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MCAT Bio > Bio #2 > Flashcards

Bio #2 Flashcards

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1
Q

problems with spindles attaching to kinetochore would first be observed in _____

A

prophase

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2
Q

the oocyte is first released into the _______ and then cilia bring it into the ________

A

abdominal cavity

fallopian tube

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3
Q

cells remain diploid until _____

A

the very end of telophase I

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4
Q

there are two groups of mammals that birth their young slightly differently:

A 
o	Prototherians (platypus): encase their developing embryos within hard-shelled amniotic eggs and lay them to be hatched (oviparity). 
o	Metatherians (marsupials): some development in the mother’s uterus but then grow in the pouch after climbing out of the birth canal.
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5
Q

we inherit _____ chromosomes from each parent

A

23 from each parent

we have 23 pairs of chromosomes, 46 total

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6
Q

autosomal cells are _____ while germ cells are _____

A

diploid (2n)

haploid (1n)

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7
Q

the cell cycle

A

a specific series of phases during which a cell grows, synthesizes DNA, and divides.

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8
Q

what are the stages of the cell cycle

A

G1, S, G2, M

G0 will occur during G1 if the cell does not plan on dividing

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9
Q

what parts of the cell cycle make up interphase

A

G1, S, G2

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10
Q

During interphase, chromosomes are in a _______ chromatin state and individual ones cannot be seen. During mitosis, the DNA is ______

A

less dense

condensed into tight coils so that some genetic information is not lost when the cell divides.

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11
Q

cell cycle: G0 stage

A

cells that do not divide spend all of their time here.

 The cell is living and carrying out its functions without any preparation for division

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12
Q

cell cycle: G1 stage

A

presynthetic gap
 Cells create organelles for energy and protein production and increase their size
 Restriction point: must pass here to get to S phase.

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13
Q

cell cycle: S phase

A

synthesis of DNA
 Replicates genetic material so each daughter cell has identical copies.
 Each chromosome now consists of identical chromatids attached at the centromere (ploidy is still 2n)

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14
Q

cell cycle: G2 phase

A

Postsynthetic Gap

 Quality control checkpoint: DNA was replicated properly, there is enough cytoplasm and organelles for two cells.

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15
Q

cell cycle: M phase

A

mitosis

 Mitosis and cytokinesis (splitting of the cytoplasm and organelles between the daughter cells)

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16
Q

DNA is always double stranded. When replicated, it is paired with sister chromatid (4 strands, 2 DNA molecules, identical). Then for meiosis I, the pairs of chromosomes with sister chromatids are paired with each other (homologous chromosomes). Homologous chromosomes split in meiosis I and then sister chromatids split in meiosis II

A

ss

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17
Q

in autosomal cells, the daughter cells are _______

in germ cells, the daughter cells are _______

A

equivalent

not equivalent

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18
Q

in autosomal cells, the daughter cells are _______

in germ cells, the daughter cells are _______

A

equivalent

not equivalent

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19
Q

what are the checkpoints in the cell cycle

A

G1/S checkpoint

G2/M checkpoint

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20
Q

G1/S checkpoint

A

(restriction point): the cell determines if the condition of the DNA is good enough for synthesis.
 If DNA damage, cell goes into arrest until has been repaired,
 Controlled by p53 control protein.

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21
Q

G2/M checkpoint

A

the cell is adequate size and organelles have been properly replicated.
 P53 is involved.

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22
Q

Cyclins and cyclin dependent kinases (CDKs

A

Molecules responsible for the cell cycle
 Increase or decrease their concentration at specific parts of the cell cycle. Activated CDKs can phosphorylate transcription factors that promote transcription of genes required to move onto the next stage of the cell cycle

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23
Q

cancer

A

: the cell cycle becomes deranged and damaged cells are allowed to undergo mitosis.
 When p53 is damaged, the cell cycle is not stopped to repair damaged DNA. The damaged DNA acquires mutations and it grows out of control.
 Tumor: when cancer cells undergo rapid cell division.
 Metastasis: distant spread of cancer cells throughout the bloodstream or lymphatic systems.

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24
Q

p53 protein

A

DNA repair

damaged: cell cycle does not stop to repair any potential damages ==> mutations in the DNA

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25
Q

tumor

A

when cancer cells undergo rapid cell division.

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26
Q

metastasis

A

distant spread of cancer cells throughout the bloodstream or lymphatic systems.

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27
Q

oncogenes

A

genes that when mutated actively promote cell division.

