Cause and Effects of Variation in the Genome

Question 1

What are some of the effects of altered proteins/ control of genes

Answer 1

Normal variation
Different response to medication
Likelihood of disease
Genetic condition

Question 2

What are polymorphisms

Answer 2

Non-harmful mutation in non-functional DNA

Doesnt alter protein function

Question 3

What are microsatellites

Answer 3

Tandem repeats of 2-6 BP

Question 4

What are minisatellites

Answer 4

Tandem repeats of 10-60 BP

Question 5

How does the Polymerase chain reaction work

Answer 5

Heat to denature DNA. Primers put in. Heat stable polymerase then builds the complementary chain

Question 6

What is the size of DNA fragments limited by

Answer 6

Polymerase enzyme

Question 7

How do you define length of amplifier

Answer 7

dDistance between annealed primers

Question 8

What is the Sanger method

Answer 8

Anneal specific oligonucleotide primer to each template strand.
Strand synthesis catalysed by DNA polymerase, dNTPs and ddNTPs
ddNTPs = No 3 prime hydroxyl group so next nucleoside trisphosphate cannot bind. Fluorescently tagged

Question 9

How could errors in DNA replication & meiotic cell division cause human disease

Answer 9

Meiosis = transmitted to children
DNA replication = change in base sequence
Crossing over = structurally abnormal chromosomes
Dealing out chromosomes = numerical abnormalities

Question 10

What are the endogenous mechanisms causing mutations

Answer 10

Depurination = spontaneous fission of link between purine base and sugar
Deamination = cytosine deaminates to uracil
Reactive O2 = attack purine/pyrimidine rings
C methylated to 5-methyl-cytosine which deaminates to thymine

Question 11

What are the extracellular agents that cause mutations

Answer 11

UV = Cross linking of adj thymines to form stable dimer
Chemicals
Ionising radiation = break DNA

Question 12

What is germline mutation

Answer 12

Present in eggs/sperm

Heritable

Question 13

What is somatic mutation

Answer 13

Non-germline tissue

Non-heritable

Question 14

What is the DNA mismatch repair

Answer 14

Back-up to DNA polymerase

Question 15

What occurs if protein complex recognise mismatch

Answer 15

Excise mismatched strand + Re-synthesise strand

Question 16

What occurs if there is mutation in mismatch repair genes

Answer 16

Accumulation of permanent somatic mutations.

Question 17

How is damage due to ionising radiation and reactive O2 repaired

Answer 17

Broken ends processed by nuclease
Ends joined by DNA ligation
Break repaired but deletion of nucleotides at repair site

May use homologous chromosome to synthesise missing DNA = homologous recombination

Question 18

What are some of the types of DNA mutations

Answer 18

Silent Mutations = change in BP but not aa
Missense mutation = change in BP and aa
Nonsense mutation = Change in BP leading to STOP codon
Splice site mutation = prevent correct splicing
Frameshift mutation
Copy number variants