Download UNIT IV: REPRODUCTION

BIO 30 – A. REGIER
UNIT IV: REPRODUCTION
1. Reproductive Strategies in Animals
A. ASEXUAL vs. SEXUAL REPRODUCTION
ASEXUAL
SEXUAL
examples:
examples:
Q: From an evolutionary perspective, is one method of reproduction more
advantageous that the other?
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BIO 30 – A. REGIER
B. REPRODUCTIVE SYSTEMS
-
hermaphrodites:
-
separate sexes:
-
Gametogenesis:
- oogenesis:
- spermatogenesis:
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BIO 30 – A. REGIER
Oogenesis - Involves the following steps:
1. eggs develop from cells called oogonia
(2n).
oogonium
(2n)
Many oogonia are developed in the female
ovaries. The production of oogonia
stops at birth. Each human female is
therefore born with all of the oogonia
she will ever have.
mitosis
primary oocyte
(2n)
2. oogonia develop into primary oocytes
(2n) by mitosis. This occurs by the 3rd
month of development of a human female
inside of the mother.
meiosis
I
3. At birth the primary oocytes are in
the first meiotic division.
Meiosis will stop until the female
reaches sexual maturity. A human
female’s ovaries contain about
2 million primary oocytes.
secondary oocyte
(n)
polar
body
(n)
4. In puberty, meiosis I is
completed to produce a larger
secondary oocyte (n) and a
smaller polar body (n).
meiosis II
polar bodies (n)
polar body
(n)
5. In meiosis II, a secondary
oocyte divides unequally
to form an ootid (n) and
a polar body (n). The
other polar body also
divides into two polar
bodies (n).
ootid (n)
mitosis
6. The ootid grows by mitosis into
an egg (ovum) (n). The
polar bodies die and are
discarded.
mature ovum (n)
Result of oogenesis:
____________________________________________________________________
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BIO 30 – A. REGIER
Spermatogenesis – Involves the following steps:
spermatogonium
(2n)
1. sperm develop in the testes from
immature cells called spermatogonia
(2n). Beginning in childhood the
spermatogonia divide by mitosis
many times. The number of sperm is
therefore not limited in males.
mitosis
2. Spermatogonium increases in size to
become a primary spermatocyte (2n).
primary spermatocyte
(2n)
3. Primary spermatocyte goes
through meiosis I to produce
two secondary spermatocytes
(n).
meiosis I
secondary
spermatocyte
(n)
meiosis II
4. Secondary spermatocytes
go through meiosis II
to produce four equally
sized spermatids (n).
spermatids
(n)
5. Each spermatid
develops into a
mature, flagellated
sperm cell(n).
Result of spermatogenesis:
____________________________________________
Sperm structure:
A sperm cell has three main parts:
1. head:
2. midpiece:
3. tail:
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BIO 30 – A. REGIER
C. MALE REPRODUCTIVE SYSTEM

testes (2):
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BIO 30 – A. REGIER

scrotum:

epididymis:

vas deferens:

urethra:

seminal vesicles, Cowper’s glands, prostate:
-
semen
-
ejaculation
D. FEMALE REPRODUCTIVE SYSTEM

ovaries: (2)
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BIO 30 – A. REGIER

oviducts: (2)

uterus:

cervix:

vagina:

labium majora, labium minora:

clitoris:
E. FEMALE MENSTRUAL CYCLE
1. follicular stage:
2. ovulation:
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3. corpus luteum stage:
4. menstrual flow:
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BIO 30 – A. REGIER
menopause:
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BIO 30 – A. REGIER
F. NON-SURGICAL METHODS OF BIRTH CONTROL
DEVICE
ACTION
% EFFECTIVENESS
ADVANTAGES
DISADVANTAGES
1. symptothermal
method
- no foreign devices or
- requires a period of abstinence
drugs put into the body during ovulation – can be
- female often becomes
challenging for some couples
more ‘in tune’ with her - can be difficult for women
bodily changes
with very irregular cycles
- promotes co-operation
b/t male & female
2. oral
contraceptives
(the “pill”)
- convenient; effective
- must be taken daily
- many possible side effects
such as blood clots which are
increased greatly in those that
smoke
3. injectable
contraceptive
- convenient & effective
- often eliminates
period (no hassle)
- cancer links?
- weight gain
- irregular bleeding
4. subdermal
implant
- convenient & effective
- long lasting (5 yrs)
- absent periods?
- irregular or absent periods
- surgery to insert & remove
- many possible side effects
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BIO 30 – A. REGIER
non-surgical methods of birth control cont………
DEVICE
ACTION
% EFFECTIVENESS
ADVANTAGES
5. birth control
patch
- convenient
6. withdrawal
(coitus
interruptus)
- no foreign device/drug
7. condom
- easy to use; effective
inexpensive
- offers some protection
against STDs include.
AIDS
8. intrauterine
device
- convenient; effective;
needs to be replaced
infrequently
DISADVANTAGES
- effects similar to birth
control pill
- skin sensitivity at site of
patch, menstrual cramps
- requires strong willpower on
behalf of male; timing
difficult
- sperm may be present in
secretions that precede
ejaculation
- requires male co-operation
- decrease in male sensitivity
- can be uncomfortable for
female
- can cause excess menstrual
bleeding & pain; danger
of becoming damaged during
intercourse which could
result in infection (possible
lead to infertility)
- dangerous during
pregnancy
9. diaphragm
with
spermicide
- no known dangerous - requires careful fitting
side effect
- some inconvenience assoc.
- reliable if used
with insertion & removal
properly
- could become dislodged
during sex
10. sponge
- no known side effects - some sensitivity &
- easy to insert
removal problems
- protects against
some STDs
- can be left in for 24h
- no known side effects - can be messy
- must be used 5-10 min
before intercourse
11. foams,
creams,
jellies,
vaginal
suppositories
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BIO 30 – A. REGIER
The “morning after” pill:
G. SURGICAL METHODS OF BIRTH CONTROL
In females……
tubal ligation:
In males…
vasectomy:
2. From Fertilization Onward
A. TYPES OF FERTILIZATION

