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MCAT > Bio: Ch 2, 6 > Flashcards

Bio: Ch 2, 6 Flashcards

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MCAT flashcards
1
Q

diploid (2n) cells have…

A

two copies of each chromosome

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2
Q

haploid (n) cells have…

A

one copy of each chromosome

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3
Q

cell cycle stages

A
  1. interphase
    1. G1
    2. S
    3. G2
  2. M
  3. G0
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4
Q

interphase

A

inlcudes G1, S, G2

DNA is uncoiled in the form of chromatin

longest part of cell cycle, cells spend 90% of their time in this phase

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5
Q

cell cycle

A

phases during which a cell grows, synthesizes DNA, and divides

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6
Q

G0 phase

A

cell is living and carrying out its functions

without preparing for division

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7
Q

G1 phase

A

presynthetic gap

cells create organelles for energy and protein production, and increase their size

need to pass G1 checkpoint before going to S phase

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8
Q

G1 check point/restriction point

A

need to pass into S phase

DNA checked for quality

if fails: cell cycle arrests until DNA is repaired

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9
Q

S phase

A

synthesis

DNA is replicated (each daughter cell will have identical copies)

each chromosome will have two identical chromatids bound by centromere

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10
Q

chromatid is composed of

A

complete double stranded molecule of DNA

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11
Q

sister chromatids

A

identical copies of the same DNA held together at the centromere

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12
Q

G2 phase

A

postsynthetic gap

further cell growth and replication of organelles in prep for mitosis

checkpoint to enter M phase

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13
Q

G2 checkpoint

A

must pass to enter M phase

checks that there’s enough organelles and cytoplasm for two daughter cells

checks that DNA replication proceeded correction (to avoid passing on error to daughter cell)

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14
Q

M phase

A

mitosis

mitosis and cytokinesis occur

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15
Q

cytokinesis

A

occurs at end of telophase

splitting of the cytoplasm and organelles between the two daughter cells

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16
Q

p53

A

plays important role in the two major checkpoints of cell cycle (G1 and G2 checkpoints)

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17
Q

cyclins and cyclin dependent kinases (CDK) during cell cycle

A

rise and fall

cyclins bind to CDKs, phosphorylating and activating transcription factors for the next stage

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18
Q

transcription factors during cell cycle

A

promote transcription of genes required for the next stage of cell cycle

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19
Q

in order to be activated, CDKs require…

A

presence of the right cyclins

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20
Q

cancer

A

occurs when cell cycle control becomes deranged, allowing damaged cells to under mitosis without regard to quality or quantity of the new cells produced

cancerous cells may begin to produce factors that allow them to delocalize and invade adjacent tissues or metastasize elsewhere

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21
Q

common mutations found in cancer and what happens

A

mutation of the gene that produces p53, called TP53

cell cycle is not stopped to repair damaged DNA –> allows mutations to accumulate, resulting in cancerous cell that divides continuously

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22
Q

mitosis

A

two identical daughter cells are created from a single cell

only occurs in somatic cells

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23
Q

somatic cells

A

cells that are not involved in sexual reproduction

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24
Q

mitosis phases

A
  1. prophase
  2. metaphase
  3. anaphase
  4. telophase
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25
Q

prophase

A

1

  • chromosomes condense
  • spindle apparatus begins to form
  • nuclear membrane dissolves
  • nucleoli disappear
  • centrioles migrate to opposite sides of the cell
  • kinetochore of each chromosome is contacted by spindle fiber
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26
Q

kinetochore

A

protein structures located on centromeres that serve as attachment points for specific fibers of the spindle apparatus

appear at centrosome during prophase

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27
Q

metaphase

A

2

chromosomes line up along metaphase plate (done by kinetochores)

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28
Q

anaphase

A

3

sister chromatids are separated and pulled to opposite poles

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29
Q

telophase

A

4

  • nuclear membrane reforms
  • spindle apparatus disappears
  • cytosol and organelles split between two daughter cells through cytokinesis
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30
Q

gametes

A

sex cells

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31
Q

gametocytes

A

germ cells

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32
Q

meiosis

A

produces up to 4 nonidentical haploid sex cells (gametes)

occurs in gametocytes

has one round of replication and two rounds of division (reductional and equational divisions)

