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MCAT > Biology > Flashcards

Biology Flashcards

1
Q

True or false: mitochondrial DNA is double stranded

A

TRUE: mitochondrial DNA are double stranded

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2
Q

Which of the following organelles is membrane bound, lysosomes or ribosomes?

A

Lysosomes are membrane bound

Ribosomes do not have membranes- they are found in prokaryotes which lack membrane bound organelles

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3
Q

What is a mature sperm cell called?

A

Spermatozoan

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4
Q

What is the product of the first meiotic division?

A

Meiosis I, or reductional division, results in 2 haploid (n) daughter cells

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5
Q

When in meiosis do the dividing cells become haploid?

A

Telophase I is the last time when cells are diploid- first meiotic (reductional) division results in 2 haploid daughter cells

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6
Q

What happens to GnRH levels during pregnancy?

A

GnRH induces FSH/LH secretion from anterior pituitary- high estrogen and progesterone inhibit GnRH to prevent onset of new menstrual cycle

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7
Q

Which of the following developmental stages has the greatest nuclear to cytoplasmic ratio?
Eight-cell embryo, morula, blastula, zygote

A

Blastula- embryo volume does not increase significantly until after implantation (implanted cell is zygote)

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8
Q

Why would feral hemoglobin not be found in a maternal blood test?

A

Hemoglobin is a large protein that cannot pass through placenta

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9
Q

A patient presents with hyponatremia and ambiguous genitalia. Which endocrine organ is most likely affected?

A

Adrenal cortex (sugar, salt, sex)

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10
Q

Patients with emphysema have difficulty exhaling completely. Why is this?

A

Emphysema causes destruction of alveolar walls, which decreases recoil of lung tissue

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11
Q

Which of the following is a brush border enzyme:

Carboxypeptidase, trypsin, chymotrypsin, aminopeptidase

A

Aminopeptidase is a brush border enzyme

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12
Q

What is the purpose of creating urine that is hypertonic to the blood?

A

Helps retain water

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13
Q

Describe how to find the frequency of a dominant or recessive allele given the percent of the population that is homozygous dominant/ recessive

A

Take the square root of the frequency

If 9% of population is homozygous dominant, the dominant allele has a frequency of 30%
p2 + 2pq + q2 = 1

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14
Q

If 9% of the population is homozygous dominant, what is the frequency of the recessive allele, the portion of the population that is heterozygous, and the proportion of the population with a dominant phenotype?

A

Frequency of dominant allele is square root of 0.09, so 0.3/30%

So the frequency of the recessive allele is
.3 + x = 1 so 0.7

2pq = heterozygous population, so 2x0.3x0.7 = 0.42

p2 + 2pq is population with dominant phenotype, so 0.09+0.42 = 0.51

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15
Q

A male with hemophilia (XhY) is crossed with female carrier of both color blindness and hemophilia (XcXh)- what is the probability that a female child will be phenotypically normal?

A

50%- two daughters of 4 offspring, 1 will be a carrier of both (XcXh)

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16
Q

What is the minimum inhibitory concentration?

A

MIC is least amount of drug/inhibitor needed to be effective

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17
Q

Why do virions carry RNA polymerase?

A

Eukaryotic host cells cannot synthesize RNA from RNA

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18
Q

Anti-sense mRNA is identical to what

A

Anti-sense mRNA is same as template strand

Both are complements to mRNA transcript

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19
Q

Where are the replicated chromosomes in meiosis I, and how many are there?

A

Meiosis I begins with 4 replicated chromosomes/ 2 pairs of homologues (tetrads) aligned in homologous pairs across from each other at the equatorial plate

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20
Q

A normal mother is crossed with a X-linked dominant affected father. How many sons and daughters will be affected, respectively?

A

All unaffected sons (will receive normal X from mother) and all affected daughters (X dominant)

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21
Q

If a primer sequence is ATG GCC TCT, what is the complementary sequence? What is the mRNA sequence?

A

Primer —> complementary sequence in same direction with complementary nucleic acids:
TAC CGG AGA

Complementary sequence is transcribed to mRNA with original nucleic acids except U instead of T:
AUG GCC UCU

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22
Q

What type of accommodation do the eye lens provide?

A

Ciliary muscles control lens curvature to accommodate focal point

Lens accommodation is for distance only

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23
Q

How do the pH values of the matrix and intermembrane space compare?

