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Biochem exam 1 > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

Isoform

A

Proteins that perform the same function but have different primary structures

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2
Q

Isozymes

A

Proteins isoforms that function as enzymes recall that isoforms are proteins that perform the same function but have different primary structures

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3
Q

Protein folding is…

A

A complex trial and error process that sometimes results in improper folding

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4
Q

What happens to misfolded proteins?

A

They are usually tagged and degraded by the cell however sometimes the aggregates of misfolded proteins can accumulate especially as we age— causing diseases

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5
Q

Misfolding of proteins can cause what diseases?

A

Amyloid and prion diseases

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6
Q

Amyloid disease (protein misfolding)

A

Disease where there is an accumulation of insoluble spontaneously aggregating misfolded proteins called amyloids consisting of beta pleated sheets

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7
Q

Examples of amyloid diseases

A

Alzheimer’s and Parkinson’s (neurodegenerative)

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8
Q

Prion disease (protein misfolding)

A

Disease caused by the prion protein (PRP), infectious PRP is highly resistant to proteolytic degradation and tends to form insoluble aggregates of fibroids similar to the amyloid found in some other diseases of the brain

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9
Q

Examples of prion diseases

A

TSE (spongiform), scrapie in sheep, creutzfeldt jakob in people, bovine spongiform in cattle

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10
Q

Creutzfeldt Jakob disease

A

Prion disease in humans

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11
Q

Scrapie

A

Prion disease in sheep

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12
Q

Bovine spongiform encephalopathy

A

Prion disease in cattle (mad cow disease)

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13
Q

Non-infectious prion protein

A

Prp C (prion protein cellular)

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14
Q

Infectious prion protein

A

Prp Sc (prion protein scrapie)

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15
Q

Prp Sc does what to make it infectious?

A

It induces a 3-D confirmational change in prion proteins cellular (prp C) resulting in resistance to degradation

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16
Q

Where is Prp C?

A

It is found in cell membranes and seems to play an important role in the brain

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17
Q

What are specialized group of proteins that contain the prosthetic group heme?

A

Hemoglobin and myoglobin

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18
Q

Heme _______ binds oxygen

A

Reversibly

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19
Q

Structure of heme

A

Iron can form six bonds four with nitrogen and two additional bonds one above and one below the porphyrin ring; above iron binds oxygen and below iron binds histidine

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20
Q

In globular proteins, heme ________ binds

A

Reversibly

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21
Q

Where is myoglobin found?

A

Heart and muscle

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22
Q

What are the two myoglobin functions?

A
  1. It is a reservoir for oxygen
  2. An oxygen carrier that increases the rate of transport of oxygen within the muscle cell
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23
Q

Myoglobin consists of

A

A single polypeptide chain

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24
Q

What makes tissues red?

A

Myoglobin

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25
Q

Where is hemoglobin found

A

RBCs

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26
Q

Hemoglobin main function

A

Transport oxygen from the lungs to the capillaries of tissues

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27
Q

Hemoglobin can transport

A

Hydrogen and carbon dioxide from tissues to the lungs as well

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28
Q

How many molecules of oxygen can hemoglobin transport from the lungs to the cells?

A

4

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29
Q

How many molecules of oxygen can myoglobin bind?

A

1

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30
Q

Hemoglobin A (the main hemoglobin in adults) is composed of…

A

4 polypeptide chains: 2 alpha and 2 beta chains held together by noncovalent interactions

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31
Q

What kind of interactions hold together for two alpha and two beta chains in myoglobin?

A

Non covalent

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32
Q

Oxygenated form of hemoglobin

A

R or relaxed state
- ionic or hydrogen bonds broken

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33
Q

Deoxygenated form of hemoglobin

A

T or taut state (more bonds in this state)
- hydrogen bonds form and hydrophobic pull together

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34
Q

The oxygen dissociation curve of hemoglobin has what shape?

A

Sigmoidal

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35
Q

What is cooperative binding

A

As the first oxygen binds to the hemoglobin the binding of additional oxygen to the same molecule is enhanced

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36
Q

Where is hemoglobin quickly saturated?

A

In lungs where o2 is high

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37
Q

What happens to hemoglobin in tissues depleted of oxygen?

A

Hemoglobin gives up half its oxygen

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38
Q

__________ Has a greater affinity for oxygen causing oxygen to move from blood to muscle

A

Myoglobin

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39
Q

When does myoglobin give up oxygen?

A

Only when muscle cell oxygen is very low such as during strenuous exercise

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40
Q

The Bohr effect

A

The effect of a change in the oxygen binding affinity of hemoglobin due to the binding of other ligands to hemoglobin

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41
Q

What do the Ligands do in the Bohr effect?

A

The leg and stabilize the taut state a.k.a. the deoxygenated form

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42
Q

Is the deoxygenated form the taut or relaxed state?

A

Taut

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43
Q

Increase H (lower pH)

A

Decrease affinity for O2

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44
Q

Increase 2,3 BPG

A

Decrease affinity for O2

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45
Q

Increase CO2

A

Decrease affinity for O2

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46
Q

What happens when carbon monoxide binds to one or more of the heme sites?

A

Hemoglobin shifts to the R state causing the other heme sites to buy in to oxygen tightly

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47
Q

What does Carbon monoxide do for oxygen affinity

A

Increases (extreme) it… Hb won’t let go of oxygen to tissues

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48
Q

Family genetic disorders caused by the production of

A
  1. Structurally abnormal hemoglobin molecule
  2. Insufficient quantities of normal hemoglobin
  3. Both (rare)
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49
Q

Examples of hemoglobinopathies

A

Sickle cell anemia (Hb S)= val instead glu
Hemoglobin C disease = lys instead of glu
Hemoglobin SC disease= both above
Thalassemia= decreased normal hemoglobin

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50
Q

Fibrous proteins typically contain what

A

Regular secondary structural elements mostly structural proteins

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51
Q

Fibrous proteins are mostly

A

Structural

52
Q

Structural proteins are mostly

A

Functional

53
Q

Examples of fibrous proteins

A

Collagen, elastin, keratin

54
Q

What is the most abundant protein in the human body?

A

Collagen

55
Q

Collagen is composed of

A

Three polypeptide helices that are twisted around each other to form a right handed triple helix

56
Q

There are more than ___ collagen types but most of them are type ____

A

25, 1

57
Q

Collagen type one is found in what?

A

Teeth bone skin and tendons

58
Q

What is the amino acid composition of collagen?

A

Glycine, proline, 4 hydroxyproline, 3 hydroxyproline, 5 hydrolysine

59
Q

What is present in collagen but not present in most other proteins?

A

Hydroxyproline and hydrolysine

60
Q

Biosynthesis of collagen

A
  1. Nucleus
  2. Translated then enters RER
  3. Proline and lysine residues hydroxylated
  4. Hydroxylysine residues are glycosylated
  5. Three pro alpha chains assemble
  6. Triple helix (pro collagen) formed and enter golgi
  7. Secrets into ECM
  8. Tropocollagen formation
  9. Multiple tropocollagen forms collagen by cross linking
61
Q

Name two collagen defects

A
  1. EDS- fragile skin and joints
  2. OI- bones bend and fracture
62
Q

What is elastin?

A

A connective tissue proteins with rubber like properties

63
Q

Where are elastin fibers found?

A

Lungs, walls of large arteries and elastic ligaments

64
Q

How does elastin stretch?

A

It can be stretched several times the normal length but recoil to the original shape when the stretching force is relaxed

65
Q

Keratin is made of what?

A

Alpha helical polypeptides

66
Q

keratin is found in

A

Hair, wool, skin, horns

67
Q

Enzymes

A

Protein catalyst that increase the rate of reactions without being changed in the overall process

68
Q

RNA with catalytic activity

A

Ribozymes

69
Q

How many kinds of enzymes?

A

6

70
Q

Oxidoreductase

A

Redux rxns (alcohol dehydrogenase)

71
Q

Transferase

A

Add groups (hexokinase)

72
Q

Hydrolase

A

Chymotrypsin

73
Q

Lyase

A

Lyse or break apart (pyruvate decarboxylase)

74
Q

Isomerase

A

D to L (alanine racemase)

75
Q

Ligase

A

Join or add (pyruvate carboxylase)

76
Q

What are additional enzyme classes?

