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Biology Flashcards

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1
Q

What does the nucleolus do? Is it membrane-bound in the nucleus? What cells is it in?

A

site of rRNA synthesis (ribosome assembly)
Not membrane-bound
All nuclear cells (so no anuclear cells like RBCs)

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2
Q

ER is the synthesis site for three things mainly:

A

lipids
hormones
proteins

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3
Q

A macrophage phagocytizes a radioactive-labeled bacterium. Where in the cell do we expect to see it?

a) ER
b) Golgi
c) mitochondria
d) lysosomes

A

Lysosomes

Macrophages consume and destroy pathogens, so bacterium is sent to lysosomes for breakdown

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4
Q

What function does the Golgi have:
I. glycosylation
II. lipid synthesis
III. protein sorting

A

I and III only

  • glycosylation: protein modification where glycans attach to proteins and lipids
  • lipid synthesis happens in the ER, not Golgi
  • protein sorting is a classic fxn
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5
Q

Pinocytosis is an example of:

A

endocytosis

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6
Q

Na+ and K+ channels are ____-gated channels whereas Cl- channels that are mediated by GABA are ____-gated channels

A

voltage; ligand

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7
Q

Where does ß-oxidation of long-chain fatty acids take place?

A

peroxisomes (has a shit ton of H2O2)

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8
Q

What major role does clathrin play?

A

vesicle coating

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9
Q

hemidesmosomes vs desmosomes

A

hemidesmosomes are cell-basement

desmosomes are cell-cell

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10
Q

what are two major things that happen during prophase?

A
  1. the unraveled DNA (chromatin) will condense into chromosomes
  2. centrioles create cell poles along which the chromosomes will align
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11
Q

List out the sequence of the fertilization stage in embryonic development, from the diploid primary oocyte undergoing its 1st meiotic division to the formation of the zygote.

A

diploid primary oocyte →meiosis I→ haploid secondary oocyte → sperm meets secondary oocyte in fallopian tube most of the time → sperm releases acrosomal (digestive) enzymes that help penetrate the zona pellucida → sperm grows out acrosomal process that fuses with oocyte’s cell membrane to inject pronucleus into oocyte → Ca2+ release → allows secondary oocyte to undergo meiosis II → ovum (mature egg) + pronucleus of sperm = zygote (1-cell)

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12
Q

During fertilization, the Ca2+ release after the sperm’s pronucleus enters the secondary oocyte also does what and for what purpose besides just initiating meiosis II?

A

triggers cortical rxn

Ca2+ released → cortical GRANULES are released which make zona pellucida IMPASSABLE (to PREVENT POLYSPERMY!)

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13
Q

List out the progression of the zygote’s growth in the morulation and blastulation stages.

A

zygote → morula → blastula → gastrula (“My Baby Grows”)

morula: solid mass of undifferentiated cells

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14
Q

What are the two components of the blastula and what do they each consist of?

A

blastocoel (cavity in blastula) + outer cells

outer cells = trophoblast + inner cell mass

trophoblast: extraembryonic (ultimately not part of embryo) cells that give rise to placenta, chorion, and amniotic sac that all support fetus as it grows
inner cell mass: consisted of embryonic (pluripotent) stem cells that will then undergo gastrulation

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15
Q

What is gastrulation? What are the three primary germ layers?

A

the process of when the INNER MASS CELLS develop into 3 primary germ layers: ectoderm (epiblast), mesoderm, endoderm

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16
Q

What does the ectoderm (epiblast) give rise to?

A

hair, epidermis, eyes, nervous system, EPITHELIUM OF UPPER RESPIRATORY TRACT

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17
Q

What does the mesoderm give rise to?

A

systems: musculoskeletal, circulatory, genitourinary, lymphatic
others: adipose and connective tissue, adrenal cortex

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18
Q

What does the endoderm give rise to?

A

internal organs: lungs, pancreas, liver, bladder, GI TRACT, OVARIES, DISTAL URINARY TRACT

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19
Q

T/F: Neurulation happens after gastrulation, and once the neurulation is complete, embryogenesis is completed.

A

TRUE

After neurulation, embryogenesis is completed and then the fetus keeps growing until all its organs have matured enough

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20
Q

What structure does the anterior part of the baby’s spinal column derive from? What germ layer cells does it derive from?