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33
Q

meiosis I

A

reductional division

results in homologous chromosomes being separated, generating haploid daughter cells

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34
Q

homologues

A

related chromosomes of opposite parental origin

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35
Q

meiosis II

A

equational division

results in the separation of sister chromatids without a change in ploidy

(like mitosis)

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36
Q

prophase I

A

meiosis

  • same as in prophase of mitosis EXCEPT:
  • synapsis and crossing over
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37
Q

synapsis

A

homologous chromosomes come together and intertwine

during prophase I

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38
Q

tetrad

A

a synaptic pair that contains 4 chromatidds

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39
Q

synaptonemal complex

A

group of proteins that hold together homologous chromosomes during synapsis

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40
Q

chiasma

A

point of contact between two chromatids during synapsis where DNA is exchanged

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41
Q

crossing over

A

exchanges genetic material between one chromatid and material from a chromatid from the homologous chromosome

mendel’s second law of independent assortment

during prophase I of meiosis

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42
Q

mendel’s second law

A

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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43
Q

metaphase I

A

meiosis

homologous chromosomes line up on opposite sides of the metaphase plate

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44
Q

disjunction

A

chromosome of paternal origin separates from its homologue of maternal origin

during anaphase I of meiosis

accounts for mendel’s first law of segregation

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45
Q

segregation

A

separation of two homologous chromosomes

during anaphase I

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46
Q

anaphase I

A

meiosis

homologous chromosomes are pulled to opposite poles (disjunction, segregation)

mendel’s first law of segregation

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47
Q

mendel’s first law

A

of segregation

during gamete formation, the two alleles at a gene locus segregate from each other; each gamete has an equal probability of containing either allele

during anaphase I

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48
Q

interkinesis

A

chromosomes partially uncoil

may occur between telophase I and prophase II

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49
Q

telophase I

A

meiosis

chromosomes may or may not fully decondense

cytokinesis

cell may enter interkinesis

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50
Q

mitosis vs meiosis

ploidy

A

mitosis: 2n –> 2n
meiosis: 2n –> n

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51
Q

mitosis vs meiosis

homologous chromosomes

A

mitosis: homologous chromosomes do not pair
meiosis: homologous chromosomes align on opposite sides of metaphase plate

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52
Q

biological sex is determined by

A

23rd pair of chomosomes in humans

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53
Q

X chromosome

A

carries sizeable amount of genetic information

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54
Q

sex linked disorder

males vs females

A

can be caused by mutations of X linked genes

males will express sex-linked orders, even if they only have one recessive allele

women with only one copy of the affected allele are carriers

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55
Q

Y chromosome

A

carries little genetic info

contains SRY (sex determining region Y) gene

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56
Q

SRY gene

A

causes the gonads to differentiate into testes

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57
Q

pathway of sperm through male reproductive system

A

SEVE(N) UP

  1. seminiferous tubules
  2. epididymis
  3. vas deferens
  4. ejaculatory duct
  5. (nothing)
  6. urethra
  7. penis
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58
Q

seminal vesicles

A

contribute fructose to nourish sperm and produce alkaline fluid

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59
Q

seminiferous tubules

A

where sperm developes

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60
Q

sertoli cells

A

nourish the sperm

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61
Q

interstitial cells of leydig

A

secrete testosterone and other male sex hormones (androgens)

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62
Q

scrotum

A

where testes are located

hangs outside the abdominal cavity

has temp 2-3 C lower than rest of body

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63
Q

epididymis

A

store sperm until ejaculation

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64
Q

prostate gland

A

produces alkaline fluid that give the semen mildly alkaline properties so the sperm can survive in the relative acidity of the female reproductive tract

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65
Q

bulbourethral glands

A

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

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66
Q

semen

A

sperm and seminal fluid

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67
Q

spermatogenesis

A

four haploid sperm are produced from a spermatogonium

occurs in seminiferous tubules

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68
Q

spermatogonia

A

male diploid stem cells

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69
Q

spermatogenesis steps

A
  1. after S stage: primary spermatocytes
  2. after meiosis I: secondary spermatocytes
  3. after meiosis II: spermatids
  4. after maturation: spermatozoa
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70
Q

spermatogenesis

what are germ cells called after S stage?