A

Intermembrane space is more acidic due to proton pumping

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24
Q

What is the result of mitochondrial uncouplers?

A

Decreased ATP production

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25
Q

True or false: mitochondria are the only organelles involved with lipid metabolism

A

FALSE: peroxisomes contribute to lipid metabolism

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26
Q

Where are desmosomes likely to be found (characteristically, regarding their function)?

A

Desmosomes: weld cells together, found in stratified epithelium in tissues subject to stress

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27
Q

What are chromatin made of?

A

DNA + proteins

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28
Q

What does meiosis yield?

A

4 genetically distinct, haploid daughter cells

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29
Q

Which one is correct?:
AT- 3 H bonds
GC- 2 H bonds
GC- 3 H bonds

A

GC- 3 H bonds, why it’s so strong

AT- 2 H bonds

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30
Q

What are the pyrimidines, and what is their defining feature?

A

Pyrimidines- thymine, uracil, cytosine

1 ring (purines have 2 rings)

*pies have 1 ring of crust

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31
Q

What piece of information must be known to perform PCR?

A

Target DNA sequence

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32
Q

Describe the effect/ reason for genetic imprinting?

A

Gene expression different depending on which parent the gene came from

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33
Q

What would be the effect of a pleiotropy gene?

A

Single gene contributes to multiple phenotypic traits

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34
Q

What phenotypic ratios should you get for a dihybrid cross? For a monohybrid cross?

A

Dihybrid cross-> 9:3:3:1

Monohybrid cross-> 3:1

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35
Q

Which of the following would not be found in higher concentrations in cancer cells?
Mitochondria
Chromosomes
Lysosomes

A

Chromosomes- chromosomes are replicated during cell division but number of chromosomes is the same (concentration is the same)

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36
Q

What is a nucleosome?

A

4 histone proteins wound together

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37
Q

What is the number of chromosomes per human cell at the end of meiosis I, mitosis, and meiosis II?

A

23, 46, 23

Sister chromatids are not counted as separate chromosomes (dyad = 1 chromosome)

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38
Q 
Which of the following is not a component of DNA strand?
Nitrogenous base
Phosphodiester linkage 
Amines
Disulfide bonds
Hydrogen bonds
A

Disulfide bonds- folded proteins, not DNA strand

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39
Q

Patient with HSV presents with no symptoms. What cycle is the virus in?

A

Lysogenic cycle = dormant

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40
Q

Viruses evolve faster than all other systems. Why?

A

Viruses lack proof reading- highest mutation rate

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41
Q 
Which of the following are true of most fungi?
Cell walls with chitin
Haploid during large portion of life 
Digest food before absorbing it 
Sexual and asexual reproduction
A

All true!

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42
Q

If the coding strand is
5’ATTCG3’
What is the Pre-mRNA?

A

3’GCUUA5’

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43
Q

Which is not true of bacteria?
Gram + have 2 cell membranes
Gram - stain pink and have thinner cell walls
Gram + stain purple and have peptidoglycan cell walls
All bacteria contain organelles

A

All are true (nucleus and ribosomes are organelles!) except first

Gram + have 1 cell membrane, gram - have 2

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44
Q

Where are the cones located in the eye?

A

Fovea

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45
Q

What are the respective sizes of eukaryote and prokaryote ribosomes?

A

Human- 60S and 40S, 80S total
Prokaryote- 50S and 30S, 70S total

(Just remember to add/subtract 10)

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46
Q

What’s left in your lungs after forced exhalation?

A

Residual volume

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47
Q

In what vasculature is velocity the slowest?

A

Capillaries- greatest total cross section. Allows time for nutrient exchange

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48
Q

Name the granulocytes

A

Neutrophils, eosinophils, basophils

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49
Q

Describe the metabolism of neurons (where do they get their energy)

A

Depend entirely on glucose, insulin independent

Very low glycogen and oxygen storage capability- require high perfusion (rate of blood flow)

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50
Q

Just before max depolarization is reached, what ion channel begins to close, which begins to open?

A

Right before max depolarization- Na+ channels close, K+ channels open

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51
Q

What are the neurotransmitters of the sympathetic and parasympathetic nervous division?

