Brainscape's Knowledge GenomeTM

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


See full index

► Med - Anatomy & Physiology > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

What has more carbon oxidation: alkane (in fats) or carbon dioxide?

A

Carbon dioxide

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

What is the final product of catabolism?

A

Carbon dioxide

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

What is more reduced: alcohol or aldehyde?

A

Alcohol

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

What are three biomolecules used for information storage?

A

DNA
RNA
NADH/NAD

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

What is the energy currency?

A

ATP

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

What do peptides and proteins consist of?

A

Amino acids

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

Give three types of lipids

A

Triglycerides
Phospholipids
Steroids

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

What are the two nucleic acids?

A

DNA

RNA

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

Name 4 disaccharides

A

Lactose
Maltose
Sucrose
Cellobiose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Name two polysaccharides

A

Cellulose

Glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the first law of thermodynamics?

A

Energy is neither created or destroyed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the second law of thermodynamics?

A

When energy is converted from one form to another, some of that energy becomes unavailable to do work

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

What are reactions in which the total free energy of the product is less that the total free energy of the reactant?

A

Exergonic reactions

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

In an exergonic reaction, what is deltaG? and are the reactions spontaneous or not?

A

Negative and spontaneous

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

What are reactions in which the total free energy of the products is more than the total free energy of the reactants?

A

Endergonic

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

What is deltaG in endergonic reactions?

A

positive

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

deltaG values of near zero are characteristic of what?

A

Readily reversible reactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What enzyme catalyses the reaction of glucose-6-phosphate to glucose-1-phosphate?

A

Phosphoglucomutase

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

What are anhydride bonds?

A

High energy bonds

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

What is catabolism?

A

breaking down complex molecules into smaller ones and releasing energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is anabolism?

A

Synthesising complex molecules out of smaller ones in energy-consuming reactions

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

Give an example for a catabolic pathway?

A

Glycolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What pathway is the initial breakdown of glucose for the generation of ATP?

A

Glycolysis

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

What is the net gain of ATP molecules per glucose molecule in glycolysis?

A

Net gain of 2 ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Give an example of an anabolic pathway?

A

Gluconeogenesis

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

What pathway involves making new glucose from non-carbohydrate precursors such as pyruvate?

A

Gluconeogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are useful control points in metabolic pathways?

A

Reactions with large negative deltaG values are useful control points

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Is water polar or non-polar?

A

Polar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What shape are water molecules?

A

Tetrahedral shape and forms a dipole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are amphipathic molecules?

A

Both hydrophilic and hydrophobic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What type of molecule is sodium palmitate?

A

Amphipathic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What do peptides have at each end of their molecules?

A

N-terminal residue and C-terminal residue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What direction is the peptide chain in?

A

From N-terminal to C-terminal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

State three things about peptide bonds?

A

Peptide bonds have a partial double bond character
Peptide bonds are planar
Peptide bonds are strong and rigid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is pH?

A

The measurement of the amount of protons in a solutions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What important equation lets us calculate the properties of buffer solutions?

A

Henderson-Hasselbalch equation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

State the Henderson-Hasselbalch equation

A

pH = pKa + log [A-]/[HA]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What substances tend to resist a change of pH on addition of moderate amounts of acid or base?

A

A buffer solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What are zwitterions?

A

Amino acids without charged side groups exist as these in neutral solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is the pH at which a molecule has no net charge called?

A

The isoelectric pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What can act as buffers?

A

Proteins e.g. haemoglobin in the blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What is the primary structure of a protein?

A

The sequence of amino acid residues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What is the secondary structure of a protein?

A

The localised conformation of the polypeptide backbone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What is the tertiary structure of a protein?

A

The three-dimensional structure of an entire polypeptide chain, including its side chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is the quaternanry structure of a protein?

A

The spatial arrangement of polypeptide chains in a protein with multiple subunits

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What two angles can polypeptides rotate around?

