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MCAT Prep > Random: Bio/Biochem > Flashcards

Random: Bio/Biochem Flashcards

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1
Q

Flat vs. long bones

A

flat: skull, ribs, vertebrae “protective functions”
-red bone marrow, high blood cell production, little movement required
long bones: hands, feet, arms, legs
-yellow marrow, little blood cell production

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2
Q

Pentose Phosphate Pathway

A

metabolic, parallel to glycolysis

generates: NADPH, pentose (5C sugars), and ribose 5-phosphate (precursor to nucleotides)

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3
Q

Low carbohydrates in ER and golgi apparatus

A
  1. inappropriate intracellular transportation
  2. decreased levels of post-translational processing
  3. decreased glycogen storage within the cell
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4
Q

Polymerase Chain Rxn

A

uses Taq polymerase almost exclusively
usually a standard set of temperatures, independent of sequence
uses an excess of each nucleotide
they need to know the sequence in order to know what primer to use

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5
Q

pyloric sphincter disfunction causes _____

A

allows greater amount of chyme into the small intestine (drastically decreases pH) – causes the pancreatic enzymes (that require an alkaline environment) to decrease their functionality – decreasing digestion of lipids

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6
Q

Albinism

A

melanin synthesis is blocked, melanin is synthesized from Tyr, which means that Tyr cannot be processed

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7
Q

“sense RNA”

A

single stranded RNA
very vulnerable to attack – to mitigate this vulnerability, RNA needs to assume a 3D conformation in a very tight hair pin loop or lariat – allowing the RNA to bind to itself

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8
Q

Diabetes: Glycosuria

A

glucose in the urine
due to insufficient glucose reabsorption in the proximal tubule
filtrate levels of glucose are so high and the glucose transporters are overwhelmed)

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9
Q

Breast-feeding, nipple stimulation

A

two stage response: oxytocin and prolactin levels increase

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10
Q

Prolonged high blood sugar effects

A

damage to multiple organs: retina of the eye, glomeruli of kidneys, coronary vessels of the heart, cerebral vessels of the brain, nerves in extremities

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11
Q

Cells of Leydig

A

produce testosterone, an abnormality would lead to low levels

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12
Q

Expressivity vs. Penetrance

A

expressivity: variance in phenotype despite identical genotype
penetrance: population measure, proportional of individuals carrying the allele who actually express the phenotype

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13
Q

Mendel’s law of segregation occurs when

A

during anaphase I of Meiosis

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14
Q

Asthma

A

allergic reaction in alveoli, this inflammation is initiated by an allergen bonding with the mast cells

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15
Q

Layers of the chest, outward to inward

A

skin to chest wall to parietal pleura, visceral pleura, lungs

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16
Q

Transplant

A

specificity of the immune response (mediated by B and T cells) so during transplants their fx is reduced greatly as not to reject the new organ

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17
Q

O2-Hb dissociation curve

A

‘exercise is the RIGHT thing to do’

as CO2 levels rise during exercise, the curve shifts to the right

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18
Q

vasectomy

A

effective male contraception, segment of the vas deferens is excised
epididymis and ejaculatory duct were disconnected

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19
Q

Saltatory Conduction

A

to jump ‘saltar’
occurs in myelinated neurons (afferent and efferent)
allows impulses to jump down the neuron and is necessary for action potentials to transmit at necessary speeds for function

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20
Q

Gastric cells/glands

A

3 different cell types:
Mucous cells: secrete alkaline mucous
Chief Cells: secrete pepsinogen
Parietal cells: secrete HCl, intrinsic factor
and Pyloric glands contain G cells = secrete gastrin (peptide hormone)

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21
Q

Renin-Angtiotensin-Aldosterone System

A

First: renin is released by juxtaglomerular cells (in kidney, in response to low BP), renin cleaves angiotensinogen to angiotensin I.
Moving to the lungs: angiotensin-converting enzyme (ACE) converts angiotensin I to angiotensin II

purpose: angiotensin II causes the release of aldosterone from the adrenal cortex

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22
Q

Folate

A

essential for neural tube development, deficiency results in neural tube defect (anywhere from the spinal cord to cranium)
common defect: anencephaly: brain fails to develop, skull is left open

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23
Q

Embryo Implantation

A

trophoblasts form chorionic villi, which penetrate the endometrium of uterus – chorionic villi develop the placenta

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24
Q

where does steroid synthesis occur?

