3.4.1 DNA, genes and chromosomes

Question 1

DNA storage

Answer 1

Eukaryotic DNA: long, linear, associated with proteins (histones), tightly coiled into chromosomes (

Prokaryotic DNA: short, circular, not associated with proteins

Question 2

Mitochondria and chloroplasts DNA

Answer 2

Similar to prokaryotic DNA - short, circular, not associated with proteins

Question 3

Genes

Answer 3

Sequence of DNA bases that code for:
The amino acid sequence of a polypeptide (primary sequence)

A functional RNA e.g. ribosomal RNA and tRNAs

Occupies a fixed position (locus) on a particular DNA molecule

Question 4

Nature of the genetic code

Answer 4

Sequence of DNA triplets (mRNA codons) codes for sequence of amino acids

Universal: the same specific DNA base triplets code for the same amino acids in all living organisms

Non-overlapping: discrete, each base can only be used once and in only one triplet

Degenerate: the same amino acid can be coded for by more than one base triplet

Question 5

DNA triplet (mRNA codon)

Answer 5

sequence of 3 bases which code for a specific amino acid

Question 6

Eukaryotes DNA

Answer 6

Non-coding multiple repeats between genes

Within genes - only exons code for amino acid sequences, which are separated by one or more non-coding sequences (introns)

Question 7

Genome

Answer 7

Complete set of genes in a cell, including those in mitochondria and/or chloroplasts

Question 8

Proteome

Answer 8

The full range of proteins that a cell/genome is able to produce

Question 9

Allele

Answer 9

Different versions (sequence of bases/triplets) of the same gene

Question 10

Homologous pair of chromosomes

Answer 10

Same size chromosomes with same genes, but different alleles