A

angle between:

The alpha-carbon and the amino group
The alpha-carbon and the carboxyl group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What are the three types of secondary protein structures?

A
  1. Alpha helix
  2. Beta strands and sheets
  3. Triple helix
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

How many polypeptide chains does an alpha helix have?

A

One

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What residues break alpha helixes?

A

Proline residues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What two directions could betasheets be in?

A

Parallel or antiparallel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What are the turns between strands on beta sheets?

A

Glycine and proline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Give an example of a triple helix?

A

Collagen triple helix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What type of protein structure is the component of bone and conective tissues?

A

Collagen triple helix (secondary)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

In what protein structure does this occur: three left handed helical chains twisted around each other form a right-handed superhelix?

A

Collagen triple helix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What 2 types of bonds do collagen triple helixes have?

A

Inter-chain H-bonds - involving hydroxylysine and hydroxyproline
Covalent inter- and intra-molecular bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What type of protein structure are fibrous proteins and globular proteins?

A

Tertiary structures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What type of proteins contain polypeptide chains organised approximately parallel along a single axis?

A

Fibrous proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Give two examples of fibrous protein?

A
  1. Keratin of hair and wool

2. Collagen of connective tissue of animals including cartilage, bones, teeth, skin and blood vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What proteins are folded into more or less spherical shapes?

A

Globular proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Which are soluble in water: Globular proteins or Fibrous protiens?

A

Globular protiens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Give two examples of globular proteins?

A

Myoglobin

Haemoglobin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What 5 forces stabilise tertiary protein structures?

A
  1. Covalent disulphide bonds
  2. Electrostatic interactions = salt bridges
  3. Hydrophobic interactions
  4. Hydrogen bonds: back bone, side chain
  5. Complex formation with metal ions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Where are charged (polar) side groups normally located?

A

On the outside of proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Where do amino acids with hydrophobic side-chains tend to cluster?

A

In the centre of globular proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

In sickle cell anaemia - what is the single nucleotide sequence change?

A

In coding region of the beta-chain of haemoglobin A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

What does the single nucleotide sequence change in sickle cell anaemia result in?

A

Valine instead of glutamic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

What happens to haemoglobin under low oxygen conditions?

A

Haemoglobin polymerises which results in rigid, sickle shape cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Give 2 examples of disease caused by malfunctions with folding polypeptide chains

A

Alzheimers

Parkinsons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

What are prion proteins?

A

Normal components of teh brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

Where are disease-causing forms of prion proteins?

A

Enriched in beta-sheets (aggregates into multimeric complexes, resistant to degradation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

What do Thiol agents and reducing agents do to disulphide bonds?

A

Reduce and therby disrupt disulphide bonds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

In myoglobin - what does the haem group contain?

A

An iron ion (Fe II) and a prosthetic group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

How many subunits does haemoglobin have?

A

4 - two alpha and two beta chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

How many oxygen molecules can each sub unit of haemoglobin bind?

A

ONE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

What is nucleotide to nucleotide?

A

Transcription

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

What is nucleotide to amino acid?

A

Translation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

What is a nucleoside?

A

A base and sugar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

What is a nucleotide?

A

A nucleoside and a phosphate group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

What does ribose have attached to carbon 2?

A

OH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

What does 2-deoxyribose have attached to its carbon 2?

A

H

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

What are the purines?

A

Adenine and Guanine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

What are the pyrimidines?

A

Uracil, Thymine and Cytosine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

What is a phosphodiester bond formed between?

A

A free 3’ OH group and a 5’ triphosphate group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

What end of the DNA strand are new nucleotides added to?

A

3’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

What drug is used to suppress HIV?

A

Retrovir

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

How many hydrogen bonds are between A and T?

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

How many hydrogen bonds are between C and G?

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

What type of replication is semi-conservative?

A

DNA replication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

What is DNA replication catalysed by?

A

DNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

What is required to start DNA replication?

