Biochem sem1 Flashcards
(141 cards)
1
Q
What does the:
atomic number
atomic mass
Represent
A
Number: protons
Mass: protons and neutrons
2
Q
what is the most common chemical formula for a monosaccharide?
A
(CH2o)n
n=3,5,6
3
Q
What is the name of:
1 sacharide
2 sacharides
3-10 sacharides
10+ sacharides
A
1 = monosaccharide
2 = disaccharide
3 = ogliosaccharide
10+ = polysaccharide
4
Q
How do multiple saccharides bond?
A
Through condensation reaction
glycosidic bond (type of ether bond)
5
Q
what makes up
sucrose
lactose
maltose
A
sucrose = glucose + fructose
lactose = glucose + galactose
maltose = 2 alpha glucose
6
Q
What is Van Der Waals?
A
cloud of - charge around atom, can congregate in one section to attract other atoms
7
Q
What are 5 roles of lipids?
A
- cell membranes
- protection/insulation
- neurone myelination
- hormone production
- absorb fat soluble vitamins
8
Q
what are the 3 classifications of lipids?
A
- triglycerides
- phospholipids
- sterols
9
Q
Describe triglycerides?
A
TRIGLYCERIDES:
- glycerol backbone 3FA condensation reaction, sat (c-c) bonds or unsat (at least 1 c=c)
- double bond can be cis or trans
10
Q
Describe phospholipids?
A
arranged in bilayers
hydrophilic tails
hydrophobic head
11
Q
Describe sterols?
A
- cyclic organic compound
- found in most eukaryotic cells
- e.g: cholesterol
12
Q
what are proteinogenic amino acids?
What do they consist of?
A
- only 20 genetically coded amino acids in DNA
- amine group, carboxyl group, hydrogen atom, organic side chain (R group)
13
Q
How and what is a protein formed of?
A
Peptide chains = amino acids joined by condensation reaction, peptide bond between carboxyl and amine groups
14
Q
What is the primary structure?
A
amino acid sequence from N- terminus to C- terminus?
15
Q
what is the secondary structure?
A
alpha helix =
- c=o forms H bond with amine hydrogen between carboxyl and amine group
- turns right handed
beta sheet =
- parallel or antiparallel structure
- zig zag peptide chain
- backbone forms H bonds between segments
16
Q
what is the tertiary and quaternary structure?
A
Tertiary =
- a helix or b sheet folds itself, 3D, intermolecular forces change shape
Quaternary =
- multiple subunits
- intermolecular forces change behaviour
17
Q
What is avogadros constant?
A
6.02 X 10^23
18
Q
how do you calculate molarity?
A
mass of substance (g)
molecular| number of
weight | moles
19
Q
what is a heterocyle?
A
ring that has another element in it
20
Q
what are 3 regular classes of functional groups?
(draw them ideally)
A
hydroxyl
amine
carbonyl
21
Q
what are the 2 laws of thermodynamics?
A
1 = energy cant be created or destroyed only interconverted between forms
2 = total entropy of a system always increases
22
Q
what is entropy and enthalpy?
A
entropy = level of disorder
enthalpy = energy
23
Q
what is the definition of Gibbs free energy?
A
the amount of available energy to do work
24
Q
what is the equation for Gibbs free energy?
A
△G = △H-T △S
G= Gibbs free energy
H = enthalpy
T= temperature
S= entropy
25
When △G is more than zero reaction is?
When △G is less than zero reaction is?
More than 0 = not spontaneous (requires addition of energy to occur)
Less than 0 = spontaneous (happens on its own)
26
Explain what a coupled reaction is?
when an exergonic reaction drives an endergonic reaction
27
What is an:
anabolic reaction
catabolic reaction
anabolic = smaller --- bigger
catabolic = bigger --- smaller
28
What is energy stored as by activated carrier molecules?
transferable chemical group or electrons
instead of being lost as heat
29
when △S (entropy):
bigger than zero
less than zero
Entropy is ordered or disordered
?
bigger than zero = disordered
less than zero = ordered
30
how do cells get energy? where is the energy stored?
energy from oxidising organic molecules by metabolism
store in covalent bonds
31
explain REDOX?
