Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

S MCAT > Bio MCAT Review > Flashcards

Bio MCAT Review Flashcards

You may prefer our related Brainscape-certified flashcards:
MCAT flashcards
1
Q

Noncompetitive Inhibition

A

This is when an inhibitor binds an allosteric site on the enzyme or enzyme-substrate complex, preventing the reaction from occurring.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Mixed inhibition

A

Inhibitor can bind to the allosteric site of an enzyme or enzyme-substrate complex, but displays a preference for one over the other.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the importance of the excretory system?

A
  • Regulates blood pressure
  • Removal of nitrogeneous wastes
  • Maintains pH balance
  • Maintains blood osmolarity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What organs make up the excretory system?

A

Kidney, bladder, ureters, and urethra

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is termination factor Þ (rho)?

A

The rho termination factor exists in prokaryotes, and is responsible for the termination of transcription.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How do the renal cortex and medulla compare in terms of solute concentration?

A

The medulla, compared to the cortex, is very “salty” - high concentration of solutes in there.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What allows water to passively diffuse out of the descending limb of the loop of Henle?

A

The active transport of sodium across the ascending limb keeps the medulla “salty,” which allows for the diffusion of water across the descending limb (as this is only permeable to water).

This is known as the countercurrent multiplication system.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What’s the difference between a nonsense and missense mutation?

A

Nonsense: Point mutation in DNA results in an early stop codon

Missense: Point mutation in DNA results in a different amino acid encoded

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are phenols, and what is special about them? Why?

A

Hydroxyl groups attached to aromatic rings

  • The hydroxyl hydrogens are very acidic because of the resonance from the phenol ring
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Name the different positions of substitutions for a benzene ring

A

When there are two substituents on a benzene ring, it’s important to name where they are:

  • Ortho - substituent is adjacent
  • Meta - substituent has one carbon between
  • Para - substituent located on opposite end of ring
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

For a benzyl ring with a substituent about to undergo an additional substitution, how can the substituent “direct” where the substitution will take place on the ring?

A

This depends on the type of substituent it is:

  • Electron-donating group or “activating” groups - donate electron density to the ring, such as alkyl groups (-CH3), lone pairs (-OH, NH3), electronegative atoms (actually deactivating) (Br, F, I) - Ortho/para substitution directing
  • Electron-withdrawing groups or “deactivating” groups - usually an atom bonded to an electronegative atom, like C=O, NO2, CN - Meta substitution directing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How can we oxidize a primary or secondary alcohol to an aldehyde or ketone?

A

With Pyridinium chlorochromate (PCC), this is a mild anhydrous oxidant that can oxidize alcohols to aldehydes or ketones.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does blood come to the glomerulus?

A

Through the afferent arterioles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where are macula densa cells located?

A

They are located in the distal convoluted tubule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where are juxtaglomerular cells located?

A

By the afferent arterioles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where is renin physically located?

A

In juxtaglomerular cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the three triggers for release of renin?

A
  • Low blood pressure, directly sensed by the juxtaglomerular cells
  • Sympathetic nerves fire onto the juxtaglomerular cells to release renin
  • Low sodium in the filtrate, sensed by macula densa cells in the distal convoluted tubule. The macula densa cells then send prostaglandins to juxtaglomerular cells to release renin.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Where is angiotensinogen created?

A

In the liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What happens when renin encounters angiotensinogen?

A

It cleaves it to angiotensin I.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How is angiotensinogen converted to its active enzyme form?

A
  • First, when it encounters renin in the bloodstream, it is cleaved to Angiotensin I.
  • When Angiotensin I reaches the capillaries’ endothelial cells, which have ACE - Angiotensin Converting Enzyme - it is cleaved to Angiotensin II.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What happens when angiotensin I encounters ACE (angiotensin converting enzyme)?

A

It is cleaved to angiotensin II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How does angiotensin II act when it’s active?

A
  • Rapidly: It triggers the vasoconstriction of smooth muscle around blood vessels, increasing resistance
  • Slow: It increases sodium reabsorption in kidney
  • Triggers pituitary gland to release ADH
  • Triggers adrenal gland to release aldosterone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the stimuli for producing aldosterone?