A

smooth ER

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25
Final e- acceptor in anaerobic respiration
S or NO3-
26
Five Hardy-Weinberg Conditions
1. pop is very large (no genetic drift) 2. No mutations that affect the gene pool 3. Mating between individuals in population is random (no sexual selection) 4. No net migration in or out 5. genes in a population are equally successful at reproducing
27
Excess ACTH
excess adrenocorticotropic hormone causes elevated cortisol levels, growth of the adrenal cortex, hypertension, and weight gain
28
Transposons
genetic elements, insert into or remove themselves from the genome subclass: integrates into human genome, undergo transciprtion, stably reinserts into new regions of the genome reverse transcriptase is needed: converts the transposon RNA into DNA (allowing it to reinsert)
29
What allows a cell to feel compression but survive?
intermediate filaments compress and handle to impact allowing the cell to survive cytoplasm is incompressible, does not help in that type of cell survival
30
Zymogen
inactive form of an enzyme, converted to active form by a biochemical change (like the cleavage of a regulatory domain)
31
How do enzymes lower activation energy
binding, stabilizing the Transition State transient covalent bonds to bring substrates into optimal position to react increase in local reactant concentrations, increases the likelihood being in position to react
32
What happens to Amino Acids released by the liver?
taken up by skeletal muscle to replace lost amino acids
33
Protein contains 494 amino acids, what is the length of the mRNA transcript?
494 x 3 = 1500 nucleotides (+ 500-1000 nucleotides in the 5' and 3' untranslated regions
34
Defect in Schwann cells would result in?
if something is inhibiting their function, then there could be a slowed impulse transmission in PNS
35
Linked Genes
distance measured by the probability of crossing over events | genes that are FARTHER apart = more likely to cross over
36
Megakaryocytes
large cells that give off small cell fragments that become platelets
37
How do steroid hormones regulate gene expression?
hormone-receptor complex travels to the nucleus, binds to segments of the DNA -- so when the steroid inhibits gene expression -- they inhibit transcription -- by inhibiting binding of transcription factors
38
conversion of ln to log
ln(x) = 2.3 log(x)
39
precursor to the synthesis of cholesterol
acetyl coA
40
Protein association
groups of similar polarity tend to associate/group together (contributing to 3 structure) nonpolar hydrocarbon side changes = interior of the protein
41
Hybrid DNA melting point
determined by the degree of homology between two strands | highly homologous = match more closely = anneal more tightly = higher temp will be required to separate
42
pepsin
gastric protease, fx best at acidic pH
43
kcal/g for Carbs, proteins, alcohol, fat
``` carbs = 4 proteins = 4 alcohol = 7 fat = 9 ```
44
what happens to sperm mitochondria?
it is targetted and destroyed by maternal organelles
45
Amidine derivative
replaces the carbonyl carbon with an NH group
46
Glucagon
peptide hormone, secreted by alpha-cells of the pancreatic islets of Langerhans primary target of action = hepatocytes
47
Effects of glucagon
increase glycogenoLYSIS, increase liver gluconeoGENESIS, increased liver ketogenesis, decreased lipogenesis, increased lipolysis of liver
48
How do Amino Acids show up in UV Spectroscopy?
amino acids can be seen depending on the presence of aromatic groups (tyrosine, tryptophan, and phenylalanine
49
G Proteins
``` either stimulate or inhibit adenylate cyclase they are a class of signaling receptors that have 7 transmembrane domains (membrane spanning alpha-helices) Can couple a receptor to the opening of an ion channel ```
50
How do insulin dependencies of tissues differ?
they are based on glucose needs, various forms of glucose transporters have differential insulin dependencies - adipocytes and myocytes: absorb/store glucose when blood levels are high - other cells need a constant supply of glucose = so they do not depend on insulin (neurons in particular)
51
Flavoproteins
2 predominant: FAD and FMN embedded in the inner mitochondrial membrane, act as e- carriers in the ETC the bind flavins, are electron carriers in chloroplasts of plants and mitochondria
52
Lactate dehydrogenase produces
lactic acid (causes a more acidic environment
53
Effects of high [NADH]
inhibits a-ketoglutarate dehydrogenase complex = in citric acid cycle converts a-ketoglutarate and produces CO2 and NADH (inhibited by NADH, ATP and succinyl-coA
54
(+) and (-) sense RNA (ssRNA)
(+) sense: genome translated to fx proteins by ribosomes in cytoplasm (-) sense: synthesis of RNA complementary to (-) sense ssRNA
