Nuclear DNA - Classes and organisation

Question 1

Define genome structure and chromosomal structure.

Answer 1

Genome structure entails: Gene density, gene regions, %repeats.

Chromosomal structure entails: Circular/linear, synteny, telomeres

Question 2

What’s haploidy?

Answer 2

It’s the number of alleles that host a certain gene.

Example: ZEB1 is present in three alleles - the cell line is at least partially triploid.

Question 3

What’s the difference between a haplodiploid and a dihaploid?

Answer 3

Haplodiploid: An organism that is haploid and diploid during different times in its cell cycle.

dihaploid: A diploid organism that derives from a haploid one. (chromosomal duplication is required).

Question 4

Provide three genomic rules of thumb.

Answer 4

1. Organism complexity doesn’t correlate with genome size.
2. There are as many pseudo-genes as there are coding genes.
3. There are few introns in unicellular organisms.

Question 5

What’s the approximate size of the human genome and what’s the approximate size of repetative sequences?

Answer 5

Human genome: 3200 Mb

Repetitive seqs: 1400 Mb (Of which 640Mb LINEs, 420Mb SINEs, 250Mb LTRs.

Question 6

What’s two requirements for a region to be a CpG island?

Answer 6

> 1kb, >50% GC

(Present upstream of 1% of vertebrate genes)

Question 7

What are the two types of homologous genes?

Answer 7

Paralogues : Genes of common ancestry found in the same genome. The gene function doesn’t need to be preserved, the origin is likely from a duplication event. (Para ~ near)

Orthologues : Genes of common ancestry present in two or more species. (Ortho ~ Straight)