A

Synthase, phosphatase, phosphorylase, kinase

77
Q

Synthase

A

Catalyzes a synthesis process

78
Q

Phosphatase

A

Removes a phosphate group

79
Q

Phosphorylase

A

breaks bond by using inorganic phosphate PI (adds phosphate)

80
Q

Kinase

A

Adds a phosphate group from a high energy molecule such as ATP

81
Q

Oxidase

A

catalyzes oxidation reduction reactions using oxygen as the electron acceptor but oxygen atoms are not incorporated into the substrate… they remove electrons and make it positive

82
Q

Oxygenase

A

Oxidize a substrate by transferring oxygen atoms to it

83
Q

Enzymes have an active site which contains…

A

Amino acids side chains that participate in substrate binding and catalysis

84
Q

What is the efficiency of enzymes?

A

10^3-10^8 times faster

85
Q

Enzymes are _____

A

Specific (only one type of reaction with one or few substrates)

86
Q

What does it mean to say enzyme activity can be regulated?

A

Increased or decreased

87
Q

Where are most enzymes located?

A

Specific organelles within a cell

88
Q

Holoenzyme

A

Enzyme with its non-protein component (active)

89
Q

Apoenzyme

A

Enzyme without its non-protein component (inactive)

90
Q

Cofactor

A

Non-protein moiety that is in organic or organic of the enzyme

91
Q

Coenzyme

A

non-protein small organic molecule frequently derived from vitamins such as NAD plus and FAD

92
Q

Prosthetic group versus co-substrate

A

A prosthetic group refers to coenzymes that are permanently associated with an enzyme while cosubstrate refers to coenzymes that are only transiently associated with the enzyme

93
Q

Allosteric enzymes

A

Can be activated or inhibited

94
Q

An Apoenzyme, coenzyme and cofactor are all considered what?

A

Holoenzyme

95
Q

Organic

A

Coenzyme

96
Q

In organic

A

Cofactor

97
Q

Chemical reactions have an energy barrier called what?

A

The free energy of activation and it has the energy difference between that of the reactants and a high energy intermediate that occurs during the formation of the product

98
Q

Free energy of activation

A

Energy difference between the reactants (starting material) and a high energy intermediate (transition state) that occurs during the formation of the product

99
Q

What must be overcome for molecules to react?

A

Sufficient energy to overcome the transition state

100
Q

What does an enzyme do?

A

Lowers the free energy of activation

101
Q

What factors affect reaction velocity?

A

Substrate concentration, temperature, pH

102
Q

Increased substrate concentration does what to an enzyme catalyzed reaction?

A

Increases the rate of the reaction until the max velocity is reached

103
Q

Most enzymes follow the Makaylas Menton kinetics hyperbolic curve

A

Single active site

104
Q

Allosteric enzymes do not follow what?

A

Michaelis mentin bc they have multiple active sites

105
Q

Increase temperature does what to reaction velocity?

A

Increase is it by increasing the number of molecules to have sufficient energy to pass over the energy barrier but too much can cause denaturation

106
Q

PH and reaction velocity

A

Different PH’s are better for different enzymes but catalytic activity may require an amino group to be in the protonated form

107
Q

What foremost the amino group of the enzyme be in for catalytic activity to occur?

A

Protonated

108
Q

What does the Michael is menten equation describe?

A

It describes how velocity varies with substrate concentration

109
Q

Km

A

Affinity of the enzyme for the substrate

110
Q

A higher Km value means what?

A

Lower affinity of the enzyme for the substrate

111
Q

1st order

A

When substrate is much less than Km (it’s the little box)

112
Q

0 order

A

Everything after the little box and it’s one substrate is greater than Km

113
Q

LineweaverBurke plots help us to see when _____ has been achieved

A

Vmax

114
Q

Lineweaver x and y axis

A

X is 1/S
Y is 1/V0

115
Q

In lineweaver plot….

A

The numbers get larger moving closer to the origin

116
Q

X axis intercept

A

-1/Km

117
Q

Y axis intercept

A

1/Vmax

118
Q

_______ Are the most abundant and diverse molecules

A

Proteins

119
Q

Proteins are______ made of_____ made of ________

A

Polymers, monomers, amino acids

120
Q

______ common or standard amino acids coded by DNA

A

20

121
Q

Which group determines the property of an amino acid?

A

R group

122
Q

_______ has an H for the R group

A

Glycine

123
Q

Standard amino acids have a 1° amino group except for

A

Proline (2° amino group has a ring shape)

124
Q

_______ forms extended fibrous structure of collagen

A

Proline

125
Q

Protein contains what

A

Polyproline type two helix more than alpha helix

126
Q
A

Biochem exam 1 (1 decks)

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