Ch 2,3- Reproduction and Embryogenesis Flashcards
2 Groups of mammals that birth their young differently (development wise)
Prototherians (monotremes) and metatherians (marsupials)
Echidna (spiny anteater) and duckbilled platypus are examples of
Prototherians (monotremes) (oviparity)
Group of mammals that encase their developing embryos within hard-shelled amniotic eggs and lay them to be hatcehd
Prototherians (monotremes)
Method of development call oviparity
Examples includes duck billed platypus and echidna (spiny anteater)
Koalas and Kangaroos are called
Marsupials (metatherians)
“undergoes some development in its mother’s uterus and then climbs its way out of the birth canal and into her marsupium, or pouch. ”
metatherian (marsupial)
Autosomal cells in animals are said to be
diplod (2n)
-2 copies of each chromosome
Germ cells in animals are
Haploid (n)
-only 1 copy of each chromosome
“a specific series of phases during which a cell grows, synthesizes DNA, and divides”
Cell cycle
“Derangements of the cell cycle can lead to unchecked cell division and may be responsible for”
Cancer
4 stages of the cell cycle
G1, S, G2, M
The first 3 stages of the cell cycle (G1, S, G2) are known as
Interphase
The longest part of the cell cycle is
Interphase (G1 , S , G2)
“Cells that do not divide spend all of their time in an offshoot of G1 called ”
G0
The cell is simply living and serving its function, without any preparation for division in what stage?
G0
Interphase chromosomes look like
Less condensed form (chromatin)
-Not visible with light microscopy
2 Main things that occur during G1 stage
- Cell create organelles for energy and protein production
2. Cell grows
Passage into s phase is governed by a
restriction point (The G1/S Checkpoint)
Is the DNA good enough to replicate?
“the cell replicates its genetic material so that each daughter cell will have identical copies during what stage
S phase
“After replication, each chromosome consists of two identical
chromatids
chromatids are bound together at a specialized region known as the
centromere
TF: Cells entering g2 have twice as much DNA as cell in G1
True
“The term chromosome may be used to refer to ”
- A chromatid before s phase
- A pair of chromatids attached at the centromere after s phase
2 checks that occur in G2
- Did Dna replicate correctly?
2. Are there enough organelles and cytoplasm to divide
M stage consists of
Mitosis with cytokinesis
4 stages of mitosis
Prophase Metaphase Anaphase Telophase (PMAT)
In autosomal cells mitosis results in
2 identical daughter cells
2 Main checkpoints of the cell cycle
G1/S (restriction point)
and G2/M
Main protein in control of arresting cell cycle at the checkpoints
p53
Checkpoint where cell is concerned with ensuring cell achieved adequate size and organelles have been properly replicated to support 2 daughter cells
G2/M
Molecules responsible for the cell cycle are known as
Cyclins and cyclin-dependent kinases (CDK)
“In order to be activated, CDKs require the presence of the right”
Cyclins
Name the pathway to move to the next cell cycle
- Cyclins bind to CDK (creates an activated CDK-Cyclin complex
- Complex phosphorylates transcription factors
- Transcription factors promote gene transcription needed for the next state
“One of the most common mutations found in cancer is
mutation of the gene that produces p53 called TP53
-Cell cycle not stopped to repair damaged DNA
“genes that, when mutated, actively promote cell division”
Oncogenes
Genes that when mutated lose their ability to regulate or pause the cell cycle
Tumor Supressor Genes
2 types of cancer causing genes
Oncogenes and Tumor-Suppressing Genes
After anaphase (Chromatids split) chromatids are called
Chromosomes
Meiosis results in
4 non-identical cells
After s phase how many chromatids and chromosomes in humans
92 Chromatids, 46 chromosomes
Organized into 23 homologous pairs
3 Things that happen in Prophase 1
- Chromatin condenses into chromosomes
- Spindle apparatus forms
- Nuclear membrane dissaperars
- Synapsis (homologous chromosomes come together)
Synaptic pairs in prophase 1 is referred to as
Tetrads
Crossing over happens at the
Chiasma (points of synapsis)
Exchanging equivalent pieces of DNA at the chiasma
Crossing over
“tendency for genes to be inherited together”
linkage
Broken in recombinations and increases genetic variety
“genes that are located further from each other physically are”
Less likely to be inherited together
-more likely to cross over
Advantage of sexual reproduction
Genetic diversity
“genes coding for alternative forms of a given trait”
Allele
Crossing over explains what law
Mendels second low of inheritance (independent assortment)
Mendels second law of inheritance is
Law of independent assortment
“states that the inheritance of one allele has no effect on the likelihood of inheriting certain alleles for other genes.”
