
Excavata
-
characterized by its exoskeleton
a. Diplomonads
o
Have modified mitochondria called mitosomes
o
Derive energy anaerobically through
glycolysis
o
Have two equal sized nuclei and many flagella
|
|
Giardia intestinalis
-
May be in the intestine of humans, and in
wild and domestic animals
-
Millions of cysts pass in the feces
-
Wilderness streams or lakes are contaminated
with cysts
-
Cysts are durable; they may last for 2-3 months
-
Cysts can be taken by drinking contaminated
water
b.
Parabasalids
o
Have reduced mitochondria called hydrogenosomes that generate some energy anaerobically
o
Trichomonas vaginalis – greatest infection
|
|
Trichomonas vaginalis
-
Largest (7-32 micrometers long) of
trichomonads present in humans
-
Inhibits vagina primarily; associated w
lowered acidity
-
Treatment: suppositories, douche with dilute
vinegar, powders containing boric acid or acid creams or jellies, antibiotics
-
Males: invades prostate
-
STD
c.
Euglenozoans
o
diverse clade that includes predatory
heterotrophs, photosynthetic autotrophs
i. Kinetoplastids
§ Single
mitochondrion with an organized mass of DNA – kinetoplast
§ Trypanosoma – causes sleeping
sickness in humans
|
|
Trypanosoma congolense
-
Disc-shaped DNA containing organelle within a
large mitochondrion
-
3
subspecies:
o Trypanosoma
brucei
o Trypanosoma
gambiense
o Trypanosoma
rhodesiense
-
Trypanosomiasis
-
Vector: tse-tse fly Glossina (insecta: Diptera)
ii. Euglenids
§ 1 or 2
flagella that emerge from a pocket at one end of the cell
§ Some
species can be both autotrophic and heterotrophic
§ Parts:
· Light
detector
· Eyespot
· Short
flagellum
· Long
flagellum
|
|
Budo – free living
and does not harm anyone
2.
Chromalveolates
o
Alveolates
o
Stramenopiles
a.
Dinoflagellates
o
Freshwater
o
Cells that are reinforced by cellulose plates
o
Mixotrophic or heterotrophic
o
Dinoflagellate blooms – “red tide”
|
|
-
All the Waters Turned into Blood
o
About dinoflagellates
|
|
Pyrodinium bahamense var compressum
-
First discovered in the Red Sea
-
Causes red tides in the Philippines
Pyrodinium bahamense var bahamense
-
Never been reported as toxic
|
|
-
In North Atlantic Ocean
-
24 stages in life cycle:
o
Cyst – bottom à breakout into flagellates
o
Flagellated stages suck out juices of
menhader and oily fishes, amoeboid stages feast of the dead fish
-
Called “the cell from hell”
Ceratium hirundinella, Notiluca
-
Bioluminescent
Zooxanthellae
-
Endosymbionts in hard corals in gastrodermis
of hermatypic corals
b.
Apicomplexans
o
Parasites of animals and can cause serious
human diseases
o
One end – apex – contains a complex set of
organelles specialized for penetrating a host
o
Have a non-photosynthetic plastid, the apicoplast
o
Complex life cycles
o
Not motile
|
|
Plasmodium
-
Causes malaria
-
Number 1 parasite killer
-
Requires both mosquitos and humans to
complete its life cycle
-
Approximately 2 million (1%) die each year from malaria
-
200
million – 300 million victims of malaria
-
Efforts are ongoing to develop vaccines that
target this pathogen
-
Vector: mosquito Anopheles
(Diptera), female
-
No. of species of mosquitoes: 3000-3500
o
Anopheles: 100
o
Those that transmit malaria: < 2 dozen
Species and periodicities of episodes of chills and
fevers:
- Plasmodium
vivax
o
Tertian/benign malaria, every 48 hours
- Plasmodium
falciparum
o
Subetertian, malignant tertian malaria, every
40 – 48 hours
o
Most virulent
-
Schizogony – asexual
reproduction of Plasmodium
-
Plasmodium falciparum Erythrocyte Membrane Protein (PfEMP1) – mediates
adhesion to host cells
-
|
|
-
Merozite
Peritrophic membrane of the gut:
-
SM1 gene
-
PLA 2 gene
-
Both multiple effector genes.
-
From another mosquito. These are inserted to
the genome of the other mosquito to prevent ookinete from becoming oocyot
-
Single chain antibody
-
Genetically modified Anopheles
Difficulties in controlling malaria:
The vector mosquito Anopheles:
-
Persistence of breeding places
-
Different susceptibilities of Anopheles individuals to insecticides
The human host:
-
Exposure to the mosquito
Parasite:
-
Alters surface chemistry of RBC so that RBC
sticks to the tissue lining of the blood vessel
-
Intracellular
-
Different species of Plasmodium
-
Different stages of Plasmodium
c.
Ciliates
-
Micronuclei – function during conjugation,
a sexual process that produces genetic variation
-
Conjugation – separate from reproduction
(binary fission)
-
Macronuclei – control the everyday functions
of the cell, such as feeding, waste removal, and maintaining water balance
3.
Rhizarians
-
Have threadlike pseudopodia
a.
Forams/foraminiferans
o
Tests – porous multichambered
shells that hardened with calcium carbonate.
b.
Radiolarians
o
Delicate, symmetrical skeletons made of
silica
4.
Unikonta
a.
Amoebozoans
o
Amoebas that have lobe- or tube-shaped
pseudopodia
i. Entamoebas
§ Parasites
§ Infect all
classes of vertebrates as well as some invertebrates
|
|
Entamoeba gingivalis
-
Stays inside the mouth
o
Feeds on bacteria
-
Acquired through oral contact
Entamoeba histolytica
-
Number 3 parasite killer
-
Causes amoebic dysentery
-
Spread via contaminated drinking water, food,
or eating utensils
-
100,000 deaths worldwide per year
Iodamoeba buetschii
-
May cause intestinal ulceration in humans
Life cycle of Naegleria fowleri
-
Causes primary amoebic meningoencephalitis
(PAM)
-
Found in hot springs (they enjoy high
temperatures)
__________________________________
INVERTEBRATES
-
Spirobranchus giganteus – “Christmas tree
worm”
o
the main part is wrapped in a calcareous tube
o
pink – tentacles )radioles)
§ for gas
exchange and capturing food
|
|
Charles
Darwin
-
Talked about:
o
How different species have come about
o
Diversity and unity
o
1,300,000 species of animals
-
12 Feb
1809
– birthday
-
24 Nov
1959
– wrote a book
o
150th anniversary of the
publication of his book “The Origin of Species”
§ Editor: James
D. Watson
-
27 Dec
1831
– the HMS left Plymouth and went on a five year trip and he was on board
|
|
Mamaril’s QOTD!
“True love has no happy ending
because true love has no end.”
Main three species infecting humans:
Schistosoma japonicum
Schistosoma haematobium
Radix guadras
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