Reproductive and Development Biology Flashcards
1
Q
Asexual reproduction includes:
A
1) Binary Fission
2) Budding
3) Regeneration
4) Parthenogenesis
2
Q
Binary Fission
A
- Done by Unicellular organisms
(prokaryotes and the mitochondria and
chloroplasts of eukaryotes). DNA is replicated,
migrates to opposite ends of the cell. Septum
forms in the middle and separates, creating
two separate cells.
3
Q
Budding
A
- bud (outgrowth) forms on the
organism. DNA is replicated and deposited into
bud, which buds off, eg. hydra, yeast.
4
Q
Regeneration
A
- piece of organism breaks off.
Can regenerate broken piece or sometimes a
new organism can grow from a fragment.
This is exhibited in hydra and planaria. Fungi
are also able to reproduce via regeneration.
5
Q
Parthenogenesis
A
- unfertilized egg develops
to a viable organism, eg. Honeybees exhibit
haplodiploidy (males haploid, females
diploid).
6
Q
Human Reproduction = sexual reproduction:
A
- joining of two gametes (male sperm and female egg) to create offspring.
Germ cells (male spermatogonia, female oogonia) produce gametes via meiosis.
7
Q
Spermiogenesis
A
- is the maturation of haploid
spermatids into mature, motile spermatozoa. This
process occurs in immature (haploid) spermatids,
therefore, there is no change in the amount of
genetic material.
8
Q
Spermatogenesis
A
- is the formation of haploid
spermatids from spermatogonium. In this process,
diploid germ cells (spermatogonium) become
haploid gametes (spermatids).
9
Q
Spermatogenesis - Process
A
- Spermatogonia undergo two meiotic divisions to
become 4 spermatids and differentiate into
sperm.
1. Seminiferous tubules of testes = site of
spermatogenesis (sperm production) and
contain:
● Sertoli cells: activated by follicle
stimulating hormone (FSH). Surround and
nourish sperm. Produce inhibin (inhibits
FSH - negative feedback).
● Spermatogenic cells: produce
spermatozoa.
- Sperm (not yet mature) transported via
peristalsis to epididymis (duct around testes)
for maturation and storage. - Sperm moves through vas deferens (group
of tubules) to ejaculatory duct (where vas
deferens meets seminal vesicles) which
propels sperm into urethra and leads to
ejaculation out of penis as semen (sperm +
accessory gland secretions).
Mnemonics (SEVEn UP): Seminiferous tubules →
Epididymis → Vas Deferens → Ejaculatory Duct →
Urethra → Penis.
10
Q
______ of testes = site of
spermatogenesis (sperm production) and
contain:
● ______: activated by ______. Surround and
______ sperm. Produce ______ (inhibits
FSH - negative feedback).
● ______: produce
spermatozoa.
A
1) Seminiferous tubules
2) Sertoli cells
3) FSH
3) nourish
4) inhibin
5) spermatogenic cells
11
Q
Sperm (not yet mature) transported via
______to ______ (duct around testes)
for maturation and storage.
A
1) peristalsis
2) epididymis
12
Q
Sperm moves through ______ (group of tubules) to ______ (where vas
deferens meets seminal vesicles) which propels sperm into ______ and leads to ejaculation out of ______ as semen (sperm + accessory gland secretions).
A
1) vas deferens
2) ejaculatory duct
3) urethra
4) penis
13
Q
Sperm Structure includes:
A
● Head: contains nucleus and acrosome
● Midpiece: mitochondria (ATP production).
● Tail: long flagellum (microtubules) to
propel sperm.
14
Q
Male Accessory Glands:
A
1) Seminal Vesicles
2) Prostate Gland
3) bulbourethral Gland
15
Q
Seminal Vesicles
A
-secrete fructose (nutrients
to produce ATP), viscous mucus (cleans and
lubricates urethra), and prostaglandins
(causes urethral contractions which propels
sperm).
16
Q
Prostate Gland
A
- : alkaline secretions (basic) to
counteract uterine acidity.
17
Q
Bulbourethral Glands:
A
- viscous mucus (cleans
and lubricates urethra).
18
Q
Male Hormones
A
1) FSH
2) LH
3) Testosterone
19
Q
Male: Follicle Stimulating Hormone (FSH)
A
- stimulates sperm development in seminiferous
tubules.
20
Q
Male: Luteinizing Hormone (LH)
A
- stimulates Leydig
cells to produce testosterone.
21
Q
Testosterone
A
- matures sperm, gives rise to
male secondary sex characteristics.