Law of independent assortment (2nd law)
“During metaphase I, homologous pairs (tetrads) align at the ”
Metaphase plate
Each pair of a homologous chromosome during metaphase 1 attaches to a separate spindle fiber by its
kinetochore
“in meiosis, homologous chromosomes are lined up across from each other at the metaphase plate and are held by”
one spindle fiber
-in mitosis each chromosome at the metaphase from is lined up by 2 spindle fibers (one from each pole)
During anaphase 1 what happens
Homologous pairs separate
Homologous pairs separate in a process called
Disjunction
Disjunction (where homologous pairs separate) accounts for what law
Mendel first law
Law of segregation
Meiosis 2 is very similar to what
Mitosis
What stage is the reductional division in?
Meiosis 1
Events that happens in Telophase 1
Nuclear membrane forms around each new nucleous
Cells are now haploid (n)
A short rest period in between cell divisions where chromosomes partially uncoil
Interkinesis
During anaphase______get pulled apart
Sister chromatids
Sex linked disorder are
X-linked
Males are termed
Hemizygous (only one copy of gene on ex chromosome)
Most x-linked disorders are
recessively inherited
“Females carrying a diseased allele on an X-chromosome, but not exhibiting the disease, are said to be”
Carriers
One notable gene on the Y chromosome
SRY Gene
(sex-determining region Y)
Codes for a transcription factor that initiates testes differentiation (male gonad differentiation)
A father will pass y-linked diseases to
All his sons
2 functional components of the tests
Seminiferous tubules and interstitial cells (Of Leydig)
Sperm are produced in the coiled
Seminiferous tubules
Noroushes sperm in the seminiferous tubules
Sertoli Cells
Lydig cells secrete
Testosterones and Androgens
“As sperm are formed, they are passed to the _______ where their flagella gain motility, and they are then stored until ejaculation”
Epididymis
“During ejaculation, sperm travel through the ___________ to the _______ at the posterior edge of the prostate gland.”
Vas deferens, Ejaculatory Duct (at posterior prostate)
Pathway of sperm through the male reproductive system
Seven Up
Seminiferous tubules Epididymis Vas deferens (also called the ductus deferens) Ejaculatory duct (Nothing) Urethra Penis
Sperm is mixed with
Seminal fluid
Produced by seminal vesicles, prostate glade, and bulbourethral glands
3 glands that make the seminal fluid in male reproductive system
seminal vesicles, prostate glade, and bulbourethral glands
Gland that contribute fructose to nourish sperm and give fluid alkaline properties
Seminal vesicles
“give the fluid mildly alkaline properties so the sperm will be able to survive in the relative acidity of the female reproductive tract.”
Seminal vesicles and prostate gland
“produce a clear viscous fluid that cleans out any remnants of urine and lubricates ”
“The bulbourethral (Cowper’s) glands ”
Sperm and seminal fluids are called
Semen
Formation of haploid sperm through meiosis
Spermatogenesis
Spermatogenesis occurs in the
Seminiferous tubules
Diploid stem cells are call
Spermatogonia (give rise to 4 spermatozoa eventually)
Spermatogonia (diploid stem cells) replicated in s phase, after they develop into
diploid primary spermatocytes
The first meiotic division in spermatogenesis results in
Secondary spermatocytes (Haploid)
Secondary spermatocytes (haploid) undergo meiosis II to generate
Haploid spermatids
When spermatids mature they become
mature spermatozoa
Spermatogenesis results in
4 functional sperm for each spermatogonium
Parts of a mature sperm
head (containing the genetic material),
a midpiece (which generates ATP from fructose)
flagellum (for motility)”
Midpeace of the sperm is filled with
mitochondria (generates ATP from fructose)
“Each sperm head is covered by a cap known as ”
Acrosome
- Derived from the golgi apparatus
- Necessary to penetrate Ovum
Gonads of females
Ovaries
Ovaries produces
Estrogen and progesterone
Ovaries consists of thousands of
Follicles
Follicles in the ovaries are
“multilayered sacs that contain, nourish, and protect immature ova (eggs). ”
Eggs are ovulated thru the
Peritoneal sac
-lines abdominal cavity
After ovulation the ova is drawn into the
Fallopian tube or Oviduct
External female anatomy
Vulva
“The production of female gametes is known as
Oogenesis
“By birth, all of the oogonia have already
“undergone DNA replication and are considered
Primary oocytes (diploid)
- just like primary spermatocyte
- Arrest in prophase 1
Once a month one primary oocyte (2n) will complete meiosis I, producing a
secondary oocyte and a polar body
-polar body generally doesn’t divide any further
“The secondary oocyte, on the other hand, remains arrested in _______ and does not complete the remainder of meiosis II unless _______ occurs.”