A

Sympathetic: acetylcholine at ganglia (far from effectors), norepinephrine at effector

Parasympathetic: acetylcholine

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52
Q

Are norepinephrine and epinephrine water or lipid soluble?

A

Water soluble

Tyrosine derivative, from adrenal medulla

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53
Q

Name the lipid soluble hormones (hint- 5 total, from 2 organs)

A

Aldosterone (adrenal cortex)
Cortisol (adrenal cortex)

Testosterone (testes)
Estrogen (ovaries)
Progesterone (ovaries)

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54
Q

Which hormone causes sodium reabsorption at the distal convoluted tubule and collecting duct?

Where is the hormone from?
What type of hormone is it?
What’s it’s solubility?

A

Aldosterone

Adrenal cortex

Steroid hormone

Lipid soluble

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55
Q

True or false: the peptide hormones are all water soluble

A

True

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56
Q

Which hormone causes a surge in LH during menstruation?

What kind of hormone is it, what’s it’s solubility?

A

Estrogen

Steroid, lipid soluble

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57
Q

Which hormone causes production of sperm?

What organ is it from, what kind of hormone is it, what’s it solubility?

A

FSH

anterior pituitary (FLAT PEG)

Peptide/ water soluble

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58
Q

Which is the correct path of an action potential in the PNS?

  • dendrite, cell body, axon hillock, axon, Schwann cell, node of Ranvier, terminal bouton, synaptic gap
  • dendrite, cell body, axon hillock, axon, terminal bouton, synaptic gap
  • dendrite, cell body, axon hillock, axon, oligodendrocyte, terminal bouton, synaptic gap
A

dendrite, cell body, axon hillock, axon, Schwann cell, node of Ranvier, terminal bouton, synaptic gap

(Oligodendrocytes are CNS, also need to include Nodes of Ranvier)

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59
Q

You carb up for hibernation! Which hormones will be in high concentrations during fall and winter, respectively?

  • insulin, then glucagon
  • glucagon, then insulin and cortisol
  • insulin, then glucagon and cortisol
A

-insulin, then glucagon and cortisol

Cortisol promotes gluconeogenesis and fat metabolism

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60
Q

In which PNS division, sympathetic or parasympathetic, has cell bodies located far from the effector?

A

Sympathetic neuron cell bodies are far from the effector

Parasympathetic cell bodies are close to effector

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61
Q

True or false: flow rate is at maximum in the aorta

A

FALSE: according to Q=AV, flow rate is constant in a closed system

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62
Q 
Patient develops a disease caused by hypoactivity of anterior pituitary. Which hormone won’t necessarily be in low concentrations?
ACTH
TSH
Prolactin 
Oxytocin
A

FLAT PEG

oxytocin is not anterior pituitary (it’s from posterior pituitary)

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63
Q 
Which is NOT an effect of increased ACTH?
Decreased glycolysis 
Increased cortisol 
Increased blood glucose 
Decreased insulin
A

Decreased insulin is not likely

ACTH stimulates glucocorticoid secretion from adrenal cortex (stress hormones)—> increased gluconeogenesis and fat metabolism. More blood glucose would cause increased insulin

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64
Q

Will TSH dissolve through the nuclear membrane or bind to membrane receptor?

A

TSH is peptide hormone/ water soluble

Will bind to membrane receptor (polar), initiate GPCR cascade

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65
Q

What does breathing into a paper bag do?

A

Increase blood CO2, Decrease blood pH

CO2 + H2O <> HCO3- + H+

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66
Q

How does rapid breathing after exercise affect blood chemistry?

A

Increased blood pH because loss of CO2 from the blood

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67
Q

Which describes starling forces of arteriolar and venous sides of capillary, respectively?

  • high hydrostatic/low osmotic, low hydrostatic/low osmotic
  • low hydrostatic/low osmotic, high hydrostatic/high osmotic
  • high hydrostatic/low osmotic, low hydrostatic/high osmotic
A

Arteriolar: high hydrostatic/low osmotic

Venous: low hydrostatic/high osmotic

Osmotic pressure increases so at venous end there is net flow into capillary (already dropped off the nutrients on arteriolar side)

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68
Q

Does aldosterone affect sodium réabsorptions at the distal convoluted tubule, or water permeability at the collecting duct?