A

notochord

mesodermal (musculoskeletal, so in charge of making bone such as spinal column)

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21
Q

Cells from what structure ultimately develop into the CNS? That structure comes from what?

____ releases molecules that cause cells from which germ layer to fold inward and create what a ____ down the length of the embryo surface?

A

neural tube, which comes from neural groove

Notochord, ectodermal (gives rise to nervous system), groove (which is the neural groove)

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22
Q

What cells develop the PNS and where are those cells located? What other things do these cells develop into?

A

neural crest cells
located around the neural tube
other: melanocytes, calcitonin-producing cells in the thyroid, sensory and autonomic ganglia

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23
Q

What cells develop the PNS and where are those cells located? What other things do these cells develop into?

A

neural crest cells
located around the neural tube
other: parasympathetic NS (nerves), melanocytes, calcitonin-producing cells in the thyroid, sensory and autonomic ganglia

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24
Q

If the neural tube does not completely close, what condition does this lead to?

A

spina bifida

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25
Q

T/F: sympathetic and parasympathetic NS is autonomic, unlike the somatic NS which is voluntary

A

TRUE

SPNS, PSPNS, and ANS = involuntary
SNS = voluntary

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26
Q

Parasympathetic vs sympathetic NS based on primary NT it releases and their association with glycogen

A

Para NT: acetylcholine (plays a role in ↓ HR) VS Symp NT: norepinephrine

Para: ↑ glycogen storage VS Symp: depletion of glycogen storage to usable glucose

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27
Q

T/F: Sodium leak channel and sodium/potassium pumps are moderated by APs.

A

FALSE: they are NOT moderated by APs

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28
Q

Where do voltage-gated sodium channels primarily exist? What do they propagate?

A

along the axon

APs

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29
Q

When do voltage-gated calcium channels open? What does this allow?

A

When AP reaches the axon terminal

allow Ca2+ influx → NT release

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30
Q

What structure maintains the negative membrane potential in order to prepare the cell membrane for an AP and how does it do this?

A

Na+/K+ pump

moves more cations out of the cell (3 Na+ out) than it brings into the cell (2 K+ in)

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31
Q

Depolarization is primarily facilitated by:

A

voltage-gated sodium channels

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32
Q

Repolarization is primarily facilitated by:

A

voltage-gated potassium channels

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33
Q

Hyperpolarization occurs for why and for what?

A

voltage-gated potassium channels stay open longer than needed

To get back to resting potential!

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34
Q

summation

A

integration of multiple subthreshold signals and can trigger an AP

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35
Q

When does depolarization occur in terms of AP?

A

START of AP, once it has already been triggered

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36
Q

When does repolarization occur in terms of AP? For what purpose?

A

AFTER AP has already been triggered

To bring membrane potential back to resting state

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37
Q

When does hyperpolarization occur in terms of AP? Specifically after what stage in AP firing?

A

AFTER AP has already been triggered

after REPOLARIZATION

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38
Q

Where does the sensory nerve transmit impulses from and to? What is an example of a sensory nerve?

A

sensory organs → CNS

ie. nerve impulse from OPTIC NERVE → visual cortex → occipital lobe

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39
Q

Where does the effector nerve transmit impulses from and to? What is an example of an effector?

A

CNS → effectors (ie. muscles, glands)

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40
Q

T/F: Motor nerves are specialized effector nerves which transmit impulses to muscles only

A

TRUE

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41
Q

Where does the autonomic nerve exist? What is it connected to and what does it do?

A

spinal cord + brainstem

internal organs

control involuntary actions

42
Q

The parasympathetic and sympathetic nervous systems are both ____ systems to one another that act on organs such as the ____, _____, and _____ system.

A

antagonistic

heart, eyes, digestive system

43
Q

What is the pathway of a simple reflex arc? Does it directly involve higher-order structures like the brain? What is the spinal cord’s role in simple reflex arcs and what does this allow?

A

afferent (sensory) → interneuron → efferent (motor)

No

houses interneurons b/w afferent and efferent neurons, allowing for fast transmission by circumventing the need for processing in the brain

44
Q

What gland does the sympathetic NS act upon to increase blood sugar levels during the “fight-or-flight” response? What is the primary hormone released by the gland to do this?

A

pancreas

glucagon

45
Q

The sympathetic NS sends impulses to the adrenal gland, releasing what hormone?