A

primary spermatocytes

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71
Q

spermatogenesis

what are germ cells called after meiosis I?

A

secondary spermatocytes

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72
Q

spermatogenesis

what are germ cells called after meiosis II?

A

spermatids

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73
Q

spermatogenesis

what are germ cells called after maturation?

A

spermatozoa

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74
Q

sperm structure

A

head, midpiece, flagellum

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75
Q

sperm structure

head

A

contains genetic material

covered with acrosome

76
Q

acrosome

A

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

77
Q

sperm structure

midpiece

A

generates ATP from fructose and contains many mitochondria

78
Q

sperm structure

flagellum

A

promotes motility

79
Q
A
80
Q

ova

A

eggs

81
Q

ova are produced in

A

follicles in the ovaries

82
Q

ovaries

A

produce estrogen and progesterone

83
Q

follicles

A

multilayered sacs that contain, nourish, and protect immature ova

84
Q

peritoneal sac

A

lines th eabdominal cavity

85
Q

fallopian tube/oviduct

A

lined with cilia to propel egg forward

86
Q

uterus

A

site of fetal development

87
Q

vulva

A

external female anatomy

88
Q

vaginal canal

A

lies below cervix

site where sperm are deposited during intercourse

site of natural childbirth

89
Q

oogenesis

A

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

90
Q

oogenesis steps

A
  1. at birth, all oogonia have undergone replication and are arrested in prophase I –> primary oocyte
  2. ovulated egg each month is arrester in metaphase II –> secondary oocyte
  3. if oocyte is fertilized, it will complete meiosis II –> ovum
    1. haploid pronuclei of sperm and ovum join, creating diploid zygote
91
Q

polar body

A

cell during oogenesis that receives very little cytoplasm and organelles during cytokinesis

92
Q

oocyte structure

A

surrounded by zona pellucida and corona radiata

93
Q

zona pellucida

A

acellular mixture of glycoproteins that protect the oocyte and contain the compounds necessary for sperm binding

94
Q

corona radiata

A

layer of cells that adhered to the oocyte during ovulation

95
Q

mature ovum

A

very large cell consisting of large quantities of cytoplasm and organells

contributes nearly everything to zygote

96
Q

how is zygote formed

A

once meiosis II of ovum is completed, haploid pronuclei of sperm and ovum join, creating diploid zygote

97
Q

sexual development once puberty hits

A

hypothalamus stops restricting the production of GnRH –> anterior pituitary makes and releases FSH and LH –> trigger production of other sex hormones

98
Q

sexual development in males

FSH

A

stimulates sertoli cells and triggers spermatogenesis

99
Q

sexual development in males

LH

A

causes the interstitial cells to produce testosterone

100
Q

testosterone

A

responsible for the maintenance and development of male reproductive system and male secondary sex characteristics

101
Q

male secondary sex characteristics

A

facial and axillary hair

depending of voice

increased bone and muscle mass

102
Q

sexual development in females

FSH

A

stimulates development of ovarial follicles

103
Q

sexual development in females

LH

A

causes ovulation

104
Q

sexual development in femals

FSH and LH

A

stimulate production of estrogens and progesterone

105
Q

sexual development in females

estrogen

A

secreted in response to FSH

development and maintenance of female reproductive system and female secondary sex characteristics

106
Q

female secondary sex characteristics

A

breast growth, widening of hips, changes in fat distribution

107
Q

estrogen in embryo

A

stimulate development of reproductive tract

108
Q

estrogen in adults

A

lead to thickening of lining of uterus each month in perp for implantation of a zygote

109
Q

endometrium

A

lining of uterus

110
Q

sexual development in females

progesterone

A

secreted by corpus luteum in response to LH

development and maintenance of endometrium (not initial thickening)