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28
Q

tumor suppressor genes

A

when mutated, lose their ability to regulate or arrest the cell cycle

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29
Q

mitosis

A

the process by which two identical daughter cells are created from a single cell. Occurs in somatic cells (not involved in sexual reproduction)

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30
Q

prophase

A

chromosomes condense, spindle forms

 Condense the chromatin into chromosomes.
 Centrioles migrate (once held in the centrosome) to opposite sides of the cell and form spindle fibers which are microtubules. Thus, the centrosome is one of the microtubule organizing centers of the cell. Some form asters which anchor the centriole to the cell membrane.
 The nuclear membrane dissolves and thus microtubules (spindle apparatus) can attach at kinetochores (kinetochore fibers, which are part of the spindle apparatus and connect to kinetochores) on the centromeres.

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31
Q

the centrosome is one of the two _______. What is the other?

A

micortubule organizing centers

other is flagella or cilia

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32
Q

asters

A

microtubules coming out of centrioles that attach to the cell membrane and anchor the centriole in place

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33
Q

kinetochore

A

location on chromosomes where microtubules attach

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34
Q

the nuclear membrane _____ during prophase

A

dissolves

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35
Q

metaphase

A

chromosomes align

 Centriole pairs are now at opposite ends of the cell.
 Kinetochore fibers interact with the fibers of the spindle apparatus and align the chromosomes at the metaphase plate (equatorial plate).

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36
Q

anaphase

A

sister chromatids separate

the centromeres split, and the sister chromatids are pulled toward opposite poles of the cell by the shortening kinetochore fibers

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37
Q

telophase

A

new nuclear membranes form

 the reverse of prophase, the spindle apparatus disappears, nuclear membrane forms around each set of chromosomes, and the nucleoli reappear.
 Cytokinesis: occurs at the end of telophase, the separation of the cytoplasm and organelles.

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38
Q

cytokinesis

A

occurs at the end of telophase, the separation of the cytoplasm and organelles.

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39
Q

gametocytes

A

cells in which meiosis occurs and results in up to four nonidentical sex cells (gametes)

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40
Q

Overall Meiosis

A

o Consists of one round of replication and two rounds of division.
o Meiosis I: homologous chromosomes are separated, generates haploid daughter cells, known as reductional division.
o Meiosis II: similar to meiosis I, separates sister chromatids without a change in ploidy, equational division.

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41
Q

Overall Meiosis

A

o Consists of one round of replication and two rounds of division.
o Meiosis I: homologous chromosomes are separated, generates haploid daughter cells, known as reductional division.
o Meiosis II: similar to meiosis I, separates sister chromatids without a change in ploidy, equational division.

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42
Q

the human genome has ____ homologous pairs

A

23

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43
Q

prophase I

A

 Differences than mitosis
 Homologous chromosomes come together and intertwine in a process called synapsis.
• Here, each synaptic pair consists of four chromatids: tetrad.
• Homologous chromosomes are held together by synaptonemal complex
• Chiasma: locations where DNA can break and exchange information, crossing over. Can be different number of events, single crossovers, double crossovers.
o Genetic recombination: increases diversity
o Separates linked genes that tend to be inherited together.
o Goes hand in hand with Mendel’s second law of independent assortment: the inheritance of one allele has no effect on the likelihood of inheriting certain alleles for other genes.

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44
Q

synapse

A

homologous chromosomes intertwine during prophase I

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45
Q

chiasma

A

locations where DNA can break and exchange information, crossing over. Can be different number of events, single crossovers, double crossovers.

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46
Q

genetic recombination

A

increases diversity

occurs during prophase I

o Separates linked genes that tend to be inherited together.
o Goes hand in hand with Mendel’s second law of independent assortment: the inheritance of one allele has no effect on the likelihood of inheriting certain alleles for other genes.

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47
Q

crossing over only occurs_____

A

between prophase I and anaphase I

between homologous chromosomes, not sister chromatids

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48
Q

metaphase I

A

 Homologous pairs are lined up at the metaphase plate and each one has one spindle fiber attached to it.

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49
Q

anaphase I

A

 Disjunction: Homologous pairs separate and are pulled to opposite poles of the cell (accounts for Mendel’s first law of segregation)
• Maternal and paternal alleles are separated and it is random which daughter cell gets what.
 Centromeres between the sister chromatids do not break

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50
Q

nondisjunction

A

uneven splitting of the chromosomes during anaphase I

can result in a gamete having no copies of a particular chromosome or too many copies

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51
Q

telophase I

A

 The cells are now haploid, new nuclear membrane has formed around the nucleus, but consists of two sister chromatids.
 Interkinesis: between cell divisions, the chromosomes partially uncoil.