A

norepinephrine

46
Q

T/F: epinephrine and norepinephrine are primarily released by the adrenal gland, specifically the adrenal cortex.

A

FALSE

It is the adrenal gland, but specifically adrenal MEDULLA!!

47
Q

What gland does the parasympathetic NS act upon to decrease blood sugar levels during the “rest-or-digest” response? What is the primary hormone released by the gland to do this?

A

pancreas

insulin

48
Q

T/F: Dendrites receive and transmit chemical (NTs) impulses directly but do not receive nerve (electric) impulses directly.

A

FALSE

They ONLY receive chemical impulses directly and do not receive nerve impulses directly

THEY DON’T TRANSMIT JACK SHIT, BOTH CHEM AND ELEC!

49
Q

rapid/methodical firing of subthreshold excitatory and inhibitory neurons would result in:

A

canceling each other out

50
Q

methodical firing of subthreshold excitatory neurons would result in:

A

not enough additive effect to generate AP

51
Q

rapid firing of subthreshold excitatory neurons would result in:

A

summation, which would most likely result in AP!

52
Q

T/F: Not all hormones are proteins or produced in the brain, but all are chemical messengers used by glands to communicate with cells and tissues

A

TRUE

53
Q

Glucagon is released by _____ in pancreas to ____ blood glucose levels

A

α-cells

increase

54
Q

trophic vs direct hormones

A

trophic: act on other endocrine glands to facilitate the release of direct hormones (more indirect pathway)
direct: act directly on tissues or cells

55
Q

DNA _____ of ___ and ____ bases at gene promotors can inhibit transcription by hindering the ability of ___ polymerase to transcribe

A

methylation

A + C

RNA

56
Q

The addition of ___, ____, and ____ groups to _____ can make DNA more accessible for transcription by decreasing their ____ for DNA.

A

methyl, ACETYL, phosphate (“MAP groups on the histone!”)

histone

affinity

57
Q

RNA polymerase I vs II vs III based on what genes they transcribe

A

I: rRNA genes (EXCEPT for 5S rRNA gene)
II: mRNA, miRNA, snRNA, snoRNA genes
III: tRNA and 5S rRNA genes

58
Q

RNA polymerase I vs II vs III based on where they reside

A

I: nucleolus (core of nucleus)

II and III: nucleoplasm (cytoplasm in nucleus)

59
Q

RNA polymerase I vs II vs III based on what process they PRIMARILY catalyze

A

I: transcription of ONLY rRNA (EXCEPT 5S rRNA)
II: DNA-directed mRNA synthesis
III: transcription of small untranslated RNAs (ie. tRNAs)

60
Q

Which ribosomal subunit binds to the mRNA first? Which one has the A, P, and E sites?

A

small

large

61
Q

3 general steps that happen in the initiation stage of translation

A
  1. small subunit binds to mRNA before the start codon
  2. AUG on mRNA is paired with either Met/fMet tRNA
  3. large subunit locks in place, bringing A, P, and E sites with it
62
Q

3 general steps that happen in the elongation stage of translation

A
  1. aminoacyl tRNA (tRNA w/ AA) binds at the A site
  2. The growing AA chain on the aminoacyl tRNA at the P site gets transferred over to aminoacyl tRNA at the A site by peptidyltransferase
  3. The aminoacyl tRNA at the A site (with the new AA + the existing growing chain) moves over to the P site, and the now empty tRNA on the P site moves over to the E site → exits the ribosome to be recycled
63
Q

3 general steps that happen in the termination stage of translation

A
  1. stop codons read by the ribosome
  2. a protein called release factor comes + binds to the A site which releases the new protein (polypeptide chain)
  3. The ribosome subunits separate and release the ribosome from the mRNA + tRNAs
64
Q

What are the 3 stop codons?

A 
UAA = U Are Annoying
UGA = U Go Away
UAG = U Are Gone
65
Q

Prokaryotes vs eukaryotes in the initiation stage of translation in terms of what the small subunit binds to (step 1) and what the AUG on mRNA is paired with (Step 2)

A

Step 1
Pro: binds to Shine-Dalgarno sequence
Euk: binds to 5’ cap (NOT THE SAME THING AS KOZAC SEQ!)

Step 2
Pro: fMet tRNA
Euk: Met tRNA

66
Q

List the scale (from smallest → largest) of DNA organization, starting from the DNA double helix.

