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MCAT BB > Biochemistry > Flashcards

Biochemistry Flashcards

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MCAT flashcards
1
Q

Noncometitive Inhibition

A

Decreases vmax, same Km

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2
Q

Uncompetitive Inhibition

A

Bind to enzyme-substrate complex. Lower both vmax and Km

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3
Q

Mixed inhibition

A

Lower vmax. Can bind to either enzyme or ES. If bind more to ES: lower Km. If bind more to enzyme, increase Km.

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4
Q

Cell adhesion molecules (CAMs)

A
  1. Cadherins
  2. Integrins
  3. Selectins
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5
Q

Cadherins

A

calcium-dependent adhesion, hold similar cell types together

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6
Q

Integrins

A
  1. Have 2-membrane spanning chains (a and b).
  2. Important in cellular signaling, promote cell division/apoptosis/other process
  3. Can be used to activate platelets, white blood cell migration, stabilization of epithelium on its basement membrane
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7
Q

Selectins

A

Bind to carbohydrate molecules that project from other cell surfaces.

  1. Expressed on WBC and endothelial cells that line blood vessels
  2. Role in host defense, including inflammation and WBC migration
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8
Q

Isoelectric focusing

A

Basic gel at positive anode, acidic gel at negative cathode

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9
Q

Lowry reagent assay

A

Determine level of protein using copper ions getting reduced to tungsten blue

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10
Q

a vs. b anomer

A

a: anomeric carbon OH group on opposite side of ring as the CH2OH group on C6.
b: on same side

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11
Q

Sucrose, lactose, maltose

A
  1. Sucrose: glucose-a-1,2-fructose
  2. Lactose: galactose-b-1,4-glucose
  3. Maltose: glucose-a-1,4-glucose
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12
Q

Vitamin A (carotene)

A

retinal, rentinoic acid

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13
Q

Vitamin D (cholecalciferol)

A

calcitriol in kidneys, Ca and P homeostasis in intestines, cause rickets

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14
Q

Vitamin E (tocopherols)

A

Biological antioxidants

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15
Q

Vitamin K (phylloquinone/menaquinones)

A

important for forming prothrombin

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16
Q

Eukaryotic DNA polymerases

A
  1. DNA polymerase a: synthesize new DNA with polymerase d
  2. DNA polymerase b: DNA repair
  3. DNA polymerase gamma: Replicate mitochondrial DNA
  4. DNA polymerase delta: Synthesize new DNA with polymerase a, fill in gaps after RNA removal with DNA, assisted by PCNA that assemble into trimer for sliding clamp DNA
  5. polymerase epsilon: DNA repair, assisted by PCNA that assemble into trimer for sliding clamp
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17
Q

RNA Polymerase Types

A
  1. RNA polymerase I: located in nucleolus, synthesizes rRNA
  2. RNA polymerase II: located in nucleus, synthesizes hnRNA (heterogenous, pre-processed mRNA) and some snRNA
  3. RNA polymerase III: located in nucleus, synthesizes tRNA and some rRNA
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18
Q

Histone acetylation

A

Transcription enhanced

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19
Q

Osmotic pressure

A

𝛱 = iMRT

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20
Q

Nernst equation

A

E = (61.5/z)(outside ion/inside ion conc)

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21
Q

Goldman-Hodgkin-Katz voltage equation

A

Applies nernst equation to find that Vm is related to permeability as well (look at notes)

22
Q

Inner mitochondrial membrane

A

Has high level of cardiolipin, which does not have cholesterol

23
Q

Functions of NADPH

A
  1. Biosynthesis (mainly FA and cholesterol)
  2. Assist in bleach production in certain WBC
  3. Maintain supply of reduced glutathione to protect against reactive oxygen species
24
Q

Glutathione

A

Reducing agent that can help reverse radical formation before damage is done to cell

25
Q

Rate-limiting enzymes for: 1. Glycolysis 2. Fermentation 3. Glycogenesis 4. Glycogenolysis 5. Gluconeogenesis 6. Pentose phosphate pathway

A
  1. Glycolysis: phosphofructokinase-1
  2. Fermentation: lactate dehydrogenase
  3. Glycogenesis: glycogen synthase
  4. Glycogenolysis: glycogen phosphorylase
  5. Gluconeogenesis: fructose 1,6-bisphosphatase
  6. Pentose phosphate pathway: glucose 6-phosphate dehydrogenase
26
Q

Ways to obtain acetyl-CoA

A
  1. From pyruvate (pyruvate dehydrogenase complex)
  2. Beta-oxidation of fatty acids
  3. Amino acid catabolism (ketogenic AA)
  4. Ketones
  5. Alcohol: alcohol dehydrogenase and acetaldehyde dehydrogenase
27
Q

Citric Acid Cycle substrates

A

Please, Can I Keep Selling Seashells For Money, Officer?