A

An RNA primer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

What are the fragments called on a lagging strand?

A

Okazaki fragments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

What unwinds the double helix?

A

DNA helicase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

What are the 4 building blocks of DNA replication?

A

dATP
dTTP
dCTP
dGTP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

During DNA replication one phosphate group froms phosphodiester bond, what do the other two leave as?

A

Pyrophosphate - energy supply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

What strand is the leading strand?

A

(3’ - 5’)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

What strand is the lagging strand?

A

(5’ - 3”)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

What is the RNA primer synthesised by?

A

Primase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

What are the 3 main classes of RNA?

A
  1. Ribosomal RNA (rRNA) - combines with proteins to form ribosomes where protein synthesis takes place
  2. transfer RNA (tRNA) - carries the amino acids to be incorporated into the protein
  3. messenger RNA (mRNA) - carries the genetic information for protein synthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

What are the two stable types of RNA?

A

Ribosomal RNA and Tranfer RNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

How many types of RNA polymerases do prokaryotic cells have?

A

One

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

How many types of RNA polymerase fo eukaryotic cells have?

A

Pol I, Pol II and Pol III (3 types)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

How can Pol I, Pol II and Pol II be distinguished?

A

By their sensitivity to toxins like alpha-amanitin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

What does Pol II synthesise?

A

All mRNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

What are the five steps of transcription?

A 
RNA polymerase binding
DNA chain seperation
Transcription initiation
Elongation
Termination
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

What does RNA polymerase binding require?

A

Transcription factors

106
Q

What are initiation sites on DNA called?

A

Promoters

107
Q

Where is the TATA box found?

A

In a promoter

108
Q

What does a TATA box binding protein do first?

A

Recognises TATA box

109
Q

What is TFIID?

A

a general transcription factor

110
Q

What is TFIID required for?

A

All Pol II transcribed genes

111
Q

What two steps occur after TATA box binding protein has recognised a TATA box?

A
  1. Introduces a kink into DNA - determines transcriptional start and direction
  2. Provides a landing platform for further transcription factors and for RNA polymerase
112
Q

What do Pol II and TFIID do on their own?

A

Extend transcript

113
Q

What kind of structure does newly synthesised RNA make?

A

A stem loop structure

114
Q

Specific regulation of transcription requires ‘specific’ transcription factors - what are they?

A

DNA-binding proteins

115
Q

What do DNA-binding proteins do?

A

Bind to specific DNA sequences in the vicinity of a promotor

Regulate transcription postively or negatively

116
Q

Name a family of transcription factors

A

Steroid receptors

117
Q

What 3 domains do steroid receptors have?

A

Transactivation domain
DNA-binding domain
Ligand-binding domain

118
Q

What can be said about the DNA-binding and ligand-binding domains on a steroid receptor?

A

They are highly conservative

119
Q

Where are steroid receptors located?

A

In the cell cytoplasm (inactive)

120
Q

What do steroid receptors do once they have binded to a ligand?

A

Move to nucleus and bind to DNA at steroid-response elements

121
Q

In eukaryotic genes what are the coding regions (exons) interrupted by?

A

Non-coding regions (introns)

122
Q

What has to be removed before translation into a protein?

A

Introns (splicing)

123
Q

When processing the ends of mRNAs, what two things are added?

A
  1. Addition of poly(A) TAIL

2. Addition of 5’ cap

124
Q

During translation, anticodons of tRNA molecules form base pairs with what?

A

Codons on mRNA

125
Q

What are the 7 components of translation?

A
  1. Amino acids
  2. tRNAs
  3. Aminoacyl-tRNA synthetases
  4. Set of protein factor for initiation of protein synthesis, elongation of polypeptide chain and translocation and termination
  5. ATP and GTP as sources of energy
  6. Ribosomes
  7. mRNA
126
Q

What binds amino acids to their corresponding tRNA molecules?

