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Biology MCAT > Reproduction > Flashcards

Reproduction Flashcards

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1
Q

Explain what is meant by diploid (2N).

A

Cells that have two copies of each chromosome

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2
Q

Explain what is meant by haploid (N).

A

Cells that have one copy of each chromosome

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3
Q

The cell cycle contains five stages. What stages are in interphase? What occurs

A

G1,SG2 stages are collectively called interphase, during which DNA is uncoiled to form chromatin

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4
Q

What is the G1 stage?

A
  • “presynthetic gap”
  • cells create organelles for energy and protein production, while also increasing their size
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5
Q

What is the restriction point?

A

G1-S transition point during which DNA is checked for quality. It and must be passed for the cell to move into the s phase.

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6
Q

What is the S phase?

A

DNA is replicated. The strands of DNA called chromatids are held together at the centromere

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7
Q

What is the G2 Stage?

A

postsynthetic gap, there is a further cell growth and replicatio of organelles in preparation for mitosis. Another quality checkpoint must be passed for the cell to enter mitosis

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8
Q

What is the M Stage?

A

mitosis and cytokinesis

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9
Q

What is the G0 phase?

A

the cell perfroms it function without perparing for division

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10
Q

Why is p53 important?

A

it plays a role in the two major checkpoints of the cell cycle and dysfunction leads to cancer

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11
Q

How do cyclins and cyclin dependent kinase regulate the cell cycle?

A

They rise and fall during the cell cycle. Cyclins bind to CDK, phosposphorylating and activating transcription factors for the next stage of the cell cycle

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12
Q

How does cancer occurs?

A

cell cycle control becomes deranged, allowing damaged cells to undergo mitosis without regard to quality or quanitity of the new cells produced.

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13
Q

How do cancer cells metastasize?

A

They may begin to produce factors (such as proteases that degrade basal membrane or blood vessels) that allow them to delocalize and invade adjacent tissues

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14
Q

What does Mitosis produce?

A

two genetically identical diploid daughter cells

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15
Q

What are the 4 phases of Mitosis?

A

prophase, metaphase, anaphase, telophase

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16
Q

In prophase…

A

the chromosomes condense, the nuclear membrane dissovles, nucleoli disappear, centrioles migrate to opposite sides of the cell, and the spindle apparatus begins to form.
The kinetochore of each chromosome is contacted by spindle fibers

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17
Q

In metaphase…

A

chromosmes line up along the metphase plate

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18
Q

In anaphase…

A

sister chromatids are separated and pulled to opposite poles

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19
Q

In telophase…

A

the nuclear membrane reforms, spindle apparatus disappears, and cytosol and organelles are split between the two daughter cells through cytokinesis

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20
Q

Meiosis occurs in

A

gametophytes

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21
Q

Meiosis produces

A

up to four nonidentical haploid cells

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22
Q

Meisosis has _______ rounds of repilciation/ division

A

one round of replication
2 rounds of division

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23
Q

In meiosis I…

A

homologous pairs of chromosomes (homologues) are separated from each other (reductional divison 2N->N)

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24
Q

Homologues are

A

Chromosomes that carry the same genes but are from different parents

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25
Q

In prophase I…

A

the same events occurs as in prophase of mitosis, except that homologues come together and interwine in a process called synpasis. The four chromatids are refeered to as a tetrad and crossing over exchnages genetic material between one chromatid and material from a chromatid in the homologous chromosome.

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26
Q

Crossing over accounts for

A

mendels second law (of independent assortment)

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27
Q

In metaphase I…

A

homologous chromosomes line up on opposite sides of the metaphase plate

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28
Q

In anaphase I…

A

Homologous chrmosomes are pulled to the oppisite poles of the cell.

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29
Q

anaphase I accounts for

A

mendels first law (of segregation) because which homologous chromosome each daughter cell gets in independent of maternal/paternal origin

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30
Q

In telophase I….

A

the chromosomes may or may not fully decondense, and the cell may enter interkinesis after cytokinesis

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31
Q

In meiosis II…

A

sister chromatids are separated from each other in a process that is functionally identical to mitosis.

32
Q

Sister chromtids are

A

copies of the same DNA held together at the centromere

33
Q

Biological sex is determined by the ___________ pair of chromosomes in humans

A

23rd
with XX being female and XY being male

34
Q

The X Chromosome carries:

A

a sizeable amount of genetic information compared to the Y

35
Q

Describe the effects of mutations on the x chromosome.

