Biochemistry Cameron McCloskey Flashcards
(187 cards)
1
Q
How do catalysts function?
A
They speed up reaction rate by lowering activation energy
2
Q
What is the transition state (intermediate) in a reaction?
A
This is the unstable stage beween reactants and products
3
Q
What is glycogen storage disease and what are its consequences?
A
It is an enzyme deficiency that results in the failure of glycogen to reach the phosphorylated transition state
This means glucose cannot be obtained from glycogen stores
Hepatomegaly (fatty liver) will result due to glycogen build up
4
Q
What are the variants of the extra molecules (as well as enzymes) that are often reqired for some enzymatic processes to proceed?
A
- Cofactors - metal ions
- Coenzymes - organic molecules
5
Q
What are metal ions that contain metal cofactors called?
A
Metalloproteins
6
Q
Like enzymes, cofactors are always ____________ at the end of a reaction
A
Regenerated
7
Q
Tightly bound coenzymes are called what?
A
Prosthetic groups
(these confer additional function)
8
Q
What is the term given to an enzyme without a cofactor?
A
Apoenzyme
9
Q
An enzyme with a cofactor is called what?
A
Holoenzyme
=Cofactor +apoenzyme
10
Q
Give examples of metal ions that could be used as cofactors
A
- Zinc
- Copper
- Iron
11
Q
Give examples of coenzymes
A
- Vitamins
- NAD
- FAD
- Lipoate
12
Q
Binding of a substrate to an ezyme results in what?
A
Conformational change of the enzyme around the substate
This is induced fit (due to intermolecular bonding)
The enzyme/substate complex is now formed
13
Q
Which two main factors affect enzyme fucntionality?
A
- Temperature
- pH
14
Q
Describe the how temperature can affect the rate of an enzymatic reaction
A
It will increase to a point and then sharply drop off (past the optimum temp) due to enzyme denaturing
15
Q
Describe how increasing pH affect the rate of an enzymatic reaction
A
It will increase as pH increases until the optimum rate is achieved (at optimum pH) and then will decrease again
This produces a bell curve
16
Q
What are isozymes?
A
Enzymes which have almost identical function but have slightly different amino acid sequencing
17
Q
How can the number of certain isozymes in certain tissues/blood be used to diagnose a medical condition?
A
Different isozymes are synthesised in different regions of the body or at different atges in embryonic/foetal development
Finding the “wrong” isozyme at a certain time, or location in the body may be indicative of a medical condition
18
Q
How can phosphorylation regulate enzyme activity?
A
It can convert the enzyme between inactive and active forms
19
Q
Phosphorylation is a reversible process that involves which two enzymes?
A
- Kinase - adds phosphate
- Phosphotase - removes phosphate
20
Q
What are zymogens?
A
also called Proenzyme Inactive precursors of an enzyme which are converted to active forms by cleavage of a covalent bond
21
Q
What is produced after the catabolism of glucose?
A
Two pyruvate molecules
There is also a net gain of 2ATP, 2NADH, FADH2 and 2H+
22
Q
What is NAD+?
A
Nicotinamide adenine dinucleotide
It is derived from niacin - a vitamin
It is used as an electron carrier by forming NADH
23
Q
What is NADH required for?
A
The transfer of electrons to the respiratory electron transfer chain in stage 3 of ATP synthesis
24
Q
What are the three diferent terms used to describe the second stage of ATP synthesis?
A
- Citric acid cycle
- Krebs cycle
- Tricarboxylic acid cycle (TCA)
25
Where does the TCA cycle occur?
Mitochondrial matrix on the inner membrane
(this is where proteins required for the electron transport chain can be found, as well as ATP synthase and transport proteins)
26
Where is pyruvate synthesised?
The cytosol
27
How does pyruvate enter the matrix of the mitochondria? (3)
It must cross two membranes
* The intermembrane space is very acidic creating a pH gradient from the cytosol to the matrix which pyruvate can follow
* There is also a electrochemical gradient and pyruvate can utilise this as it is attracted to H+
* A pyruvate symport transporter allows entry of pyruvate into the mitochondria using H+/pyruvate symport, a form of contransport, by faciliated diffusion
28
Which process must pyruvate undergo to be converted to acetyl-CoA?
