Week 3 - Proteins, nucleic acids & gene expression Flashcards
What does the primary structure of a protein do?
Describes the amino acid sequence
What is the secondary structure of a protein?
Where a peptide folds in complex ways
What 2 structures are most widely encountered in the secondary structure of a protein?
Alpha helix and Beta pleated sheets
What is the tertiary structure of a protein?
Conformation of the entire polypeptide chain.
This is stabilised by hydrogen bonds, but also electrostatic bonds and disulphide bonds.
What is an electrostatic (ionic) bonds?
Bonds between positive and negatively charged groups
What is Van der waals interaction?
Non-covalent attraction due to movement of ions in atomic or molecular orbitals
Describe the quaternary structure of proteins
When many polypeptide chains are linked together by interactions/bonds
What are 3 main features of enzymes?
o Speed up reactions.
o Display high specificity
o Catalytic power is regulated – speed of reaction is subject to a variety of factors.
What are the 3 factors affecting enzyme reactions?
Substrate availability
Enzyme concentration
Temperature & pH
How does substrate availability affect enzyme reactions?
Increasing substrate (at same enzyme concentration) speeds up reaction rate - to a point
How does temperature and pH affect enzyme reactions?
Temp. increases kinetic energy of molecules (until denaturation)
Changes in H+ causes removal or addition of protons from active site - conformational change
What are nucleotides?
The building blocks of nucleic acids (DNA and RNA)
How are nucleotides joined in DNA and RNA?
Nucleotides are joined by phosphodiester bonds between adjacent carbons of deoxyribose sugars
What bonds are formed between complementary base pairs of a DNA double helix molecules?
Hydrogen bonds
What do histone proteins do?
They anchor and support DNA to allow dense packaging within cells as chromosomes