22
Q
Female Reproductive Anatomy includes
A
1) Ovary
2) Uterus
3) Cervix
4) Vagina
23
Q
Ovary
A
- produces eggs (singular: ovum; plural:
ova) which travel through the oviduct (or
fallopian tube) to the uterus.
24
Q
Uterus:
A
- muscular, vascular organ. Provides an ideal environment for fertilized egg (blastocyst) to implant and develop.
25
3 layers of the uterus include:
1) perimetrium (outer)
2) myometrium (middle, smooth muscle)
3) endometrium (inner epithelial, lined by mucous membranes).
26
Cervix
- narrow opening of uterus leading to vagina.
27
Vagina
- opens to an external environment (where sperm enters and birth occurs).
28
Oogenesis:
1. Many oogonia produced, majority die via apoptosis, small fraction remain and differentiate to primary oocytes (begin meiosis but are arrested in prophase I until puberty).
2. At puberty: one egg per month ovulates, completing meiosis I, which produces a large secondary oocyte (arrested in meiosis II
during metaphase II) and a polar body.
3. If fertilization occurs: meiosis II is completed.
4. At the end of meiosis II: 2-3 polar bodies (non-viable) and 1 oocyte (viable, contains majority of cytoplasm, mitochondria, and
nutrients for fetus) are produced.
29
Female Hormones include:
1) FSH
2) LH
3) Estrogen and progesterone
30
Female: FSH
- stimulates follicles in the ovary to develop
and production of estrogen and
progesterone.
31
Female: LH
- stimulates ovulation of egg, corpus luteum formation,
which produces estrogen and progesterone.
32
Estrogen and Progesterone
- menstrual cycle and reproduction, give rise to female
secondary sex characteristics.
33
______ target hormones to prevent
pregnancy. Specifically, birth control pills release
______ and ______, inhibiting
______ production during the menstrual cycle
through ______ and thus preventing
the menstrual cycle from causing ______
1) Birth control pills
2) synthetic estrogen
3) synthetic progesterone
4) GnRH
5) negative feedback
6) ovulation
34
Phases of Menstrual Cycle:
1) Follicular Phase
2) Ovulation
3) Luteal Phase
4a) If no implantation occurs
4b) if implantation occurs
35
Follicular Phase:
- hypothalamus releases Gonadotropin Releasing Hormone (GnRH)
→ anterior pituitary releases LH and FSH → FSH binds to the ovaries and induces follicles to develop → developing follicles release estrogen → endometrium thickens → rapid LH spike → ovulation. (Day 1-13)
36
Ovulation
- Ovulation (egg is released from
Graafian follicle) → fimbriae on oviduct
catches egg, cilia sweep egg into oviduct →
egg travels down oviduct (awaiting sperm
fertilization). (happens on Day 14)
37
Luteal Phase
- follicle develops into the corpus luteum (maintained by FSH and LH)
→ corpus luteum produces progesterone and some estrogen → uterine lining thickens (prepares for implantation). (Day 15-28)
38
Menstrual Cycle: If no implantation occurs:
- LH and FSH levels drop (due to hypothalamus and pituitary inhibition by increased progesterone and estrogen) → corpus luteum can no longer
be maintained → progesterone and estrogen levels drop (hypothalamus and
pituitary are not inhibited anymore) → endometrium sloughs off (menstruation) → cycle repeats.
39
Menstrual Cycle: If implantation occurs:
- outer layer of placenta produces Human Chorionic Gonadotropin (hCG) → maintains corpus luteum → progesterone and estrogen levels maintained → endometrium remains (no menstruation).
40
______can be given to women during fertility
treatment to sustain _______stimulation.
1) hCG
2) LH
41
Hormone Feedback Loop: Positive Feedback
- stimulate a pathway to increase production.
e.g.: lactation
e.g.: childbirth
42
Positive Feedback loop: Lactation
- Infant suckling increases prolactin production which causes
lactation (milk production) and further increases infant suckling. Oxytocin
releases milk (milk let down reflex).
43
Positive Feedback Loop: Childbirth
- Oxytocin induces contractions which push the baby out of
the womb. The baby pushes against a nerve in the cervix that signals the
hypothalamus and pituitary to release more oxytocin.
44
Hormone Feedback Loop: Negative Feedback
- inhibit a pathway to decrease production.
● The hypothalamus releases GnRH causing the pituitary to release FSH and LH which increase testosterone levels. High testosterone levels inhibit the hypothalamus from releasing GnRH, lowering FSH and LH and testosterone.
● The same occurs with estrogen and progesterone in the menstrual cycle.
45
Fertilization
- is the joining of a haploid sperm and a haploid egg to form a diploid zygote.