A

Aminoacyl-tRNA synthetase

127
Q

How many rRNA molecules do ribosomes contain?

A

4

128
Q

What are the 3 tRNA binding sites on ribosomes?

A 
E = exit
P = Peptidyl
A = aminoacyl
129
Q

What does inititation require?

A

Initiation factors

130
Q

What gives the energy required for initiation?

A

GTP is hydrolysed to provide energy for inititation

131
Q

What is AUG?

A

Start codon

132
Q

What base pairs with the start codon?

A

Special ‘initiator’ tRNA with UAC anticodon base pairs

133
Q

During elongation: what brings the next aminoacyl-tRNA to the A site?

A

An elongation factor (EF-1alpha)

134
Q

What regenerates EF1alpha to pick up the next aminoacyl-tRNA?

A

A second elongation factor (EFbetagamma)

135
Q

What does peptidyl transferase catalyse?

A

Peptide bond formation between amino acids in the P and A sites

136
Q

What moves the ribosome along the mRNA?

A

Elongation factor EF-2

137
Q

When does termination of protein synthesis occur?

A

When the A site of the ribosome encounters a stop codon

138
Q

What does release factor RF do in termination of protein synthesis?

A

Binds to stop codon - GTP hydrolysis

139
Q

What is a point mutation?

A

A change in a single base in DNA

140
Q

What is a missense mutation?

A

Results in a change of amino acid sequence

Can change protein function e.g. altered haemoglobin in sickle cell anaemia

141
Q

What mutation creates a new termination codon and changes the length of protein due to premature stop of translation?

A

Nonsense mutation

142
Q

What mutation is due to degeneracy of the genetic code, has no effect on protein function and has no change of amino acid sequence?

A

Silent mutation

143
Q

What is a frameshift mutation?

A

Addition or deletion of a single base

144
Q

What are the 4 chromosomal mutations?

A
  1. Deletions
  2. Duplications
  3. Inversions
  4. Translocations
145
Q

What do free ribosomes in the cytosol make proteins destined for?

A

Cytosol
Nucleus
Mitochondria
Translocated post-trranslationally

146
Q

Where do bound ribosomes on the rough endoplasmic reticulum make proteins destined for?

A 
Plasma membrane
ER
Golgi apparatus
Secretion 
Translocated co-translationally
147
Q

What is glycosylation?

A

The addition and processing of carbohydrates in the ER and the Golgi

148
Q

Give three examples of post-translational modifications?

A
  1. Proteolysis
  2. Glycosylation
  3. Phosphorlyation
149
Q

What is I-cell disease?

A

Inherited recessive disorder of protein targeting
Proteins normally destined for lysosomes are not properly sorted in the Golgi
End up secreted from cell
Lysosomes cannot properly digest material and become clogged

150
Q

What do enzymes do to the activation energy?

A

Reduce it by providing alternative reaction pathways

151
Q

What does catalytic activity of many enzymes depend on the presence of?

A

Cofactors

152
Q

What are the two types of cofactors?

A
  1. Metal ions

2. Organic molecules - also called coenzymes

153
Q

What are tightly bound coenzymes called?

A

Prosthetic goup

154
Q

What is an enzyme without a cofactor called?

A

Apoenzyme

155
Q

What is an enzyme with cofactor called?

A

Holoenzyme

156
Q

What are NAD+ and FAD?

A

Coenzymes

157
Q

What does CoA (coenzyme A) do?

A

Transfers acetyl groups

158
Q

Three pancreatic serine proteases contain reactive serine residue and they catalyse hydrolysis of peptides at specific sites. What are the three proteases and how do they work?

A
  1. Chymotrypsin: hydrophobic pocket binds aromatic amino acids
  2. Trypsin: negatively charged Asp interacts with positively charged Lys or Arg
  3. Elastase: active site partially blocked, only amino acids with small or no side chains can bind
159
Q

Would trypsin active site be affected by a small change in pH?