Oxidative decarboxylation
This is an irreversible reaction
29
Describe the four stages of the oxidative decarboxylation of pyruvate
1. Pyruvate dehydrogenase converts pyruvate to hydroxyethyl thiamine pyrophosphate (HETPP), CO2 is given off as a by product
2. Dihydrolipoyl transacetylase transfers (and oxidises) the hydroxyethyl group to lipoic acid which forms acetyl dihydrolipoamide
3. The acetyl group is transferred to CoA forming one acetyl CoA per pyruvate
4. NAD+ reoxidises dihydrolipoamide which forms one NADH - this is mediated by dihydrolipoyl dehydrogenase
30
what enzymes that are involved in the highly exergonic and irreversible reactions of the Krebs cycle?
* **Citrate synthase**, Both NADH , citrate and succinyl CoA inhibits,
* **isocitrate dehydrogenase , ADP, Ca2+ activates whereas NADH inhibits**
* **α-ketoglutarate dehydrogenase, Both NADH and succinyl CoA inhibits, where Ca2+ stimulate it**
31
Describe the TCA cycle
1. Acetyl CoA forms citric acid upon binding to a four carbon subunit
2. Decarboxylation of citric acid occurs twice yielding 2CO2
3. Citric acid will also go through four oxidation reactions yielding 3NADH, 3H and FADH2
4. As a result GTP is produced, and by the end the 4-carbon subunit is reformed
32
Where are all enzymes for the TCA cycle found and what is the exception?
Mitochondrial matrix
Succinate dehydrogenase is found in the inner mitochondral membrane - this is required to allow FADH2 to be synthesised
33
Overall, what does one molecule of glucose yield until the stage at the end of the TCA cycle?
* 4 ATP
* 10 NADH
10 H+
* 2FADH2
* 6CO2
34
What is PDC deficiency?
A sex linked condition only survivable by carrier females.
It will largely present as a neurological diseas ein childhood.
35
What is VMAX?
The maximum rate at which an enzyme can function
36
What is Km?
The Michaelis-Menten constant
This is the concentration of substrate required to elicit a reaction rate equal to 50% of VMAX
37
How is Km calculated?
Km = (k2 + k-1)/k1
* k1 is the forward rate constant for enzyme association with the substrate.
* k-1 is the backwards rate constant for enzyme dissociation from the substrate.
38
What is a Lineweaver-Burk plot?
This is a method of accurately determining Vmax and Km
The Michaelis-Menten equation (V0 = (Vmax[s])/Km + [s]) can be rearranged to the form y = mx + c
Therefore it can be plotted as a straight line
* The gradient = km/Vmax
* The y intercept equals = 1/Vmax
39
What are the two types of enzyme inhibition?
1. Reversible
2. Irreversible
40
What are the two types of reversible enzyme inhibition and describe them
1. Competitive - inhibitor binds to active site used by substrate (orthosteric inhibition)
2. Non-competitive - Inhibitor binds to an allosteric site to cause inhibition by changing conformation
41
Describe irreversible enzyme inhibition
This is non-competitive and involves a breakage of covalent bonds and change of structure - hence it is irreversible
42
How is Vmax affected by competitive inhibition of enzyme activity?
Vmax does not change
With enough substrate, the inhibitor can always be outcompeted
43
How is Km affected by competitive inhibition of enzyme activity?
Km is increased
As more substrate is required to over come it
44
How is Vmax affected by non-competitive inhibition of enzyme activity?
It is reduced
Some enzymes will become inactive and no increase in substrate can cause Vmax to reach the level it once
This is because enzyme activity will become the limiting factor
45
How is Km affected by non-competitive inhibition of enzyme activity?
It does not change
This is because any increase in substrate concentration will not impact Vmax which is already at its limit under these conditions
46
Which type of enxyme will not follow the Michaelis-Menten model of kinetics?
Allosteric enzymes
47
What is highlighted when Vmax is plotted against substrate concentration for allosteric enzymes?
The cooperation behaviour of the enzymes
A Sigmoidal curve will be present on the graph
48
What is hydrolysis?
A reaction, when water is used to help split up a molecule
49
What is the first law of thermodynamics?
Energy, or matter, cannot be created or destroyed
50
What is the second law of thermodynamics?
When energy is converted from one form to another, energy is always lost - entropy will always increase
51
What is free energy?
The energy that is "free", or available, to do work
52
How can free energy be calculated?
ΔG = ΔH - TΔS
or
ΔG = energy of products - energy of reactants
53
Whe calculating free energy, what is tempertaure measured in?