  1. Pyruvate
  2. Citrate
  3. Isocitrate
  4. a-Ketoglutarate
  5. Succinyl-CoA
  6. Succinate
  7. Fumarase
  8. Malate
  9. Oxaloacetate
28
Q

Repair mechanisms, phase of cell cycle, key enzymes repaired

A
  1. Proofreading: S phase, DNA polymerase
  2. Mismatch repair: G2, MSH/MLH1 in euk or MutS/MutL in prok
  3. Nucleotide excision repair: G1, G2, Excision endonuclease
  4. Base excision repair: G1, G2, glycosylase, AP endonuclease
29
Q

Blot types

A
  1. Southern blot: presence and quantity of various DNA strands in a sample. Restriction enzymes, palindromes
  2. Northern blot: detect RNA
  3. Western blot: detect protein levels
  4. Eastern blot: post-translational modifications on proteins
  5. Far eastern blot: lipids, from high-performance TLC
30
Q

GLUT 2 vs. GLUT4

A
  1. GLUT2: low-affinity transporter in hepatocytes and pancreatic cells. High Km, pick up glucose proportional to its blood concentration. Not responsive to insulin, but serve as glucose sensor for insulin release.
  2. GLUT4: high-affinity transporter in adipose tissues and muscle. Km similar to normal [glucose] in blood. Responsive to insulin, increase intake of glucose by increasing number of GLUT4 receptors.
31
Q

Absorption of digested lipids

A
  1. Short-chain fatty acids: diffuse to blood
  2. Bile salts: active transport to blood
  3. Packaged into chylomicrons, that leave intestine as lacteals and re-enter bloodstream via thoracic duct
32
Q

How insulin affects fatty acid mobilization

A

Fall in insulin levels activate hormone-sensitive lipase (HSL) that hydrolyzes triaglycerols. HSL effective within adipose cells, but need lipoprotein lipase (LPL) for metabolism of chylomicrons and VLDL.

33
Q

Lipoprotein definition

A

Aggregates of apolipoproteins and lipids

34
Q

Lipoproteins and their functions

A
  1. Chylomicrons: transport dietary triaglycerols, cholesterol, and cholesteryl esters from intestine to tissues
  2. VLDL: transports triaglycerols and fatty acids from liver to tissues
  3. IDL (VLDL remnants): picks up cholesteryl esters from HDL to become LDL. Picked up by liver
  4. LDL: delivers cholesterol into cells
  5. HDL: picks up cholesterol accumulating in blood vessels. Delivers cholesterol to liver and steroidogenic tissues. Transfers apolipoproteins to other lipoproteins.
35
Q

Where is VLDL produced and assembled?

A

Liver cells

36
Q

Apoproteins

A

Also called Apolipoproteins. Protein component of lipoproteins. Receptor molecules, involved in signaling leading to diverse purposes.

37
Q

Cholesterol sources

A

Mostly from LDL or HDL, but de novo synthesis in liver

38
Q

Cholesterol de novo synthesis

A

In the liver, driven by acetyl-CoA and ATP.

Rate-limiting step: synthesis of mevalonic acid in SER, catalyzed by HMG CoA reductase.

39
Q

Cholesterol synthesis regulation

A
  1. Increased levels of cholesterol inhibit
  2. Increased insulin promotes
  3. Depends on regulation of HMG-CoA reductase gene expression in cell
40
Q

Lecithin-cholesterol acyltransferase (LCAT)

A

Enzyme in bloodstream, activated by HDL apoproteins. Adds fatty acid to cholesterol, producing soluble cholesterol esters as in HDL.

41
Q

Cholesteryl ester transfer protein (CETP)

A

Facilitates transfer of cholesteryl esters from HDL to other lipoproteins such as IDL (which becomes LDL after this transfer)

42
Q

Essential fatty acids

A

a-linolenic acid, linolenic acid (important for cell membrane fluidity)

43
Q

Ketogenic amino acids

A

Leucine, lysine, isoleucine, phenylalanine, threonine, tryptophan, tyrosine

44
Q

Glucogenic amino acids

A

All except for leucine and lysine

45
Q

Tissues in which glucose uptake is not affected by insulin

A
  1. Nervous tissue
  2. Kidney tubules
  3. Intestinal mucosa
  4. Red blood cells
  5. b-cells of pancreas
46
Q

How plasma glucose levels affect insulin levels

A

Increased plasma glucose = higher ATP. Increased ATP lead to higher calcium release in cell, promoting exocytosis of preformed insulin from intracellular vesicles

47
Q

What promotes secretion of glucagon

A
  1. Low plasma glucose levels

2. Amino acids (especially basic ones)

48
Q

T3 and T4

A

T3: rapid increase in metabolic rate
T4: slow increase in metabolic rate
1. Accelerate cholesterol clearance
2. Increase glucose absorption from small intestine
3. Epinephrine requires T3 and T4 for function

49
Q

Preferred fuels in well-fed and fasting states in 1. Liver 2. Resting skeletal muscle 3. Cardiac muscle 4. Adipose tissue 5. Brain 6. RBC

A
  1. Liver: well-fed = glucose and AA, fasting = FA
  2. Resting skeletal muscle: well-fed = glucose, fasting = FA, ketones
  3. Cardiac muscle: same as resting skeletal
  4. Adipose tissue: well-fed = glucose, fasting = FA
  5. Brain: both glucose, but ketones in prolonged fast
  6. RBC: both glucose
50
Q

Respiratory quotient

A

RQ=CO2 produced/O2 consumed

51
Q

Orexin

A

Further increases appetite

52
Q

BMI

A

mass/(height^2)

MCAT BB (7 decks)

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