metaphase II
“Oocytes are surrounded by two layers:
the zona pellucid (surrounds oocyte itself) (has glycoproteins that protect oocyte and compounds for sperm binding)
and the corona radiate (outside pellucida and layer of cells around oocyte during ovulation)
After fertilization
“The secondary oocyte undergoes the second meiotic division to split into a mature ovum and another polar body, which will eventually be broken down. ”
“Upon completion of meiosis II, the haploid pronuclei of the sperm and the ovum join, creating a diploid
zygote
“Prior to puberty, the hypothalamus restricts production of
gonadotropin-releasing hormone (GnRH)
-triggers anterior gland to secrete FSH and LH
Gonadotropin releasing hormone stimulates the _______ to produce______ and ________
anterior pituitary
Follicle Stimulating (FSH) Hormone and Luteinizing Hormone (LH)
“produced by the testes, increases dramatically during puberty, and sperm production begins.”
testosterone
“FSH in males stimulates _____whereas LH causes____
Excerpt From: Kaplan. “Kaplan MCAT Biology Review: Created for MCAT 2015 (Kaplan Test Prep).” iBooks.
the Sertoli cells—-triggers sperm maturation
Interstitial cells to produce testosterone
2 roles of testosterone
- Develops and maintains male reproductive system
2. Results in development of secondary sexual characteristics
The ovaries produce what
Estrogen and Progesterone
In the embryo, estrogens stimulates
development of the reproductive tract
“secreted in response to FSH, and they result in the development and maintenance of the female reproductive system and female secondary sexual characteristics”
Estrogen
“In adults, estrogens lead to ”
“the thickening of the lining of the uterus (endometrium) each month in preparation for the implantation of a zygote.”
Hormone secreted by the corpus luteum
Progesterone
“involved in the development and maintenance of the endometrium, but not in the initial thickening of the endometrium”
Progesterone
“EStrogen EStablishes and PROgesterone PROtects the endometrium.”
After 3rd trimester, progesterone is supplied by
Placenta
before it was the corpus luteum
What are the 3 events of the menstrual cycle
Follicular, Ovulation, Luteal Phase
The peak of LH marks
Ovulation
“The follicular phase begins when”
“the menstrual flow, which sheds the uterine lining of the previous cycle, begins”
“The higher concentrations of GnRH cause
Excerpt From: Kaplan. “Kaplan MCAT Biology Review: Created for MCAT 2015 (Kaplan Test Prep).” iBooks.
“increased secretions of both FSH and LH”
Estrogen provides negative feedback and decreases
GnRH, LH, FSH
“Estrogen works to regrow the endometrial lining, stimulating vascularization and glandularization of the
decidua (the thick layer of modified mucous membrane that lines the uterus during pregnancy and is shed with the afterbirth)
“Eventually, estrogen concentrations reach a threshold that paradoxically results in positive feedback, and GnRH, LH, and FSH levels”
Increase
LH surges at day 14 and induces ovulation
“After ovulation, LH causes the ruptured follicle to form the”
corpus luteum
The corpus lute secretes
progesterone
“The high levels of progesterone from the corpus lute in the Luteal phase again cause
Negative feedback on GNRH, FSH, and LH
“Assuming that implantation does not occur, the corpus luteum loses its stimulation from LH and
progesterone levels decrease.
