Unit 1.2c(ii) Flashcards
(38 cards)
What is a ligand?
A substance that binds to a protein
What do R groups stabilise?
Folding of tertiary structures in proteins
What facilitates molecule binding?
R-groups on the proteins outer surface
What causes ligand binding sites on the protein surface?
Proteins folding
What on binding sites is complementary to ligands?
Their shape and chemistry
What matching elements bind the protein and ligand together?
Charged, polar and non-polar R-groups
What is the enzyme specific shape called?
The active site
What is ligand binding essential for?
Cell signalling that activates receptors or channels
Why is DNA considered a ligand?
Because it binds to proteins involved in replication, transcription and translation regulation in operons
How do DNA-protein interactions help fit DNA into the nucleus?
They help package long DNA into chromosomes
In eukaryotes how does DNA Lind to histone protein?
DNAs negatively charged backbone binds to the positively charged histone
What is formed when DNA wraps around a histone?
It forms a nucleosome
What happens when double stranded DNA binds to transcription factors?
Transcription is inhibited or initiated
What do transcription factors do?
Control gene expression
What happens if an activator protein binds to a specific DNA sequence?
Transcription of downstream genes is stimulated
What is the enhancer?
The part of DNA that that recruits transcription factors and RNA polymerase to the promoter region of the transcribed gene
Why do conformational changes occur?
The interaction between the ligand and protein binding site pull the polypeptide towards the ligand
What is a proteins change in shape called?
Conformational change
What does a change in protein shape cause?
A change in the proteins function
What regulates the proteins activity?
Conformational change
What is an allosteric enzyme/protein?
An enzyme/protein that has multiple sub-units (quaternary structure) with multiple binding sites
What happens when a ligand binds to an allosteric subunit?
The affinity of the rest increases
What causes allosteric enzymes activity to vary?
Small changes in substrate concentration
What are ligands that bind to allosteric enzymes called?
Modulators
