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mcat biochem textbook > ch 6 > Flashcards

ch 6 Flashcards

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MCAT flashcards
1
Q

lipids are what and do what (three things)

A

oily/fatty substances that 1) in adipose cells, fat (triglycerides) store energy 2) in membranes, phospholipids make barriers 3) cholesterol is a special lipid that servers a precursor to steroid hormones

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2
Q

lipids are what in regards to water, whats another word for the two terms

A

lipids are hydrophobic due to their c-c and c-h bonds that are nonpolar, hydrophobic are lipophilic and hydrophilic are lipophobic

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3
Q

what are fatty acids made of?

A

long unsubstituted alkanes with a carboxylic acid at the end, and it is usually even numbered

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4
Q

what is a unsaturated or saturated fatty acid? whats their respective fluidity?

A

unsaturated FA: FA’s with a double bond that causes them to have a kink to them which makes them more fluid.
saturated FA: FA’s without any double bonds but saturated with hydrogens which allows them to be densely packed together which makes them less fluid.

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5
Q

what is the bond of the double bonded FA?

A

the bond is usually z or cis

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6
Q

FA in a water solution creates what? why?

A

it creates a micelle which is a circular structure with hydrophilic heads and hydrophobic tails. this is driven by the hydrophobic effect, increased entropy in the water and decreased entropy in the grease

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7
Q

what is the storage form of fatty acids? what is it made up of

A

triglycerides or triacylglycerol , it is made up of 3 fatty acids esterified to a glycerol backbone

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8
Q

how is soap made, whats the name of this process, what makes soap special

A

soap is made by base-hydrolysis of triglycerides from fat to FA salts. this process is called saponification. soap is amphipathic

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9
Q

what does amphiphatic mean?

A

has both hydrophilic and hydrophobic parts

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10
Q

what is the more efficient storage of energy, glucose or fatty acids? why?

A

fatty acids because 1) the can be densely packed together more closely 2) stored fats are reduced by glucose is partly oxidized.

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11
Q

why is reduced molecules better for energy

A

energy metabolism begins with oxidation to release energy

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12
Q

membrane lipids are ? what are they derived from

A

they are phospholipids and they are derived from diacylglycerol or DG-P

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13
Q

phospholipids are usually attached to what? give three examples

A

they are attached to a bigger more polar molecule and they can be choline, ethanolamine, and inositol

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14
Q

phospholipids have what structure

A

hydrophobic head and hydrophilic tail

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15
Q

what are the three determinants of fluidity in lipids?

A

degree of saturation, tail lengths, and amount of cholesterol

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16
Q

how do hydrophilic molecules pass through cell membranes

A

membranes have proteins, channels, shunts that allow charged molecules to pass through

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17
Q

what hormones can pass straight through the cell membrane? which ones cannot. where are each receptor

A

steroid hormones can pass through the membrane because hydrophobic and receptors are in cell. the peptide hormones cannot pass through membrane needing to use channels and proteins, receptors are on the cell membrane

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18
Q

once a peptide hormone binds what occurs

A

the protein receptor transmits a signal into the cell and starts the second messenger cascade

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19
Q

what are terpenes and whats their formula

A

they are built from isoprene units with (C5H8)n as formula

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20
Q

how are isoprenes named? what are the names of the main ones?

A

they are named by how many isoprene units they have. monoterpene (2) , sesquiterpene (3), and diterpene (4)

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21
Q

monoterpene

A

2 isoprene units

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22
Q

sesquiterpene

A

3 isoprene units

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23
Q

diterpene

A

4 isoprene units

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24
Q

what is squalene

A

triterpene (6 units) that helps with making steroids and part of earwax

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25
Q

terpenoids

A

natural or synthetic derived species built from isoprene skeleton and bonded together with other elements

26
Q

what is an example of a terpene that is also a vitamin

A

vitamin A

27
Q

what are steroid? once carried through blood, where do steroids go?

A

steroid is a cholesterol with a tetracyclic rings and a polycyclic amphipath. they are carried through blood with fats and proteins into the lipoproteins

28
Q

what are the two sex hormones made from steroids

A

testosterone and estradiol

29
Q

what is a sphingolipid and what makes it different to phospholipids

A

just like phospholipid but instead of glycerol backbone, it has a sphingosine backbone

30
Q

what is the most important sphingolipid and what does it do

A

sphingomyelin, it is a component of the myelin sheath that protects neurons

31
Q

what are waxes

A

long chain fats esterified to long chain alcohols, very hydrophobic

32
Q

what are fat soluble vitamins and what are some examples of them

A

they are vitamins absorbed with dietary fats, and stored in adipose tissue and liver. they are vitamin A, D,E, and K

