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MCAT > Bio/Biochem > Flashcards

Bio/Biochem Flashcards

1
Q

chirality and configuration of amino acids

A

L (except glycine is not chiral), and S (except cysteine)

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2
Q

nonpolar nonaromatic amino acids (7)

A

glycine, alanine, valine, leucine, isoleucine, methionine, proline

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3
Q

aromatic amino acids

A

tryptophan (W), phenylalanine (F), tyrosine (Y)

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4
Q

negatively charged amino acids

A

aspartatic acid (D), glutamic acid (E)

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5
Q

positively charged amino acids

A

lysine (K), histidine (H), arginine (R)

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6
Q

general pI’s of amino acids

A 
acidic anions ~3
polar, uncharged ~5
aromatic ~5.5
nonpolar, aliphatic ~6
basic cations ~9
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7
Q

peptide bond formation is a _____ rxn with a nuc amino group attacking an electrophilic carbonyl. Peptide bonds are broken by _____

A

condensation (dehydration); hydrolysis

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8
Q

actin

A

Microfilament that mysosin will crawl along

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9
Q

tubulin

A

Microtubule that kinesins walks along

Spindle fibers

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10
Q

Cell Adhesion Molecules (CAMs)

A

bind cells to other cells or surfaces. Include cadherins, integrins, and selectins

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11
Q

antibodies

A

Y shaped things released by B cells that recognize antigens on the cell surface of pathogens

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12
Q

Three types of ion channels

A

ungated, voltage gated, ligand gated

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13
Q

Enzyme-linked receptors

A

Participate in cell signaling through extracellular ligand binding and initiation of 2nd messenger cascades

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14
Q

GTPase

A

1) ligand binds and induces conformational change
2) GDP –> GTP
3) alpha subunit separates to activate protein/enzyme (eg. adenylate cyclase)
4) protein/enzyme works as 2nd messenger

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15
Q

Cyclic AMP 2nd Messenger System

A

1) adenylate cyclase converts ATP –> cyclic AMP
2) cyclic AMP activates PKA
3) PKA phosphorylates (activates) downstream targets

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16
Q

Enzymes do what?

A

Lower the activation energy of a reaction

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17
Q

Ligases

A

Join two large biomolecules

eg. DNA Ligase joins Okazaki fragments

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18
Q

Lyases

A

Cleave without water and without the transfer of e-

The reverse reaction (synthesis) is usu. more important

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19
Q

Hydrolases

A

Cleave with water

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20
Q

Transferases

A

Move functional groups

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21
Q

Competitive Inhibitor

A

Binds to active site

No change Vmax, Increase Km

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22
Q

Noncompetitive Inhibitor

A

Binds allosterically

Decrease Vmax, No change Km

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23
Q

Uncompetitive Inhibitor

A

Binds to [E-S] Complex

Decreases Vmax, Decreases Km

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24
Q

A high Km means

A

Low binding affinity

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25
Q

A high Ka means

A

High binding affinity (its an association constant)

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26
Q

triose

A

Three carbon sugar

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27
Q

aldose

A

sugar with an aldehyde

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28
Q

ketose

A

sugar with a ketone

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29
Q

D and L forms of the same sugar are called

A

enantiomers

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30
Q

Diastereomers

A

Differ at at least one, but not all, chiral centers

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31
Q

Chiral

A

4 different substituents attached to a carbon

CANNOT be where there is a double bond.
usually where there is an oxygen

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32
Q

Epimers

A

Differ at one chiral carbon

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33
Q

Anomers

A

Differ at one chiral carbon, the anomeric one

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34
Q

Anomeric Carbon

A

The carbon to the right on the oxygen

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35
Q

β-sugar

A

Where the anomeric carbon points up (cis as the CH2OH group)

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36
Q

α-sugar

A

Where the anomeric carbon points down (trans to the CH2OH group)

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37
Q

Mutarotation

A

Interconversion between alpha and beta anomers

measured by a change in specific rotation

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38
Q

Monosaccharides can undergo 3 main reactions:

A

1) Oxidation/Reduction
2) Esterification (OH > O- > attack of acetic anhydride > H’s replaced with acetals)
3) Glycoside Formation (glycosidic bond/ stabilized by oxocarbenium ion)

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39
Q

Deoxy sugar

A

When an OH group is replaced with an H (deoxyribose in DNA vs ribose in RNA)

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40
Q

Sucrose

A

glucose α 1,2 fructose

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41
Q

lactose

A

galactose β 1,4 glucose

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42
Q

maltose

A

glucose α 1,4 glucose

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43
Q

glycogen main chain

A

α 1,4 linkages

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44
Q

glycogen branching

A

α 1,6 linkages

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45
Q

stereoisomers

A

2^n chiral carbons

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46
Q

reducing sugar

A

Any monosaccharide with a hemiacetal ring
aka reducing agent (helps reduce something)
detected by Tollens and Benedict’s reagents

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47
Q

hemiacetal/hemiketal

A

C bonded to OR, OH, H, R

C bonded to OR, OR, H, R

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48
Q

Recombination

A

Crossing over during meiosis

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49
Q

Prophase

A

chromatin condenses into chromosomes

centrosomes move to opposite poles of the cell

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50
Q

Metaphase

A

chromosomes line up on plate

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51
Q

Anaphase

A

chromosomes start to separate

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52
Q

Telophase

A

opposite of prophase

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53
Q

Metastasis

A

traveling cancer

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54
Q

mismatch repair

A

proofreading that happens in G2

aka after replication

55
Q

nucleotide excision repair

A

proofreading that fixes T=T binding within the same strand as a result of UV radiation

endonuclease used

56
Q

base excision repair

A

proofreading that fixes an incorrect base (the backbone is correct)

57
Q

recombination

A

When you take DNA and stick some other DNA inside and you get recombinant DNA

58
Q

What happens in starvation?

A

First glycogenolysis

Then, 12 hrs later, gluconeogenesis. Depleting supplies of aa, ketones, oaa

59
Q

How do proofreading enzymes distinguish between the correct and incorrect strand?

A

The correct, template strand has been in the nucleus for longer so it is more heavily methylated

60
Q

miRNA

A

silence translation

61
Q

postranslational modifications

A

1) folding assisted by chaperone proteins
2) quaternary structure
3) cleavage of proteins/signal sequences
4) addition of biomarkers (phosphorylation, glycosylation, carboxylation, prenylation)

62
Q

posttranscriptional modification

A

1) intron/exon splicing
2) poly A tail
3) 5’ guanine cap

63
Q

regulation of gene expression at DNA level

A

promoter

64
Q

convergent evolution example and structure

A

sharks and dolphins

paired with analogous structures

65
Q

homologous structures

A

similar structure, different function
indicate a common ancestor
// divergent evolution
eg. arms/flippers/wings

66
Q

analogous structures

A 
different structure
similar function
not common ancestors
//convergent evolution
eg. bird wing/fly wing
67
Q

osmotic pressure

A

the pressure created by water moving across a membrane due to osmosis

water follows solute

pi = iMRT
i: vant hoff's factor (# of ions of solute that form when dissolved in water)
M: mol/L [conc]
R: ideal gas constant .08 Latm/molK
T: temp (K)
68
Q

If you have 1/4 the osmotic pressure, you will have ___ [solute]

A

1/4

69
Q

Helicase

A

catalyzes the separation of parent DNA strands at the origin of replication

70
Q

ssDNA binding protein

A

stabilizes unwound template strand to keep it from coming back together

71
Q

Primase

A

synthesizes RNA primer. RNA primer is spliced out and replaced with DNA by DNA Polymerase I

72
Q

DNA Polymerase

A

III: synthesizes DNA 5’ > 3’ (reads 3>5)
I: replaces RNA primer with DNA

73
Q

Leading and lagging strands

A

Leading strand requires one primer. lagging strand requires many and okazaki fragments are annealed together with ligase