A

Yes

160
Q

What are isozymes?

A

They are isoforms of enzymes that catalyse the same reaction but have different properties and structure

161
Q

What isozyme is involved in developmental variation?

A

Haaemoglobin

162
Q

Give an example of a tissue specific isoform?

A

Lactate Dehydrogenase (LDH)

163
Q

Where are the two types of subunit in LDH present?

A

One predominantly in the heart

One predominantly in skeletal muscle

164
Q

What does an increase in LDH in blood suggest?

A

Tissue damage

165
Q

What is Creatine Kinase (CK)?

A

A dimeric protein which binds to the muscle sacromere

166
Q

Where is the M form of CK produced?

A

In the muscle

167
Q

Where is the B form of CK produced?

A

In the brain

168
Q

What are phosphorylation reactions carried out by?

A

Protein kinases

169
Q

What are zymogens?

A

Inactive precursors of an enzyme - are irreversibly transformed into active enzymes by cleavage of a covalent bond

170
Q

In the pancreas: what two zymogens are formed?

A
  1. Trypsinogen

2. Chymotrypsinogen

171
Q

What is the formation of the enzyme-substrate complex (ES) described by?

A

KM - The Michaelis constant - a combination of all rate constants in the reaction

172
Q

What is Vmax?

A

The maximal rate of reaction at unlimited substrate concentration

173
Q

How is the initial rate of an enzyme reaction is measured?

A

The tangent at the curve at time 0

174
Q

What is the Michaelis constant KM equivalent to?

A

The substrate concentration where the intitial reaction rate is half-maximal

175
Q

KM = [S] at?

A

at 0.5 Vmax

176
Q

What does a low KM mean?

A

That an enzyme only needs a little substrate to work at half-maximal velocity

177
Q

What does a high KM mean?

A

That an enzyme needs a lot of substrate to work at half-maximal velocity

178
Q

What describes the rate of catalysis as a function of substrate concentration?

A

The Michaelis-Menton equation

179
Q

On a Lineweaver-Burk plot how can Vmax be determined?

A

From the intersection of the straight line with the Y axis

180
Q

On a Lineweaver-Burk plot, how can KM be determined?

A

From the intersection with the X axis

181
Q

What is glucokinase?

A

An isozyme in liver and pancreas

182
Q

Where is hexokinase I found?

A

In red blood cells

183
Q

What is caused by mutations in pancreatic glucokinase which affect KM or Vmax?

A

MODY - Maturity-Onset Diabetes of the Young

184
Q

What is a reversible inhibitor?

A

A substance that binds to an enzyme to inhibit it, but which can be reversed

185
Q

What is an irreversible inhibitor?

A

A substance that causes inhibition that cannot be reversed

186
Q

How can the competetive inhibitor of an enzyme be ‘out-competed’?

A

By the addition of lots of substrate

187
Q

How can a non-competitive inhibitor be ‘out-competed’?

A

It cannot

188
Q

What are the 5 methods of enzyme control?

A
  1. Allosteric control
  2. Regulation of traanscription - varies rate of protein synthesis
  3. Reversible covalent modification - we have seen phosphorylation as one mechanism
  4. Irreversible covalent modification - we have seen proteolytic cleavage
  5. Degradation
189
Q

Inhibition of rate limiting enzymes by end products is a common mechanism of what?

A

Allosteric control

190
Q

What type of enzymes do not follow Michaelis-Menten kinetics?

A

Allosteric enzymes

191
Q

Give an important example for allosteric regulation

A

Binding of oxygen to haemoglobin

192
Q

What is the binding of oxygen to haemoglobin controlled by?

A

H+
CO2
2,3 bisphosphoglycerate (side product of glycolysis)

193
Q

In the absence of substrate - what are most enzyme subunits in?

A

The inactive from (tight form)

194
Q

The binding of a substrate induces a conformational change from which forms?

A

T form to R form

195
Q

What do allosteric activators or inhibitors do to the binding of a substrate?