46
Sperm: head (with ______ at its tip), midpiece
(contains ______), tail.
1) acrosome
2) mitochondria
47
Egg: Outermost layer, corona radiata (jelly coat,
made of follicular cells), nourishes developing egg.
Underneath is the vitelline layer (known as the
zona pellucida/jelly coat in mammals), made of
glycoproteins. Plasma membrane is under the
zona pellucida.
1) corona radiata
2) vitelline layer
3) glycoproteins
4) zona pellucida
48
Egg: Outermost layer, ______ (jelly coat,
made of follicular cells), nourishes developing egg.
Underneath is the ______ (known as the
zona pellucida/jelly coat in mammals), made of
______. Plasma membrane is under the
______.
1) corona radiata
2) vitelline layer
3) glycoproteins
4) zona pellucida
49
Fertilization: Capacitation
- the final maturation step for sperm prior to fertilization. Triggered by
secretions in uterine wall. Destabilizes sperm plasma membrane proteins and lipids resulting in:
● Preparation of sperm tip for acrosomal reaction.
● Increased calcium permeability causing a hyperactive state (flagella beats harder, sperm swims faster).
50
Fertilization: Acrosomal Reaction
- recognition process between sperm and egg before fusion. Ensures same-species fertilization. Sperm goes through the corona radiata to reach
zona pellucida. Actin from sperm binds to ZP3 protein of egg’s zona pellucida (mutual recognition). Membranes of sperm head and
acrosome fuse, releasing hydrolytic acrosomal enzymes (hydrolases) to digest zona pellucida and allow sperm to fuse with plasma membrane of egg (fertilization).
51
Fertilization: ______ - recognition process between ______ and ______ before fusion. Ensures ______ fertilization. Sperm goes through the ______ to reach zona pellucida. ______ from sperm binds to ______ protein of egg’s zona pellucida (mutual recognition). Membranes of sperm head and acrosome fuse, releasing ______ acrosomal enzymes (______) to digest zona pellucida and allow sperm to fuse with plasma membrane of egg (fertilization).
1) Acrosomal Reaction
2) sperm
3) egg
4) same-species
5) corona radiata
6) Actin
7) ZP3
8) hydrolytic
9) hydrolases
52
Fertilization: Polyspermy Block
- prevents polyploidy by inhibiting polyspermy (multiple sperms
penetrating egg). Includes: 1) Fast Block and 2) Slow Block
53
Polyspermy Block: Fast Block
- occurs first when sodium ions diffuse into the egg, depolarizing its
membrane and prevents sperm binding.
54
Polyspermy Block: Slow Block
- gradual, long-lasting occurs second. Calcium ions released in egg
stimulate cortical reaction (exocytosis of cortical granules). Cortical granules
make zona pellucida (jelly coat) impenetrable and stimulate proteases to
separate zona pellucida from plasma membrane.
55
Fertilization: Completion of Meiosis II for 2ndary Oocyte
- During meiosis II, the egg is arrested
in metaphase. After penetration, meiosis in
the secondary oocyte continues creating a
haploid oocyte and producing a second
polar body.
56
Fertilization: Zygote Formation
● Monozygotic twins: identical twins. One
zygote splits. Two embryos with identical
genetic material.
● Dizygotic twins: fraternal twins. Two
separate eggs fertilized by two separate
sperms. Two zygotes with
57
______ have their own DNA, separate from the ______. Unlike ______, which is passed down from both the mother and the father, ______is
inherited exclusively from the mother.
1) mitochondria
2) nucleus
3) nuclear DNA
4) mitochondrial DNA
58
Cleavage
- is rapid cell division without changing
the total mass of cells. The subsequently smaller
cells resulting from cleavage are called
blastomeres.
- division of blastomeres depend on:
1) axis of cleavage
2) fate of cells
3) evenness of embryo division
59
Axis of Cleavage
● Radial Cleavage: cells aligned in vertical
axis (eg. deuterostomes).
● Spiral Cleavage: misaligned cells, deviate
from axis (eg. protostomes).
60
Fate of Cells
● Determinate (or mosaic) Cleavage: blastomeres have decided fate.
● Indeterminate (or regulative) Cleavage: blastomeres do not have
pre-set fate. Cells that result from indeterminate cleavage are totipotent.
61
Evenness of Embryo Division
1) holoblastic cleavage
2) meroblastic cleavage
62
Holoblastic Cleavage
- throughout entire embryo, evenly divides embryo, in
animals with little yolk (eg. humans, sea urchins)
- Exception: Frogs have lots of yolk
and also undergo holoblastic
cleavage that is uneven (exhibit
polarity).