111
Q

corpus luteum

A

remains of the ovarian follicle following ovulation

112
Q

menstrual cycle

A

periodic growth and shedding of endometrial lining

113
Q

menstrual cycle steps

+ graph**

A
  1. follicular phase
  2. ovulation
  3. luteal phase
  4. menstruation (if no fertilization)
114
Q

follicular phase

A

follicles mature

  • mentrual flow
  • GnRH secretion stimulates FSH and LH secretion –> follicle development
  • estrogen release –> vasicularization and glandularization of decidua
115
Q

ovulation

A

release of ovum from ovary into abdominal cavity

  • stimulated by LH surge
  • LH surge triggered when estrogen levels reach threshold and switch from negative to positive feedback effects
116
Q

luteal phase

A
  • LH causes ruptured follicle to become corpus luteum
  • corpus luteum secretes progesterone –> maintains uterine lining
  • high estrogen and progesterone levels cause neg feedback on GnRH, LH, and FSH
117
Q

menstruation

A

occurs if no fertilization

estrogen and progesterone levels drop –> endometrial lining comes off –> block on GnRH production removed –> FSH and LH levels begin to rise again

118
Q

menstrual cycle

what happens when fertilization occurs

A

blastula implants in uterine lining and produces human chorionic gonadotropin (hCG) –> maintain corpus luteum

near end of 1st trimester, hCG levels drop as placenta takes over progesterone production

119
Q

menopause

A

occurs when ovaries stop producing estrogen and progesterone

  • usually between ages 45-55
  • menstruation stops
  • FSH and LH levels rise
  • flushing, hot flashes, bloating, headaches, irritability
120
Q
A
121
Q

Interphase has three main phases. Compare these three.

A

G1 (Growth Phase 1) is the longest phase in which a cell grows, making more organelles and proteins.

S Phase (Synthesis Phase) occurs when the cell is replicating its DNA.

G2 (Growth Phase 2) is when cells prepare for Mitosis by editing DNA for errors/mutations, making microtubules, etc.

122
Q

Sometimes a cell will go into G₀ instead of continuing into S Phase. What is G₀ characterized by? Give an example of a cell that might enter G₀.

A

A cell that enters G₀ is essentially done dividing for the rest of its lifespan. A Neuron is an example of a cell that enters G₀.

123
Q

CRB Compare what is being checked for at each of the 2 major checkpoints.

A

Before the cell enters S phase, the cell wants to make sure its DNA has no mutations, irregularities, mismatches, etc.
During G2, the cell wants to make sure that there is enough organelles, cytoplasm, etc. for two separate daughter cells to survive. The replication that occurred in S phase is also double-checked here

124
Q

True or False? CDK’s are always present in the cell.

A

True. CDK’s are always present in the cell. It is the production of the Cyclin proteins that is regulated. Different Cyclin proteins are produced at different times.

125
Q

A single Chromosome replicates. How many chromosomes result? Chromatids?

A

Two sister chromatids attached at the centromere count as one chromosome. Once the sister chromatids detach, then they are considered two distinct chromosomes.

126
Q

When the cell is in G1, in what state is its DNA?

(A) The densely compacted Chromatids
(B) The less condensed Chromatids
(C) The densely compacted Chromatin
(D) The less condensed Chromatin

A

(D) The less condensed Chromatin

Chromatin is less condensed than Chromatid. During interphase, DNA is not very condensed, and is considered Chromatin.

127
Q

What is happening with the Centrosomes during each phase of Mitosis?

(1) Prophase
(2) Metaphase
(3) Anaphase
(4) Telophase

A

(1) Prophase - Centrosomes move toward the poles of the cell.
(2) Metaphase - Centrosomes are now at the poles of the cell. The microtubules are attached to the chromosomes lined up in the center of the cell.
(3) Anaphase - The microtubules pull the chromosomes apart from each other to opposite poles of the cell.
(4) Telophase - A single Centrosome (with its centriole pair) ends up in each cell.

128
Q

CRB True or false? Crossing over can happen multiple times in the same Tetrad, and can unlink previously-linked genes.

A

True. Crossing over can happen multiple times in the same Tetrad, and can unlink previously-linked genes.
This is called Recombination.

129
Q

True or False: Meiosis I produces diploid cells, and meiosis II produces haploid cells.

A

False. Meiosis I produces HAPLOID cells, and meiosis II produces haploid cells.

130
Q

A Nondisjunction event is when homologous pairs do not separate and are not pulled to separate poles of the cell. When could a nondisjunction event affect the number of chromosomes in the daughter cell or gamete?