74
Q

Retrovirus aka HIV

A

Contains ssDNA and reverse transcriptase enzymes to make more DNA from host RNA

75
Q

Viral DNA or RNA is contained in a

A

capsid

76
Q

mRNA will have the same sequence as the DNA ____ strand (3 names)

A

Coding//sense//nontemplate

77
Q

mRNA is coded from the template strand also known as the ___ or ___

A

noncoding strand/antisense strand

78
Q

protease

A

cleaves by hydrolysis (usu. peptide bonds)

79
Q

renin/angiotensin

A

vasoconstrictive system that raises blood pressure. inhibited by ACE inhibitors. (angtiotensin converting enzyme)

80
Q

aldosterone

A

steroid hormone released from adrenal glands. increases sodium reabsorption in the distal tubules and water follows, raising BP

81
Q

Calcium’s role in muscle contraction

A

Ca++ binds to troponin (nail) and causes it to change it’s conformation, denailing the tropomyosin from the actin, allowing myosin to crawl

contained in sarcoplasmic reticulum. acts in cytoplasm of muscle cell

82
Q

tropomyosin

A

blocks the myosin from crawling along the actin. nailed in my troponin. moves out of the way when Ca++ binds troponin

83
Q

troponin

A

nail tropomyosin into actin. released by ca++ binding

84
Q

early stages of development from egg to ball of cells

A

oocyte, zygote(fertilized egg), embryo (zygote post mitotic cleavage), morula (ball of cells), blastula(hollow ball of cells)

85
Q

ADH does what and is released when?

A

Stimulates movement of aquaporins in the collecting duct and distal convoluted tubule to increase water reabsorption. Decreases blood osmolarity and need to pee. Raises BP.

Released when blood is very salty, when blood volume is low, when BP is low, when RAAS system tells you that BP is low

86
Q

histone acetylation

A

removes the positive charge on histones, weakening the interaction with negatively charged phosphate groups of DNA, increasing transcription

87
Q

Why is DNA negatively charged

A

negatively charged phosphate groups on the 5’ end

88
Q

pentose phosphate pathway

A

anabolic pathway for generating NADPH and pentoses for nucleotides. Offshoots from glycolysis at G6P

89
Q

Adrenal Medulla

A

Inner part of the adrenal glands. releases epinephrine and norepinephrine

90
Q

Adrenal Cortex

A

Outer part of adrenal glands. releases gluco/mineralcorticoids

91
Q

Anterior Pituitary releases which hormones

A

FSH, LH, ACTH, TSH, Prolactin, Endorphins, GH

92
Q

Thyroid produces which 3 hormones

A

T3, T4, and calcitonin (decreases blood Ca2+)

93
Q

Pancreas produces which 3 hormones

A

glucagon (@ low gluc)
insulin (@ high gluc)
somatostatin (inhibits gluc/insulin)

94
Q

Key event of follicular phase

A

FSH causes growth of a follicle

95
Q

Key event of ovulation

A

LH surge causes follicle to rupture and release egg

96
Q

key event of luteal phase

A

corpus luteum forms

97
Q

Restriction Enzyme

A

PALINDROMES

98
Q

NADH/Ubiquinone Oxidoreductase, NADH-CoQ reductase, or NADH dehydrogenase

A

Complex I of ETC

99
Q

Succinate Dehydrogenase

A

Complex II of ETC

100
Q

Cytochrome C Reductase

A

Complex III of ETC

101
Q

Cytochrome C Oxidase

A

Complex IV of ETC

102
Q

In the ETC, protons are transfered from the ___ to the ___

A

mitochondrial matrix, intermembrane space

103
Q

The proton-motive force is the electrochemical gradient generated by the electron transport chain across the inner mitochondrial membrane. The ___ has a higher conc. of protons than the ___. The energy of this gradient helps form ATP in a process called _____

A

intermembrane space, matrix, chemiosmotic coupling

104
Q

Where is translated protein cleaved?

