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Nutr 3210 > Lecture 8 - Proteins > Flashcards

Lecture 8 - Proteins Flashcards

1
Q

What is the 21st AA in humans that is not apart of the standard 20

A

selenocysteine

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2
Q

In humans, how many proteinogenic AAs are there

A

21

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3
Q

What is a proteinogenic AA

A

AA incorporated into protein during translation

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4
Q

What is an example of a non-proteinogenic AA

A

GABA (some neurotransmitters)

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5
Q

How many AAs are essential

A

9

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6
Q

What does it mean to be an essential AA

A

body cannot make it, must come from diet

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7
Q

What is the newest addition to the essential amino acids

A

histidine

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8
Q

What types of tissues have protein in the body

A

adipose tissue, blood, connective tissue, eye lens, skeletal muscle, cortical bone, and skin

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9
Q

What are the 3 main tissues in the body for protein location

A

blood (RBC), connective tissue, and the eye lens

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10
Q

What are enantiomers

A

D & L configurations, mirror images of one another

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11
Q

What are zwitterions

A

H transferred from COOH to NH2 in AA structure to make a negative COO- and positive NH3+, making a more polar structure

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12
Q

AAs are connected by ____________ bonds

A

peptide bonds

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13
Q

What is another term for peptide bond

A

amide bond

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14
Q

How do 2 AAs bond

A

carboxyl end of one reacts with amino group of another, releasing H2O as condensation and forming a peptide bond

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15
Q

What is the difference between the term polypeptide and protein

A

polypeptide = >50 AAs (long chain of amino acids)
more than 1 polypeptide = biologically active protein

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16
Q

What is primary structure

A

polypeptide chain of AAs held together by peptide bonds

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17
Q

What is secondary structure

A

hydrogen bonds that create a more stable structure of the polypeptide chain (think alpha helix and beta sheets)

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18
Q

What is tertiary structure

A

arrangement of secondary structure in 3D space

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19
Q

What is quaternary structure

A

combination of 2 or more tertiary structures required to make a functional protein

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20
Q

What is a native protein

A

normal 3D structure conformation

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21
Q

What is denatured protein

A

loss of bioactivity and conformation via pH, heat, detergents, etc.

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22
Q

What level of structure is not affected by denaturation

A

primary structure

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23
Q

What is a conditionally essential AA

A

not normally required in the diet in a healthy individual, but essential under certain contexts

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24
Q

What is an example of a genetic problem (from birth) that would result in a conditionally essential AA being essential

A

phenylketonuria: person is unable to breakdown Phe into Tyr (build up of Phe in the body causes mental defect)

