PPT-Richard Flashcards
2 types of metabolism
Catabolism and anabolism
What is catabolism?
Energy-releasing, carbon-oxidising and degradative
What is anabolism?
Energy-storing and biosynthesis
What is a futile cycle?
When two biochemical reactions run simultaneously, expending a lot of energy
What are the two types of control?
Internal and external
What are the two types of control?
Internal and external
What is internal control?
Participants on the pathway itself accept how it progresses
What is external control?
Factors form elsewhere affect the pathways progress
What is external control?
Factors form elsewhere affect the pathways progress
What is negative feedback?
Inhibition of a process by presence of large amounts of final product (sending the message that the process has produced enough product
What is precursor/reactant activation?
Activation of a process by the presence of large amounts of initial reactant (sending the message that the process hasn’t consumed enough reactant)
Types of mechanisms
Indirect allosteric mechanisms
Direct mechanisms
What is allosteric control?
Regulator molecule binds to the enzyme at a different site that the one to which the substrate binds to altering enzyme conformation
Common form of allosteric control?
ATP & AMP
What is direct inhibition?
Inhibitor competes with substrate for the active site
What is the michaelis-menton equation?
V = Vmax.([S]/[S] + [Km])
What is the lineweaver-Burke plots?
Vmax and Km: 1/V=Km/Vmax.1/[S] + 1/Vmax
AKA
y=mx+c
What is the lineweaver-Burke plots?
Vmax and Km: 1/V=Km/Vmax.1/[S] + 1/Vmax
AKA
y=mx+c
What is concept of affinity?
The higher the affinity, the less ligand is needed to induce 50% maximal binding
What are signals?
Hormones and nerve impulses
What are the hormones that act as signals?
Amino acid-derived hormones
Steroid hormones
Properties of amino acid-derived hormones
Can’t cross plasma membrane
Initiate intracellular responses
Gene expression
Properties of steroid hormones
Hydrophobic (can cross plasma membrane)
Ligands for cytoplasmic receptors
Complex binds to DNA
Types of non-steroids hormone receptors
Extracellular regions
Cytosolic regions
What are extracellular regions?
Interact with hormones
Series of repeated stretches of hydrophobic amino acids
What are cytosolic regions?
Interact with transducers
Initiate intracellular responses to signals
What are the 3 functional domains in steroid hormone receptors?
Binding hormone
DNA binding
Receptor to activate the promoters of gene being controlled
What is saturation binding?
As hormone concentration rises, concentration of hormone bound to receptor rises until no more can bind
What is scatchard plot?
Mathematical manipulation allows saturation binding to be expresses as straight line
What is an autocrine?
A cells signals itself via a chemical signal that it synthesises and responds to
What is a paracrine?
Chemical signals interact with receptors on nearby cells
What is an endocrine?
Chemical signals are secreted into the blood and carried to the cells they act upon
Definition of signal transduction
A basic process in molecular cell biology involving the conversion of a signal from outside the cell to a functional change within the cell
What are the 5 major classes of steroid hormones?
Mineralocorticoids (increase blood volume & pressure)
Glucocorticoids (promote high blood glucose)
Androgens (development of male sexual characteristics)
Estrogens (development of female sexual characteristics)
Protestagens (maintenance of pregnancy)
Where do the receptor proteins sit?
In the cytoplasm
What is the zinc finger domain?
DNA binding domain
4 pairs of cys that pushes out the 13 basic amino acids to zinc
Ligand binding-conformation change in receptor- zinc finger assembly
How many zinc fingers does a receptor dimer have?
2- stabilises the structure and allows specificity of binding
What do the receptors bind to?
‘Labels’ identifying genes as targets for transcription factors
2 half sites within the DNA sequence
What are the two types of specific response elements?
Palindromic-TGTTCT…TCTTGT
Direct repeats-TGACCT…TGACCT
What forms the RNA polymerase catalysing site?
Two binding sites for the DNA (promoter and enhancer)
Causes a loop
What causes electrical or nervous signalling?
Because of the concentration gradients that exist across the membrane
What do gated channels do?
Can bring about changes in the ionic environment in the cell, and cause a cellular response
What are the consequences of changes in membrane permeability?
Changes in pH or oxidation state
Supplying proteins with ionic co-factors
Supplying cells with energy
Changes in potential difference across membrane
What are the different forms of Ca2+ as a signal?
Buffered form-bound to soluble or membrane linked Ca2+ buffers
Mineral form- collagen rich matrix onto which crystals of insoluble calcium phosphate are laid
What is conformational change?
Ca2+ presence with cells rigger changes in enzymatic activity/ protein movement
What are regulated discrete localised releases of Ca2+?
Signal’s which trigger a range of cellular responses
Where does Ca2+ signalling occur?
In all eukaryotic cells
Flow diagram of Ca2+ system
-Stimulation of cell:
Entry of calcium into localised parts of cell and binding of calcium to biological molecules
-Cellular response:
Expulsion of calcium from cell
-Cell recovery
Why does the ER have a larger surface area than the plasma membrane?
To mop/pump up Ca2+ that has leaked into the cytoplasm and act as a Ca2+ store
How many Ca2+ mobilisation systems do cells have?
2 parallel systems
How many Ca2+ mobilisation systems do cells have?
2 parallel systems
How is Ca2+ released into the cytoplasm?
Channels in the plasma and ER membrane
How is Ca2+ removed from the cytoplasm?
PMCA pump in PM and SERCA pump in ER membrane
What is catabolism?
Stimulation of glycogen breakdown signalled by glucagon and adrenaline
What is anabolism?
Stimulation of glycogen synthesis signalled by insulin
What does hyperglycaemia lead to?
Excess glycation of proteins and lipids
What is dyslipidaemia?
Inability of body to deal with excess fat
What are two cardiovascular complications of type 2 diabetes?
Atherosclerosis-inflammation associated accumulation of fatty/glycated deposit is on interior surface of coronary arteries
Coronary heart disease-blood trapped in the occluded artery closes, causing a coronary thrombosis
What are PPARs?
Ligand activated transcription factor receptor proteins that change express if genes in order to act as insulin sensitising agents, lower blood glucose and boost anti inflammatory defence