A
  • Angiotensin II
  • High potassium levels

Aldosterone is synthesized in the adrenal cortex when either of these are present.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Where does aldosterone work on?

A
  • Late part of the distal convoluted tubule
  • Collecting duct
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Once we reabsorb important nutrients and electrolytes in the kidney, how does that exit the kidney?

A

Renal vein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How many nephrons are in one kidney?

A

1 million

27
Q

What gets reabsorbed at the proximal convoluted tubule?

A
  • Amino acids (100% reabsorbed)
  • Glucose (100% reabsorbed)
  • HCO3- (90% reabsorbed)
  • Water (65% from filtrate reabsorbed)
  • K+
  • NaCl (65% from filtrate reabsorbed),
28
Q

What occurs at the proximal convoluted tubule of the kidney?

A
  • This is where reabsorption begins, and is the primary site of reabsorption. 2/3 of reabsorption occurs here.
  • Also a site of secretion.
29
Q

What are common substances you’ll see in the glomerulus filtrate?

A
  • Water
  • NaCl, K+, HCO3-
  • Urea
  • Creatinine
  • Amino acids
  • Glucose
30
Q

What gets secreted into the proximal convoluted tubule?

A
  • Uric acid
  • Organic acids - antibiotics/drugs are removed from the body this way
31
Q

What gets reabsorbed at the descending loop of Henle?

A

Water! It is permeable to water, and water is reabsorbed here.

32
Q

What gets reabsorbed at the ascending loop of Henle?

A

NaCl! It is permeable to ions, but is not permeable to H2O.

33
Q

What gets secreted and reabsorbed at the distal convoluted tubule?

A
  • Reabsorbed - NaCl, and water
  • Secreted - K+, H+
34
Q

What gets reabsorbed at the collecting duct?

A
  • NaCl
  • Water
  • Urea
35
Q

Describe the concentration of the filtrate at the loop of Henle

A

It is highly concentrated, because as it goes down the descending loop of Henle, due to the very salty environment of the medulla, the water from the filtrate leaves through osmosis.

36
Q

How do efferent arterioles carry blood out of the kidney?

A

They turn into the peritubular capillaries, where the ions/molecules reabsorbed from the nephron are pulled into, and then this turns into the renal vein - carrying blood away from the kidney.

37
Q

Where is aldosterone produced and secreted from?

A

Adrenal gland, specifically by adrenal cortex cells

38
Q

How does the aldosterone function at the principal cells?

A
  • It drives the sodium-potassium pump to work more quickly in the principal cells at the collecting duct. (Increases K+ in cells, increases Na+ in blood)
  • It inserts K+ channels into the principal cells, so that K+ can escape into the urine/filtrate.
  • It inserts Na+ channels into the principal cells. This allows for Na+ to move from the urine to the principal cells. Na+ then moves into the blood through Na+/K+ pump.
  • Water pulled into the blood because of the increased Na+ in the blood. This causes increase in stroke volume/blood pressure.
39
Q

How does aldosterone affect alpha intercalated cells?

A
  • It gets rid of excess H+
  • It increases the rate at which two transporters work:
    • H+ active transport - transports H+ from inside of cell to urine
    • H+/Na+ antiporter - H+ transported to urine, while Na+ from urine is transferred down its gradient to the inside of the cell
40
Q

What does ADH stand for?

What is another name for it?

A

ADH - Anti Diuretic Hormone

Also called, “vasopressin”

41
Q

Where is ADH produced?

A

Hypothalamus, in nerve cells extending from the supraoptic nucleus

42
Q

What kind of hormone is ADH?

A

Peptide hormone

43
Q

What triggers the release of ADH?

A
  • High blood osmolarity
  • Low blood volume
  • Decreased blood pressure
  • Angiotensin II
44
Q

Where does ADH work?

A

Collecting duct

45
Q

How does ADH affect the collecting duct?