A

Aldosterone—> sodium réabsorptions

ADH- water permeability

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69
Q

Oxidative phosphorylation vs substrate level phosphorylation- what’s different?

A

Oxidative phosphorylation has to do with sharing electrons with oxygen, pretty much exclusive to ETC and ATP synthase

Substrate level phosphorylation- any other phosphorylation event, glycolysis and TCA good examples

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70
Q

How many electrons does cytochrome c transport in oxidative phosphorylation?

A

1

Fe2+ —> Fe3+

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71
Q

What type of primer is good for PCR?

A

Lots of GC content on ends- more stable with 3 H bonds

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72
Q

When does nondisjunction occur in meiosis?

A

Anaphase I

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73
Q

How does increasing the concentration of a transporter change its affinity for its substrate?

A

It doesn’t! Affinity stays the same

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74
Q

What secretes epinephrine and norepinephrine? What types of hormones are these?

A

Adrenal medulla

Tyrosine derivative
Water soluble

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75
Q

What is a reasonable result of transfection with a retroviral expression vector?
Enhanced transcription
Enhanced translation
Enhanced transcription and possible enhanced translation

A

Enhanced transcription and possible enhanced translation

Adding in a viral vector, so transcription will happen, but can’t assume translation (other things could occur after transfection)

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76
Q

If there are x number of H2B histone proteins in a cell, hoe many H1 proteins are expected?

A

0.5x

2 of each core histone, only 1 linker (H1) protein

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77
Q 
Which of these (one or multiple) would be found at the site of infection 15 hours post-infection?
DC
macrophages
Neutrophils 
T cells
B cells
A

DC
neutrophils
Macrophages

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78
Q 
If HLA II is absent from a patients cells, which of these cannot be performed?
Phagocytosis 
Antigen presentation to T cells
Antigen presentation to B cells
Inflammation
A

Antigen presentation to T cells

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79
Q

Which are both in prokaryotes and eukaryotes? (One or multiple)
Cell walls
Ribosomes
DNA

A

All

Plants and fungi are eukaryotes- have cell walls

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80
Q

Which can cause depolarization of postsynaptic neuronal membranes?
Acetylcholine
Glutamate

A

Both (both excitatory)

Glutamate just does depolarization, ACh can do re/depolarization depending on where it is in the body

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81
Q

Which effects speed of action potential?
Axon diameter
Axon length

A

Axon diameter only

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82
Q

True or false: both introns and exons are included in primary mRNA transcript

A

True. Introns are removed during post-transcriptional processing.

Primary mRNA transcripts are shorter than genes because regulatory sequences are not transcribed

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83
Q

Which is higher in the resting cell, sodium or potassium?

A

Potassium, sodium is much higher outside of the cell

Sodium potassium pump moves sodium out, potassium in (against concentration gradient)

84
Q

You see a patient with nerve injury. The injured nerve has its cell body near its effectors. What kind of nerve is it?

A

Parasympathetic nervous system

Sympathetic neurons have cell bodies far from effector

85
Q 
Which of these hormones is not likely to diffuse through the cell membrane and enter the nucleus?
Aldosterone 
Triiodothyronine 
Cortisol 
Epinephrine
A

Epinephrine and norepinephrine are secreted from adrenal medulla, water soluble tyrosine derivatives

The rest are lipid soluble

86
Q

What’s most likely different about homologous genes between humans and bacteria?

A

Have almost identical DNA sequences

But respective binding interactions between other proteins cannot be inferred

87
Q

Under anaerobic conditions, pyruvate is converted to lactate why?

A

To regenerate NAD+ so glycolysis can continue

88
Q

What happens to water if you increase the Kw?

A

Kw = [H+][OH-] = 1x10^-14

If Kw is increased than pH would decrease because there would be a higher concentration of hydrogen

89
Q

Give an example of a DNA palindrome

A

DNA palindromes read same from 5’-3’ on one strand as they do 5’-3’ on complementary strand
Example:
5’-GAATTC-3’ and complement strand of
5’-CTTAAG-3’

90
Q

What would oligomycin do to oxygen consumption?

A

ATP synthase inhibitor- decreased oxygen consumption

Uncoupler would increase oxygen consumption

91
Q

Biologists label sulfur and introduce it into bacteriophage proteins, then inoculate cultured bacteria with labeled phases. Will radiolabeled sulfur be detected in bacterial proteins from cytosol fraction or viral coat proteins from extra cellular fraction?