A

DNA double helix → nucleosomes (10 nm chromatin) → nucleofilament (30 nm chromatin) → loops attached to scaffolding proteins (30 nm fiber forms) → heterochromatin (higher-order packaging)

Everything before heterochromatin is euchromatin!

67
Q

euchromatin vs heterochromatin in terms of DNA wounding, accessibility for transcription, and activity levels.

A

Euchromatin vs heterochromatin (in this order, respectively)

DNA wounding: unwounded (loose) VS highly wounded (tight)

Accessibility for transcription: accessible VS inaccessible

Activity levels: more active VS less active

68
Q

Southern blot vs PCR in terms of its purpose and when gel electrophoresis is executed

A

Southern blot vs PCR (in this order, respectively)

Purpose: to ID + quantify cells VS to mass-produce DNA

GE: denaturing as well as hybridizing DNA w/ probe is done AFTER GE VS denaturing + hybridizing DNA to desired primer is done BEFORE GE

69
Q

Which enzyme catalyzes transcription? What guides the enzyme where to bind and what does it bind to itself in order to do this?

A

RNA polymerase II

transcription factors (TF) bind to response elements (located in promoter regions of every gene)

70
Q

General TFs vs Specific TFs in terms of function and purpose

A

General vs specific TFs (in this order, respectively)

Fxn: recruits RNA Pol II and unwinds DNA helix VS binds to specific enhancers (specific response element only found in some genes)

Purpose: ensures transcription happens (transcription cannot happen without general TFs) VS regulate gene expression by acting as enhancers or repressors

71
Q

2 general steps that happen in the initiation stage of transcription (What do TFs may have to do with this?)

A
  1. RNA polymerase II binds to a specific region (different in pro and euk) in the promotor (upstream of the actual start site) that signal the binding site for RNA polymerase
  2. DNA helicase unwinds DNA

(TFs may bind to the promoter to help signal that RNA Pol should bind + may aid in unwinding DNA)

72
Q

2 general things RNA polymerase does simultaneously in the elongation stage of transcription

A
  1. matches RNA bps based on template (antisense) strand

2. catalyzing new phosphodiester backbone that binds between growing mRNA and next RNA nucleotide

73
Q

What is rho protein? What process is it involved in for which organisms?

A

a protein that combines onto a specific RNA sequence

prokaryotic termination stage of transcription

74
Q

Explain the rho-dependent mechanism for prokaryotic termination stage of transcription

A

Rho binds onto a specific RNA sequence which introduces steric strain → tugs on RNA and pulls it away from RNA pol → mRNA is immediately ready to be translated

RNA pol seals DNA strands and detaches to go find another gene to transcribe

75
Q

Explain the rho-independent mechanism for prokaryotic termination stage of transcription

A

GC rich seq in DNA is transcribed to GC rich seq of mRNA → GC rich mRNA seq forms a little loop which introduces steric strain → tugs mRNA away from DNA → mRNA is immediately ready to be translated

RNA pol seals DNA strands and detaches to go find another gene to transcribe

76
Q

Prokaryotes vs eukaryotes in the initiation stage of transcription in terms of:

  • what region of the promoter the RNA pol binds to
  • what base pairs that region is rich in
  • how far away it is from the actual start site
A

Region of promoter RNA pol binds to
Pro: Pribnow Box (aka -10 sequence, or even TATA box)
Euk: TATA box

Base pairs the region is rich in
Pro and Euk: A + T

Distance from actual start site
Pro: 10 bp upstream (aka -10 sequence)
Euk: 25-35 bp upstream

77
Q

What are the 5 components of a mature eukaryotic mRNA that has undergone post-transcriptional modifications?

A
  1. 5’ cap
  2. 5’ UTR
  3. Exons only
  4. 3’ UTR
  5. 3’ Poly-A tail
78
Q

5’ cap structure and fxn

A

structure: backward guanine nucleotide (G)
fxn: PREVENTS mRNA degradation by exonuclease (this enzyme recognizes the 5’ cap and can’t chew it off!)

79
Q

What is the 5’ UTR? Is it generally translated into protein? What is its significance? What important sequence does it contain for pro and euk?

A

An untranslated region next to the 5’ cap and directly upstream of exons

No

ribosome relies on it to bind mRNA and initiate translation

Pro: Shine-Dalgarno sequence
Euk: Kozak sequence

80
Q

What are the 3 things that PCR requires? Does it also require restriction enzymes?