internal fertilization:
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BIO 30 – A. REGIER

external fertilization:

parthenogenesis:
B. AVIAN EMBRYOLOGY
1) outer shell membrane (chorion):
2) inner shell membrane (allantois):
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3) albumen:
4) chalazae:
5) yolk:
6) blastoderm:
C. HUMAN FERTILIZATION & DEVELOPMENT
i) Fertilization
(4 steps)
TECHNOLOGICAL CONNECTION
in vitro fertilization:
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BIO 30 – A. REGIER
ii) Human Embryology
-
After the sperm fertilizes the egg and a ____________ is formed, a
series of changes occur as the zygote undergoes development. The
single zygote divides and ____________________ into the various
tissues and structures that comprise the multicellular organism.
The zygote is initially __________________, which means that it has
the ability to give rise to every type of cell in the adult body.
In early stages of development, the organism is called an
_____________. _________________ is therefore the study of embryos.
-
The basic process of development include three steps:
1. Cleavage
zygote  2 cells  4 cells  8 cells ……
mitosis
mitosis
mitosis
Morula
- A blastula forms as the cells continue to divide to
form a hollow sphere. The layer of cells in the sphere is
about 1 cell thick & the sphere is filled with fluid. The
fluid-filled inside of the sphere is called the _____________.
Blastula
* The manner in which cells are distributed during cleavage and the
number of cells present depends on the amount of yolk present in the
egg. Human eggs have little yolk *
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BIO 30 – A. REGIER
2. Gastrulation
- There are ____ main germ layers of
the gastrula that will
eventually __________________
(specialize) into different
tissues of the body:
1) endoderm:
2) mesoderm:
3) ecdoderm:
* A second opening will form opposite the blastopore to form the
second opening of the gut (later, the digestive system). *
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BIO 30 – A. REGIER
3) Growth & Differentiation
- Differentiation occurs when the 3 germ layers begin to change into
specialized cells, tissues and organs.
- The first signs of differentiation are when a __________ _________
forms on the upper surface of the gastrula. The two raised edges
of the neural plate are called _____________ ___________.
- The neural folds will come together over the centre of the neural
plate to form a ___________ ____________. The neural tube will
develop into the brain & spinal cord.
- top portion of human embryo showing
the neural plate surrounded by the
neural folds
- top portion of human embryo showing the
neural tube
iii) Human Implantation & Development
implantation:
ectopic pregnancy:
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chorion:
placenta:
umbilical cord:
amnion:
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TECHNOLOGICAL CONNECTION:
a) amniocentesis:
b) ultrasound:
iv) Birth
-
The length of human pregnany (gestation) is….
-
Five steps of labor & birthing process:
MULTIPLE BIRTHS
-
fraternal twins:
-
identical twins:
-
conjoined twins:
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BIO 30 – A. REGIER
3. CLONING:

The Techniques & the Ethics
There are two main types of human cloning:
1. reproductive cloning:
1. Scientists take egg
from the donor &
remove the nucleus
of the egg
2. A cell is taken from
the person being
cloned
3. The enucleated egg
(nucleus removed) is
fused with the cloning
subject’s cell using
electricity
4. Embryo is created in
the culture dish &
is implanted into a
surrogate mother’s
uterus
- If it were to be a
success, the cloned
baby would be born
just over 9 mths later
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BIO 30 – A. REGIER
2) therapeutic cloning:
1. Human eggs from a donor are
coaxed into maturing in a
culture dish. Each egg cell has
a remnant egg cell, a polar
body, and some cells of the
ovary clinging to it.
2. The egg is held still with a
pipette and a needle is used
to drill through the egg cell
membrane and remove a plug of
the membrane.
3. The
the
the
egg
needle is reinserted into
hole in the membrane &
polar body & DNA of the
are removed.
4. Another cell (ex: skin cell,
egg cell) or just its nucleus
is removed using a needle.
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BIO 30 – A. REGIER
5. The cell to be cloned or
just its nucleus is
injected into the egg that
has been stripped of its
genetic material
6.The injected egg is exposed
to chemicals and growth
factors used to activate it
to divide
7. After about 24 h, the egg
cell begins to divide &
contains genetic material
only from the cell to be
cloned.
8. By the 4-5 day a hollow
ball of cells (blastocyst)
has formed. It holds
a clump of cells called
the inner cell mass that
contains stem cells.
9. The blastocyst is broken
open & the inner cell
mass is grown in a
culture dish to yield
stem cells.
10. The stem cells can be
coaxed to grow into a
variety of patients
may someday be injected
into patients.
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BIO 30 – A. REGIER
LOOKING BACK….
1.
Reproductive Strategies in Animals
A. Asexual vs. Sexual
B. Reproductive Systems
- hermaphroditism; gametogenesis (oogenesis & spermatogenesis)
C.
D.
E.
F.
G.
Male Reproductive System
Female Reproductive System
Female Reproductive Cycle
Non-Surgical Methods of Birth Control
Surgical Methods of Birth Control
2. From Fertilization Onward
A. Types of Fertilization
B. Avian Embryology
C. Human Fertilization & Development
i) Fertilization
ii) Embryology
iii) Implantation
& Development
iv) Birth
3. Cloning
1. reproductive cloning
2. therapeutic cloning
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