A

Viral coat proteins

Sulfur is not found in nucleic acid so won’t be injected into bacteria (only inject genetic material)

92
Q

Describe the cori cycle

A

Glucose is transported from liver to muscle. NAD+ is reduced to NADH while glucose becomes pyruvate and ATP is released (glycolysis)

In liver NAD+ can be reduced to convert lactate to pyruvate. Pyruvate can be converted to glucose in liver using ATP (gluconeogenesis)

93
Q

Dp equilibrium constants for reactions include solids in the expression

A

No

Solids are In a different phase

94
Q

Single somatic motor neuron innervates single/group of muscle fiber? What would a group of muscle fibers be called? What are fascicles?

A

Single somatic motor neuron innervates group of muscle fibers, called motor unit

All receive same frequency as action potential

Fascicle- large group of bundled muscle fibers

95
Q

Can H-H hydrogen bond

A

No, no dipole moment

H must be bonded to F, O, or N

96
Q

How many daughter cells will be normal if nondisjunction occurs in anaphase I? What about anaphase II?

A

Anaphase I- none of 4 daughter cells will be normal. Duplicated copies of both homologues in one cell (homologous pairs supposed to separate here)

Anaphase II- 2 normal cells. 1 of daughter cells will have 2 copies of chromosomes, 1 will have neither copy

97
Q

What reaction breaks down macromolecules in digestion?

A

Hydrolysis

98
Q

Which cells in the intestines and respiratory tract secrete mucus?

A

Goblet cells

Mucus cells secrete mucus in stomach

99
Q

What do chief cells secrete?

A

Zymogen pepsinogen- low pH of stomach cleaves to pepsin

100
Q

What do parietal and g cells secrete, respectively?

A

Parietal- HCl

G cells- gastrin. Released into BLOOD and circulates back to parietal and chief cells (pepsinogen) to stimulate them

101
Q

What type of hormone is gastrin, and will it bind a membrane receptor?

A

Peptide- yes binds receptor on membrane

102
Q

Glucagon stimulates ___, insulin stimulates ___ (both in liver)

A

Glucagon- glycogenolysis

Insulin- glycogenesis

103
Q 
What are the 6 pancreatic digestive enzymes?
2 for protein
1 for carbs
1 for fat
2 for nucleic acids
A

Trypsin
Chymotrypsin

Pancreatic amylase

Lipase

Ribonuclease, deoxyribonuclease

104
Q

Where do pancreatic enzymes empty into?

A

Duodenum- most of digestion occurs here

105
Q

What is mutualism? Give an example from the body

A

Symbiosis where both parties benefit

Ex- commensal bacteria in GI

106
Q

Where does carb digestion begin? Proteins? Lipids? By what enzymes?

A

Carbs- mouth, salivary amylase

Proteins- stomach, pepsin and HCl

Lipids- duodenum, pancreatic lipase

107
Q

What are the 2 ways lipids are transported in blood or lymph?

A

Bound to carrier protein (albumin)

Formed into chylomicron or micelle

108
Q

What are the granulocytes?

A

Never Eat Bananas

Neutrophils (phagocytic)
Eosinophils (parasitic infections)
Basophils (rare, allergy)

109
Q

What 2 cells are involved in allergy response and how do they differ?

A

Basophils- recruited (granulocytes are recruited)

Mast cells- resident of tissues

110
Q

What are the APC?

A

Macrophages
DC
B cells

111
Q

B cells become what after activation/ replication?

A

Plasma cells (clones)

Secrete antibodies

112
Q

What do helper T cells do?

A

Stimulate original B cells to divide into a plasma cell and a memory B cell

113
Q

A muscle group is a bundle of many ___

Repeating units of actin and myosin fibers are ___

A

Fasciculi

Sarcomeres

114
Q

Myosin binds actin except when blocked by ___

A

Tropomyosin

115
Q

What is the only neurotransmitter used at the neuromuscular junction?

A

ACh

116
Q

When calcium is released from the SR, it binds ___, freeing the binding site from ___ which allows ___ to bind ____

A

When calcium is released from the SR, it binds troponin, freeing the binding site from tropomyosin which allows myosin to bind actin

117
Q

What does ATP binding allow to happen in muscular contraction?

