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MCAT Biology > Reproduction > Flashcards

Reproduction Flashcards

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1
Q

in animals, autosomal cells are said to be _ , which means they contain two copies of _

A

diploid (2n)

each chromosome

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2
Q

What are the four stages of the cell cycle also known as _

A

G1, S, G2, and M

interphase

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3
Q

Cells that do not divide spend their time in?

A

G0

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4
Q

during interphase individual chromosomes are not visible with light microscopy because they are in a less condensed form known as _ . and why

A

chromatin

bc DNA must be available to RNA polymerase so that genes can be transcribed

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5
Q

Describe the G1 stage

A

cells create organelles for energy and protein production while increasing their size. passage into the S phase is governed by a restriction point.

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6
Q

Describe the S stage

A

During the Synthesis phase the cell replicates its genetic material so that each daughter cell will have a copy.

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7
Q

describe the chromosomes During the S stage

A

replicates to two sister chromatids bound by a centromere

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8
Q

Describe the ploidy and amount of DNA in S stage

A

ploidy is still diploid. Humans still have 46 chromosomes but DNA is doubled because there are 92 chromatids present

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9
Q

Describe the G2 stage

A

cells pass through another restriction point making sure there are enough organelles for two daughter cells. And checks DNA replication

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10
Q

Describe the M stage

A

mitosis and cytokinesis. Mitosis is divided into 4 stages

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11
Q

What is the main protein in control of the G1/S restriction point

A

p53

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12
Q

What are the molecules responsible for the cell cycle

A

cyclins and cyclin-dependent kinases (CDK)

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13
Q

How do cyclins and CDKs work

A

cyclins bind to CDKs creating an activated CDK-cyclin complex. this complex can phosphorylate transcription factors that promote the transcription of genes required for the next stage of the cell cycle

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14
Q

what is metastasis

A

local invasion and distant spread of cancerous cells through the bloodstream or lymphatic system

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15
Q

What are the 4 phases of mitosis

A

prophase, metaphase, anaphase, and telophase.

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16
Q

mitosis occurs in _ whereas meiosis occurs in _

A

somatic cells; gametocytes (germ cells)

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17
Q

Describe prophase

A

first phase of mitosis;
first step; involves condensation of the chromatin into chromosomes and the centriole pairs separate and move toward opposite poles of the cell.
2nd step; spindle fibers form (made of microtubules), some form asters. the nucleoli become less distinct and may disappear.

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18
Q

where are centriole pairs located

A

in a region called the centrosome; a region located outside the nucleus

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19
Q

Describe metaphase

A

the centriole pairs are at opposite sides of the cell. kinetochore fibers interact with spindle fibers and align the chromosomes at the metaphase plate or equatorial plate.

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20
Q

Describe anaphase

A

sister chromatids separate to opposite sides of the cell

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21
Q

Describe Telophase

A

reverse of prophase; spindle fibers disappear. nuclear membrane reforms around each set of chromosomes. chromosomes then uncoil resuming interphase form.

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22
Q

Describe cytokinesis

A

separation of the cytoplasm and organelles

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23
Q

Meiosis results in four nonidentical _

A

gametes

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24
Q

Meiosis I results in

A

homologous chromosomes being separated generating haploid daughter cells. (reductional division)

25
Q

Meiosis II results in

A

reparation of sister chromatids without change in ploidy (equatorial division)

26
Q

Whats different in Prophase 1 compared to Prophase

A

homologous chromosomes come together and intertwine in a process called synapsis. chromatids may break at the point of contact called a chiasma and exchange equivalent pieces of DNA.

27
Q

importance of the synaptonemal complex

A

a group of proteins that holds homologous chromosomes together in prophase 1.

28
Q

Mendel’s second law

A

the inheritance of one allele has no effect on the likelihood of inheriting certain alleles for other genes

29
Q

What is different in Metaphase 1 compared to Metaphase

A

in meiosis, homologous chromosomes are lined up at the metaphase plate and held by one spindle fiber. in mitosis they’re held by 2 spindle fibers

30
Q

What is different in Anaphase 1 compared to Anaphase

A

In anaphase 1 in meiosis, homologous pairs are separated but sister chromatids stay joined together. In anaphase 1 of mitosis the sister chromatids do separate.

31
Q

What is different in Telophase 1 compared to Telophase

A

At the end of Telophase 1 during meiosis, we get a haploid set of chromosomes with complete homologous chromosomes separated at each pole.
At the end of Telophase during Mitosis, we get a haploid set of chromosomes with discrete homologs (sister chromatids) of homologous chromosomes separated at each pole.

