DNA, RNA and protein synthesis

Question 1

Name the properties of eukaryotic DNA

Answer 1

Linear DNA molecules
Chromosomes found in nucleus
Very long, wound up to fit in the nucleus
Wrapped around histones
Chloroplasts and mitochondria has own DNA

Question 2

Name the properties of prokaryotic DNA

Answer 2

Carry DNA as chromosomes
Shorter and circular
Supercoils to fit in cell

Question 3

Define what a gene is

Answer 3

A sequence of DNA bases coding for either a polypeptide or functional RNA

Question 4

What are introns and exons?

Answer 4

Introns are non coding sections of DNA, exons are coding

Question 5

What does mRNA do?

Answer 5

Made during transcription

Carries genetic code

Question 6

What does tRNA do?

Answer 6

Involved in translation 
Carries the necessary amino acids to ribosomes
Folded into clover shape
H bonds between specific bases
Three bases at one end 
Has amino binding site

Question 7

How does transcription work?

Answer 7

RNA polymerase attaches to binding site at start of gene
DNA helicase breaks hydrogen bonds between the two strands, exposing bases
RNA polymerase lines up free floating nucleotides and forms the phosphodiester backbone
H bonds reform of DNA strand
RNA polymerase detaches at the stop signal
mRNA moves out of the nucleus and attaches to ribosome

Question 8

How does translation work?

Answer 8

mRNA attaches to a ribosome and tRNA carries amino acids (bonded using ATP)
tRNA has an anticodon which is complementary to the first codon on mRNA, they bind
The next mRNA does the same
The two amino acids are bonded by a peptide bond
The tRNA molecule moves away
The process repeats until a stop codon is reached

Question 9

Describe genetic code in three ways

Answer 9

Degenerate, lots of combinations and more than one codon can code for the same amino acid
Universal, the same base triplets code for the same amino acid in all organisms
Non-overlapping, each triplet code is read once

Question 10

Name the base pairs of DNA

Answer 10

Adenine and Thymine

Cytosine and Guanine

Question 11

Name the base pairs of RNA

Answer 11

Adenine and Uracil

Cytosine and Guanine