Oxidation is loss of electrons
reduction is gain of electrons
32
Describe haemoglobins structure
2 alpha subunits, 2 beta subunits
globular, compact
tetrameric protein
o2 binds to haem groups
33
what are enzymes?
- biological catalysts
- regenerated at end of reaction so not used up
- globular
- powerful
34
Name 5 biological functions enzymes are used in?
- metabolism
- movement
- digestion
- cell signalling
- gene expression
35
describe the structure of an enzyme?
- globular protein
- AA sequence decides catalytic activity
- active site has different AA, some for binding substrate, some for catalysing reaction
36
What are the two theories of enzyme binding?
LOCK AND KEY: rigid and fixed, complementary geometry
INDUCED FIT: conformational change in binding
37
Describe the allosteric site?
- can induce conformational change e.g: change in active site/ROR
- regulatory molecule binds and inhibits/activate enzyme
38
what is a:
- cofactor
- coenzyme
- prosthetic group
cofactor: inorganic, required for enzyme/protein to work
coenzyme: organic, directly involved in enzyme reaction, transiently bond, required for optimal
prothetic group: non protein molecule covalently bonds for enzyme function
39
What is an enzyme called when It needs a cofactor/enzyme when:
- cofactor hasn't bound?
- cofactor has bound?
Hasn't bound: APOENZYME
Has bound: HOLOENZYME
40
What enzyme? pt1
1. transfer H or O2 or E- from one substrate to another
2. transfer functional groups from one substrate to another
3. hydrolysis of a substrate
1. oxidoreductases
2. transferases
3. hydrolases
41
What enzyme? pt2
4. add or remove a group to form a double bond
5. transfer groups within a molecule
6. bond formation coupled with ATP hydrolysis
4. lyases
5. isomerases
6. ligases
42
what is:
1.activation energy
2. transition state
1. energy barrier required to be overcome for reaction
2. not substrate not product, transient molecular state
43
9 ways which enzymes reduce activation energy?
1. exclusion of water
2. induced fit
3. close proximity of substrate and enzyme
4. metal ion cataylses
5. covalent catalyses
6. acid base catalyses
7. chemical complementarity
8. transition state stabilisation
9. substrate binding and orientation
44
describe the 4 main catalytic mechanisms
1. metal ion catalyses: use metal ion to help with catalyses
2. covalent catalyses: briefly substrate binds with covalent bond until substrate fully bonds
3. enzyme transfers H to catalyses can occur
4. approximation = further away is harder
45
What is enzyme velocity?
When must it be measured
1. initial ROR, amount of substrate covered to product per unit of time
Must be measured before 10% of substrate is converted
46
What is VMax?
What is Km? How do you calculate it
Vmax = max enzyme ror
Km = measure of affinity for substrate to enzyme
also conc of substrate when 1/2 Vmax
1. Calc vmax, calc 1/2 vmax, draw line down to substrate conc
47
what does.... indicate?
1. high Km
2. Low Km
1. weak binding , need high substrate conc to reach Vmax
2. strong bonding, need low substrate conc to reach vmax
48
how to regulatory mechanism control enzyme activity?
- allosteric inhibition/activation
- confine enzymes into compartments
- cell controls quantities of enzymes so is controlled
- covalently modify to control activity
- rate of protein destruction by targeted proteolyses
49
describe 4 types of reversible inhibition?
how is Vmax effected for each?
1. end product inhibition: end product inhibits earlier pathways
2. competitive: inhibitor blocks actual substrate. Vmax = same, longer to get there
3. non competitive: inhibitor binds to allosteric site, conformational change, Vmax lower
4. uncompetitive: substrate already bound, inhibitor binds and stop catalysis. Vmax lower
50
what is metabolism?
series of anabolic and catabolic reactions that happen in living cells
51
Name 4 examples of catabolic reactions
1. protein breakdown
2. lipid oxidation
3. carbohydrate oxidation
4. nucleotide hydrolysis
52
Name 4 examples of anabolic reactions
1. protein synthesis
2. lipid synthesis
3. carbohydrate synthesis
4. nucleotide synthesis
53
if deltaG is large is ATP more or less willing to give up its phosphates?
more
54
Where does lactate come from?
