Human molecular genetics

Question 1

Why was the human genome sequenced?

Answer 1

• To identify all human genes and their roles
• To analyse genetic variation between humans
• To sequence the genomes of several model organisms used in genetics

Question 2

What is a genome?

Answer 2

Complete set of DNA of an organism, including all its genes

Question 3

What are some properties of nuclear DNA?

Answer 3

22 Autosomes, X and Y
6 billion base pairs
Half from each parents
<21,000 genes

Question 4

What are some properties of Mitochondrial DNA?

Answer 4

Single, circular
16,569 base pairs
All from mother
37 genes

Question 5

What are the key findings from sequencing the human genome?

Answer 5

• Fewer genes than expected
• > 2% of our genome codes for proteins
  Dynamic
• Don’t know what many protein coding genes do (around 25%)
• 99.9% similar genome among humans
• The genome is dynamic
• Most human genes are related to those of other animals

Question 6

What are Exons and in what proportion are they?

Answer 6

Making functioning proteins (1.5% coding)

Question 7

What are Introns and in what proportion are they?

Answer 7

Determine whether genes are turned on or off (20%)

Question 8

Where does the most genetic variation come from in the world?

Answer 8

Africa

Question 9

What proportion of genes have a unknown function?

Answer 9

25%

Question 10

What are SNPs?

Answer 10

Single Nucleotide Polymorphisms

• Sites in the DNA that commonly vary within the population
• They are common, 1 in every 300 neuleotides
• Mostly inherited from parents
• Most SNPs don’t do anything

Question 11

What are STRs

Answer 11

Short term repeats.

• Are repeats of 2-5 nucleotides, found in specific regions of genome
• Each inherited allele can be at different lengths
• Can be used to create genetic profiles, or “DNA fingerprints”

Question 12

What are InDels?

Answer 12

Small insertions or deletions

• Second most common variant type
• Cystic fibrosis is caused by CFTR deltaF508 which is a 3 nucleotide deletion.
• Change the way the DNA is read, causing protein deformation “frame shift”

Question 13

What are CNVs?

Answer 13

Copy number variations.

• Chucks of DNA > 500bp that are present at different amount of “copy numbers” relative to a reference genome
• Can be deleted or duplicated
• Can span multiple genes
• Around 10,000 CNVs in humans

Question 14

Why is variation in the genome important?

Answer 14

Variation within the genome is a key driver of evolution and a signature of descent.

Question 15

What is diversity in the human genome good for?

Answer 15

It adds to the knowledge of variation in the human species