A

primers (complementary to DNA that flanks target seq)
nucleotides (dNTPs)
DNA polymerase (Taq polymerase)

NO

81
Q

What is the significance of the 3’ poly-A tail? What are the downstream effects the longer the poly-A tail is?

A

DELAYS mRNA degradation (exonucleases can STILL chew of As one by one)

LONGER poly-A tail → ↑ time mRNA intact → ↑ total protein prod.

82
Q

What is the 3’ UTR? Is it generally translated into protein? What is its significance? Is it in both pro and euk?

A

An untranslated region next to the exons and directly upstream of the 3’ poly-A tail

No

often forms secondary structures that help stabilize the mRNA OR
recognized by specific enzymes that degrade transcript

Yes

83
Q

T/F: Both prokaryotes and eukaryotes have 5’ cap and 3’ poly-A tail

A

FALSE

Pro does NOT have any of those! Only have 5’ and 3’ UTR

84
Q

What process is cell differentiation and specialization regulated by?

a) translation
b) transcription
c) alternative splicing
d) post-translational modification

A

B

SELECTIVE TRANSCRIPTION

85
Q

What is leakage in evolution?

A

gene flow, the introduction of new alleles from one species to another

86
Q

incomplete penetrance

A

a genetic trait is expressed in only a proportion of the population

87
Q

variable expressivity

A

degree of phenotypic variation in individuals with the same genotype

88
Q

Some people that have the mutated BRCA 1 gene get breast cancer but some don’t. Is this incomplete penetrance or variable expressivity?

A

incomplete penetrance

89
Q

heterozygous vs hemizygous

A

heterozygous vs hemizygous (in this order, respectively)

each chromosome has the copy of the gene vs only one chromosome has the copy of the gene

90
Q

What means nullizygous? What doe these mutations cause?

A

2 null alleles for the same gene

complete loss of fxn

91
Q

multifactorial inheritance

A

more than 1 factor or multiple genes cause an inherited condition

92
Q

cytoplasmic inheritance

A

transmission of genetic material outside the nucleus from parent to offspring

ie. microorganism in a symbiotic relationship with its eukaryotic host confer its beneficial phenotype to offspring

93
Q

What is hybrid vigor? What are 4 examples of traits that can experience hybrid vigor? What can this increase the chance of?

A

improved traits in hybrid offspring

growth rate, biomass, stress tolerance, fertility

fitness

94
Q

What is the probability of double crossover?

A

the pdt of their recombinant frequencies

95
Q

T/F: when the question shows you two sister chromatids and shows you the distance of the genes, the probability of crossover occurring between the genes can be directly translated by the literal portrayal by the lengths between them

A

TRUE

96
Q

T/F: There are more Y-linked than X-linked disorders

A

FALSE

There are more X-linked than Y-linked disorders because the X chromosome is bigger

97
Q

T/F: X-linked recessive disorders are more common in females and X-linked dominant disorders are more common in males

A

FALSEEE!!!

X-linked recessive = more common in MALES b/c only need one recessive allele to get the disease

X-linked dominant = more common in FEMALES b/c has two X chromosomes, which increases the risk of inheriting the X chromosome that’s dominant for the disease

98
Q

What is a mutagen? What are two things that mutagens result in?

A

DEF: agents that cause genetic mutations

99
Q

What is a mutagen? What are two things that mutagens result in in terms of cell differentiation and cell division?

A

DEF: agents that cause genetic mutations

↓ degree of cell differentiation

uncontrolled cell division

100
Q

T/F: Meiosis is consisted of 2 rounds of DNA replication and followed by 2 rounds of cell division

A

FALSE

1 ROUND OF DNA REPLICATION + 2 ROUNDS OF CELL DIVISION

101
Q

T/F: non-sister chromatids of homologous chromosomes exchange genetic material in meiosis

A

TRUE

102
Q

What is a tetrad? What is it formed by? What stage of meiosis is it in? What are two components of it?

A

DEF: group of 4 sister chromatids of a homologous pair of chromosomes

formed by synapsis

Prophase I

pair of homologous chromosomes + synaptonemal complex (zipper-like structure associated with the synapsis of homologous chromosomes)

MCAT (6 decks)

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