Genes And Gentic Code

Question 1

Define gene

Answer 1

Section of DNA that contains the information for making polypeptides or functional RNA

Question 2

What is a gene locus?

Answer 2

Where a gene is found on a chromosome

Question 3

What is meant by the DNA code being Degenerate

Answer 3

1 amino acid can be coded for by multiple triplets

Question 4

What is meant by the DNA code being non overlapping?

Answer 4

Each base only read once

Question 5

What is meant by the DNA code being universal?

Answer 5

Same triplet codes for the same acid in each species

Question 6

Not all of the DNA sequence is coding what do you call the coding and non coding sections?

Answer 6

Exons are coding

Introns are non coding

Question 7

Describe DNA within a prokaryote

Answer 7

Shorter
Circular
Not histone associated
Not in chromosomes

Question 8

Describe DNA in eukaryotes

Answer 8

Longer DNA
Linear DNA
associated with histones to form chromosomes
Some DNA like prokaryotes within individual organelles

Question 9

Describe the structure of a chromomes

Answer 9

DNA is coiled around histones and then further looped to form the chromosome

Question 10

Describe homologous pairs of chromosomes

Answer 10

One set of genetic infomation from both parents

They will have the same genes but not the same alleles of the genes

Question 11

Define allele

Answer 11

Variations of the same gene with a different base sequence

Question 12

What is a codon, genome and proteome?

Answer 12

Codon =. Sequence of three bases that codes for an amino acid
Genome = complete set of genes within a cell
Proteome = full range of proteins coded for by the DNA

Question 13

Describe transcription

Answer 13

1) DNA strands seperate exposing nucleotides
2) template strand pairs with complementary nucleotides
3) RNA polymerase joins RNA nucleotides together
4) DNA Strands rejoin behind
5) RNA polymerase reaches stop codon

Question 14

Describe the process of splicing, which type of organism will splicing occur? Why this organism and not others ?

Answer 14

Pre mRNA to mRNA
The removal of introns and the joining of exons
Eukaryotes- not in prokaryotes as they done have introns

Question 15

Once mRNA is spliced what happens to it?

Answer 15

Diffuses out of nuclear pores

Associates with a ribosome to undergo translation

Question 16

Translation

Answer 16

1) mRNA associates with ribosome on AUG start codon
2) tRNA with complementary anticodon pairs with codon, carrying an amino acid (methionine)
3) another tRNA molecule binds to next codon with its complementary codon carrying another amino acid
4) ATP used to form a peptide bond between the proteins on adjacent tRNA molecules
5) thrid moves in and repeats whilst first detaches
6) process stops when it meets at stop codon

Question 17

Describe the structure of mRNA

Answer 17

Single helix
No introns (after splicing form pre mRNA)
Ribose sugar in nucleotides
Uracil replaces thymine as nitrogenous base

Question 18

Describe the structure of tRNA

Answer 18

Small molecule
Single stranded chain folded into a clover shape
Has a specific anticodon and a specific binding site for an amino acid