63
Meroblastic Cleavage
- partial cleavage, embryo not evenly divided, in animals with lots of yolk (eg. birds, fish, reptiles). Exhibits polarity with animal pole (active cleavage) and vegetal pole (mainly yolk, negligible division).
64
Embryogenesis in Mammals: Start to finish
- Morula (ball of blastomeres): forms at 12-16 cell stage.
- Blastula stage (hollow cavity): forms at 128 cell stage. Blastocoel is hollow, fluid filled center.
- Blastocyst stage: cells of blastula divide and differentiate to form:
1) Trophoblast
2) Inner Cell Mass
65
Trophoblast (outer ring of cells)
● Forms chorion (extraembryonic membrane) - support embryo.
● Implants embryo in the uterus.
● Produces HCG (maintains corpus luteum and endometrium).
66
Inner Cell Mass (ICM)
- forms embryo and three other extraembryonic membranes
(amnion, yolk sac and allantois). Differentiates into two layers (bilaminar
stage) - 1) Epiblast and, 2) Hypoblast
67
Epiblast
- Layer that contributes to main embryo. Cells thicken to form primitive streak which defines left-right and top-bottom axes and is crucial for
gastrulation to begin.
68
Hypoblast
- Layer that partially contributes to yolk sac, remainder
degenerates via apoptosis.
69
Fertilization occurs in the ______, ______ occurs as fertilized egg travels to the uterus. In the uterus, the fertilized egg is at ______ stage. To implant in the uterine wall, blastocyst undergoes ______. ______ replace zona pellucida and ______ can occur.
1) oviduct
2) cleavage
3) blastocyst
4) zona hatching
5) trophoblasts
6) implantation
70
Gastrulation
- is the formation of a trilaminar
embryo. Epiblast cells invaginate inwards through
the primitive streak to form three germ layers:
endoderm, mesoderm, ectoderm. Embryo is
now at the gastrula stage.
71
______ invaginate inwards through
the primitive streak to form three germ layers:
______, ______, ______. Embryo is
now at the ______ stage.
1) Epiblasts cells
2) endoderm
3) mesoderm
4) ectoderm
5) gastrula
72
As cells invaginate they create an opening called the ______ , which
forms the gut tube ( ______ ), the center cavity that becomes the ______
1) blastopore
2) archenteron
3) digestive tract
73
Ectoderm (outer germ layer) forms:
● CNS (brain and spinal cord) and PNS, as well as neural crest cells and neural ganglia.
● Sensory parts of ear, eye, and nose.
● Epidermis layer of skin, hair, and nails.
● Mammary and sweat glands.
● Pigmentation cells.
● Enamel of teeth.
● Adrenal medulla.
74
Mesoderm (middle germ layer) forms:
● Bone and skeleton.
● Muscles.
● Cardiovascular system.
● Gonads.
● Adrenal cortex.
● Spleen.
● Notochord (induces spinal cord formation from ectoderm).
75
Endoderm (inner germ layer) forms:
● Epithelial lining of digestive, respiratory, and excretory systems.
● PLTT (Pancreas, Liver, Thyroid and parathyroid, Thymus).
76
Organogenesis
- formation of new organs.
77
Neurulation
- is nervous system development: An
embryo at this stage is known as a neurula.
1.Notochord stimulates ectoderm to thicken, forming the neural plate.
2. Neural plate folds onto itself forming the neural fold / neural groove.
3. Neural fold continues to fold, forming a hollow tube (neural tube).
● Some cells roll off to form neural crest cells (migrate to form teeth,
craniofacial bones, skin pigmentation, etc.).
4. Neural tube differentiates into CNS. Mesoderm cells (somites) form two masses alongside notochord. Becomes vertebrae and skeletal muscles associated with axial skeleton.
78
Notochord
-stimulates ectoderm to thicken, forming the neural plate.
79
Neural plate
- folds onto itself forming the neural fold / neural groove.
80
Neural fold
- continues to fold, forming a hollow tube (neural tube).
81
Some cells roll off to form __________ (migrate to form teeth,
craniofacial bones, skin pigmentation, etc.).
- neural crest cells
82
________ differentiates into CNS. ________ (somites) form two masses alongside notochord. Becomes vertebrae and ________ muscles associated with ________ skeleton.
1) Neural tube
2) mesoderm cells
3) skeletal
4) axial
83
Stem cells
-are undifferentiated cells with potential (potency) to become many types of
cells: 1) Totipotent, 2) Pluripotent, and 3) Multipotent
84
Totipotent stem cells
- can become any cell (eg. zygote, blastomeres of morula).