Loss of high levels of estrogen and progesterone removes block on GnRH
“On the other hand, if fertilization has occurred, the resulting ______ will develop into a _________”
Zygote, Blastocyst
The blastocyst secretes (hCG)
HCG secreted by the _______ maintains the _______
Blastocyst, Corpus Luteum
hCG looks chemically similar to LH and stimulates its receptors
During the first trimester, what secretes estrogen and progesterone
The corpus luteum
After second trimester, hug levels decline because
Placenta now secretes progesterone and estrogen
continues negative feedback for GnRH
Follicles mature during what phase of the menstrual cycel
Follicular phase
What hormone surge triggers ovulation
LH
“Ruptured follicle becomes ________, which secretes estrogen and progesterone to build up uterine lining in preparation for implantation; LH and FSH are inhibited”
corpus luteum
During menopause, because the negative feedback on FSH and LH is removed (estrogen/progesterone levels drop) the blood levels of these two hormones (FSH,LH) ________
Go up
Once formed, sperm gain motility in the epididymis and are stored there until ejaculation.
Epididymis
“a modified Golgi apparatus that contains enzymes that help the sperm fuse to and penetrate the ovum.”
Acrosome
“In males, FSH stimulates the ________and triggers __________”
Sertoli Cells, Spermatogenesis
In males LH cause the interstitial cells to produce
Testosterone
In female FSH stimulates development of ________ while LH causes _______
Ovarian Follicles, Ovulation
“From the time of birth until shortly before ovulation, all egg cells are arrested at the ”
Prophase 1 of meiosis
-Referred to as Primary oocytes
“At ovulation, the egg cell has completed meiosis I and is now arrested in ________as a haploid cell called a _______
Metaphase 2
Secondary Oocyte
“The spindle apparatus first interacts with the kinetochore fibers near”
The end of prophase
“formation of the neural tube is called
Neurulation
fertilization usually occurs in the wider part of the fallopian tube called the
Ampulla
“Once the first sperm comes into direct contact with the secondary oocyte’s cell membrane, it forms a tubelike structure known as the”
Acrosomal Apparatus
“After penetration of the sperm through the cell membrane what happens
The cortical reaction occurs
A release of calcium ions
What are the 2 purposes of the cortical reaction, where a release of calcium ions occur to depolarize the cell membrane of the ovum
- Prevents fertilization of the ovum by multiple sperm cells
- Increase Ca2+ increases metabolic rate of the newly formed diploid zygote
The depolarized and impenetrable membrane is called the
Fertilization membrane
Form from fertilization of two different eggs released during one ovulatory cycle by two different sperm
Dizygotic or fraternal
Each develops its own placenta, chorion, and amnion
“Fraternal twins are no more genetically similar than any other pair of siblings.”
“form when a single zygote splits into two. Because the genetic material is identical, so too will be the genomes of the offspring.”
Monozygotic or identical twins
Monozygotic twins that don’t divide completely
Conjoined twins
Monochorionic/Monoamniotic twins share the same
Amnion and chorion
Mono chorionic/Diamniotic twins
Have their own amnion but star the same chorion
Zygote undergoes rapid mitotic cell divisions in a process called
cleavage
Although several rounds of mitosis occur, total size of embryo
remains unchanged
When the embryo divides into progressively smaller cells the cell increases what 2 rations
Nuclear to cytoplasmic and surface area to volume ration
Increases area for gas and nutrient exchange
2 type of cleavage
Indeterminate and determinate cleavage
Results in cells that can still develop into complete organisms
Indeterminate cleavage
How monozygotic twins are formed
Results in cells that are committed to differentiating into a certain type of cell
Determinate cleavage
After several division the embryo becomes a solid mass of cells known as the
Morula
Once the morula is formed it undergoes what
Blastulation, (forms the blastula)
A _______ hollow ball of cells with a fluid filled inner cavity called a ________
Blastula, Blastocoel
The mammalian blastula is the blastocyst
An embryo with a BLASTed-out cavity is a blastula
The mammalian blastula is known as the _______ and consists of 2 noteworthy cell groups called the _______ and ________
Blastocyst
Trophoblast, inner cell mass
Surrounds the blastocoel and give rise to the chorion and later the placenta
The Trophoblast cells of the blastocyst
the inner cell mass protrudes into the blastocoel (inner space) and gives rise to the organism
The trophoblast cells give rise to the
Chorion
An extra embryonic membrane that develops into the placenta
Chorion
The chorion also forms and outer membrane around the amnion
Microscopic fignerlike projections that penetrate into the endometrium
