Ch 2 - Reproduction Flashcards
1
Q
What is the difference between a diploid and a haploid?
A
- diploid (2n) cells have 2 copies of each chromosome
- haploid (n) cells have one copy
2
Q
What are the 5 stages of the cell cycle?
A
- G1: cells create organelles for energy and protein production and increase their size
- S: DNA is replicated (strands of DNA - chromatids - are held together at the centromere) - only DNA molecules double, chromosome number stays the same
- G2: further cell growth and replication of organelles in preparation for mitosis
- M: mitosis and cytokineses occur
- G0: cell performs its functions without preparing for division
3
Q
What is interphase?
A
- G1, S, and G2 phase
- the DNA is uncoiled in the form of chromatin making the DNA available to the RNA polymerase so that the genes can be transcribed
- individual chromosomes are not visible with light microscopy
- longest part of cell cycle
4
Q
What is p53?
A
- plays a role in the 2 major checkpoints of the cell cycle (G1 to S and G2 to M)
5
Q
What is the role of cyclins and CDK in the cell cycle?
A
- the rise and fall during the cell cycle
- cyclins bind to the CDKs, phosphorylating and activating transcription factors for the next stage of the cell cycle
6
Q
What is cancer and when does it occur?
A
- occurs when cell cycle control become deranged, allowing damaged cells to undergo mitosis without regard to quality and quantity of the new cell produced
- cancerous cells may begin to produce factors that allow them to delocalize and invade adjacent tissues or metastasize elsewhere
7
Q
What does mitosis produce and where does it occur?
A
- produces 2 genetically identical diploid daughter cells from a single cell
- occurs in somatic cells
8
Q
What are the 4 phases of mitosis?
A
- Prophase: chromosomes condense, nuclear membrane dissolve, centrioles migrate to opposite sides of cells, spindle apparatus begins to form (kinetechore of each chromosome is contacted by a spindle fiber)
- Metaphase: chromosomes line up along the metaphase plate
- Anaphase: sister chromatids are separated and pulled to opposite poles
- Telophase: nuclear membrane re forms, spindle apparatus disappears, cytosol and organelles are split between the 2 daughter cells through cytokineses
9
Q
What does meiosis produce and where does it occur?
A
- occurs in gametocytes (germ cells)
- produces up to 4 non identical haploid sex cells (gametes)
10
Q
How many rounds to meiosis have and of what?
A
- one round of replication
- 2 rounds of division ( the reductional and the equational)
11
Q
What happens in meiosis 1?
A
- homologous pairs of chromosomes (homologues) are separated from each other
- homologues are chromosomes that are given the same number, but are of the opposite parental origin
12
Q
What happens in prophase 1?
A
- the same events as in prophase of mitosis, except the homologues come together and intertwine (synapsis)
- the 4 chromatids are referred as a tetrad
- crossing over exchanges genetic material between one chromatid and material from a chromatid in the homologous chromosome
- mendel’s first law of independent assortment
13
Q
Metaphase 1?
A
homologous chromosomes line up on opposite sides of the metaphase plate
14
Q
Anaphase 1?
A
homologous chromosomes are pulled to opposite poles of the cell
- mendel’s first law of segregation
15
Q
Telophase 1?
A
the chromosomes may or may not fully decondense and the cell may inter interkinesis after cytokineses
16
Q
What happens in meiosis 2?
A
- sister chromatids are separated from each in a process that is functionally identical to mitosis
- sister chromatids are copies of the same DNA held together at the centromere
17
Q
What chromosome determines biological sex?
A
- 23rd pair of chromosomes in humans
- XX being female and XY being male
18
Q
What do X chromosome carry? What affects to mutations to X linked genes cause?
A
- carry a sizeable amount of genetic information
- mutations can cause sex linked disorders
- males are hemizygous with respect to the unpaired genes on the X chromosome, so they will express sex linked disorders, even if they only have one recessive diseases carrying allele
- women with one copy of the affected allele are called carriers
19
Q
What do Y chromosomes carry?