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52
Q

interkinesis

A

between cell divisions for meiosis, chromosomes partially uncoil

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53
Q

prophase II

A

 The nuclear envelope dissolves, nucleoli disappear, centrioles migrate to opposite poles, and the spindle apparatus begins to form

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54
Q

metaphase II

A

 The chromosomes line up on the metaphase plate.

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55
Q

anaphase II

A

 The centromeres divide, splitting the sister chromatids, which are then pulled to opposite poles by the spindle fibers.

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56
Q

telophase II

A

o Telophase II:
 A nuclear membrane forms around each new nucleus. Cytokinesis follows.
 Up to 4 haploid daughter cells.

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57
Q

sex

A

determined by the 23rd pair of chromosomes
o XX: female
o XY: male

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58
Q

XX

A

female

59
Q

XY

A

male

60
Q

X chromosome

A

carries a sizable amount of genetic information and mutations in these genes can cause sex-linked (X-linked) disorders.

61
Q

Y chromosome

A

contains very little genetic info other than the SRY gene (sex determining region Y) which codes for a transcription factor that initiations testis differentiation and the formation of the male gonads.
o Presence or absence strictly determines male or female.

62
Q

the presence or absence of what, strictly determines male or female?

A

SRY gene on Y chromosome

63
Q

the presence or absence of what, strictly determines male or female?

A

SRY gene on Y chromosome

64
Q

hemizygous

A

when you only have one copy of a gene

males with X chromosome parts

65
Q

female carriers

A

females carrying a diseased allele on the X chromosome but not exhibiting disease.

66
Q

Mnemonic for pathway of sperm

A

SEVE UP

67
Q

in males, the primitive gonads develop into the _____

A

testes

68
Q

two functional components of the tests

A
  1.  Seminiferous tubules: sperm are produced in the highly coiled seminiferous tubes, where they are nourished by Sertoli cells.
  2. Interstitial cells of Leydig: secrete testosterone and other male sex hormones (androgens)
     The testes are located in the scrotum, an external pouch that hangs below the penis
    • Hangs outside of the body to be cooler than body temp.
69
Q

the testes are located in the

A

scrotum

70
Q

As sperm are formed, they are passed to the ______, where their flagella gain motility, and they are stored here until _____

A

epididymis

ejaculation

71
Q

During ejaculation, sperm travel through the _____ and enter the _____ at the posterior edge of the ______.

A

vas deferens
ejaculatory duct
prostate gland

72
Q

The two ejaculatory ducts fuse to form the _____, which carries sperm through the penis as they exit the body.

A

urethra

73
Q

seminal fluid is produced by _____

A

seminal vesicles, prostate gland, and bulbourethral gland.

74
Q

seminal vesicles contribute _____

A

contribute fructose to nourish sperm.

75
Q

seminal vesicles and prostate gland function together to ____

A

give sperm alkaline properties.

76
Q

Bulbourethral (Cowper’s) glands function to ______

A

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

77
Q

semen = ____ + _____

A

sperm + seminal fluid

78
Q

spermatogenisis

A

the formation of haploid sperm through meiosis.

79
Q

spermatogonia

A

the diploid stem cells in males.
 After replicating their genetic material (S stage), they develop into diploid primary spermatocytes.
 First meiotic division results in haploid secondary spermatocytes.
 After meiosis II, they are spermatids.
 Spermatids undergo maturation to become spermatozoa.

80
Q

different names during spermatogenisis

A

spermatogonia (diploid stem cells) ==> primary spermatocytes (after replication S stage) ==> secondary spermatocytes (after first meiotic division) ==> spermatids (after meiosis II) ==> spermatozoa (mature sperm)

81
Q

describe sperm structure

A

 Head: genetic material, covered with acrosome cap, necessary to penetrate the ovum.
 Midpiece: generates ATP from fructose, full of mitochondria.
 Flagellum: for motility.

A modified golgi apparatus that contains enzymes that help the sperm fuse with and penetrate the ovum.

82
Q

the ____ is necessary for sperm to penetrate the ovum

A

acrosome cap

83
Q

what part of sperm generates mitochonidra

A

midpiece

84
Q

what is the name of the female gonads?