When no o2 present, anaerobic respiration uses glycolysis to produce ATP
NADH passes electrons to pyruvate to form lactate
55
give 5 examples of membrane function
1. chemical/physical barrier
2. cell/cell communication
3. energy conversion
4. recognition
5. allow cellular processes
56
what is the word for: hydrophillic+hydrophobic parts?
amphipathic
57
how can mutation in enzyme lead to disease?
over/under production , deletion leads to wrong enzymes created, regulate cell cycle = lead to cancers
58
how is an enzymes structure specific to substrate?
amino acid sequence specifies 3D conformation
active site has different AA sequence
Cleft on surface of active site
59
Describe the allosteric site
can induce conformational change
activate or inhibit reactions
60
what is the standard unit of enzyme activity?
U
61
how does temp effect enzyme activity?
rise = overcome activation energy, increase ror
too high = breaks bonds, alter active site, denature protein
62
spontaneous or not?
1) △S﹥0 and △H < 0
2) △S﹥0 and △H﹥0
3) △S < 0 and △H < 0
4) △S < 0 and △H﹥0
1) spontaneous
2) spontaneous at high temp
3) spontaneous at low temps
4) not spontaneous
63
what is the most important activated carrier molecule?
what reactions does it drive?
ATP
endergonic
64
what is △G°
standard conditions, 25°c, 298K
65
what is △G°' (delta G nought prime)
standard biological conditions, 37°, 310K
66
what do the different parts of this equation mean?
△G=△G° + RT ln Q
△G = change in gfe
△G° = delta g in standard conditions
R = 8.314J mol-1, K-1
T = temp
ln = log
Q = [products] / [reactants]
67
with this reaction: △G=△G° + RT ln Q,
what do you do when calculating Q if there's e.g: 2 reactants and e.g: 2O^2
[C][O2]^2
instead of times by 2, you square, if 3 lots you will cube
68
METABOLISM
what reactions occur in stages 1-3 of glycolysis? what enzymes do this?
1) phosphorylation - HEXOKINASE
2) isomerisation - PHOSPHOGLUCOSE ISOMERASE
3) phosphorylation - PHOSPHOFRUCTOKINASE
69
METABOLISM
what is the importance of glucose being isomerised to fructose in step 2?
2 G3P molecules can be created in step 5 , if didn't happen 2 isomers (2 and 4c molecules would be created instead
70
METABOLISM
summarise steps 1-5 of glycolysis
1) Glucose --- glucose 6phosphate by HEXOKINASE, uses ATP
2) Glucose6phosphate --- fructose6phosphate by PHOSPHOGLUCOSE ISOMERASE
3) fructose6phosphate --- fructose1-6bisphosphate by PHOSPHOFRUCTOKINASE , uses ATP
4) fructose1-6bisphosphate --- DHAP + 1XG3P by ADOLASE
5) DHAP --- G3P so = 2xG3P instead
71
what do kinases do?
add a phosphate, phosphorylated
72
METABOLISM
Summarise stages 6-10 of glycolysis
6) 2xG3P --- 2x1.3 bisphosphoglycerate by G3P DEHYDROGENASE , 2 NAD -- 2 NADH (activated carrier molecule)
7) 2x1,3 bispho.... --- 2x3phosphoglycerate by PHOSPHOGLYCERATE KINASE, 2 ADP --
2 ATP *couple reaction with NAD-NADH prev*
8) 2x 3 phosphoglycerate --- 2x 2 phosphoglycerate by PHOSPHOGLYCEROMUTASE
9) 2x 2phosphoglycerate -- 2x phosphoenolpyruvate by ENOLASE , loose 2H20
10) 2x phosphoenolpyruvate --- 2xPyruvate by PYRUVATE KINASE , 2 ADP -- 2ATP
73
metabolism
what are the products of glycolysis?
net 2 ATP
2 NADH
2 pyruvate
74
what is the rate limiting enzyme of glycolysis?
what is it activated and inhibited by?