A

When ADH floats through the blood, it binds to the cells of collecting duct, triggering aquaporin channels to be added to the membrane facing the urine. This allows the water to enter the cells, and the water can also enter blood.

46
Q

How is the blood osmolarity affected by aldosterone vs. ADH?

A
  • Aldosterone - doesn’t affect osmolarity
  • ADH - reduces osmolarity
47
Q

What is the function of parathyroid hormone (PTH) and calcitriol?

A
  • These both increase the concentration of calcium and phosphate in blood.
  • Both decrease osteoblast activity.
  • Both increase osteoclast activity.
48
Q

Calcitonin

A
  • The hormone that causes decrease in calcium and phosphate in blood.
  • Increases osteoblast activity.
  • Decrease osteoclast activity.

CalciTONIN = TONES down the calcium in serum

49
Q

What are the two types of neural cells?

A

Neurons and glia.

50
Q

What are pluripotent stem cells and where do you find them?

A

They are located in the blastocyst - in the inner cell mass. They can specialize into other cell types.

51
Q

What is meant through ploidy?

A

Ploidy refers to the number of copies of chromosomes a cell has. For instance, “n” or haploid, refers to a cell with 1 set of chromosomes. 2n would have 2 sets of chromosomes. 30n would have 30 sets of chromosomes.

52
Q

How are leukocytes involved in inflammation?

A

When the body has an injury, leukocytes travel to the site to initiate and maintain the inflammatory response as a defense

53
Q

What are essential amino acids?

A

These are amino acids that cannot be made by the body, and must come from food.

That includes: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

54
Q

What types of cells are highly proliferative?

A
  • Skin cells
  • GI epithelial cells
  • Blood cells
55
Q

Identify the different positions of the phosphate groups in ATP.

Which position tends to be hydrolyzed to power reactions?

A

Alpha, Beta, Gamma

The gamma is hydrolyzed, for energy use in biological reactions.

56
Q

Give the full chemical reaction for glycolysis

A

C6H12O6 + 2 NAD+ + 2 ADP + 2 P —–> 2 pyruvic acid, (CH3(C=O)COOH + 2 ATP + 2 NADH + 2 H+

57
Q

Monocytes come from what cell line, and differentiate into what types of cells?

A

They come from the myeloid line.

They differentiate into macrophages and dendritic cells.

58
Q

What are the three antigen-presenting cells? What does this phrase mean?

A

These are: dendritic cells, macrophages, and B lymphocytes.

This means that these cells will encounter a pathogen, phagocytose them, and then present a piece of the pathogen on the MHC II complex outside of it, to as a method of alerting helper T-cells.

59
Q

Which cell do antigen-presenting cells, present their MHC II to?

A

To T-cells, specifically helper T-cells.

60
Q

What is penetrance, in genetics?

A

This refers to when individuals carry a certain genotype, and whether they express the associated phenotype or not.

61
Q

What is meant by the catalytic efficiency of an enzyme?

A

This is Kcat/Km

Note that Kcat * [Enzyme] = Vmax; Kcat refers to the “turnover rate” of an enzyme, and is measured in s-1.

Km = the conc of substrate when the enzyme rate/velocity is equal to half of Vmax. Therefore, we’re relating Kcat - the turnover rate of the enzyme - to Km - the substrate affinity for the enzyme.

62
Q

Describe how values of Km relate to substrate binding affinity

A

Km refers to the substrate conc when the velocity is equal to half of Vmax.

When Km increases - this means that you need more substrate to reach half the Vmax. This means that the substrate has less affinity for the enzyme.

When Km decreases - this means that you need less substrate; the substrate has more affinity for enzyme.

63
Q

Kcat

A

This is the turnover rate of the enzyme.

Vmax = Kcat * [enzyme]

Vmax = mol/L*s

Kcat units are in s-1

64
Q

Michaelis-Menten equation

A

This is an equation for enzyme kinetics.

V = Vmax*[Substrate]/Km + [Substrate]

V= the velocity we calculate for some substrate concentration

Vmax = the maximum velocity of the enzyme

Km = the conc of substrate at 1/2 of Vmax

S MCAT (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions