MCBG 15 - More mutations and techniques

Question 1

What’s a Mutation?

Answer 1

A mutation is a change in a DNA sequence

Question 2

What’s a somatic mutation?

Answer 2

mutations occur in the eggs or sperm, affect all cells in the body and can be passed on to offspring

Question 3

What’s a Germ line (genetic or hereditary) mutation?

Answer 3

mutation occur in a body cell and is not passed on to offspring

Question 4

What are the functions of DNA POLYMERASE? 2

Answer 4

Forms strands of DNA from bases

Proof reads

Question 5

Why are RNA mistakes less worrying? 3

Answer 5

RNA is not long term ( they get degraded especially if they are “bad”)
Small effect
RNA is not inherited

Question 6

Name 3 symptoms of Mitochondrial DNA conditions?

Answer 6

Muscle weakness/Wasting
Diabetes
Kidney Failure
Heart Disease
Demenia
Hearing loss

Question 7

In a genetic pedigree tree what signs would you look for?

Answer 7

1) Only inherited from affected mothers.

2) Children of affect mothers are all affected

Question 8

Why could it be bad to inherit multiple copies of a chromosome?

Answer 8

If the genes function to slow growth, the extra copy may be fatal to the cell. However, ifthe genes promote growth, the cell may grow uncontrollably, leading to
cancer

Question 9

Explain how an ovum is formed? Processes, name, N?

Answer 9

Oogonium2n(Mitosis to form more) -[maturation]-> Primary Oocyte2n+Polary body-[Meiosis1]->Secondary Oocyte2n -[Meiosis2]-> Ootide + 3 polar bodies -[Maturation]-> Ovum

Question 10

The oocyte becomes arrested twice. One in meiosis 1 and once in meiosis 2. What stage of each of these?

Answer 10

MEI1 - Prophase 1

MEI2 - Metaphase 2

Question 11

What comes before an oogonium/spermatogonium?

Answer 11

Primordial Germ Cells

Question 12

Do female PGCs and then oogonia and then primary oocytes
increase hugely in number in the fetus, then decline hugely by birth
and thereafter until puberty? would you predict the loss is due to
apoptosis or necrosis?

Answer 12

Apoptosis

Question 13

Do PGCs in males only start to differentiate into spermatazoa at puberty?

Answer 13

They are only needed when oocytes are available to fertilise!

Question 14

Which has a higher mutation rate before fertilisation?

Answer 14

Females. The mutation rate in male gametes is approx 5x higher than in
female gametes

Question 15

What % of sperm are aneuploid?

Answer 15

6%

Question 16

What % of oocytes are aneuploid?

Answer 16

20%

Question 17

What % of clinically recognised pregnancy loss results from chromosomal abnormalities?

Answer 17

75%

Question 18

Name a Mutation in early embryogenesis

Answer 18

Chymerism

Question 19

What do you think are the possible outcomes if a very early embryo
was exposed to radiation (a mutagen) 3

Answer 19

Death/aborted
• Teratogenesis (bnormalities of physiological development)
• Cancer when born

Question 20

In general what do recessive mutations cause?

Answer 20

In general recessive mutations cause loss of function and often affect
biochemical pathways (not a rule!)

Question 21

In general what do dominant mutations cause?

Answer 21

In general dominant mutations cause increased function and often
cause structural abnormalities (not a rule!)