Kelvin
54
Describe exergonic reactions
1. ΔG is negative
2. Total free energy of products is less than total free energy of reactants(The reaction is feasible)
3. The reaction can proceed spontaneously
55
Describe endergonic reactions
1. ΔG is positive
2. Energy is required in order for the reaction to proceed
56
At equilibrium, what will ΔG equal?
0
57
What is coupling?
This is when an unfavourable process will combine with a favourabe process ensuring the overall reaction is feasible
58
What are amphipathic molecules?
Molecules possessing both hydrophobic and hydrophilic properties
| e.g lipids
59
What are the two types of amino acid and why do two isoforms exist?
L & D
They have tetrahedral molecular formations so can have stereoisomers
60
Both secondary structures utilise _hydrogen bonds_ between the side groups of the amino acids and not between the peptide bonds True / False
Both secondary structures utilise hydrogen bonds **between the peptide bonds** (i.e., the amine [NH2] and carboxyl [COOH] groups) and not between the side groups of the amino acids
61
What are the three types of 3D arrangement in a secondary protein structure?
1. Alpha helices
2. Beta sheets
62
type of bond which hold the .α sheet and .β sheet of the secondary structure
* i**ntramolecular hydrogen bonds**
* i**ntermolecular hydrogen bonds**
63
What are the two directions possible in a beta sheet?
1. Parallel
2. Antiparallel
64
Type of bond present in
Primary
Secondary
Tertiary
Quaternary
structures of amino acid
* primary structure is where amino acids are joined together by strong covalent bond between the amino and carboxyl groups known as peptide bond thus is not freely rotating.
* Secondary structure present in two types Alpha helices which forms intramolecular hydrogen bond with side chain facing outward and Beta sheets forms intermolecular hydrogen bond between the peptide chains and side chain locate above or below the plane.
* Tertiary this where both Alpha helices and Beta sheets join together forming nonspecific hydrophobic interaction (e.g van der Waals) and disluphide bonds of the side chains.
* Quaternary aggregation of two or more individual polypeptides which link two each other by the same noncovalent nonspecific hydrophobic bonds and side chains by disluphide bonds.
65
Albumins act as a protein carrier for fatty acids and steroid-based hormones in the blood. TRUE ?FALSE
True
(cholesterol page)
66
What type of saccharide is lactose?
Disaccharides are also called double sugars. They are formed from two monosaccharides joined together via a glycosidic bond (also known as glycosidic linkage). Examples include sucrose, lactose, and maltose. Do not confuse lactose with galactose; the latter is a monosaccharide
67
What are the two types of tertiary structures in proteins?
1. Fibrous
2. Globular
68
What are the four bases in DNA?
1. Adenine
2. Thymine
3. Cytosine
4. Guanine
69
To which "end" of the RNA strand are more nucleotides added during transcription?
3' end
70
What is the catalyst for DNA replication?
DNA polymerase
71
What is required to commence DNA synthesis and replication?
An RNA primer
(DNA polymerase can take over after this)
72
In which two ways is DNA formed and why?
Continously or discontinuously
* Continuously - DNA is built up from the 5' to the 3' end easily - this is the leading strand
* Discontinuously - the other strand is built from 3' to 5' as it is orientated the other way around - this is the lagging strand
73
The lagging stand in DNA formation must utilise which type of fragments to enable 5' to 3' directional growth?
Okazaki
74
Which enzyme is reponsible for unwinding DNA?
DNA helicase
75
Which enzyme is reponsible for synthesising an RNA primer to initiate replication on the lagging strand?
Primase
76
Describe how Okazaki fragments aid the growth of the lagging strand
* Short newly synthesised DNA fragments - Okazaki fragments are added at intervals from the open DNA strands downwards
* This allows nucleotides to be sythesised in the "correct" direction by essentially filling in the gaps the Okazaki fragments created
* Each time DNA helicase opens up the strand a little more, a new Okazaki fragment can jump in and allow synthesis back down the chain
77
Which enzyme is key in proofreading?
DNA polymerase
78
What are the three differences between DNA and RNA?
1. Single vs double stranded
2. DNA - thymine, RNA - uracil
3. RNA - ribose sugar, DNA - deoxyribose sugar
79
Which enzymes are responsible for RNA production?
RNA polymerases
80
Which variation of RNA polymerase will synthesise mRNA?
Pol II
81
Where will RNA polymerase bind on a section of DNA?