PFK phosphofructokinase
activated by: AMP, F2,6 BP
inhibited by: ATP, as already high energy so don't need more, low pH
75
GLUCONEOGENESIS
1. what is it
2. where does it happen
3. what does it use
1. reversal of glycolysis, forms glucose
2. liver
3. non carbohydrate precursors: lactate, glycerol,
76
GLUCONEOGENESIS
why is gluconeogenesis not a direct reversal of glycolysis?
If it was, deltaG would be +84Kj/mol = energetically unfavourable
77
GLUCONEOGENSIS
1. what does pyruvate carboxylase do?
2. what does it have attached to it?
3. what has to be present for biotin to be carboxylated? what type of regulation is this?
1. adds co2 to a molecule
2. biotin prosthetic group
3. Acetyl CoA, allosteric regulation
78
GLUCONEOGENISIS
what molecule can't exit the mitochondria?
what does it need to be converted to?
oxaloacetate
malate
79
When lactate is produced by heavy exercise, it can be:
1.
2.
1. converted to pyruvate by tissues and used for energy (TCA cycle)
2. transported to liver and converted to glucose (Cori Cycle)
80
1. What is the proper name for the link reaction?
2. what happens in this?
1. pyruvate dehydrogenase reaction
2. pyruvate ---- acetyl coA, large enzyme does this, reduces NAD--- NADH
81
structure of triacylglycerols?
3 FA bound to glycerol molecule
82
FATTY ACID OXIDATION
1) summarise stage 1
ACTIVATION
- FA react with atp
- atp hydrolysed --- AMP + pyrophosphate
- pyrophosphate --- 2 inorganic pi , releases energy
- AMP is on acyl adenylate
- acyl adenylate attacked by sulfhydryl on CoA
- AMP removed = Acyl CoA formed
83
FATTY ACID OXIDATION
summarise stage 2
CARNITINE
carnitine --- acyl carnitine using CPT 1, so can get inside mitochondria
once in mitochondria
acyl carnitine ---- carnitine using CPT II
84
FATTY ACID OXIDATION
summarise stage 3
what does it produce?
what is the aim of it?
when does it stop?
B OXIDATION
produces|: acetyl coA, NADH, FADH2
aim|: reduces carbons
will stop when|: FA fully degraded
1. FA Acyl CoA oxidised by FAD
2. +h20
3. oxidation by NAD+
4. thiolysis by coA
5. = acetyl CoA , Fatty Acyl CoA (2C less than start)
85
FATTY ACID OXIDATION
what happens when a fatty acid is unsaturated in B oxidation?
what does cis and trans double bonds look like?
isomerase convert cis -- trans , cis not substate of B oxidation
cis = on same side, trans = on both sides
86
KETOGENESIS
what does acetyl coA usually enter|?
why would it not?
where would it go instead?
tca cycle
lack of oxaloacetate, diabetes or starvation
ketogenesis, in liver, use ketones over glucose
87
FATTY ACID SYNTHESIS
summarise the steps
1) acetyl ACP + malonyl ACP = 3 ketoacyl ACP
release co2
2) 3 ketoacyl acp --- butyryl ACP
reduced + dehydrated v
3) butyryl acp + malonyl ACP
4) cycle continues until C16 Palmitate formed
88
FATTY ACID SYNTHESIS
what enzymes regulate this process?
AMPK: detects energy charge/ATP , if atp low , AMPK phosphorylate ACC so FA synthase doesn't happen
89
METABOLISM 2: ACETYL CoA TRANSFER
summarise the cycle, where each bit happens, why it happens and how much product is formed
acetyl coA in mitochondria
converted to citrate via tca cycle to get into cytosol
citrate --- oxaloacetate --- malate --- pyruvate
malate -- pyruvate produces NADPH (used in FA synthesis)
pyruvate driven to continue cycle
1 NADPH produced per cycle
90
METABOLISM 2: ACETYL CoA TRANSFER
how many acetyl coA needed to form palmitate (16c fa from fa synthesis?)
how many NADPH are formed?
how many are needed?
