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Week 3
Descrição
Undergraduate Degree BMSC1110 (week summary) Mapa Mental sobre Week 3, criado por 06watkinse em 19-12-2013.
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bmsc1110
week summary
bmsc1110
undergraduate degree
Mapa Mental por
06watkinse
, atualizado more than 1 year ago
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06watkinse
mais de 10 anos atrás
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Resumo de Recurso
Week 3
Genes to Proteins
DNA to RNA to Protein
DNA to RNA
transcription - 3' to 5'
RNA polymerase
nucleus
RNA to Protein
translation - 5' to 3'
ribosome and cytoplasm
Proteins
Processes
enzyme catalysis
transport
signal transduction
immune protection
coordinated motion
mechanical support
storage
structure
amino acid chain
starts at the N terminus
finishes at the C terminus
primary
amino acid sequence - 2D
secondary
alpha helix
each aa forms a hydrogen bond with an aa 4 above and below
clockwise helix
3.6 aa per turn
beta sheet
beta strands
parallel or anti-parallel
chain held together in conformational shape with hydrogen bonds
hydrophobic forces bind alpha helices and beta sheets together
tertiary
folded into globular structure
quaternary
3D
multi-part protein complex
globular proteins
interior - hydrophobic
exterior - hydrophilic
composed of secondary structure proteins
amino acid chain change direction
the turns often require conformational properties of Gly and Pro amino acids
domains
individual globules on a globular protein
self contained units
Amino Acids
20 naturally occuring
all L isomers
peptide bonds link the individual acids
bonds don't rotate
fixed in trans formation
Disulphide Bonds
attachement between 2 side chains
doesn't occur in the cytoplasm
DNA & RNA Structure
phosphodiester bonds link the 3rd carbon of one sugar to the 5th carbon of another
DNA
helix has a major and minor groove
LAC processor binds to major groove and blocks RNA polymerase
bases form hydrophobic stacking interactions with bases above and below
when lactose is present LAC processor can't bind and replication can occur
LAC processor stops energy being wasted on enzyme production for a substance that isn't present
DNA forms a complex with proteins to form chromatin
proteins in chromatin are histones
nucleosome is made up of 8 histones and 200 base pairs
RNA
forms fuctional structures - stem & loop, hairpin and pseudo-knot
riboswitch - segment of RNA that regulates mRNA's activities
ribozyme - RNA molecule that acts in a simliar way to enzymes
tRNA
single chain of 73-93 ribonucleotides
contains unusual bases
amino acid attaches to the adenosine at the 3' end
DNA Replication
helicases unwind the DNA
ss binding proteins bind to the strands to stop them reforming
happens at the replication fork
transcription bubble
RNA polymerase is 17 base pairs long
NTPs are added to the 3 end
promotor region where the bubble attaches
translation
differences within an individual amino acid arise from the redundancy of codons
a common difference between codons that code for the same aa is the 3rd base
3rd base is the wobble base
Met aa is the start codon so is always the first codon present
Protein Synthesis
a small subunit recognises the ribosome binding site and binds to the mRNA
this area is about 15 bases to the 3' end of the start codon
a large subunit binds to the small subunit
the large subunit is divided into A and P sites
tRNA binds at the A site
tRNA is then moved into the P site and a new tRNA binds in the A site
the 2 amino acids form a peptide bond
the tRNA in the P site is released and the ribosome translocates by 1 codon
Bioenergetics
Definitions
metabolism - all reactions in the body
catabolism - breakdown of nutrients to make energy and raw materials
anabolism - synthesis of complex molecules from simple building blocks
Nutritional Requirements of Organisms are Reflected in their Sources of Metabolic Energy
autotrophs
produces complex complounds from simple mollecules in its surroundings
phototrophs use light energy
chemolithotrophs use energy from the oxidation of inorganic compounds
heterotrophs
obtain energy from oxidation of organic compounds
depend on autotrophs for these substances
require a balanced intake of proteins, carbs and lipids
cannot synthesise vitamins
minerals are required for biomolecules and tissues
Respiration
glycolysis
T.I.M. enzyme catalyses the interconversion of P-GAP and DHAP-P
producing pyruvate from simple sugars
link reaction
krebs cycle
ETC
10 protons pumped per NADH
Quino carries electrons down the ETC
28 ATP net yield
anaerobic
lactate - homolactic fermentation in animals, 31% efficient
CO2 & ethanol - alcoholic fermentation in plants, 26% efficient
produces 2 ATP
Glycogen
each granule is about 120,000 monomers
blood glucose should be about 5mM
Gluconeogenesis
synthesis of glucose from non-carb precursors
all precursors are converted to oxaloacetate
leucine and lysine aa's can't be converted
fatty acid breakdown provides most of the ATP needed
generation of oxaloxacetate only occurs in the mitochondria
the enzymes that convert phosphenolpyruvate are cytosolic
location of PEPCK can either be in the cytosol or mitochondrion
to continue generation of glucose oxalocetate or PEP must leave the mitochondria
PEP is transported by transport systems but oxaloacetate is more complex
oxaloacetate transportation
must be converted to either malate or aspartate
specific transporters for malate and aspartate
difference between routes lies in the reducing equivalent transfer
conversion to malate and malate transfer results in transfer of reducing equivalents into the cytosol
conversion of aspartate doesn't transport reducing equivalents
gluconeogenisis requires NADH so the malate route is the most common route
Phosphofructokinase
catalyses the major rate determining step of glycolysis
other regulatory points of glycolysis are hexokinase and pyruvate kinase but both can be over rided
tetramer
2 conformational states in equilibrium - R and T
ATP is an inhibitor of PFK
ADP, AMP and Fructose-2,6-bisphosphate are activators
each subunit has 2 ATP binding sites so there is a total of 8 sites
the active site binds ATP in both states
the inhibitor site binds ATP in the inactive state
F6P binds only in the active state
T state - inactive
R state - active
high ATP concentrations shift the TR equilibrium towards T, which decreases PFKs affinity for F6P
activators bind to the R state
low metabolic demand
[ATP] high
PFK inhibited
flux through glycolysis is low
high metabolic demand
[ATP] low
PFK active
flux through glycolysis is high
[ATP] varies by 10%
glycolysis flux varies by more than x100
inhibition
inhibited by ATP
relieved by ADP and AMP
[ATP] only drops 10% when exercising as it is buffered by creatine and adenylate kinase
adenylate kinase catalyses 2ADP -> ATP + AMP
adenylate kinase equilibrates the ADP generated
a 10% change in [ATP] can result in more than 400% increase in [AMP]
a metabolic signal, decrease in [ATP], too small to activate PFK is amplified by adenylate kinase to a strong signal, [AMP], that can activate PFK
Glycogen Phosphorylase
dimer
large n-terminal domain
small c-terminal domain
phosphorylated form is phophorylase A and the dephosph form is phophorylase B
A is sensitive to ATP, G6P and AMP
B is sensitive to glucose
T and R states
phosphorylation of Ser14 promotes conversion of T to R
negative regulators preferentially bind the T state of the dephospho enzyme
AMP preferentially binds to the R state of the dephospho enzyme
only glucose binds the phosphorylates T state acting as an inactivator
Transport and Storage of Lipids
lipids - collective term for natural molecules that don't dissolve in water
Triacylglycerols can't cross the cell membrane but can be broken down into fatty acids by lipoprotein lipase - lipolysis
lipids are transported by lipoproteins with a TAC in the core
there are several classes of lipoproteins depending on the amount of TAC and cholesterol they contain
chylomicron
very low density
intermediate density
low density
high density
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