Sections of DNA called promotors
82
What is characteristic about promotor regions on DNA?
They all have the TATA box sequence which marks the beginning of the relevant gene
83
What is a transcription factor, and what is the specific one for TATA box?
A protein that binds to DNA and controls the rate, or allows for transcription
TATA box binding protein will form part of the TFIID protein, the general transription factor for all pol II transcribed genes
84
Once TFIID is present what does it allow for?
It provides a landing site for other transcription factors (RNA polymerase) and allows for the formation of the preinitiation complex
85
Describe the process why which DNA strands are pulled apart
TFIIH - pulls a DNA strnad down into the RNA polymerase cleft
TFIID - hold the other strand in place
86
What are enhancers?
Short regions of DNA that can be bound by protein activators to increase the liklihood of transcription
87
How can enhancers have an influence if they are far from the promotor sequences?
Looping of the strand allows them to come into contact
88
Initially exons and introns are coded together, what is the name of this strand?
Pre-mRNA
89
How is "mature" mRNA created?
Introns are spliced out of the stand leaving only the exons
The 5' end is then capped with GTP preventing degredation
The 3' end has a poly A tail added allowing for recognition
This is **_alternative RNA splicing_**
90
Why are there many more codon oftens for relatively few amino acids?
The coding for amino acids is ***degenerate***
Amino acids can be encoded by more than one codon
91
What are the three tRNA binding sites in ribosomes?
1. E - exit
2. P - peptidyl
3. A - aminoacyl
92
At which point does translation begin?
A ribosomal subunit binds to the 5' end of the mRNA and will move along until the AUG codon
Here, a special initiator tRNA will bind with its UAC anticodon and translation begins
93
Where is the initiator tRNA held?
P site of the ribosome
94
The A site of the ribosome holds what?
The tRNA waiting to be translated
95
What does the P site in the ribosome hold?
The tRNA being translated
96
Which enzyme catalyses the peptide bond formation between amino acids in the P and A positions
Peptidyl transferase
97
What does the E site in the ribosome occupy?
The "empty" tRNA
98
When does termination of translation occur?
When a stop codon is encountered
The is no tRNA base pairing for this, so instead release factor binds and allows for cleavage
99
What is a polysome?
A structure formed when many ribosomes attach to an mRNA sequence
This speeds up the translation process
100
What are the two forms of ribsomes?
1. Free - makes proteins for cytosol, nucleus, mitochondria
2. Bound - makes proteins for plasma membrane, ER, golgi, secretion
101
What are the two main types of post-translation modification?
1. Addition of chemical groups
2. Covalent modification (proteolysis)
102
Metabolism is composed of which two processes?
1. Anabolism - assembly of molecule requiring energy
2. Catabolism - breakdown of products releasing energy
103
What is NAD?
Nicotinamide adenine dinucleotide
It is a coenzyme exising in two forms
1. Reduced - NADH
2. Oxidised - NAD+
104
What is NAD normally involved in?
Catabolic pathways for ATP synthesis
105
What is NADP?
Nicotinamide adenine dinucleotide phosphate (NADPH)
It is a cofactor that exists in two forms:
1. Reduced - NADH
2. Oxidised - NADP+
106
What is NADP normally involved in?
Anabolic pathways for ATP synthesis
107
What are the two equivalent forms of glucose?
1. D-glucose - straight chain molecules
2. Alpha/beta-D-glucose - cyclic molecules
108
How are alpha and beta glucose differentiated?
The first carbon (counting clockwise after oxygen) is orientated up (so the hydroxyl group points up) in the beta form
The opposite is true in the beta form
109
How can glucose be stored? 3
1. Glucose molecules (monosaccharide)
2. Disaccharide sugars (maltose, lactose etc)
3. Long polysaccharides (cellulose or glycogen)
110
How is glucose transported into cells? 2
* Na+/glucose symporters
* Passive diffusion glucose transporters
111
What are the three pathways for glucose breakdown?
1. Oxidation through aerobic glycolysis - yields pyruvate
2. Fermentation anaerobic glycolysis - yields lactate
3. Oxidation through the pentose phosphate pathway - yields ribose-5-phosphate
112
Where does glycolysis occur?
Cytosol
113
The three main sources of glucose for the glycolysis pathway
* dietary carbohydrates,
* glycogen stores,
* recycled glucose from other metabolic pathways (i.e., gluconeogenesis).
