Protein Structure And Function

Question 1

What are the stop codon bases

Answer 1

AUU

AUC

Question 2

What is mRNA used for

Answer 2

To determine the amino acids sequence of proteins that are synthesises in the cytoplasm

Question 3

What is a codon

Answer 3

The sequence of 3 bases on mRNA that code for a single amino acid

Question 4

What the the RNA bases

Answer 4

Adenine
Guanine
Cytosine
Uracil

Question 5

Describe the process of transcription

Answer 5

DNA helicase breaks hydrogen bonds, 2 strands separate
Free nucleotides join complementary bases on the strand
RNA polymerase enzyme allows this
RNA polymerase recognises stop triplet code so detaches

Question 6

Describe what happens in splicing

Answer 6

Introns interfere with polypeptide synthesis

So
Splicing removes introns
Exons recombine

Question 7

Different between exons and introns

Answer 7

Introns don’t code so non-functional

Exons code for protein

Question 8

Describe translation

Answer 8

Ribosome attaches to starting codon on mRNA
tRNA carries amino acid
tRNA has complementary anticodon
Ribosome move along mRNA
2 tRNA pairs with 2 codons on mRNA
Enzyme + ATP used to form peptide bonds between amino acids
Ribosome moves to next codon
tRNA released from amino acid earlier
Process continues until ribosome reaches stop codon

Question 9

What changes if there’s a DNA mutation in base sequence

Answer 9

mRNA base sequence changes
mRNA codon changes
Amino acid sequence of protein changes
Protein structure changes
Protein function changes
Cell function changes

Question 10

What is substitution

Answer 10

Base replaced

Question 11

What is deletion

Answer 11

Base removes

Question 12

What is insertion

Answer 12

Base added

Question 13

What happens when deletion occurs

Answer 13

Frame shift
So sequence read differently
Likely amino acids change 
Only causes harm depending on where
Ie more harmful at end of sequence

Question 14

Name the types of substitution mutations

Answer 14

Nonsense
Mis-sense
Silent

Question 15

What happens in nonsense mutation

Answer 15

If change in base results in stop codon being produced

Polypeptide stopped prematurely

Question 16

What happens in mis-sense mutation

Answer 16

Different amino acid coded for
Polypeptide produced different by 1 amino acid
Significance depends on role of amino acid
Important if it helps form structure of final protein (would lead to not functioning properly)

Question 17

What happens if silent mutation

Answer 17

Still codes for same amino acid as before

Due to degenerate nature

Question 18

Explain why the genetic code is describes as universal

Answer 18

Codon codes same amino acid in all organisms

Question 19

Explain why the genetic code is described as degenerate

Answer 19

Amino acids have more than one codon

Question 20

Explain why the genetic code is describes as non-overlapping

Answer 20

Bases only read once

Question 21

How do you distinguish between a codon and an anticodon

Answer 21

Anticodon only on tRNA

Condone on DNA or mRNA

Question 22

What are single strands and contain ribose sugar

Answer 22

mRNA and tRNA

Question 23

How many nucleotides made tRNA

Answer 23

Around 80

Question 24

What outside factors increase the chance of mutations

Answer 24

High energy radiation

Certain chemicals

Question 25

What are mutagenic agents or mutagens

Answer 25

Things that increase the chances of mutation occurring

Eg high energy radiation or certain chemicals

Question 26

How can mutations be positive

Answer 26

They create variation and genetic diversity

Question 27

Name the 2 genes that control cell division

Answer 27

Proto-oncogenes

Tumour suppressor genes

Question 28

What do proto-oncogenes do?

Answer 28

Stimulate cell division

Question 29

What do tumour suppressor genes do

Answer 29

Slow cell division

Question 30

List the key word stages of protein synthesis

Answer 30

Helicase
Unzipping
Nucleotides
Complementary
Polymerase
Splicing
mRNA
Cytoplasm
Ribosomes
Codons
tRNA
Peptide bonds 
Polypeptide chain