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25
What is a developed disease that would result in a conditionally essential AA being essential
liver disease that impairs Phe and Met catabolism (Tyr and Cys are synthesized from Phe and Met, so here Tyr and Cys are indispensable)
26
What are non-essential AAs
not needed in diet, completely synthesized in the body
27
What are 3 basic AAs
lysine, arginine, histidine
28
What are the characteristics of the basic AAs
polar +ve charge on NH3 group enabling DNA binding
29
What are the characteristics of lysine
essential simple straight chain absent from grain products
30
What are the characteristics of arginine
non essential in healthy adults
31
What are characteristics of histidine
essential ring structure used to produce histamine
32
What are the 4 acidic AAs
aspartate, glutamate, asparagine, and glutamine
33
What are the characteristics of acidic AAs
polar -ve charge on carboxyl side chain
34
What are the characteristics of aspartate
non-essential transmitted to oxaloacetate (Krebs)
35
What are the characteristics of glutamate
non-essential transmitted to a-ketogluterate (Krebs) used to produce GABA
36
What are the characteristics of asparagine
non-essential
37
What are the characteristics of glutamine
non-essential important in AA catabolism because it is a carrier of nitrogen
38
What are the neutral AAs
glycine and alanine
39
What are the characteristics of the neutral AAs
no charge, non-polar, aliphatic (C and H atoms join in straight or branched chains)
40
What are the characteristics of glycine
non-essential no enantiomers used primarily to produce porphorin
41
What are the characteristics of alanine
non-essential important in AA catabolism because it is a carrier of nitrogen important role in the glucose-alanine cycle
42
What are some branched chain AAs
leucine, isoleucine, and valine
43
What are the characteristics of branched chain AAs
neutral aliphatic, non-polar, all are branched, all are essential, not catabolized in the liver (high levels found in ciruclation)
44
What AAs are found in high amounts in circulation and why
branched chain: not catabolized in liver, so lots is found in circulation
45
What are the hydroxylated AAs
serine and threonine
46
What are the characteristics of hydroxylated AAs
OH group on side chain is important for protein phosphorylation polar
47
What are the characteristics of serine
non-essential OH group on side chain important for phosphorylation
48
What are the characteristics of threonine
essential OH group on side chain important for phosphorylation
49
What are sulphur containing AAs
cysteine and methionine
50
What are the characteristics of sulphur containing AAs
contain sulphur non polar
51
What are the characteristics of cysteine
non-essential made from methionine "spares" methionine when cysteine is consumed in the diet used to form disulphide bonds used in glutathione synthesis
52
What are the characteristics of methionine
essential methionine is limiting in legumes
53
What are aromatic AAs
phenylalanine, tyrosine, tryptophan, and proline
54
What are the characteristics of aromatic AAs
contain rings non polar (except tyrosine)
55
What are the characteristics of phenylalanine
essential used to make tyrosine
56
What are the characteristics of tyrosine
non-essential "spares" Phe used to synthesize neurotransmitters
57
What are the characteristics of tryptophan
essential used to make serotonin used for niacin synthesis
58
What are the characteristics of proline
non-essential important for collagen production aliphatic side chain
59
What are the 9 essential amino acids
lysine, histidine, leucine, isoleucine, valine, threonine, methionine, phenylalanine, and tryptophan
60
Is there enzymatic break down of proteins in the mouth during digestion
no
61
What breaks down proteins in the stomach
HCl in gastric juice pepsin
62
What does the pancreas have to do with protein break down
pancreatic juice used to digest proteins enzymatically
63
What breaks down proteins in the small intestine
enzymes break down proteins, zymogens are active, and AAs are absorbed
64
What cells secrete HCl in protein digestion in stomach
parietal cells
65
What are the two functions of HCl
denature proteins activate pepsin
66
What bonds are disrupted in denaturing of protein
hydrogen bonds electrostatic bonds
67
Pepsin is secreted as _________________, which is an inactive zymogen
pepsinogen
68
How does pepsinogen activate in HCl
since HCl is acidic, pepsinogen can activate as pepsin via conformational change (cannot do this in neutral pH)
69
What is meant by pepsin is an endopeptidase
cleaves peptide bonds within a polypeptide chain
70
What activates trypsinogen to trypsin in the small intestine
enteropeptidase enzyme in the brush border
71
Activation of trypsin activates what other enzymes
chymotrypsin elastase carboxypeptidase
72
What two ways are AAs absorbed in the small intestine
facilitated diffusion active transport
73
What are absorbed faster, essential or non essential AAs
essential
74
Do free AAs have advantage for absorption over protein from foods
no
75
What happens to proteins in terms of use
used for energy or synthesis of new proteins
76
What is the function of glutamine in intestinal enterocytes
generate energy for the cell stimulate cell proliferation increase synthesis of heat shock proteins drive mucus production
77
Liver uses 20% of AAs to...
make new protiens/enzymes and make peptide hormones
78
Liver uses 80% of AAs to...
catabolize them so NH3 is sent to urea cycle, carbon skeleton sent to Krebs for energy
79
What are the 4 aspects to consider in protein quality
AA composition digestibility presence of toxic factors species consuming the protein
80

Nutr 3210 (9 decks)

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