A

Lock subunits in the T or R form

196
Q

Where is fat stored?

A

In adipose tissue

197
Q

Where are ketone bodies formed?

A

In liver mitochondria

198
Q

What type of process is catabolism?

A

Oxidative, endergonic

199
Q

What type of process is anabolism?

A

Reductive, endergonic

200
Q

What are proteins broken down into?

A

Amino acids

201
Q

What are polysaccharides broken down into?

A

Simple sugars

202
Q

What are lipids broken down into?

A

Fatty acids and glycerol

203
Q

During catabolism: small molecules from the degradation of macromolecules enter cells and are converted into a small number of very simple molecules, what are they?

A

2- carbon acetyl-CoA

some ATP is produced

204
Q

What group of acetly-CoA enters the Krebs cycle?

A

Acetyl group

205
Q

What happens to the acetyl group one it has entered the Krebs cycle?

A

It is completely degraded to CO2 and water

206
Q

What allows glucose to transport into cells?

A

Na+/glucose symporters, via passive facilitated diffusion glucose transporters

207
Q

Where is GLUT 1 transporter present?

A

In teh brain

208
Q

Where is GLUT 2 transporter present?

A

In the liver

Beta-cells

209
Q

Where is GLUT 3 transporter present?

A

In the brain

210
Q

Where are GLUT 4 transporters present?

A

In muscle and adipose tissue

211
Q

Where are GLUT 5 transporters present?

A

In teh gut

212
Q

What is the initial pathway for the conversion of glucose to pyruvate?

A

Glycolysis

213
Q

What is hexokinase involved in?

A

The conversion of glucose to glucose-6-phosphate

214
Q

What is phosphofructokinase involved in?

A

The conversion of fructose 6-phosphate to fructose 1,6-biphosphate

215
Q

What controls the conversion of phosphoenolpyruvate to pyruvate?

A

Pyruvate kinase

216
Q

What is the key enzyme in the control of glycolysis?

A

Phosphofructokinase

217
Q

What are the 3 negative modulators of phosphofructokinase?

A
  1. ATP
  2. Citrate
  3. H+ - prevents the excessive formation of lactic acid
218
Q

What are the 2 positive modulators of phosphofructokinase?

A

AMP

fructose 2,6-bisphosphate

219
Q

The ATP/AMP ratio is called the energy charge: if all adenylate nucleotides are in the shape of ATP what is the cell said to be in?

A

A fully charged state

220
Q

What does glycolysis reduce NAD+ to?

A

NADH + H+

221
Q

What must happen to NADH for glycolysis to continue?

A

It must be re-oxidised

222
Q

What are the 2 fates of pyruvate anaerobically?

A
  1. Alcohol fermentation - yeast can form ethanol from pyruvate
  2. Lactic acid fermentation - some microorganisms can convert pyruvate to lactate
223
Q

What is the fate of pyruvate in aerobic conditions?

A

Further oxidation and more energy released

224
Q

What enzyme is involved in the conversion of pyruvate to lactate?

A

Lactate dehydrogenase

225
Q

In what cycle does further oxidation of pyruvate occur?

A

The citric acid cycle or Krebs cycle or TCA cycle

226
Q

What does the matrix of the mitochondria contain?

A

Enzymes for the TCA cycle

227
Q

What do the inner membranes of mitochondria contain?

A

Proteins for electron transport chain, ATP synthase and transport proteins

228
Q

Once in the mitochondria what does the pyruvate dehydrogenase complex (PDC) do to pyruvate?

A

Catalyses the oxidative decarboxylation of pyruvate to acetyl-CoA

229
Q

Is the reaction of pyruvate to acetyl-CoA reversible?

A

NO ACETYL-COA CANNOT BE CONVERTED TO PYRUVATE

230
Q

The pyruvate dehydrogenase complex consists of 3 enzymes involved in the actual reaction - what are they?