A

ATP binds to myosin head, facilitating its release from actin filament

ATP hydrolysis gives energy to cock myosin head

118
Q

In muscular contraction, what happens if no ATP is present? What happens if no calcium is present?

A

No ATP- rigor mortis- myosin heads cannot detach from actin, stuck in contracted position (straight)

No calcium- flaccidity- inability to contract

119
Q

What does the acrosome do in sperm?

A

Contains hydrolytic enzymes to penetrate ovum

120
Q

What is an example of positive feedback in the menstrual cycle?

A

LH stimulates estrogen (estradiol) secretion

Normally estrogen inhibits LH

but day 14, estrogen induced LH surge (luteal surge)

121
Q

How do menstruation and ovulation differ in hormone levels?

A

Menstruation caused by drop in hormone levels

Ovulation caused by surge in hormone levels

122
Q

How many cells are in morula?

A

8 celled zygote

123
Q

do peripheral and autonomic nervous systems develop from ectoderm, mesoderm, or endoderm?

A

Ectoderm

124
Q

Most internal organs develop from:
Ectoderm
Mesoderm
Endoderm

A

Mesoderm

125
Q

What regulates pepsin secretion

A

Gastrin (endocrine hormone) secreted by g cells

126
Q

Inability to polymerize tubulin most directly affects:
Cilia in microvilli of small intestine
Ependymal cells in cerebrospinal fluid
Cell division in myocytes

A

Ependymal cells in cerebrospinal fluid

Microvilli not made of cilia, mature myocytes don’t divide

127
Q

Where does bicarbonate secretion occur:
Mouth
Duodenum
Both

A

Duodenum

pH of mouth maintained by buffer

128
Q

Where does primary absorption of water and vitamins occur

A

Large intestine

129
Q

___ produces bile

___ stores bike

A

Liver produces

Gallbladder stores

130
Q

How does decreased FSH affect GnRH

A

Decreased FSH increases GnRH due to loss of negative feedback

131
Q

___ is bound to actin until calcium replaces it

A

Tropomyosin

132
Q

Liver, pancreas, and gallbladder are part of what germ cell layer

A

Endoderm

133
Q

Fasciculi are bundles of ___

T tubules are invaginations in ___

A

Fasciculi- muscle fiber bundles

T tubules- invaginations in sarcolemma (NOT SER)

134
Q

Sperm production occurs where

A

Seminiferous tubules

Nurtured/ stored in epididymis

135
Q

Hematopoeisis occurs in spongy or compact bone?

A

Spongy

136
Q

ATP hydrolysis used to muscle contraction why

A

To transition myosin head from bent to straight (low to high energy position)

137
Q

Where is myosin head before calcium enters Sarcomere

A

Cocked, not attached to actin

Calcium displaces tropomyosin, myosin grabs actin and relaxes to bent position, drags actin with it

138
Q

Which of these will occur with starvation?
Elevated cortisol
Insulin resistance

A

Both

Insulin resistance to save glucose for essential organs (brain)

139
Q

What are the 3 fates of water-insoluble waste products?

A

Stored

Converted to water soluble

Eliminated in feces

140
Q

How does acidemia affect hemoglobin’s affinity for oxygen?

Left or right shift on curve?

A

Acidemia = DECREASED oxygen affinity in order to allow it to be given up more freely in tissues (because blood CO2 is too high)

Binding of H+ to oxyhemoglobin enhances oxygen release

RIGHT shift

141
Q

How much ATP does fermentation produce?

A

2 ATP, both from glycolysis

142
Q

Man with AB blood has child with women of type O. What blood types can the children have?

A

A or B

Child will inherit either AO or BO

143
Q

Neural crest is derived from

A

Ectoderm

144
Q

In lac operon, repressor binds __

A

Repressor binds operator

Not promoter gene- site of binding for RNA Pol

145
Q

Following action potential, calcium binds ___

A

Calcium binds TROPONIN complex

This allows tropomyosin to expose myosin binding sites on actin

146
Q

What part of nephron is glucose reabsorbed?

