Genetics

Question 1

What are the names of the 4 Bases/Nucleotides? And which are paired?

Answer 1

Adenine - Thymine

Guanine - Cytosine

Question 2

How many chromosomes in each nucleus?

Answer 2

46 (23 pairs)

Question 3

How many Nucleotides in Human Genome (46 chromosomes)?

Answer 3

3.2 Billion Nucleotides

Exons: 30 Million Nucleotides

Question 4

What are exons? What are introns?

Answer 4

Exons = Expert = Instructional Manuel
Instructions for how to make proteins encoded on Exons = 1% of genome

Introns = Introductory lecture = LOGISTICS
Instructions for where the proteins get made, how much to make etc on Introns

Question 5

Where are the chromosomes kept in cells?

Answer 5

Nucleus

• Chromosomes are the master blueprint
• Stay locked up and safe!
• When need to build something, make COPIES of the pages that are required for that task! = mRNA -> spliced mRNA -> translated to generate protein

Question 6

What is a mutation/variation in genes?

Answer 6

A spelling error
Alphabet has 4 letters
= point mutation (change of nucleotide)
= deletion 
= truncation (shortens it)

Question 7

How many mutations do each of us have?

Answer 7

Each of us have 60-100 mutations that neither of our parents have

• • 10-20 of these affect protein expression/function = makes us unique!
• • Identical twins even have some differences

Question 8

Effects of mutations of protein function:

1. Wild type?
2. Loss of function?
3. Gain of function?
4. Haplo-insufficiency

Answer 8

1. Wild type = 100% function
2. Loss of function = no function
3. Gain of function = increase function
4. Haplo-insufficiency = produce less protein than normal, and unable to function properly

**Note: the same mutation in one patient may cause loss of function, and someone else with the mutation may cause gain of function!

Question 9

What is Sanger sequencing?

Answer 9

• Make copies of each exon
• Fluorescent markers
• Each colour is a different Nucleotide
• Sequence each exon one at a time

Question 10

What is Next Generation Sequencing?

Answer 10

Less labour intensive than Sanger sequencing

• Break chromosomes into fragments of DNA
• Attach pieces at the end and attach to a solid matrix ie glass slide
• Add Nucleotides
• Sequences all at the same time

Gives so much data! Can be hard to find the problem/mutation

Question 11

What is the difference whole genome vs exome sequencing?

Answer 11

Genome = all of the DNA (introns + exons)
Exome = just the exons  (1% of genome)

– 25% chance of finding the causative mutation