A

can cause sex linked disorders. Males are hemizygous with respect to upaired genes on the x chromosome, so the will express sex-linked disorders, even if they only have one recessive disease carrying allele. Women with on copy of the affected allele are called carriers

36
Q

The Y chromosome carries

A

little genetic information, but does contain the SRY gene, which causes the gonads to differentiate into testes

37
Q

The male reproduction system contains both

A

internal and external structures

38
Q

Sperm are developed in the

A

seminiferous tubules in the testes

39
Q

sperm in the seminiferous tubules are nourished by

A

sertoli cells

40
Q

Explain the function of Interstitial cells of leydig

A

secrete testosterone and other male sex hormomes (androgens) in the testes

41
Q

The testes are located in the:

A

scrotum which hangs outside the abdominal cavity and has a temperature 2/4C lower than the rest of the body

42
Q

Once formed, sperm gain motility in the _________ and are stored there until ejaculation

A

epididymis

43
Q

During ejaculation the sperm travel

A

through the vas deferns to the ejaculator ducts and then to the urethra and out through the penis

44
Q

The seminal vesicles

A

contribute fructose to nourish sperm and produce alkaline fluid

45
Q

The prostate gland

A

also prouduces alkaline fluid

46
Q

The bubourethral glands

A

produce a clear viscous fluid that cleans out any remnants of urine and lubricates the urethra during sexual arousal

47
Q

Semen is composed of

A

sperm and seminal fluid from the glands above

48
Q

Explain what happens during spermatogenesis.

A

four haploid sperm are produced from a spermatogonium

49
Q

Describe the order of spermatogenesis.

A

S phase
primary spermatocytes (2N)
meosis I
secondary spermatocytes (1N)
meiosis II
spermatids (1N)
matuation
spermatzoa

50
Q

Sperm contain a

A

head, midpiece, and flagellum

51
Q

The Sperm head contains

A

the genetic material and is covered with acrosome from the golgi apparatus

52
Q

What does the sperm midpiece contain?

A

generates ATP from fructose and contains many mitochondria

53
Q

Explain the role of the flagellum.

A

promotes motility

54
Q

The female reproductive system only

A

contains internal structures

55
Q

Ova are produced in

A

follicles in the ovaries

56
Q

Once each month

A

an egg is ovulated into the peritoneal sac and is drawn down the fallopian tube or oviduct

57
Q

The fallopian tubes are connected to

A

the uterus, the lower end of which is the cervix

58
Q

the vaginal canal lies

A

below the cervix and is the site where sperm are deposited during intercourse

59
Q

the external female anatomy is known as

A

The vulva

60
Q

Explain what happens during oogenesis.

A

on haploid ovum and a variable number of polar bodies are fromed from one oogonium

61
Q

At birth, all..

A

oogonia have already undergone replication and are considered primary ooctytes. they are arrested in prophase I

62
Q

The ovulated egg each month is a _______, which is arrested in _______.

A

secondary oocyte
metaphase II

63
Q

If the occyte is fertilized it will

A

complete meiosis II to become a true ovum

64
Q

Cytokinesis is ________– in oogenesis

A

uneven, The cell receiving very little cytoplasm and organelles is called a polar body

65
Q

Oocytes are surrounded by

A

zona pellucida an acellular mixture of glycoproteins that protect the occyte and contain the compounds necessary for sprem binding; and the corona radiata which is a layer of cells that adhered to the occyte during ovulation

66
Q

GnHR from the hypothalamus causes

A

the release of follice-stimulating hormone (FSH0 and luteinizing horomone (LH)

67
Q

In males, FSH stimulates

A

the sertoli cells and triggers spermatogensis

68
Q

In males ,LH causes

A

the interstitital cells to produce testosterone. Testosterone is responsible for the maintainence and development of the male reproductive system and male secondary sex characteristiscs (facial and axillary hair, deeping of the voice, increased bone and muscle mass)

69
Q

In females FSH stimulates

A

development of ovarian follicles

70
Q

In females, LH causes

A

ovulation

71
Q

In females, FSH and LH also stimulate

A

production of estrogens and progesterones

72
Q

In the follicular phase…

A

GnRH secretion stimulates FSH and LH secretion, which promotes follicle development. Estrogen is released, stimulating vascularization and glandularization of the decidua

73
Q

Ovulation is stimulated by

A

a sudden surge in LH. This surge is triggered when estrogen levels reach a threshold and switch from negative to positive feedback effects

74
Q

In the luteal phase

A

LH causes ruptured follicle to form corpus luteum (secretes progesterone to maintain the uterine lining) High estrogen and progesterone levels cause negative feedback on GnRH, LH, and FSH

75
Q

Mensturation occurs if

A

there is no fertilization. As the estrogen and progesterone levels drop, the endometrial lining is sloughed off and the block on GnRH production is removed

76
Q

If fertilization does occur, the blastula produces

A

human chorionc gonadotropin (hCG) which as an LH analog can maintain the corpus luteum. Near the end of the first tirmester. hCG levels drop as the placenta takes over progesterone production

77
Q

Menopause occurs when the

A

ovaries stop producing estogen and progesterone, usually betwenn ages 45 and 55. Menstraution stops and FSH and LH levels rise. Physcial and Phsyiological changes accompanying menopause including flushing, hot flashes, headaches, and irritability

Biology MCAT (5 decks)

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