A

ovaries

85
Q

follicles

A

contained in the ovaries

multilayered sacs that contain, nourish, and protect immature ova (eggs).

86
Q

Between puberty and menopause, ____ egg per month is ovulated into the ______ which lines the _____.

A

one
peritoneal sac
abdominal cavity

87
Q

route of egg

A
  • ovulated into peritoneal sac which lines the abdominal cavity
  • pulled into fallopian tube/oviduct
  • egg travels to uterus, can get shed or imbedded in endometrium
88
Q

egg is drawn out out of the abdominial cavity into the ____ , which is lined with cilia to propel the egg forward.

A

fallopian tube

89
Q

The fallopian tubes are connected to the _____, which is the site of fetal development

A

uterus

90
Q

the lower end of the uterus is known as the _________ and connects to the _____-

A

cervix

vaginal canal

91
Q

what is the vulva

A

collective name for external female anatomy.

92
Q

oogenisis

A

the production of female gametes.

93
Q

primary oocytes

A

all of the oogonia have already undergone DNA replication by birth and are known as this.
 2n and stuck in prophase I.

94
Q

when women are born, all of their eggs are stuck in _____

A

prophase 1 (2n)

95
Q

meiosis I completion for women results in ____

A

secondary oocyte and polar body

96
Q

secondary oocyte is stuck in ______ unless _____ happens

A

metaphase II

fertilization

97
Q

what are the names of the layers that surround the oocyte

A

zona pellucida

corona radiata

98
Q

zona pellucida

A

surrounds the oocyte itself and is an acellular mixture of glycoproteins that protect the oocyte and contain compounds necessary for sperm binding.

99
Q

corona radiata

A

lies outside the zona pellucida and is a layer of cells that adhered to the oocyte during ovulation.

100
Q

sperm penetration results in ________

A

completion the second meiotic division, one mature ovum, and another polar body.

Upon completion of meiosis II, the haploid pronuclei of the sperm and the ovum join, creating a diploid zygote.

101
Q

what does the sperm contribute to the zygote?

A

Only thing that sperm contributes is half of the DNA. Egg contributes organelles, mitochondria, cytoplasm and also some mRNA for early cell functions.

102
Q

prior to puberty versus during puberty: GnRH

A

for both boys and girls:
 Prior to puberty, the hypothalamus restricts production of gonadotropin-releasing hormone (GnRH).
 Puberty: hypothalamus releases GnRH, triggers the anterior pituitary gland to synthesize and release follicle-stimulating hormone (FSH) and luteinizing hormone (LH) which trigger the production of other sex hormones that maintain the reproductive system.

103
Q

what hormones leads to male sexual differentiation?

A

androgens

104
Q

what does testosterone do in testes?

A

 Puberty: testosterone produced by the testes increases and sperm production begins.

105
Q

what do FSH and LH do in males?

A

FSH stimulates Sertoli cells and triggers sperm maturation, while LH causes interstitial cells (leydig cells) to produce testosterone.

106
Q

testosterone

A

Testosterone maintains the male reproductive system and also results in development of secondary male characteristics: facial hair, deep voice, bone and muscle growth.

107
Q

estrogens

A

secreted in response to FSH and result in the development and maintenance of the female reproductive system and female secondary sexual characteristics (breast growth, widening of hips). Leads to thickening of the lining of the uterus (endometrium) each month in preparation for the implantation of a zygote.

108
Q

progesterone

A

secreted by the corpus luteum (the remains of the ovarian follicle following ovulation) in response to LH. Involved in the development and maintenance of the endometrium. Eventually supplied by the placenta.

109
Q

menses

A

blood and other matter discharged from the uterus at menstruation.

110
Q

During female reproductive years, _____ and _______ levels will rise and fall in a cyclic pattern, thus the endometrial lining will grow and be shed.

A

estrogen

progesterone

111
Q

granulosa cells secrete _____

A

estrogen, progesterone, inhibin

112
Q

Step 1 of menstrual cycle: follicular phase

A

o 1. Follicular phase: begins when the menstrual flow, which sheds the uterine lining of the previous cycle begins.
 GnRH increase due to low estrogen and progesterone.
 Increased FSH and LH, develop several ovarian follicles.
 Follicles produce estrogen, which causes GnRH, LH, and FSH concentration to level off.
 Estrogen stimulates regrowth of the endometrial lining, stimulating vascularization and granularization of the decidua.