A

in the endomembrane system

105
Q

y-linked gene

A

never occurs in females, will occur in all male decendants

106
Q

x-linked gene

A

common in males

107
Q

autosomal dominant

A

will never skip generations

108
Q

autosomal recessive

A

all offspring of two affected parents will be affected

109
Q

imprinted gene

A

epigenetic phenomenon that causes genes to be expressed in a parent specific manner

110
Q

inflation of the lungs is accomplished by

A

negative pumping action. a negative pressure (less than atm) is created in the alveolar sacs when the diagragm contracts and pulls to expand the lungs

111
Q

efferent

A

away (from CNS, from organs)

112
Q

afferent

A

towards (CNS, organs)

113
Q

cardiac output

A

stroke volume x heart rate

114
Q

blood pressure can be measured by examining

A

cardiac output x resistance

// Ohms Law V=IR

115
Q

Accumulation of DDT in the testes may cause reduced fertility in males because the uncoupling of oxidative metabolism from ATP production may reduce

A

sperm motility

116
Q

nuclear envelope

A

lipid bilayer that contains the nucleus, nuclear cytosol, DNA

117
Q

proteolysis

A

breakdown of proteins or peptides into amino acids by the action of enzymes.

118
Q

Would an increase in the level of plasma aldosterone be expected to follow ingestion of excessive quantities of NaCl?

A

No; aldosterone causes Na+ reabsorption by kidney tubules.

119
Q

How does aldosterone affect volume and osmolarity of blood?

A

Increases volume. Does not affect osmolarity.

It makes blood more salty, pulling Na+ out of nephron and back into blood, but water follows. so no net effect on blood concentration

120
Q

How does ADH affect volume and osmolarity of blood?

A

ADH increases volume and decreases osmolarity of blood

121
Q

neurulation

A

germ layers develop a nervous system

122
Q

gastrulation

A

endoderm, ectoderm, and mesoderm form

123
Q

bile is produced in the ____, stored in the ____, and acts on ____ in the ____

A

liver, gallbladder, fats(emulsifying them), small intenstine

124
Q

Gene regulation in eukaryotes vs prokaryotes

A

In eukaryotes, 1 promoter (DNA) upregulates the transcription of 1 gene that ends up on 1 mRNA (monocistronic mRNA)

In prokaryotes, an operon (DNA) regulates the transcription of multiple genes that end up on 1 mRNA (polycistronic mRNA)

125
Q

Prokaryotes

A

have cell walls
circular, uncondensed DNA in the cytosol
DNA transcribed and translated at the same time
no membrane bound organelles
operons though!
polycistronic mRNA (multiple genes on 1 mRNA)

126
Q

calcitonin

A

increases blood calcium. activates osteoclasts

127
Q

parathyroid hormone

A

decreases blood calcium. activates osteoblasts.

128
Q

When do you use a radiolabel and when do you use an antibody?

A

radiolabel for nucleotides, antibodies for proteins

129
Q

how does breathing affect blood pH?

A

increased respiration leads to the loss of CO2 which makes the blood more basic via Le Chatlier’s principle and bicarbonate buffer system:

H+ (aq) + HCO3- (aq) ↔ H2CO3 (aq) ↔ H2O (l) + CO2 (g)

130
Q

immunoglobulin

A

class of proteins present in the serum and cells of the immune system, which function as antibodies. Responsible for “humoral immunity” as opposed to cell based immune function. Also known as IgG

131
Q

Where might you find histidine in a protein

A

at the active site. Due to its pKa of 6.5, it is close to physiological pH and can either be protonated or deprotonated easily. t4 it can play a role in stabilizing or destabilizing substrate

132
Q

Which amino acids disrupt the alpha helix

A

proline (b/c bulky secondary amino group) and glycine (b/c flexible from two H’s)

133
Q

Zymogen (example?)

A

a proenzyme that is activated by irreversible cleavage

eg. pepsinogen –> pepsin

MCAT (4 decks)

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