8
so 8 NADPH formed, need 14 for fa synthesis so PPP
91
PENTOSE PHOSPHATE PATHWAY
what are the 2 phases called
1. oxidative phase
2. non oxidative phase
92
PENTOSE PHOSPHATE PATHWAY
summarise the 2 phases
1) OXIDATIVE : produces NADPH
glucose 6 phosphate --- ribulose 5 phosphate , produces 2NADPH
2) NON OXIDATIVE : interconvert sugars
ribulose 5 phosphate ---
2x fructose6phosphate
1x glyceraldehyde 3 phosphate
these can then produce glucose via glycolysis
93
PENTOSE PHOSPHATE PATHWAY
When would the different two phases be used
1) OXIDATIVE : the cell needs NADPH and Ribulose 5 phosphate (for eg. dna, rna)
2)BOTH OXIDATIVE + NON OXIDATIVE: cell needs NADPH and ATP
94
PENTOSE PHOSPHATE PATHWAY
what is this pathway regulated by?
1) NADP+ levels
higher = more NADPH needed for biosynthesis
2) cell requirement for ATP and ribulose 5 phosphate
95
AMINO ACID METABOLISM
TRANSAMINATION
what happens in this?
what enzyme is used?
what is an example of it?
transfer amine group from AA to keto acid
enzyme: aminotransferase
e.g: oxalocacetate accept amine group --ASPARTATE, can be transaminate to form: GLUTAMATE
96
AMINO ACID METABOLISM
DEAMINATION
what happens here?
what enzyme is used?
continue example?
where does it go next?
amine group removed to leave carbon skeleton
e.g: GLUTAMATE has amine group to be removed
enzyme: GLUTAMATE DEHYDROGENASE
UREA CYCLE
97
AMINO ACID METABOLISM
UREA CYCLE
what happens here?
remove ammonia as toxic via urea
excreted on toilet
e.g: aspartate bring NH2 to go into urea
98
AMINO ACID METABOLISM
what happens to the carbon skeletons?
what are they degraded to?
what are the 3 different types?
amino acid degraded to 1 of 7 metabolic intermediates
metabolic intermediate either considered:
ketogenic
keto + glucogenic
glucogenic
99
MITOCHONDRIA
What care the 2 complexes that allow things in?
What is needed for proteins to be recognised?
TOM COMPLEX: translocase outer membrane
TIM COMPLEX: translocase inner membrane
SIGNAL SEQUENCE: @ N terminus, certain aa sequence to cell knows where to send it
100
MITOCHONDRIA
How does pyruvate enter mitochondria?
what's needed for them to function
Outer membrane: Porin
Inner membrane: mitochondrial pyruvate carriers
needs change in ph to function
101
MITOCHONDRIA
How does NADH enter?
hint: 1st way
MALATE ASPARTATE SHUTTLE
1. NADH reduce oxaloacetate -- malate
2. malate into matrix, back into oxaloacetate
3. NAD+ regenerated , NADH regen.
malate carried electrons
alpha ketoglutarate needed to be transported other way
102
MITOCHONDRIA
How does NADH enter?
hint: 2nd way
GLYCEROL 3 PHOSPHATE SHUTTLE
1. NADH reduce DHAP --- glycerol 3 phosphate
2. G3P into mitochondria. oxidised back to DHAP
3. generate FADH2
4. G3P transfer electrons from NADH -- FADH2
103
MITOCHONDRIA
How does fatty acids enter mitochondria?
CARNITINE --- ACYL CARNITINE, using cpt1
once in
ACYL CARNITINE --- CARNITINE , using cpt2
104
MITOCHONDRIA
what is the quantity of mitochondrial DNA controlled by?
fission + fission
105
MITOHCHONDRIA
how many genes are there?