I. Mitosis
II. Meiosis I
III. Meiosis II

(A) I only
(B) I and II only
(C) II and III only
(D) I, II and III

A

(D) I, II and III

131
Q
A
132
Q

nares

A

where air enters

133
Q

vibrissae

A

nasal hairs

134
Q

larynx contains…

A

two vocal cords (glottis)

135
Q

alveoli

A

small sacs that interface with pulmonary capillaries, allowing gases to diffuse across a one cell thick membrane

where gas exchange occurs

136
Q

psurfactant

A

coats alveoli

detergent that lowers surface tension and prevents alveolus from collapsing on itself

137
Q

air -> lungs pathway

A

nares > nasal cavity > pharynx > larynx > trachaea > bronchi > bronchioles > alveoli

138
Q

pleurae

A

cover lungs and line chest wall

139
Q

visceral pleura

A

lies adjacent to lung itself

140
Q

parietal pleura

A

lines chest wall

141
Q

intrapleural space

A

lies between visceral and parietal pleura

contains a thin layer of fluid that lubricates the two pleural surfaces

142
Q

diaphragm

A

thin skeletal muscle that helps to create the pressure differential required for breathing

143
Q

inhalation steps

A

negative pressure breathing

  • diaphragm and external intercostal muscles expand thoracic cavity -> inc volume of intrapleural space -> dec intrapleural pressure
  • this pressure differential expands the lungs -> dec pressure within -> draw in air from environment
144
Q

inhalation is a ___ process

A

active

145
Q

exhalation is a __ process

A

passive or active

146
Q

passive exhalation steps

A
  1. muscles of inspiration relax
  2. elastic recoil of the lungs allows chest cavity to dec volume –> intrapleural pressure
  3. air pushed out
147
Q

active exhalation steps

A

internal intercostal muscles and abdominal muscles used to forcible decrease volume of thoracic cavity -> inc intrapleural pressure -> pushes air out

148
Q

intrathoracic volume

A

volume of chest cavity

149
Q

spirometer

A

used to measure lung capacity and volume

150
Q

total lung capacity (TLC)

A

max volume of air in the lung when one inhales completely

151
Q

residual volume (RV)

A

volume of air remaining in the lungs when one exhales completely

152
Q

vital capacity (VC)

A

difference between the min and max volume of air in lungs

153
Q

tidal volume (TV)

A

volume of air inhaled or exhaled in a normal breath

154
Q

expiratory reserve volume (ERV)

A

volume of additional air that can be forcibly exhaled after a normal exhalation

155
Q

inspiratory reserve volume (IRV)

A

volume of additional air that can be forcibly inhaled after a normal inhalation

156
Q

ventilation center

A

collection of neurons in medulla oblongata where ventilation is regulated

157
Q

chemoreceptors

A

respond to CO2 concentrations

inc or dec respiratory rate dependent on CO2 conc in blood

158
Q

what happens to respiratory rate when high conc of CO2 in blood

A

increases

159
Q

hypercarbia/hypercapnia

A

high conc of CO2 in blood

160
Q

what happens to respiratory rate when low conc of O2 in blood

A

increase

161
Q

hypoxemia

A

low o2 conc in blood

162
Q

what part of brain consciously controls ventilation when wanted?

A

cerebrum

163
Q

what happens to respiratory rate when low conc of CO2 in blood?

A

dec to raise CO2 levels

164
Q

gas exchange with lungs

A

simple diffusion across conc gradients

165
Q

deoxygenated blood with a high co2 conc is brought to the lungs via the…

A

pulmonary arteries

166
Q

oxygenated blood with low co2 conc leaves the lungs via the…

A

pulmonary veins

167
Q

pulmonary arters originate from

A

right ventricle of heart

168
Q

pulmonary arteries

A

bring deozygenated blood with high co2 conc to lungh=s

169
Q

pulmonary veins

A

bring oxygenated blood with low co2 conc away from the lungs

170
Q

thermoregulation and respiratory system

how to dissipate thermal energy

A

capillaries expand, more blood passes through vessels

171
Q

acidemia

A

low blood pH

172
Q

alkalemia

A

high blood pH

173
Q

mucociliary escalator

A

internal airways have mucus that trap invaders

underlying cilia propel the mucus up the respiratory tract to oral cavity where it can be expelled or swallowed

