Topic 3.2: Chromosomes

Question 1

Define homologous chromosomes

Answer 1

Homologous chromosomes are chromosomes that share:

The same structural features (e.g. same size, same banding patterns, same centromere positions)
The same genes at the same loci positions (while the genes are the same, alleles may be different)

Question 2

What is the difference between haploid and diploid?

Answer 2

Haploid (n): one copy of each chromosome

Diploid (2n): two copies of each chromosome

Question 3

Define karyogram

Answer 3

A karyogram shows the chromosomes of an organism in homologous pairs of decreasing length

Question 4

What is the difference between prokaryotic and eukaryotic DNA in terms of location?

Answer 4

Prokaryotic DNA: Is found freely in the cytoplasm (within a region called the nucleoid)

Eukaryotic DNA: Is contained within a nucleus

Question 5

What is the difference between prokaryotic and eukaryotic DNA in terms of form?

Answer 5

Prokaryotic DNA: Is naked (i.e. not bound with proteins and therefore doesn’t form chromatin)

Eukaryotic DNA: Is bound to histone proteins

Question 6

What is the difference between prokaryotic and eukaryotic DNA in terms of genome?

Answer 6

Prokaryotic DNA: Genomes are compact (contain little repetitive DNA and no introns)

Eukaryotic DNA: Genomes contain large amounts of non-coding and repetitive DNA (including introns)

Question 7

What is the difference between prokaryotic and eukaryotic DNA in terms of plasmids?

Answer 7

Prokaryotic DNA: Contains extra-chromosomal plasmids

Eukaryotic DNA: Do not contain plasmids (but organelles such as the mitochondria may contain their own chromosomes)

Question 8

What is the difference between prokaryotic and eukaryotic DNA in terms of shape?

Answer 8

Prokaryotic DNA: Is circular in shape

Eukaryotic DNA: Are linear in shape