A

Proximal convoluted tubule

147
Q

Cofactor

A

Molecule NECESSARY for enzyme activity that isn’t an enzyme itself

148
Q

What kind of bond does UDP-glucose form

A

UDP-glucose reacts with non reducing end of lengthening glycogen polymer

Forms alpha-1,4-glycosidic bond

149
Q

how does axon hillock respond to simultaneous excitatory and inhibitory signals

A

sums them

depolarization occurs if signal is sufficient to exceed threshold potential

150
Q

when ADH acts on collecting ducts in response to dehydration, osmolarity of ascending limb of Loop of Henle will:
increase
decrease
remain the same

A

decrease
ADH increases water reabsorption, so more water is in medulla
more dilute medulla shifts equilibrium between filtrate in ascending limb and medulla, driving ions out of ascending limb (decreasing osmolarity)

151
Q

ascending limb is permeable to ___, impermeable to ___

A

ascending limb- permeable to water, impermeable to ions

152
Q

compare gram negative and gram positive by 3 features

A

GRAM NEGATIVE- peptidoglycan, 2 membranes, LPS

gram positive- thick peptidoglycan, 1 membrane, no LPS

153
Q

ribosomes bound to RER make ___

free floating ribosomes make ___

A

RER ribosomes- hydrolytic enzymes for lysosomes and proteins to be secreted
free floating- all other proteins to be used inside cell

154
Q

small intestine parts in order

A

duodenum -> jejunum -> ilium

Does Jumping Increase [digestion]?

155
Q

which enzyme removes RNA nucleotides from primer and adds DNA nucleotides to 3’ end of Okazaki fragments?

A

DNA pol

ligase just seals afterwards

156
Q

where are action potentials generated in muscles

A

sarcolemma- contains voltage-gated channels

157
Q

where does ribosome synthesis and assembly occur

A

nucleolus

158
Q

what do you need to know to design PCR

A

length of gene and nucleotide sequence

159
Q

What’s another name for actin

A

Microfilament !!!

160
Q

tubulin

A

globular protein assembled from microtubules

161
Q

a bacterium consumes lactose, resulting in activation of lac operon, which results in:

  • dissociation of lac repressor from operon
  • association of lac regulatory protein with operon promoter
  • degradation of lac repressor
A

association of lac regulatory protein with operon promoter- when lactose is present, it binds lac repressor, causing repressor to dissociate from the lac operon, allowing transcription to occur

lac regulatory protein is a REPRESSOR- must be removed

162
Q

orientation of mRNA codon to tRNA anticodon is

A

antiparallel

163
Q

gastrin (G) cells are:
endocrine
neurosecretory
endothelium

A

endocrine

neurosecretory can only be neurons

164
Q

decrease in FSH would decrease all but:
estrogen
sperm production
GnRH

A

GnRH- would cause increase because of lack of negative feedback
(FSH stimulates follicle to release estrogen)

165
Q 
which is not derived from mesoderm?
heart
lungs
liver
peritoneum
A

liver
(liver and pancreas are from endoderm)

(mesoderm is mostly organs and their linings, except for these)

166
Q

fasciculi

A

bundles of muscle fibers

167
Q

complete lack of ATP and complete lack of calcium have what effect on skeletal muscle, respectively?

A

lack of ATP = rigor (myosin head cannot separate from actin after power stroke)
lack of Ca2+ = flaccid paralysis (tropomyosin cannot be displaced from actin)

168
Q

effect of point mutation to terminal guanine on 5’ exon?

A

intron will not be spliced. first step of intron splicing is nucleophilic attack of 2’hydroxyl at phosphate of guanine at end of 5’ exon (to form lariat)

169
Q

growth factors regulate what cell cycle checkpoint

A

G1- controls transition to S phase

170
Q

where does translation occur in prokaryotes

A

cytoplasm- they have no nuclear membrane. ribosomes are involved but they are not a cellular compartment

171
Q

what is different about anaphase of mitosis and meiosis?

A

anaphase of mitosis- sister chromatids pulled apart at centromeres
anaphase I of meiosis- homologous pairs are separated but remains two sister chromatids joined at centromere (centromeres don’t split until anaphase II)

172
Q

which 3 sources of hormonal secretion are important for the menstrual cycle?