55
Reverse Transcriptase
synthesizes DNA from ssRNA -- DNA can then be integrated into the cell genome and replicated/transcribed --allows the cells to be infected indefinitely (HIV)
56
What points in the cell cycle would chemotherapy effectively prevent cell division
S Stage Prophase Metaphase
57
Genetic Recombination occurs when
Prophase I
58
Law of segregation occurs when
*disjunction* | Anaphase I
59
Nondisjunction can occur when
Anaphase I or II
60
Female Reproductive System: Metaphase II
until fertilization, eggs are arrested during this phase
61
Female response to DROP in progesterone
Menses (uterine lining is shed)
62
FSH in embryo and adults
stimulates estrogen embryo: reproductive tract development adult: thickens uterine lining
63
LH
stimulates progesterone embryo: secreted by corpus luteum development/maintenance of endometrium
64
hollow ball of cells surrounding fluid filled center
Blastula
65
Back Mutation
2nd mutation occurs that restores the original function
66
Sense and Missense mutation
Missense: changes codon from one amino acid to another, may impact resulting protein (h/w would not cause a deletion of the remaining protein) Sense: DNA sequence codes for same amino acid (results in a normal protein)
67
Conversion of Pyruvate to Lactate
this is fermentation (eukaryotes it occurs during anaerobic respiration) this conversion occurs in the cytoplasm, which would not be a pellet post centrifugation -- but remain in the supernant
68
Mitochondrial DNA
Circular loop, dsDNA not contained in nuclear membrane, histones are not protecting it, free radicals produced from oxidative phosphorylation can attack -- all contribute to the susceptibility of mtDNA to mutations
69
Adherens junctions and desmosomes
share similar fx, connect cells together via series of connected proteins that coordinate to form an intra and extracellular domain intracellular domain: coordinates w the cell cytoskeleton extracellular domain: coordinates w neighboring cell's cytoskeleton fx: cell anchoring, cell-cell adhesion, coordination with cytoskeleton
70
Glucose and Galactose
are epimers
71
Protein-DNA interaction in prokaryotes and eukaryotes
prokaryotes: the interaction usually prevents transcription (repressor) Eukaryotes: the interaction are required to promote transcription
72
Gene control in Prokaryotes and Eukaryotes
prokaryotes: translation occurs without any modifications post transcription while in eukaryotes, RNA is processed (for additional modifications) after transcription in order to proceed to translation Prokaryotes do not rely on splicing while eukaryotes do
73
Thymine Dimer
due to UV radiation cross linking adjacent thymines
74
Insertion and/or deletion in a cell's DNA would cause?
corresponding insertion/deletion in mRNA - changing the reading frame - causing a frameshift mutation
75
Gene targets for anticancer drugs
a gene that was either up-regulation or down-regulating in either healthy or cancerous tissues
76
Proximal Convoluted Tubule (PCT)
bulk reabsorption of glucose, amino acids, vitamins, salt, and water secretes: H, K, ammonia (NH3), urea
77
Descending limb of loop of Henle
only permeable to water, NOT salt | counter current multiplier: vasa recta, nephron flow, opposite directions
78
Ascending Limb of Loop of Henle
Only permeable to Salt, not water
79
Distal convoluted tubule (DCT)
reabsorbs salts excretes waste responsive to Aldosterone
80
Collecting Duct
Responsive to aldosterone and ADH
81
Leukocytes
gravitate towards inflammation
82
How does F factor move ?
via conjugation/sex pilus
83
Adrenal Medulla
sympathetic branch of the autonomic nervous system | secretes epinephrine and norepinephrine in response to short term stress
84
Other names for the Complexes (I-IV) in the Electron Transport Chain
I - NADH-CoQ Oxidoreductase II- Succinate dehydrogenase III- cytochrome bc complex IV- Cytochrome c oxidase
85
Fx of Glomerulus in filtrate
structure of the glumerulus capillaries prevents entry of large molecules (like proteins) into the filtrate
86
germ layers that turn into the adrenal cortex and the adrenal medulla
adrenal cortex = mesoderm | adrenal medulla = ectoderm
87
Rate limiting step of citric acid cycle
isocitrate dehydrogenase
88
Peptide Hormones
first messenger binds to second messenger | usually rapid, short lived,
89
Steroid Hormones
derived from cholesterol produced by gonads and adrenal cortex carries by proteins in the blood stream
90
Amino-Acid derivative hormones
epinephrine, norepinephrine, triiodothyronine, thyroxine
91
How do both Eukaryotes and Prokaryotes produce ATP?
Via ATP Synthase BOTH: have membrane embedded ETC but, Prokaryotes = plasma membrane Eukaryotes = inner mitochondrial membrane

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