32
Q

What is SRY

A

sex determining region

33
Q

Pathway of sperm through the male reproductive system

A 
Seve(n) up
Seminiferous tubules
epididymis
vas deferens
ejactulatory duct
(nothing)
urethra
penis
34
Q

What is the function of the interstitial cells of Leydig

A

secrete testosterone and androgens

35
Q

what are androgens

A

male sex hormones

36
Q

function and purpose of the ductus deferens

A

a layer of muscle around the vas deferens that can raise and lower the testis to maintain a proper temperature

37
Q

Describe the physiology of a mature sperm

A

compact; consist of a head containing genetic material. a midpiece which generates ATP from fructose, and a flagellum.

38
Q

What is an acrosome

A

covers the sperm head and is necessary to penetrate the ovum.

39
Q

What hormones do the ovaries produce

A

estrogen and progesterone

40
Q

fallopian tubes are connected to the muscular _ and are lined with _ that propel the egg foward

A

uterus; cilia

41
Q

what are spermatogonia

A

stem cells that make sperm

42
Q

primary oocytes versus secondary oocytes; arrested phases

A

primary oocytes; are 2n, at birth are considered primary, arrested in prophase 1
secondary oocytes; 1 primary oocyte per month will undergo meiosis 1 producing a secondary oocyte; than arrested in metaphase 2 until fertilization (meiosis II)

43
Q

what layers surround the oocyte and what is their purpose

A

zona pellucida; glycoprotein layer that protect the oocyte and allow sperm cell binding.
corona radiata; lies outside the zona pellucida, layer of cells that adhere to the oocyte during ovulation.

44
Q

when is meiosis 2 triggered

A

when a sperm cell penetrates the layers around the oocyte

45
Q

Before puberty the hypothalamus restricts production of this hormone, but after releases it in pulses

A

gonadotropin-releasing hormone (GnRH)

46
Q

the anterior pituitary gland is triggered by GnRH and releases

A

follicle-stimulating hormone (FSH)

and luteinizing hormone (LH)

47
Q

What hormones trigger the production of other sex hormones that develop and maintain the reproductive system

A

GnRH
FSH
LH

48
Q

_ leads to the thickening of the lining of the _ or _ each month in preparation for the implantation of a zygote

A

Estrogen

uterus or endometrium

49
Q

What secretes progesterone in response to LH

A

corpus luteum

50
Q

by the end of the first trimester, progesterone is supplied via the _ and the _ atrophies and ceases to function

A

placenta

corpus leutem

51
Q

Explain the follicular phase of the menstrual cycle. including the hormones involved

A

the follicular phase (preovulatory) begins when the menstrual flow begins. GnRH secretion increases in response to the decreased concentrations of estrogen and progesterone. High [GnRH] cause increased [FSH] and [LH]. FSH and LH work in concert to develop several ovarian follicles. The follicles produce estrogen, which has a negative feedback and causes GnRH, LH, and FSH to level off. Endometrial lining regrows.

52
Q

Explain the ovulation phase of the menstrual cycle. including the hormones involved

A

estrogen then begins to act in a positive feedback loop where [LH], [GnRH] , and [FSH] spike. The surge in LH induces ovulation.

53
Q

Explain the luteal phase of the menstrual cycle. including the hormones involved

A

after ovulation, LH causes the ruptured follicle to form the corpus luteum. progesterone levels rise while estrogen level remain high. High progesterone causes negative feedback on GnRH, FSH, and LH.

54
Q

_ helps regenerate the uterine lining, but _ maintains it for implantation

A

estrogen

progesterone

55
Q

Assuming implantation doesnt occur; explain hormones in luteal phase

A

the corpus luteum loses stimulation from LH, and progesterone and estrogen levels decline. GnRH rises and next cycle begins.

56
Q

a blastocyst will implant in the uterine lining and secrete _

A

human chorionic gonadotropin (hCG)

57
Q

Why does menopause occur

A

ovaries become less sensitive to FSH and LH, causing ovarian atrophy.

58
Q

Upon ovulation, the oocyte is released into the _ than the _

A

abdominal cavity; fallopian tube

59
Q

What is the last point in the meiotic cycle in which the cel has a diploid number of chromosomes

A

During telophase 1

MCAT Biology (6 decks)

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