A
- little genetic information, but does contain the SRY gene which causes gonads to differentiate into testes
20
Q
Where are sperm developed and how are they nourished?
A
- develop in the seminiferous tubulues in the testes
- nourished by Sertoli cells
21
Q
What do interstitial cells of Leydig secrete and where are they located?
A
- in the testes
- secrete testosterone and other male sex hormones (androgens)
22
Q
Where are the testes located?
A
in the scrotum which hangs outside of the abdominal cavity and has a temperature 2-4 C lower than the rest of the body
23
Q
Once formed, where do sperm gain motility?
A
epididymis and are stored there until ejaculation
24
Q
What is the pathway for sperm during ejaculation?
A
SEVE(N) UP
- through the Seminiferous tubules
- Epididymis
- Vas deferens
- to the Ejaculatory duct
- Nothing
- and then to the Urethra
- and out the Penis
25
What do the seminal vesicles contribute?
fructose to nourish sperm and produce alkaline fluid
26
What doe the prostate and bulbourethral glands produce?
- prostate: alkaline fluid
- bulbourethral: a clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal
27
What is semen compose of?
sperm and seminal fluid from prostate and bulbourethral glands
28
What are the stages of spermatogenesis and what is produced?
- after S stage, the germ cells are called primary spermatocytes
- after meiosis 1, secondary spermadocytes
- after meiosis 2, spermatids
- after maturation, spermatozoa
- producing 4 haploid sperm from a spermatogonium
29
What are the 3 parts of sperm?
- head: contains the genetic material and is covered with acrosome (a modified Goligi apparatus that contains enzymes that help the sperm fuse with and penetrate the ovum)
- midpiece: generates ATP from fructose and contains many mitochondria
- flagellum: promotes motility
30
Where are ova produced?
- eggs
| - produced in follicles in the ovaries
31
What happens to the eggs once each month?
an egg is ovulated into the peritoneal sac and is drawn into the fallopian tube or oviduct
32
What are the fallopian tubes connected to?
the uterus, the lower end of which is the cervix
33
Where does the vaginal canal lie and what happens there?
below the cervix
- site where sperm are deposited during intercourse
- site of natural childbirth
34
What is the external female anatomy known as?
vulva
35
What is formed in oogenesis?
one haploid ovum and a variable number of polar bodies are formed from an oogonium
36
What is the process of oogenesis?
- at birth, all oogonia have already undergone replication and are primary oocytes (they arrest in propase 1)
- the ovulated egg each month is the secondary oocyte (arrests in metaphase 2)
- if the oocyte is fertilized, it will complete meiosis 2 and become true ovum
- cytokinesis is uneven in oogenesis, the cell receiving very little cytoplasm and organelles = polar body
37
What surrounds an oocyte?
- the zone pellucida: an acellular mixture of glycoproteins that protect the oocyte and contain the compounds necessary for sperm binding
- corona radiata: a layer of cells that adhered to the oocyte during ovulation
38
What does the Gonadotropin-releasing horomone (GnRH) from the hypothalamus cause?
- the release of follicle stimulating hormones (FSH) and luteinizing hormone (LH), the functions of which depend on the sex of the individual
39
What are the function of FSH and LH in males?
- FSH stimulates the Sertoli cells and triggers spermatogenesis
- LH causes the interstitial cells to produce testerone
40
What is testosterone?
responsible for the maintenance and development of the male reproductive system and male secondary sex characteristics (facial and axillary hair, deepening of voice, increased bone and muscle mass)
41
What are the functions of FSH and LH in females?
- FSH stimulates development of ovarian follicles
- LH: causes ovulation
- these hormones also stimulate production of estrogen and progesterone
42
What is the menstrual cycle?
a periodic growth and shedding of the endometrial lining
43
What happens in the follicular phase of the menstrual cycle?