174
Q

how respiratory system is protected from potential pathogens

A
  • vibrissae, mucus, mucociliary escalator –> filter and trap invaders
  • lysozyme in nasal cavity and saliva
  • macrophages
  • mucoseal surfaces covered with IgA antibodies
  • mast cells
175
Q

lysozyme in respiratory system

A

attacks peptidoglycal walls of gram positive bacteria

176
Q

how is respiratory system involved in pH control

A

bicarbonate buffer system

177
Q

bicarbonate buffer system

blood pH decreases

A

respiration rate increases to compensate by blowing off CO2

left shift in buffer eq -> reduces hydrogen ion conc

178
Q

bicarbonate buffer system

blood pH increases

A

respiration rate decreases to compensate by trapping co2

causes right shift in buffer eq -> inc hydrogen ion conc

179
Q

The right lung has ____ lobes, and the left lung has _____ lobes.

(A) 3, 3
(B) 3, 2
(C) 2, 2
(D) 2, 3

A

(B) 3, 2

The right lung has 3 lobes. The left lung has 2 lobes.

180
Q

Between the Internal and External Intercostals, which are associated with Inhalation, and which are associated with Exhalation?

A

The Internal Intercostal muscles contracting will pull down on the rib cage, decreasing the intrathoracic volume and causing exhalation.

The External Intercostal Muscles contracting will pull the rib cage and expand the intrathoracic volume, causing inhalation.

181
Q

CRB One of the biggest dangers for premature babies is that their lungs cannot produce enough surfactant to be able to breath effectively on their own. Explain the key role of Surfactant in respiration.

A

Surfactant is a detergent that coats the alveoli, decreasing surface tension and making it easier to inflate the alveoli. Without surfactant, alveoli have a greater chance at collapsing.

182
Q

Oxygen is 26x less soluble in water than Carbon Dioxide. Why is this the case?

A

Carbon Dioxide can form carbonic acid (H2CO3), which will auto-dissociate into H+ and bicarbonate, which is very soluble in water.

Oxygen cannot form a charged ion in a similar fashion.

183
Q

CRB True or false? Based on the previous notecard, Hyperventilation can be called Respiratory Alkalosis (trying to make the blood more basic), and Hypoventilation can be called Respiratory Acidosis.

A

True. Based on the previous notecard, Hyperventilation can be called Respiratory Alkalosis (trying to make the blood more basic), and Hypoventilation can be called Respiratory Acidosis.

184
Q

Respiration involves the diffusion of gasses, oxygen and carbon dioxide, across plasma membranes. Because respiration is passive, the difference in concentrations drives diffusion. Which of the following can increase diffusion?

I. Increased distance
II. Decreased molecular weight of molecules
III. Increased pressure

(A) I and II only
(B) III only
(C) II and III only
(D) I only

A

(C) II and III only

To increase the rate of diffusion:

  • DECREASE the distance
  • Decrease the MW of the molecules
  • Increase the pressure
  • Increase the area
185
Q

Which of the following conditions would impair gas exchange and cause hypoxia?

I. Scarring of the alveoli
II. Limiting Ventilation to the Lungs
III. Limiting Perfusion to the lungs

(A) I only
(B) I and II only
(C) II and III only
(D) I, II and III

A

(D) I, II and III

Each of the following conditions could impair gas exchange and cause hypoxia:

I. Scarring of the alveoli
II. Limiting Ventilation to the Lungs
III. Limiting Perfusion to the lungs

186
Q

At rest, humans will typically breathe in and out about 5 liters of air per minute. When exercising, this rate may increase to 50L/min. Why is this important in terms of energy generation? Why is this important in terms of thermoregulation?

A

This increased breathe rate is essential for generating more energy via aerobic respiration.

This increased breathe rate is also useful in preventing overheating. With each breath, cold air enters and hot air leaves the body.

187
Q

Which of the following does Vital Capacity NOT include?

(A) Residual Volume
(B) Tidal Volume
(C) Expiratory Reserve Volume
(D) Inspiratory Reserve Volume

A

(A) Residual Volume

Vital Capacity includes all of the volume that can be consciously changed, including Expiratory Reserve Volume, Tidal Volume, and Inspiratory Reserve Volume.

MCAT (26 decks)

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