Chorionic villi (develop into the placenta)
The umbilical chord consists of
2 arteries and 1 vein
AVA
- Vein carries oxy blood with nutrients from placenta to embryo
- Arteries carry deoxy blood and waste to placenta
Until the placenta is functional, the embryo is supported by the
Yolk Sac (also site of early RBC development)
Involved in early fluid exchange between the embryo and the yolk sac
Allantois
Surrounded by the amnion
Umbilical chord is formed from remnant of
yolk sac and allantois
Thin tough membrane filled with amniotic fluid
Amnion
Once the cell mass implants in can begin the generation of 3 distinct cell layers
Gastrulation to a gastrula
Membrane invagination into the blastocoel is called the
Archenteron (later develops in the gut)
The opening of the archenteron is call the
Blastopore
In deuterosomes (like humans) the blastopore develops into the
Anus
D for Doo-doo
In protostomes the blastopore develops into the
Mouth
What are the 3 primary germ layers
Ectoderm, mesoderm, endoderm
The outer most layer is call the _______ it gives rise to what
Ectoderm
-Skin
-Nervous System
-Inner Ear
-Hair, Nails
-Epithelia of nose, mouth, lower anal canal
-Eyes lens
-Adrenal Medulla (cuz contains some nervous tissue)
(e for epinephrine)
The middle germ layer is called the ________ it gives rise to
MesoDerm
- Musculoskeletal
- Circulatory
- Excretory Systems
- Gonads
- Adrenal Cortex (M for mineralcoricoid)
- CT of digestive and respiratory
mnemonic: “means”oderm (the means of getting around as an organism, such as bones and muscle; the means of getting around in the body, such as the circulatory system; the means of getting around, such as the gonads
The innermost germ layer is called the ________ it gives rise to
Endoderm
- Epithelial linings of digestive and respiratory tracts
- Liver, pancreas, thyroid, bladder, distal urinary tracts
How do cells differentiate?
Selective genome transcription
Related to the concept of induction where one group of cell influence the fate of other nearby cells
Mediated by inducers (diffuse from the organizing cells to the responsive cells)
After the 3 germ layers are formed what begins?
Neurulation (development of the nervous system)
Whats the first step of neurulation?
- Notochord formation
A rod of mesodermal cells (notochord) forms along axis like a primitive spin.
- It induces overlying ectodermal cell group to slide inward to form NEURAL FOLDS—These surround a neural groove.
Fuses into a neural tube which gives rise to CNS
At the tip of each neural fold are
Neural crest cells
Migrate outward to form PNS (sensory ganglia, autonomic ganglia, adrenal medulla, schwann cells)
Neural crest cells develop into
The peripheral nervous system
Commitment of a cell to have a particular function in the future
Determination
But not yet actually produces products it needs to carry out functions of the cell (thats differentiation
Presence of diff amounts of specific mRNA and proteins during cleavage may result in this
Can also be by secretion of specific molecules from nearby cells called MORPHOGENS
Molecules that may cause nearby cells to follow a particular developmental pathway
Morphogens
After cell is determined, cell undergoes
Differentiation (assumes structures function, and biochemistry of the cell type
When a cell is _______it is committed to a particular cell lineage. When the cell _______it assumes the structure, function, and biochemistry of that cell type
Determined, Differentiates
key concept
Cell that are yet differentiated or which give rise to other cells that will differentiate are known as
Stem cells
Exist in embryonic tissues as well as adult tissue
The tissues a particular stem cell can differentiate into are determined by its
Potency
Cells with the greatestt potency are called
Totipotent (includes embryonic stem cells)
Can differentiate into any cell type either in fetus or placental structures
These cells can differentiate into any cell type except for those found in placental structures
Pluripotent stem cells
Can differentiate into multiple types of cells within a particular group
Multipotent stem cells
As cell becomes more differentiated, the potency of the cells gets more
Narrower
Totipotent to pluripotent to multipotent
A cell that is induced is called
Responder
To be induced a responder must be COMPETENT (able to respond to the inducing signal)
4 methods of cell to cell communication
Autocrine, Paracrine, Juxtacrine, Endocrine
Cell to cell signaling that acts on the same cell that secreted the signal in the first place
Autocrine
Cell to cell signaling that acts on cells in the local area
Paracrine
Cell to cell signaling that don’t usually involve diffusion but rather cell cell that directly stimulates receptors of the adjacent cell
Juxtacrine
Cell to cell signaling that involves directly secreting the hormones that travel though the blood stream to a distant target tissue
Endocrine