114
Describe the stages of glycolysis
* Glucose is split using 2ATP to fructose-1,6-biphosphate
* This intermediate is broken down to 2 triose phosphates
* Each triose phosphate is oxidised by NAD to produce pyruvate
* In total 4 ATP are yielded - 2 come from each tiose phosphate oxidation
115
What happen to pyruvate through glycY
**pyruvate can be converted into acetyl-CoA via the link reaction and subsequently enter the Krebs cycle to be fully oxidised into CO2.**
116
What are the products of glycolysis?
* 2pyruvate
* 2 ATP
* 2NADH
* 2H+
117
Describe briefly the anaerobic process which happen in fast contraction of muscles ?
**anaerobic respiration, the pyruvate derived from the glycolysis pathway does not enter the link reaction and Krebs cycle. Instead, pyruvate is reduced to lactate while NADH is oxidised.** This redox reaction is catalysed by lactate dehydrogenase
118
What is the difference between lactate and lactic acid?
Latate and lactic acid are essentially the same thing
In solution (in the body) a hydrogen ion will dissociate from lactic acid (the carboxyl group) to form a conjugate base - this is lactate and is what is found in the body
119
What are the control points in glycolysis?
* Hexokinase - mediates substrate entry
* Phosphofructokinase - controls substrate movement along glycolytic pathway
* Pyruvate kinase - moderate the exit of product molecules
These are control points because they are irreversible reactions
120
What are the activators of phosphofructokinase?
* AMP
* Fructose 2,6-biphosphate
121
What are the inhibitors of phosphofructokinase?
* ATP - glycolysis slows down when energy is abundant
* Citrate - downstream pyruvate entry to the TCA cycle is slowed when energy and intermediates are already prevalent
* H+ - slows glycolysis if there is too much lactic acid being produced
122
What is energy charge?
The ATP/AMP ratio
It is a control mechanism for phosphofructokinase
123
What is the Warburg effect?
The upregulation of anaerobic glycolysis in cancer cells
124
Why is a high rate of ATP production achieved in cancer cells?
They posses more hexokinase low Km allowing for more rapid substate entry
125
Why do cancer patients lose weight?
There is high glucose demand for cancer cells
The cancer cells also produce ATP very inefficiently so more glucose is used up essentially wasting body energy stores
126
By the end of the TCA cycle what has been produced (including the products of glycolysis)?
* 4ATP
* 10NADH
* 10H+
* 2FADH2
* 6CO2
127
Where does oxidative phosphorylation occur?
Cristae of mitochondria
128
Give a basic overview of the step of ATP synthesis
* Protons are pumped across mitochondrial matric by protein complexes into inner mitochondrial membrane space
* Protons flow back into matrix along a concentration gradient through ATP synthase generating ATP
* Water will form from the hydrogen ions and oxygen
129
For the final stage of oxidative phosphorylation, how is oxygen reduced to water?
The hydrogen ions will bind to oxygen after it has been reduced by NADH and FADH2
130
How do the 2 NADH molecules produced in the cytosol during glycolysis get into the matrix of the mitochondria?
**Glycerol-3-phosphate and** Malate-aspartate shuttle
131
Describe the malate aspartate shuttle
1. Aspartate is converted to oxaloacetate due to α-ketoglutarate which now becomes glutamate
2. NADH is oxidised and generates malate from oxaloacetate
3. Malate transporters move malate into mitochondrial matrix
4. Malate is converted back to oxaloacetate which generates NADH from NAD+
5. Oxaloacetate is converted to aspartate by glutamate which again becomes α-ketoglutarate
6. Aspartate is pumped across the membrane through aspartate channels and the cycle can begin again
132
What are the two key stages in forming ATP?
Electron transport - electrons are transported through the respiratory chain and the enrgy produced from this causes protein complexes to pump electrons across the inner mitochondrial membrane
ATP synthesis - these elctrons re-enter and pass through ATP synthase forming ATP
133
How many multiprotein subunits are present in the inner mitochondrial membrane that contribute to electron transport?
4
134
At which point do electrons fron NADH enter the electron transport chain?
Complex I
135
At which point do electrons from FADH2 enter the electron transport chain?
Complex II
136
What is the function of co-enzyme A (Q)?
To transfer electrons from within the membrane that come from complex II
137
Where is complex II located in relation to the mitochondria?