33
Q

vitamin A is for

A

terpenoid, essential for vision, growth, and immune function

34
Q

vitamin D is for

A

derived from cholesterol (steroid) its essential for blood regulation of calcium and phosphate

35
Q

vitamin E is for

A

a group of compounds called tocopherols, they are essential antioxidants

36
Q

vitamin K is for

A

an important coenzyme in activation of blood clotting proteins

37
Q

what are prostaglandins

A

a group of molecules derived from 20 carbon fatty acids that do different things depending on receptor like smooth muscle contraction, blood vessel diameter, gastric integrity

38
Q

when starting fat digestion, what occurs to fat

A

chylomicrons of fat and lipoproteins are transported via lymphatic system and blood to diff organs and this fat is hydrolyzed to free the fatty acids to go through beta oxidation

39
Q

where does beta oxidation occur?

A

mitochondrial matrix

40
Q

beta oxidation uses how many ATP’s to do what (with name of enzyme)

A

it uses 2 atp’s to make fatty acid acetyl coA madeby acetyl coA synthase

41
Q

what occurs in beta oxidation

A

a fatty acid enters and acetyl-coA’s are cleaved (every 2 carbons) but the last round you cleave 4 carbons which is then made into two acetyle coA’s IMPORANT NOTE: a round is counted after every 2 c until the last round that cleaves four. 12 carbon FA has 5 rounds of b-oxidation

42
Q

how many nadh and fadh2 is made during each round of beta oxidation

A

you make 1 nadh and 1 fadh2

43
Q

can a unsaturated fa go through beta oxidation? if so, how? if not why?

A

yes, it can, it goes along the same process until it hits the double bond and then uses isomerase and a reductase enzyme to remove double bond

44
Q

why does ketogenesis occur and where does it occur

A

it occurs when all glycogen stores are depleted (starvation) and no sugar is getting to the brain and it occurs in the mitochondrial matrix in the liver

45
Q

what does ketogenesis make? where is this product derived from?

A

ketogenesis made ketone bodies and this product is derived from acetyl-coa

46
Q

if theres glucose in the blood but it doesnt enter the cell, what occurs? what disease is this?

A

ketogenesis begins and this is diabetes type 1

47
Q

what occurs when there is too many ketone bodies

A

ketoacidosis causes too much acidity in the body

48
Q

what occurs to ketones after they pass the blood brain barrier

A

they can be converted back into acetyl-coA

49
Q

where does FA catabolism occur? anabolism?

A

FA catabolism occurs in the mitochondrial matric and anabolism occurs in the cytoplasm

50
Q

what is the first step of FA synthesis

A
  1. the repeated addition of 2 carbon units creating acetyl coA and this acetyl coA is carboxylated by acetyl coA carboxylase to make malonyl coA (3c)
51
Q

second step of FA synthesis

A
  1. an acetyl coa binds to a part of FA synthase called ACYL CARRIER PROTEIN or ACP. it is then shifted to another part of the enzyme to allow malonyl coA to bind ACP
52
Q

third step of FA synthesis

A

the acetyl coa binds with that malonyl to make a 5c molecule which is then decarboxylated to make a 4c molecule that then gets reduced by NADPH.

53
Q

fourth step of FA synthesis

A

the process continues with the addition of the four carbon molecule (decarboxylated 5c molecule that came from malonyl and acetyle coa) until you make a 16 carbon FA

54
Q

what can the amine part of the amino acid be used for

A

to make urea to discard or make a nitrogenous compound

55
Q

what can the carbon skeleton part of the amino acid be used for

A

it can make glucose (glucogenic AA) or acetyl coa (ketogenic AA)

56
Q

FA synthesis occurs in what organ

A

liver

57
Q

in a well fed state, what processes are favored

A

glycolysis, glycogenesis, FA synthesis

58
Q

in a starving state, what processes are favored

A

glycogenolysis, beta oxidation, gluconeogenesis

59
Q

what are the main macromolecules? what are their monomers?

A

macromolecules: proteins, lipids, carbohydrates, and nucleic acids. their monomers are: amino acids, fatty acids, monosacc, and nucleotides

60
Q

Cholesterol in a cell membrane does what to the fluidity at low temperature? What occurs to freezing point?

A

At low temp, cholesterol allows an increase in fluidity. It causes freezing point to decreased

61
Q

Cholesterol in the cell membrane at high temperatures causes what to fluidity? The bag occur to melting point?

A

At high temps cholesterol decreases fluidity and therefore increasing melting point

mcat biochem textbook (6 decks)

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