DNA genes and chromosomes

Question 1

Describe the structure of DNA and histones

Answer 1

Very long
Linear and associated with histones
Histones are proteins
DNA is very long so wounds up to fit in the nucleus and histones help support the DNA
Histones and dna are tightly compacted to form chromosomes

Question 2

What is the difference of DNA in prokaryotes and inside chloroplasts and mitochondria ?

Answer 2

DNA is short circular and not associated with proteins

Question 3

What is a gene ?

Answer 3

A sequence of DNA which determines the amino acid sequence of a polypeptide

Question 4

What does DNA code for ?

Answer 4

tRNA rRNA

Question 5

What is a locus ?

Answer 5

Where a gene occupies a fixed position on dna

Question 6

What is an allele ?

Answer 6

Different versions of genes

Question 7

What is the sequence of three DNA bases called ?

Answer 7

Triplet code
Codes for a specific amino acid
Triplet is known as a codon

Question 8

What is a codon ?

Answer 8

Complimentary three bases on mRNA
One codon = one amino acid
The code is universal for all living things, non overlapping ( a base can only belong to one triplet ) each triplet is read separately and degenerate ( a single amino acid may be coded by more than one codon

Question 9

What is an exon ?

Answer 9

Sequences within a gene that code for amino acid sequences

Question 10

What is an intron ?

Answer 10

Non coding sequences
Prokaryotic dna don’t contain introns

Question 11

What are the similarities differences between mRNA and tRNA ?

Answer 11

mRNA is single stranded so is tRNA
tRNA is folded into a clover leaf shape whereas mRNA isn’t
mRNA is a longer chain and has more nucleotides
tRNA has hydrogen bonds mRNA doesn’t
tRNA has an anticodon mRNA doesn’t
mRNA is made up of codons
tRNA is reused
tRNA has a specific amino acid attachment site
mRNA is broken down after use
In mRNA bases are unpaired and are complimentary to the base sequence of a gene