- first step (follicles mature)
- GnRH secretio stimulates FSH and LH secretion, which promotes follicle development
- estrogen is released, stimulating vascularization and glandularization of the decidua
44
What happens during ovulation of the menstrual cycle?
- second step
- stimulated by sudden surge in LH (around 14 days)
- surge is triggered when estrogen levels reach a threshold and witch from negative to positive feedback effects
45
What happens in the luteal phase of the menstrual cycle?
- third step
- LH causes the ruptured follicle to become the corpus luteum, which secretes progesterone that maintains the uterine lining
- high estrogen and progesterone levels cause negative feedback on GnRH, LH, and FSH
46
What happens during menstruation step if fertilization does not occur?
- fourth step
- as the estrogen and progesterone levels drop, the endometrial lining is sloughed off, and the block on GnRH production is removed causing LH and FSH levels to rise again
47
What happens if fertilization does occur during the menstrual cycle?
- the blastula produces human chorionic gonadotrophin (hCG) which, as an LH analog, can maintain the corpus luteum
- near the end of the first trimester, hCG levels drop as the placenta takes over progesterone production
48
When does menopause occur and what happens?
- occurs when ovaries stop producing estrogen and progesterone, usually between 45-55
- menstruation stops and FSH and LH levels rise
- physical and physiological changes accompanying menopause include flushing, hot flashes, bloating, headache, irritability
49
How many daughter cells are there after meiosis 1 v meiosis 2?
- 1: 2 haploid daughter cells
| - 2: 4 halpoid gametes
50
What is the difference between homologous chromosomes and sister chromatids?
- homologous: related chromosomes of opposite parental origin (X and Y)
- sister: identical copies of the same DNA that are held together at the centromere
- after S phase, a cell contains 92 chromatids, 46 chromosomes, and 23 homologous pairs
51
What is the difference between prophase 1 and prophase?
in prophase 1, homologous chromosomes come together as tetrads during synapsis; crossing over
52
What is the difference between metaphase 1 and metaphase?
in metaphase 1, homologous chromosomes line up on opposite sides of the metaphase plate rather than individual chromosomes lining up on the metaphase plate
53
What is the difference between anaphase 1 and anaphase?
in anaphase 1, homologous chromosomes separate from each other; centromeres do not break
54
What is the difference between telophase 1 and telophase?
in telophase 1, chromatin may or may not decondense; interkinesis occurs as the cell prepares for meiosis 2
55
When does FSH increase/decrease throughout the menstrual cycle?
- follicular: increase
- ovulation: increase
- luteal: decrease
- menses: decrease
56
When does LH increase/decrease throughout the menstrual cycle?
- follicular: same
- ovulation: increase a lot
- luteal: same
- menses: decrease
57
When does estrogen increase/decrease throughout the menstrual cycle?
- follicular: decrease then increase
- ovulation: increase
- luteal: increase
- menses: decrease
58
When does progesterone increase/decrease throughout the menstrual cycle?
- follicular: decrease
- ovulation: decrease
- luteal: increase
- menses: decrease
59
What would excess estrogen cause?
- estrogen known to cause growth of the endometrial lining during the follicular phase and its levels stay high during luteal phase to promote vascularization and glandularization
- excess may provide a strong enough signal for cell growth to promote tumor formation or even cancer
60
Upon ovulation, where is the oocyte released to?
- the ruptured ovarian follicle releases an oocyte into the abdominal cavity, close to the entrance of the fallopian tube
- with the aid of beating cilia, the oocyte is drawn into the fallopian tube through which it travels until it reaches the uterus
61
What is the epididymis?
- the side of sperm maturation at the posterior side of the testis
- sperm gain mobility and are stored until ejaculation
62
What is vas deferens?
surrounding by muscle that raises and lowers the testis to maintain constant temperature suitable for sperm production
63
What happens in the first trimester?
- the corpus luteum is preserved by hCG and progesterone secretion by corpeus lutem is maintained
64
What happens in the second trimester?
- hCG levels decline
| - progesterone levels rise because the hormone is now secreted by the placenta itself