85
Pluripotent stem cells
- can become any of of the 3 germ layers (eg. ICM cells → embryonic
stem cells).
86
Multipotent stem cells
- can only differentiate to a few cell types of a specific tissue type (eg.
hematopoietic stem cell → many blood cells).
87
Extraembryonic development
- Development of structures outside the embryo.
- Provide protection and nourishment to fetus.
- Placental mammals have internal pregnancies while egg-laying animals such as reptiles, birds, and monotremes (egg-laying mammals) lay eggs.
Marsupials are mammals that carry their babies in a pouch.
88
Placental mammals have ______ pregnancies while ______ animals such as reptiles, birds, and monotremes (egg-laying mammals) lay eggs.
______ are mammals that carry their babies in a pouch.
1) internal
2) egg-laying
3) marsupials
89
Structural components: Extraembryonic
1) Amnion
2) Chorion
3) Allantois
4) Yolk Sac
90
Amnion
- innermost layer, membrane around embryo secretes amniotic fluid (water
cushion, protecting embryo).
● Amniotes (reptiles, mammals, birds, marsupials) have an amnion,
anamniotes (amphibians, fish) do not (surrounding water serves as cushion).
91
Chorion
- outermost layer.
● Placental mammals: forms fetal half of the placenta (platform for exchange of gases, nutrients, and waste).
● Egg-laying animals: membrane for gas exchange just underneath egg shell.
92
Allantois
- sac that buds off of the archenteron. Stores waste for disposal.
● Placental mammals: transports waste to placenta, becomes the umbilical cord, and in adults forms urinary bladder.
● Egg-laying animals: initially stores uric acid, later fuses with chorion (helps with gas exchange).
93
Yolk Sac
- contains yolk (intraembryonic, provides nutrients).
● Placental mammals: transient function until placenta develops. First site of blood cell formation.
● Egg-laying animals: provides all nutrients for developing embryo.
94
Reproductive Methods of animal embryonic models
1) Oviparity
2) Viviparity
3) Ovoviviparity
95
Oviparity
- Offspring develop and hatch outside of the mother’s body. Birds, fish,
and reptiles are oviparous.
96
Viviparity
- Offspring develops inside the mother’s body, birth follows. Most
mammals are viviparous.
97
Ovoviviparity
- Hybrid between oviparity and viviparity. Offspring develop and are
hatched within the mother’s body. Some snakes and amphibians are ovoviviparous.
98
______:
Lots of yolk, Uneven ______cleavage with ______ (darker color) and ______ (paler). ______ is opposite to the site of sperm entry. Forms due to cytoplasm rotation, causing mixing from the two poles. Any cell from the ______ cleavage that receives a bit of the gray crescent can become a full frog embryo. Frog embryos have no ______. Instead, gastrulation begins at
the ______of blastopore (forms at site of gray crescent).
1) Frog Embryo
2) holoblastic
3) animal pole
4) vegetal pole
5) gray crescent
6) first
7) primitive streak
8) dorsal lips
99
______:
Model for all ______ animals. Embryo has no direct connection to mother and needs ______ for nutrients. ______ connects yolk to ends of shell (allows nutrient distribution to entire embryo). Chicks have a ______.
______ (analogous to ICM in mammals) is flattened resulting in an ______
upon gastrulation at primitive streak.
1) chick embryo
2) egg-laying
3) large yolk
4) Chalaza
5) primitive streak
6) Blastodisc
7) elongated blastopore
100
Factors influencing Development:
1) Embryonic induction
2) Homeotic Genes
3) Egg Cytoplasm Determinant
4) apoptosis
101
Embryonic Induction:
● Organizers secrete chemicals that
influence what neighboring cells become in the future (eg. dorsal lip of blastopore in frogs).
102
2. Homeotic genes:
● Master controller, turns different gene expressions on/off.
● Homeotic genes decide which part of the embryo develops into what structures.
- This is carried out through regulating the formation of the body axes and body structures in the proper location during early embryonic development.
● A homeobox is a common DNA sequence homologous across organisms that contains homeotic genes.
● HOX genes are a subset of homeotic genes that are responsible for
anterior-posterior (head-to-tail) position of body parts during development.
103
Egg Cytoplasm Determinant:
● If egg cytoplasm is unevenly distributed
(creating animal and vegetal poles), an
axis is created, influencing how the
embryo divides during cleavage.
104
Apoptosis:
● Programmed cell death important for
normal development of fetus (eg.
removing webbing between fingers) and
adults (preventing cancer).