A

E1, E2 and E3

231
Q

Pyruvate dehydrogenase complex also contains 2 enzymes involved in the control of PDC - what are they?

A

A kinase and a phosphatase in a single polypeptide

232
Q

Pyruvate dehydrogenase complex also contains 5 coenzymes - what are they?

A

Thiamine, lipoic acid, coenzyme A, FAD and NAD+

233
Q

How many GTP is formed during the TCA cycle?

A

one GTP

234
Q

What enzyme of the TCA cycle is not located in the mitochondrial matrix?

A

Succinate dehydrogenase - integrated in the inner mitochondrial membrane

235
Q

What enzyme is involved in this reaction:

Succinate + FAD = fumerate + FADH2

A

Succinate dehydrogenase

236
Q

What is acetyl-CoA oxidised completely to in teh TCA cycle?

A

Carbon dioxide

237
Q

What does each turn of the TCA cycle involve?

A

The uptake of 2 carbon atoms in the form of acetyl-CoA and the release of 2 carbon atoms as carbon dioxide

238
Q

Each turn of the TCA cycle involves the transfer of 3 pairs of electrons to NAD+ to form?

A

NADH + H+

239
Q

Each turn of the TCA cycle also results in the transfer of 1 pair of electrons to reduce FAD to what?

A

FADH2

240
Q

From each acetyl-CoA the TCA cycle generates what?

A

3 x NADH + H+
1 x FADH2
1 x GTP
2 x CO2

241
Q

All together, the reactions of glycolysis, pyruvate dehydrogenase complex and the TCA cycle produce?

A

10 NADH + 10 H+

2 FADH2

242
Q

In oxidative phosophorylation, the electron transfer potential of NADH+ and FADH2 is converted into what?

A

The phosphoryl transfer potential of ATP

243
Q

What can phosphoryl transfer potential be measured by?

A

Free energy change for the hydrolysis of ATP

244
Q

What can the electron transfer potential be measured by?

A

The redox potential of a compound

245
Q

What is a measure of how readily a reduced substance donates an electron?

A

The standard redox potential

246
Q

What is the driving force of oxidative phosphorylation?

A

The reduction of oxygen by NADH

247
Q

What are the two stages of oxidative phosphorylation?

A
  1. Electron transport (electrons flow from NADH tand FADH2 to oxygen, respiratory chain, energy is used to pump H+ out of the mitochondrial matrix)
  2. ATP synthesis
248
Q

During electron transport - where do electrons from NADH enter?

A

At complex I

249
Q

During electron transport where do the electrons from FADH2 enter?

A

At complex II

250
Q

What are proteins which contain a haem group as a functional co-factor?

A

Cytochromes

251
Q

Where is the F1 subunit of ATP synthase located?

A

Protrudes into the mitochondrial matrix

252
Q

Where is the F0 subunit of ATP synthase located?

A

As a hydrophobic complex in the inner memrbane - contains the proton channel

253
Q

What forms stator (ATP synthase)?

A

a, b, alpha, beta and delta subunits form stator

254
Q

What forms rotor (ATP synthase)?

A

c, gamma and (greek E) subunits form rotor

255
Q

What turns the rotor in ATP synthase?

A

Flow of protons

256
Q

What three things inhibit transfer of electrons to oxygen during oxidative phosphorylation?

A

Cyanide
Azide
CO

257
Q

What does brown adipose tissue contain?

A

Uncoupling protein (UCP) = thermogenin

258
Q

Where does glycolysis take place?

A

in the cytoplasm

259
Q

How does NADH from the cytoplasm get into the oxidative phosphorylation pathway?

A

The glycerol-3-phosphate and malate shuttles overcome this

260
Q

How much ATP does one glucose molecule yield?

A

30-32 ATP molecules

261
Q

What is phosphorylation and de-phosphorylation?

A

The addition or removal of PO4

► Med - Anatomy & Physiology (130 decks)

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