37
2rRNA
22tRNA
13 protein
106
MITOCHONDRIA
RESPIRATORY CHAIN
Why are different molecules better at accepting/transferring electrons?
redox potential
more negative = donate e-
more positive = accept e-
107
MITOCHONDRIA
RESPIRATORY CHAIN
what happens are complex 1?
NADH goes to FMN on complex1
donate 2e- = nadh
2e- pass to iron sulphur clusters
2e- to coenzyme Q
4h+ matrix to inter membrane space
108
MITOCHONDRIA
RESPIRATORY CHAIN
what happens on complex 2?
succinate dehydrogenase (in C2) couples with FADH2
transfers 2e- to iron sulphur clusters
e- + 2h+ to CoQ = QH2
109
MITOCHONDRIA
RESPIRATORY CHAIN
what happens at complex 3?
explain the Q cycle
QH2 passes 2e- to C3
C3 has cytochromes, can only carry 1e-
Q CYCLE
1) QH2 arrives, 1e- pass up to cyt. c, 1e- pass down to Qi site
2) 2nd QH2 arrives, 1e- up to cyt. c, 1e- down so Qi fully reduced to QH2, can go back into pool and passed back in
110
MITOCHONDRIA
RESPIRATORY CHAIN
what happens at complex 4?
1) 2 cyt. c arrive so 2e- arrive
2) 1e- reduce iron, 1e- reduce copper
3) O2 arrives, final electron acceptor
4) O2 accept 2e- so reduced + 2 hydroxyl = 2H20
111
RESPIRATORY CHAIN
how many molecules of cytochrome c are needed to generate h20 at complex 4?
4 molecules
112
RESPIRATORY CHAIN
explain what proton motive force is
electrochemical proton gradient generated through proton pumping in respiratory chain , can generate ATP
113
ATP SYNTHASE
what's the relation between the proton motive force and atp generation by atp synthase?
protons along conc gradient from IM space -- matrix
cause c-subunits in F0 to rotate, causes y-unit to rotate
alpha + beta subunits in F1 remain fixed so position changes with each rotation
B subunits = atp synthetic centre of atp synthase so drive atp synthesis and release
114
CELL MEMBRANE
membrane functions (5)
1. facilitate diffusion (physical/chemical barrier)
2. cell to cell communication/recognition
3. energy conversion
4. platform for cellular processes
5. recognition
115
CELL MEMBRANE
describe the structure of the membrane
lipid bilayer
non covalent interactions hold lipids and proteins togryhrt
impermeable barrier to polar molecules
proteins in bilayer
lipids = amphiatic
116
CELL MEMBRANE
what is it composed of?
LIPIDS:
PROTEINS
CARBOHYDRATES
117
CELL MEMBRANE
what are 2 factors that effect membrane fluidity?
- cholesterol
- cis double bond in FA
118
CELL MEMBRANE
what are the 2 types of phospholipids?
what are the other 2 types of lipids?
PHOSPHOLIPIDS:
- glycerophospholipids
- sphingolipids
STEROLS:
- cholesterol
GLYCOLIPIDS
119
CELL MEMBRANE - PROTEINS
describe the 2 different types of proteins
INTEGRAL:
single pass or multi pass
PERIPHERAL:
embedded
covalently bonded to lipids
non covalently bonded to other proteins
120
CELL MEMBRANE
what's the name of the carbohydrate coating on the cell?
glycocalyx
121
CELL MEMBRANE
5 membrane functions
facilitate diffusion
cell - cell recognition
recognition
cellular process platform
energy conversion
122
CELL MEMBRANE
describe a lipid raft
reduces fluidity
lots of sphingolipids
more cholesterol = rigid
more proteins
123
CELL MEMBRANE
what type of molecule will:
1) dissolve easily
2) dissolve slowly
3) need a form of transporter
4) need special transport mechanism
1) small non polar
2) small polar
3) large uncharged polar
4) charged ions
124
CELL MEMBRANE: TRANSPORT PROTEINS
1) what do they need to be?
2) what are the 2 types and what do they do?
3) what type of transport do they allow?