On the inner mitochondrial membrane
138
When reduced by electrons, how many hydrogen ions do each of the following complexes pump across the inner mitochondrial membrane:
1. I
2. II
3. III
4. IV
1. 4
2. None - it is not a transmembrane protein
3. 4
4. 2
139
How many hydrogen ions will cause one ATP to be proced when they pass through the ATP synthase and back across the inner mitochondrial membrane?
4
140
How many ATP are produced from the 10NADH, 2FADH2 and two GTP?
30-32ATP
| (per glucose)
141
Name a non-competitor inhibitor of oxidative phosphorylation
Carbon monoxide
(binds to haem (in cytochrome C) preventing uptake and progression of electrons into the chain)
142
Name a competitive inhibitor of oxidative phosphorylation
Cyanide of complex IV
143
* Coenzyme Q
* cytochrome c
Coenzyme Q (ubiquinone)Receives electrons from complex IIcytochrome c (Cyt *c*)Receives electrons from complex III
144
If hydrogen ions do not enter the ATP synthase protein, where also can they enjoy and what is a side effect of this?
Thermogenin (uncoupling proteins)
Heat is produced instead of ATP
145
Which type of fat is well adapted for thermogenesis?
Brown fat
146
In order to activate the process of thermogenesis, what are required?
Fatty acids
147
Low Km indicate ?
high affinity (i.e., less substrate concentration is needed for the reaction rate to reach half of Vmax).
148
high Km
low affinity (i.e., more substrate concentration is needed for the reaction rate to reach half of Vmax)
149
How does each of the fallowing effect protein structure: Heat pH Detergents This and reduce agents
1. Increase vibration in protein 2. Interferes with the electrostatic interaction of proteins 3. Reduce and disrupt disulphide bonds
150
Number of hydrogen bonds between A-T , C-G
A-T double hydrogen bonds C-G triple hydrogen bonds
151
What is a purine and pyrimidines
Purine base with 2 carbon - nitrogen rings like in A and G Pyrimidines base with 1 carbon-nitrogen base
152
Missense mutation Nonsense mutation Silent mutation Framshift mutation
\* result in a change of amino acid sequence \* creat a new termination code \* no change of the amino acid sequence \* addition or deletion of a base
153
Acetylcholine ertherase Acetylcholine transferase
\* break down acetylcholine \* synthesize acetylcholine
154
Inhalation
Have short half life
155
Biomolecules and Reactions
•Bonds•
Covalent (share electrons),
ionic (opposite charge),
hydrogen (share H atom),
hydrophobic (non-polar in presence of polar substances),
van der Waal (electrons of non-polar substances)•
Reactions•
Condensation (water removed – polymerise), hydrolysis (water added)•
Redox (transfer of electrons): OILRIG•
Electronegativity = attractive force of atomic nucleus on electrons within bond (define reactivity)•
Determines oxidation state, e.g. CH4 – C \>**χ** H **∴ reduced**•
Polar = unequal sharing of electrons, form dipole
156
Can the buffer solution resist change of pH after adding acid base?
**Buffers are solutions that resist changes in pH, upon addition of small amounts of acid or base**
157
•Why do we care about pH??
change in pH can change ionisation of protein **∴ structure & function**
158
zwitterion
an ion possessing both positive and negative electrical charges. Therefore, they are mostly electrically neutral (the net formal charge is usually zero).
159
At which level of a protein's structure do polypeptide chains fold into simple helices and sheets, determined by amino acids and their chemical interactions with one another?
Secondary structures
The polypeptide chain forms alpha helices and beta-sheets, which are determined by hydrogen bonds between peptide groups forming the secondary structure.
160
What happen to pyruvate through glycolysis and TCA cycle ?
**pyruvate can be converted into acetyl-CoA via the link reaction and subsequently enter the Krebs cycle to be fully oxidised into CO2.**
161
What forms ‘coiled-coil alpha helices’?
If two or more helices wrap around each other in a "supercoil" structure, this forms a highly stable structure known as *coiled-coil alpha helices*.
162
How soluble are fibrous proteins?
They have low solubility in water
163
What is the function of a fibrous protein?
Their function is to provide structural support to cells and tissues.
164
What is the first step of DNA replication?
DNA replication starts when an initiator protein binds to a specific sequence in the DNA. These initiator proteins recruit others, and together cause the double-stranded DNA to "unzip", exposing its base pairs.
165
What are tight junctions made up of?
networks of proteins, predominantly claudins.
