The Human Genome

Question 1

What 2 elements lead to disease?

Answer 1

Genetics and environment

Question 2

What is the concept of precision medicine?

Answer 2

Identify and treat people who will benefit from treatment. Those who the treatment isn’t suitable for either have to get a different treatment or for some there is no suitable alternative.

Question 3

How is DNA organised?

Answer 3

Double stranded, antiparallel, when replicated read in 5’-3’ direction. Sugar backbone is 2-deoxyribose. Bases ATGC

Question 4

Where is the information in DNA held?

Answer 4

The sequence of bases held on a sugar-phosphate background

Question 5

How are DNA bases paired?

Answer 5

Adenine with thymine, cytosine with guanine

Question 6

What does the DNA strand associate with and form?

Answer 6

Wrapped around proteins (histone) and wound into chromosomes

Question 7

How much of your genome is genes?

Answer 7

2-3%

Question 8

What are the 4(/5) stages of the cell cycle?

Answer 8

G1, (sometimes G0), S(ynthesis), G2 and M(itosis)

Question 9

During what phases of the cell cycle does DNA replication occur?

Answer 9

S phase

Question 10

What is the DNA damage and repair mechanism?

Answer 10

Damage can occur during replication of DNA, and there are repair mechanisms however if the mechanisms are defected disease can be caused.

Question 11

What significance does only 2% of the genome being genes have in mutations?

Answer 11

When mutations occur during mitosis it has a very high chance of occurring in an area that isn’t genes so won’t affect the genotype

Question 12

What are the key parts of meiosis?

Answer 12

One diploid parent cell = 4 haploid daughter cells. Crossing over occurs

Question 13

When does meiosis happen?

Answer 13

During gamete formation

Question 14

How does RNA differ in comparison to DNA?

Answer 14

Single stranded, ribose sugar in backbone not deoxyribose, and uracil instead of thymine

Question 15

Which one is more stable, RNA or DNA?

Answer 15

DNA as if RNA was more stable it would stay making proteins for too long and it is only required for a short time to code

Question 16

What binds to the promotors in DNA?

Answer 16

Transcription factors

Question 17

Are introns coding or non-coding?

Answer 17

Non-coding and so cut from DNA during transcription

Question 18

Are exons coding or non-coding?

Answer 18

Coding and so spliced together after introns cut during transcription

Question 19

What factors determine the amount of protein produced?

Answer 19

Rate of transcription, rate of splicing to mRNA, half life of mRNA and rate of processing of polypeptide.

Question 20

What is DNA transcribed to?

Answer 20

Pre mRNA

Question 21

What is pre mRNA spliced to?

Answer 21

mRNA

Question 22

What is mRNA translated to?

Answer 22

A protein (remember 3 bases encode an amino acid or a stop codon)

Question 23

Why do some point mutations have no affect on the protein created?

Answer 23

As sometimes a different triplet of bases code for the same amino acid

Question 24

How do sequences vary in a gene?

Answer 24

Changes in the promotor sequence and changes in the exon sequence

Question 25

What is the promotor sequence?

Answer 25

The region of the DNA sequence where transcription of a gene by RNA polymerase begins

Question 26

What causes sequence changes in the DNA between genes?

Answer 26

Single nucleotide polymorphisms (SNPs) or larger deletions/duplications

Question 27

What is polymorphism?

Answer 27

Any variation in the human genome that has a population frequency of >1% OR any variation in the human genome that doesn't cause a disease but may be a predisposition to one.

Question 28

What is a mutation?

Answer 28

A gene change that causes a genetic disorder OR any heritable change in the human genome

Question 29

How does variation in the human genome occur?

Answer 29

Crossing over at meiosis cause variants to segregate independently of each other (unless they were close together on the chromosome)

Question 30

Why do people have genetic variants their parents don't have?

Answer 30

As DNA replication isn't perfect and so every cell in your body has mutations acquired during mitosis