Transcript Unit XVII: Reproduction

Unit 5: Chapters 19, 20 &
21 Asexual and Sexual
Reproduction
Creating
more
organisms
A. Asexual Reproduction
1. Mitosis and Cytokinesis
2. Forms of Asexual Reproduction
a) Binary Fission
- basically another name for
mitosis
- used by many one celled
organisms
b) Budding
- unequal division of cytoplasm
- yeast and hydra
c) Sporulation
- making spores – like a seed
but genetically identical to the
parent
- fungus, some bacteria
d) Regeneration
- ability of an organism to regrow lost body parts
- ability decreases as the organisms become more
complex
e) Vegetative Propagation
- asexual reproduction in plants
1) bulb
2) tuber
3) runner
4) rhizome
5) cutting
6) grafting
f) Cloning
- exact genetic copy
ADVANTAGES FOR ASEXUAL REPRODUCTION?
Don’t need to find a mate
Can quickly reproduce
Works well if the organisms is really well adapted for
the environment
B. Sexual Reproduction
1. Advantages for Sexual Reproduction
- Variation  allows for adaptation to new
environments
- Evolution
- Survival of the Species
2. Meiosis and Gamete Formation
- Diploid  Haploid
2n  n
3. Fertilization
- Restore chromosome number
- n + n = 2n
- formation of a zygote
4. Development
- Development is the process by which the zygote
becomes the organism
- Zygote  Mitosis  Differentiation and Cell
Specialization
a) Embryo Development
1) Mitosis - cell division to make more cells
2) Cells grow between divisions
- Cell layers = germ layers – become different parts
of the organism
Ectoderm – nervous, skin
Mesoderm – bones, muscle, blood, repro
Endoderm – lining of dig. & resp., liver,
pancreas
5. Human Reproduction
a) Male Reproductive System
Testes – male gonads; make testosterone and sperm cells
100,000s of sperm produced
Scrotum – sac that holds testes outside the body wall
Sperm production and storage has to be at a lower
temperature than the body
Epididymis – storage area for sperm
Vas Deferens – tube that carries sperm from the
testes to the urethra
Urethra – tube through the penis in which sperm are
ejaculated
Semen = mixture of sperm ad fluids
b) Female Reproductive System
Ovaries – female gonads, produce estrogen and egg
cells
Produces 1 egg cell per month
Ovulation = release of the egg from the ovary
Fallopian Tubes / Oviducts – tube leading from the ovary
to the uterus
the Fallopian tubes are the normal site fertilization
Uterus – thick muscular walled organ where implantation of
the egg takes place
the fertilized egg will grow and develop here
Birth Canal = Vagina – site where sperm are deposited
c) Menstrual Cycle
- hormone controlled process by which the egg develops and
is released
- the brain and ovary secrete 4 different hormones to control
the cycle
1) Follicle Stage
pituitary secretes follicle stimulating hormone (FSH) 
causes the egg to develop in the ovary 
also cause the ovary to produce estrogen 
estrogen causes the uterine lining to thicken with tissue
2) Ovulation
high levels of estrogen causes the pituitary to stop
secreting FSH and to begin secreting luteinizing hormone
LH  high levels of LH cause the ovary to release the
egg (usually occurs in the middle of the cycle)
3) Corpus Luteum
the release of the egg from the ovary causes the ovary
to secrete progesterone (pregnancy hormone) 
progesterone helps maintain the uterine lining
4) Menstruation
only if the egg is not fertilized – secretions of LH and
progesterone decrease and the uterine lining is shed
from the body with the unfertilized egg
d) Human Development
1)Fertilization
sperm deposited in the vagina and swim up the
uterus to the Fallopian tubes
One sperm fertilizes the egg
in vitro fertilization
Twins
2) Implantation
as the fertilized egg travels down the Fallopian
tubes it goes through cleavage
upon reaching the uterus the egg fastens itself to
the uterine lining and begins pregnancy
ectopic pregnancy
zygote  embryo  fetus
3) Differentiation – Cell Specialization - Growth
A – Placenta
site where mother and fetus
exchange nutrients, wastes,
O2, CO2 – blood does not cross
between mother and fetus
B – Umbilical Cord
rope like tube that carries the
nutrients and wastes to and
from the fetus
C – Uterus
D – Amniotic Fluid
surrounded by the chorion
(membrane) helps protect the
fetus and keep it stable
4) Fetal Nourishment
Substances in the mother’s blood pass to the
fetus
Proper nutrition
Avoid drugs and alcohol and Viruses
5) Birth
gestation = length of pregnancy – 40 weeks (9
mon.)
labor = muscular contractions of the uterus
premature birth
cesarian section
6) Growth  Puberty  Growth  Death