An introduction to the human genome

Question 1

how to DNA strands pair up

Answer 1

in an antiparallel fashion

Question 2

what do DNA strands associate with

Answer 2

proteins (including histones) – wound into chromosomes

Question 3

what can happen to DNA during replication

Answer 3

it can become damaged

Question 4

what happens when repair mechanisms become defective

Answer 4

disease occurs

Question 5

how many bases does the human genome contain

Answer 5

3 million bases
30,000 genes
- only about 2% of your genome is genes

Question 6

what is mitosis

Answer 6

One diploid parent cell becomes 2 identical diploid daughter cells

Question 7

meiosis

Answer 7

• One diploid parent cell becomes 4 haploid daughter cells
• Crossing over occurs
• Gamete formation

Question 8

where does DNA replication occur

Answer 8

the S phase

Question 9

what is DNA transcribed into

Answer 9

pre-mRNA

Question 10

what happens to pre-mRNA

Answer 10

spliced to mRNA (introns removed)

Question 11

what happens to mRNA

Answer 11

translated into protein
- 3 bases encode 1 amino acid or stop codon

Question 12

what happens to the protein

Answer 12

modified and moved around the cell

Question 13

describe RNA

Answer 13

• Single stranded
• Ribose sugar backbone
• U replaces T

Question 14

Sequence variations within a gene

Answer 14

• Changes in promoter sequence
• Changes in exon sequence

Question 15

what does snps stand for

Answer 15

Single Nucleotide Polymorphisms

Question 16

what do SNPs do

Answer 16

• Affect gene function, some effects may make you more prone to disease e.g. by affecting transcription (alter promoter)
• Most have no effect

Question 17

what is CVNs(copy number variation):

Answer 17

extra/missing stretches of DNA; deletions or duplications
- Number of copies of a particular gene varies from one individual to the next