Chapter 3.5: Proteins and DNA Flashcards
What is the structure of an amino acid?
1 Nitrogen, 4 Hydrogen, 2 Oxygen and a variable group (R)
What bonds are used in amino acids?
Peptide bonds
What reaction is used to join amino acids?
Condensation reaction
What are numerous amino acids joined together called?
Polypeptide bonds
What practical can be used to separate proteins?
Chromatography practical
What are the 4 types of protein structure?
Primary, secondary, tertiary and quarternary
Equation for Rf value?
Distance travelled by component divided by distance travelled by solvent
What is a primary structure?
A sequence of amino acids. Only bonds involved are peptide bonds
What is a secondary structure?
Two types - alpha helix and beta pleated sheet
Held together with hydrogen bonds and polypeptide chains. The shape is determined by where the hydrogen bonds form
What is a tertiary structure?
The folding of a protein into its final shape. Forms hydrogen and ionic bonds. Also disulphide bridges are made (strongest of the bonds) Produces a variety of complex-shaped proteinsWh
What is a quaternary structure?
Two or more subunits (individual proteins) joining together.
Globular proteins properties?
Water soluble, compact, globe shaped. Used for muscles contraction and immunity
Example of a globular protein?
Insulin
What are globular proteins?
Globular proteins that contain a non-protein component called a prosthetic group. Proteins without this are called simple proteins
Haemoglobin, what is it?
Red, oxygen carrying pigment found in red blood cells. It is a quaternary protein made up of four polypeptides ( 2 alpha, 2 beta)
What is catalase?
An enzyme and a quaternary protein. Catalyses reactions
Explain fibrous proteins?
They’re formed from long, insoluble molecules. Repetitive amino acid sequence which leads to very organised structures
What is keratin?
A fibrous protein present in hair, nails and skin. Very strong disulphide bridges making it very strong.
What is elastin?
A fibrous protein present in walls of blood vessels and alveoli. It gives these structures the flexibility to expand when needed and also return to their original size.
What is collagen?
Another fibrous protein. A connective tissue found in skin, tendons and the nervous system. Has lots of flexibility.
What 3 things make up a nucleotide?
Phosphate, sugar and a base
What sugar is present in DNA?
Deoxyribose
How are nucleotides linked together?
Condensation reactions that forms phosphodiester bonds
What are the 4 types of base?
Thymine (T), Adenine (A), Guanine (G) and Cytosine (C)
Which base changes in RNA
Thymine becomes Uracil (U)
What are pyrimidines and which bases are they?
Smaller bases which contain a single carbon ring.
Thymine, Cytosine and Uracil
What are purines and which bases are they?
Larger bases which contain a double carbon ring.
Adenine and Guanine
Shape and direction of DNA?
Double helix and antiparallel
How do the complementary base pairs bond/
A -> T is two hydrogen bonds
C -> G is three hydrogen bonds
How are DNA and RNA different?
Ribose sugar instead of deoxyribose. Thymine is replaced by Uracil
What enzyme ‘unzips’ DNA?
DNA helicase
How does helicase work?
Travels along DNA backbone catalysing reactions to break hydrogen bonds between complementary base pairings
What do the nucleotides do after being unzipped?
Free nucleotides pair with newly exposed bases on the template strand
What does DNA polymerase do?
Catalyses the formation of phosphodiester bonds between the molecules