A 
hypothalamus (GnRH)
anterior pituitary (FSH and LH)
ovary (estrogen, progesterone)
173
Q

what hormone triggers ovulation

A

LH surge

174
Q

how are estrogen and progesterone secretion related to LH

A

estrogen- triggers LH surge (which triggers ovulation)

progesterone- secreted in response to LH

175
Q

histone acetylation

A

neutralizes positive charges on histones by acetylating lysine residues, disrupting their ability to bind negative DNA

176
Q

how does amount of genetic material compare for somatic and germ cells

A

somatic- diploid, germ- haploid

germ have half genetic material of somatic

177
Q

degraded viral peptides transported to ER via TAP protein and presented as antigens by MHC I on cell surface. MHC protein complex made in free floating ribosome or RER?

A

RER used for excreted proteins/ cell surface proteins

178
Q

where are lymphocytes and all blood cells made

A

red bone marrow (yellow bone marrow is adipose!)

179
Q

cell undergoing mitosis has 32 chromatids visible at end of prophase. what is its diploid number?

A
  1. at this point DNA has been duplicated
180
Q

which will not be found in prokaryotic membrane?

proteins, glycolipids, sterols, phospholipids

A

glycolipids and sterols

181
Q

where does proteasomal degradation occur

A

cytoplasm !!!

182
Q

water acts as a ___ in hydrolysis reactions

A

nucleophile

183
Q

palindrome

A

same nucleic acid sequence on both sides of double stranded DNA going in opposite directions

184
Q

transcription factors bind at ____ which is always upstream of ____

A

transcription factors bind promoter, always upstream of coding sequence

185
Q

what migrates on the gel after RT-PCR

A

RT-PCR uses RNA template to produce cDNA, further amplification results in double-stranded DNA which is what migrates on gel

186
Q

compare the transport mechanisms of aldosterone and ADH

A

aldosterone- active transport. can increase salt reabsorption no matter blood solute concentration
ADH- alters passive water uptake via aquaporins in collecting duct

187
Q

explain why prokaryotes can’t do mRNA splicing

A

transcription is in cytoplasm and ribosomes bind and begin translation before transcription is even complete

188
Q

how many electrons does cytochrome c carry

A

1 at a time!

189
Q

what are the 3 amino acids that carry 2 N atoms, yet are neutral at neutral pH

A

asparagine, glutamine, tryptophan

190
Q

what are the 2 parts of a fatty acid (head and tail portions)

A

long hydrocarbon tail + carboxylic acid head

191
Q

which is mediated by ligand-gated ion channel?

  • release of Ca2+ from sarcoplasmic reticulum
  • influx of Na+ across motor end plate
  • re-entry of Ca2+ into sarcoplasmic reticulum
A

influx of Na+ across motor end plate occurs when Na+ ion channels bind ligand Ach

192
Q

how does Southern blot detect mutant vs WT?

A

Southern blot uses restriction digest
restriction sites are palindromes (symmetrical), so Southern blot will detect a mutation in a palindrome

(HindIII recognizes AAGCTT)

193
Q

a mutation is present only in cancerous tissue of a patient. what does this say about mutation?

A

somatic mutation, not germline

194
Q

nicotinamide nucleotide

A

NADH

195
Q

free energy is ____ property, activity is ____ property

A

free energy = thermodynamic

activity = kinetic

196
Q

what is role of Na+K+ ATPase in action potentials

A

restores resting membrane potential

3 Na+ out, 2 K+ in with each ATP hydrolyzed (against concentration gradient)

197
Q

transcription factors bind ___, recruit ___

A

bind DNA, recruit RNA pol

198
Q

what kinds of molecules freely diffuse through cell membrane

A

nonpolar (LIPID bilayer)

199
Q

initial filtration in glomerulus occurs by

A

passive flow due to pressure difference- blood pressure forces fluid from glomerulus into lumen of Bowman’s capsule

200
Q

name 3 ways enzymes work

A

co-localize substrates
alter local pH
alter substrate shape

201
Q

main input of Kreb’s cycle

A

acetyl coenzyme A (acetyl CoA)

202
Q

do prokaryotes have telomeres

A

no, they have circular DNA

203
Q

how do glucocorticoids affect muscles

A

cause breakdown of muscle proteins

204
Q

when is gluconeogenesis primarily used

A

when blood carb is low, because it makes glucose out of other molecules

205
Q

transduction vs transformation vs conjugation (bacteria)

A

transduction- genetic info via virus vector
transformation- genetic info via picking it up in the environment
conjugation- sex pillus (F+ –> F-)

MCAT (6 decks)

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