Memorisee Flashcards
What is the relative size of each of structures in the cytoskeleton and what is their function?
Actin Filaments (7nm) Cell and organelle shape, Cell migration
Intermediate filaments (10nm) Mechanical stress
Microtubules (25nm)
Cell shape, Intracellular transport, rhythmic beating of cilia and flagella
Refer to the composition of microtubules in cilia and flagella
Microtubules are arranged in a 9 + 2 formation forming the axoneme
The bending of the cilila and flagella is controlled by a motor protein known as dynein
BASAL BODY = controls the assembly of the axoneme
Why does the phospholipid bilayer form a membrane?
Because it is the most energetically stable confirmation
Describe the structure of a phospholipid?
Formation of non-covalent assemblies held by weak forces, are reffered to as amphipathic as they have both a hydrophobic and hydrophilic region in the molecule. The phosphate heads are polar and can differ.
What are the different types of phosphate heads?
Choline, serine,
Explain how co-transporters are involved in glucose transport in the gut
Na+ and Glucose are transported from the lumen of the gut into the intestinal epithelium via an SGLUT 1 transporter. Glucose is then removed from the gut by a glucose transporter and sodium is removed by a Na+/K+ and ATPase symporter and pumped into the extracellular fluid to maintain the concentration of sodium inside the cell.
What is rehydration therapy?
Re-hydration therapy (used to help diarrhoea e.g cholera or food poisoning )
Severe dehydration can result due to diarrhoea this therapy helps rehydrate the body
Targets the co-transport of glucose and sodium which are co transported into the body, glucose and sodium have an osmotic effect which will help draw in water and give energy.
8 tsp sugar, 1 tsp of salt, 1L of water
- Doesn’t treat the CAUSE however does treat the SYMPTOMS
What chemical is used as a cardiotonic steroid and helps to treat irregular heartbeats?
Foxglove contains a chemical known as digitalis which inhbits the Na+/K+ . Na+ (pumped out) and K+ is pumped in. Associated is also a Ca2+/Na+ pump. Due to the Na+/K+ pump being inhibited more sodium is used to pump in Ca2+ causing the intracellular concentration of Ca2+ to increase.
This results in more forceful and faster contractions
What are examples of genetic diseases caused by enzyme defects?
Phenylketonuria
Unable to convert phenylalanine into tyrosine which results in build up of phenylalanine which can produce toxic by-products and prevent maturation of the brain.
Tay-Sachs disease
No production of the membrane lipid
Glycogen storage disease
Unable to break down glycogen into glucose in the liver.
What enzymes are used as drug targets?
Penicillin - inhibits the bacterial peptidoglycan cell wall synthesis
Anti-inflammatory drugs - drugs e.g aspirin block the inflammatory messenger molecule known as prostaglandin
Anti cancer drugs - blocks the action of folic acid and DNA synthesis pre cursor
How is enzyme activity regulated?
Control of gene expression
Allosteric binding - regulatory molecules will work to control the protein shape and increase or decrease activity
Compartmentation - different sequences in enzymes will be targeted to different organelles
How do allosteric enzymes work?
Have catalytic and regulatory sites on subunits
Regulatory sites will regulate allosteric enzymes via conformational changes
How does the catalytic triad in serine proteases make them more reactive and how do they attack the peptide bond?
In the cleft in the active site forms a catalytic triad Ser, His and Asp. Due to the charge relay system a proton will be transferred from Ser to Asp making it more electronegative and a good nucleophile that can attack the peptide bond.
The O in the serine will then go and attack the C=O of the peptide bond forming an acyl ester. The acyl ester is then hydrolysed by water
Reminder: Nucleophile electron pair donator
How does ATP synthase work?
6 proteins make the active site
There are 3 active sites in total
Active site are used in turn to make ATP, turns 180 degrees ATP is made combining ADP + Pi
Energy from H+ is used to turn the axel motor to make ATP
How does Topo II work?
Molecular clamp that unlinks tangled chromosomes Topo II acts as a clamp that clamps the g-segment of one chromosome. ATP is used to trap the t-segment and make a break in the G-segment. This break allows t-segment to pass through and the G-segment is resealed.