113
Q

decidua

A

The decidua is the modified mucosal lining of the uterus (that is, modified endometrium) that forms in preparation for pregnancy

114
Q

what are the 4 stages of the menstrual cycle

A
  1. follicular phase
  2. ovulation
  3. luteal phase
  4. menstruation
115
Q

Step 2 of menstrual cycle: ovulation

A

release of the ovum from the ovary into the abdominal (peritoneal) cavity
 Later in follicular phase, follicles secrete more estrogen, reaches a threshold where it is positive feedback, spike in GnRH, LH, and FSH.
 Surge in LH induces ovulation.

116
Q

Step 3 of menstrual cycle: luteal phase

A

 LH causes the ruptured follicle to form the corpus luteum, which secretes progesterone.
 Progesterone levels rise, estrogen levels stay high, and progesterone negative feedback on GnRH, FSH, and LH preventing ovulation of multiple eggs.

117
Q

Step 4 of menstrual cycle: menstruation

A

 Assuming implantation does not occur, corpus luteum loses stimulation from LH, progesterone levels decline, and the uterine lining is sloughed off.
 Loss of high levels of estrogen and progesterone removes the block on GnRH, so that the next cycle can begin.

118
Q

if pregnancy occurs…

A

o If fertilization does occur, zygote will develop into blastocyst and implant into the uterine lining and secrete human chorionic gonadotropin (hCG) (analog of LH)
 Maintains the corpus luteum.
 Levels decline once the placenta has grown to a sufficient size to secrete enough progesterone and estrogen by itself.

119
Q

menopause

A

o As a woman ages, the ovaries become less sensitive to FSH and LH, stop producing estrogen and progesterone.
o Estrogen and progesterone levels drop and thus FSH and LH rise

120
Q

Mendel’s first law is known as ______. Describe.

A

Law of segregation: separate the homologous chromosomes during meiosis I

121
Q

Mendel’s second law is known as ____. Describe.

A

Law of independent assortment: regardless of where the allele of one gene goes, the allele of another gene will be segregated independently.

122
Q

sperm are produced in the _____

A

seminiferous tubules

123
Q

what nourishes sperm in the seminiferous tubules?

A

sertoli cells

124
Q

the cells of Leydig secrete _______ and other male sex hormones

A

testosterone

125
Q

the midpiece of sperm generate ATP from _____

A

fructose

126
Q

what propels the egg forward in the fallopian tube?

A

cilia

127
Q

Differences between gametogenesis for males and females

A

-Males have never ending supply of stems cells (spermatogonia) while women do not

128
Q

menarche

A

first menstrual cycle

129
Q

one primary oocyte per month will complete meiosis I to produce a _____ and _____

A

secondary oocyte and a polar body

130
Q

the _______ releases _____ which stimulates the _______ to release ____ and ____.

A

hypothalamus, GnRH, anterior pituitary follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

131
Q

Name some male secondary sexual characteristics

A

facial and axillary hair, deepening of voice, increased muscle and bone mass

132
Q

testosterone acts in a _______ with the hypothalamus and anterior pituitary

A

negative feedback loop

133
Q

Name some female secondary sex characteristics

A

breast growth, widening of the hips, changes in fat distribution

134
Q

Estrogen is secreted in response to ____

A

FSH

135
Q

____ stimulates the thickening of the endometrium

A

estrogens

this occurs each month in preparation for implantation of a zygote.

Once it is thickened, progesterone is responsible for maintaining the endometrium.

136
Q

what is the endometrium

A

the lining of the uterus

137
Q

the ____ secretes ____ after ovulation in response to _____

A

corpus luteum
progesterone
LH

138
Q

____ is involved in both positive and negative feedback in the menstrual cycle

A

estrogen

139
Q

____ directly leads to ovulation

A

estrogen

140
Q

the ___ levels of progesterone during the luteal phase prevent ____

A

high, ovulation of multiple eggs

141
Q

what is hcG

A

very similar to LH and can stimulate the corpus luteum to continue releasing progesterone and estrogen during early pregnancy.

142
Q

Estrogen levels stay high during the menstrual cycle during the luteal phase to _______

A

promote vascularization and glandularization of the endometrium.

143
Q

during pregnancy: during the first trimester, the corpus luteum is preserved by ______. During the second trimester, _____ increases as it is now secreted by the _____. High levels of estrogen and progesterone inhibit ______ and _____.

A

hCG
progesterone, placenta
GnRH, LH, and FSH

Estrogen and progesterone are produced by the placenta.

MCAT Bio (12 decks)

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