166
Rapidly contracting human muscle cells start to producing lactic acid and thus **The cells have to convert NADH into NAD+** why is that the case ?
rapidly contracting muscle cells require large amount of energy in the form of ATP and if they cant produce enough by oxydative phosphorylation they require another way, which is regenerating NAD+
167
describe the type of enregy used for different time periods
All cases ATP will supply energy to run at a moderate speed for 4 seconds, phosphocreatinine for 15 seconds. Free circulating glucose for 4 minutes and glycogen tores for 77 minutes and fat stores for 4+ days
168
ATP is an active form of phosphate and acetate is an active form of ------
UDP is an active form of ------
acetyl coA
Glucose
169
what are the net products of Beta oxidation
It occurs 8 times forming :
8FADH2
8NADH+8H+
9 acetyl -COA
120 ATP
170
Patient came in with smell of acetone on his breath what does this indicate
this indicates the accumulation of ketone in the blood leads to sever acidsosis.
171
Acetyle -COA carboxylase is an enzyme that catalyst the conversion of acetyl-CoA to malongl-CoA used for fatty acid synthesis what regulates this enzyme(6)
1. + citrate
2. + insulin
3. - Palmitoyl CoA (when fatty acid levels are high )
4. -AMP
5. -glucagon
6. - Epinephrin
172
wath are the four different type of reactions that happen during fatty acid synthesis
Condensation
reducation
dehydration
reduction and release
173
how is nitrogen is transport to the liver through the blood (2)
by Glutamine and Alanine
174
what happens to fumarate the end product of Urea Cycle
is converted to malate which is used in malate -Aspecurtate shuttle
175
DELTA
ΔG + (Nonspontaneous/endergonic) or -(Spontaneous/exergonic)
ΔH + (Endothermic) or - (Exothermic)
ΔS + (increase in entropy) or - (decrease in entropy)
176
The central dogma
The central dogma is the flow of information from DNA towards protein.
DNA-transcription >m RNA --splicing , adding to each end then translation in rRNA > Protein
177
**From each acetyl-CoA, TCA cycle generates:**
- 3 NADH + H+
- 1 FADH2
- 1 GTP
- 2 CO2
178
the major antibiotic classes that are known to increase the risk of developing Clostridium difficile (C. diff) infection
Remember the 4 Cs for C. diff: -
* CEPHALOSPORINS (E.G. CEFTRIAXONE)
* FLUOROQUINOLONES (E.G. CIPROFLOXACIN, LEVOFLOXACIN)
* CLINDAMYCIN
* CO-AMOXICLAV
179
What happen when Ribosme read stop codon
. Stop codons are bound by a specific termination protein, that leads to a change in peptydl transferase activity (this is NOT a separate activity, but intrinsic to the large ribosomal subunit), as a consequence, the finished polypeptide is cleaved off the last tRNA that it was attached to and is released. Then the ribosome dissociates from the mRNA
180
which type of proetin structure is decribes
* B. The overall shape of the polypeptide chain
* C. The path of the polypeptide backbone in three-dimensional space
* D. The relative orientation of one polypeptide to another polypeptide in a multisubunit protein
* tertiary structure
* Secondary Structue
* Quarternary structure
181
The ratio between acid and conjugate base in solution determines the pH of this solution, but not how well a solution can buffer. True / False
True
182
E. The rate of reaction is matched by NADH regeneration by
by glyceraldehyde 3–phosphate dehydrogenase
183
an example of a transcription factor binding to a specific DNA sequence?
TATA-box-binding protein (TBP) is a highly conserved RNA polymerase II
general transcription factor that binds to the core promoter and
initiates the assembly of complexes in preparation for transcription.
184
sphygmomanometer
Korotkoff sounds are heard during the recording of blood pressure with
185
Negative feedback opposes stability of the internal environment True / false
False . Help with internal environment
In negative feedback, a change in the internal environment triggers a response that opposes or reverses the change, returning the internal environment to its normal state.
186
The posterior hypothalamic centre is stimulated by cold Vasoconstriction of skin arterioles is caused by sympathetic and not parasympathetic nerves.
187
The rate limiting enzyme for glycogenolysis is glycogen phosphorylase.
The rate limiting enzyme for the citric acid cycle is isocitrate dehydrogenase.
Phosphofructokinase-1 is the rate limiting enzyme of glycolysis.
Glycogen synthase is the rate limiting enzyme of glycogenesis.