1) transmembrane, multipass
2) CARRIER PROTEINS: bind to solute, conformational change, release
CHANNEL PROTEINS: weak interact with solute, continuous pore, selective filter
3) passive transport
125
CELL MEMBRANE: ACTIVE TRANSPORT
1) what are the 2 types of coupled carriers?
1) SYMPORTER: two solutes in same direction, 1 up conc grad. 1 down conc. grad
2) ANTIPORTER: two solutes in diff directions, energy from atp hydrolysis to push against gradient
126
CELL MEMBRANE: CHANNELS
what type of diffusion do they allow?
3 types of gated channels?
passive transport/facilitated diffusion
voltage, ligand, mechanical
127
NUCLEUS what's inside?
define:
CHROMOSOME
HISTONES
NUCLEOSOME
SISTER CHROMATIDS
CHROMATIN
CHROMOSOME: specific set of genes, chromatin region
HISTONES: protein bind to dna, form eukaryotic chromosome
NUCLEOSOME: protein dna complex, 8 histones
SISTER CHROMATIDS: identical copies of same chromosome
CHROMATIN: repeating nucleosome structure
128
NUCLEUS/NUCLEOLUS
what is this the site of?
what enzyme is required?
RNA synthesis (transcription)
RNA polymerases
129
NUCLEUS/NUCLEOLUS
describe the nucleus and nucleolus membranes
NUCLEUS: double membrane, phospholipid bilayer
NUCLEOLUS: doesn't have membrane
130
NUCLEUS
describe sections of the nuclear envelope
ribosomes: protein synthesis
nuclear pore complex:
nuclear lamina: part of cytoskeleton
nucleolus: dark stain region
chromatin: beads on a string
rer: continuous with envelope
131
NUCLEUS
it is the __________ organelle In eukaryotic cells
what does it contain?
what is this packaged into?
biggest organelle
contains DNA genetic material
chromatin
132
NUCLEUS
describe the structure of the nuclear pore complex
- large quaternary protein
- ordered 8 fold symmetry
- aqueous channel, nucleoplasm - cytosol
- made of nucleoporins (30 types)
- nuclear basket, cytosillic fibres
- disordered inside
133
NUCLEUS
what can diffuse through nuclear pore complex?
freely diffuse:
diffuse but take longer:
need special mechanism:
less than 5000KDa
up to 60kDa
more than 60KDa
134
NUCLEUS
what does a protein have so it can go into the nucleus?
what are these recognised by?
nuclear localisation signal
specific nuclear import receptors/ Importins
135
NUCLEUS
what is the name of the signal proteins have
protein with nuclear localisation signal
136
NUCLEAR IMPORT
describe the process
1) protein has nls, nuclear import receptor bind
2) goes through nuclear pore complex , bind and unbind to FG repeats
3) in nucleus, RAN GTP bind, protein releases
4) receptor + GTP back to cytosol
5) Ran binding protein bind, receptor recycled, Ran binding protein+ ran gtp left
6) ran gap hydrolyse gtp --- gdp
7) gdp back to nucleus
8) GDP --- GTP by ran gef
137
NUCLEAR EXPORT
describe the process
1) GTP + nuclear export receptor bind with protein with nuclear export signal
2) complex goes through nuc pore complex by FG repeats
3) Ran binding protein + Ran GAP bind, protein released
4) GTP --- GDP by ran GAP
5) GDP goes back to nucleus
6) GDP -- GTP by Ran GEF
138
NUCLEAR BIOGENESIS
what rna is in the nucleolus?
what are its subunits?
what enzyme is used?
what is joined to it?
what does it form?
45s pre rRNA
18s, 5.8s, 28s
rna polymerase I
ribosomal proteins from cytosol
90s pre ribosome
139
NUCLEAR BIOGENESIS
what rRNA is in the nucleoplasm?
what enzyme is used?
5s rRNA
POL III
140
NUCLEAR BIOGENESIS
what is 90s pre ribosome modified by?
what are the 3 ways in which they modify?
snoRNPs
methylation, isomerisation, separate 3 groups of 45s
141
