Notatki Danniego part 8

Question 1

What can change H.W?

4) Negative assortative mating (unlike for like)

Answer 1

• Hermaphrodite flowers
  -> may not self fertile a x ab fails
  -> self incompatibility mechanism -> b x ab fails
  c x ab succeeds
  -> plant with d is advantageous as can mate with any of the others
  -> but will they become more prevalant (?) and become less advantageous
  -> anti-inbreeding mechanism

Question 2

Mice

Answer 2

• female mouse will terminate a pregnancy and absorb the foetus from a male mouse that has same antigen and she smells the scent of a male from another lineage
  - > ensures genetic diversity

Question 3

Odorant receptor

Answer 3

• single largest gene family
  - > 1/6 genes are to do with scent in humans
  - > most are matured (?) oral have no effect now

Question 4

Hutterites

Answer 4

• another religous-wolate group
• higher chance for couplers to marry people that were less (genetically) like them
• spontaneous abortion prevelant in women that had babies with genetically similar males
  - > possible anti-inbreeding mechanism

Question 5

What can change H.W?

5) Mutation

Answer 5

There is always input from mutation

Question 6

What can change H.W?

6) Natural selection

Answer 6

frequencies before selection:
AA Aa aa Total freq a
Gen 0 p^2 2pq q^2 1 q

Assume aa is lethal:
sel. value l l 0
p^2 2pq 0

p^2 + 2pq = p( p+2q) = p( 1+q)
since p + q = 1 =>/

                          AA                      Aa                    aa Rel freq                p^2/(p(1+q))        2pq/(p(1+q))       0 after selection

= p/(1+q) 2q/(1+q) ->
-> so that a= q/(1+q)

• The more common the lethal allele, the faster it is removed from the population
  - > It is in heterozygotes

Question 7

Mutagens include

Answer 7

• atomic bomb
• types of meat? (?)
• cigarettes take 20 years to show mutagenic effects. Some can take a long time to show
• even bacteria can be a mutagen
  - > helicobacter pyroli infects lower par of stomach (antrum) causing peptic ulcar disease (?)
• some genes predispose to somatic mutation
  - > BRCAI -? breast cancer gene
• old age
  - > linked to mutations
  - > maybe mutations cause old age

Question 8

Hugo de Vries

Answer 8

Dutch geneticist

• worked on Oenothera lamarckiana (?) red(?)/white flowers, wrinkled/smooth flowers
• very variable plant
• realised change was due to mutations - made the name
• these plants shatter (?) and rejoin their chromosomes

Question 9

C-14 dating average age of human body cell - … ……
- skin cells - …. ….
- RBC - … …..
Brain/heart/liver …….

Answer 9

• 10 years
• 2 weeks
• 4 months
  very slow replacement

Question 10

Cells that replace quickly are more likely to have mutations and cause cancer
->….

Answer 10

heart cell is very rare

Question 11

Early somatic mutation leads to more cells showing the mutated characteristic as more cells grow from mutated one by mitosis

Answer 11

.

Question 12

Proteus syndrome -

Answer 12

bare one growth from somatic mutation

Question 13

Drosophila mutation

Answer 13

loss/gain of functions
       -> loss of red pigment
 /     -> extra thorax - 2 extra wings
/      -> legs replace anernae (?)
L->  homeotic mutants

Question 14

Loss of function mutation tends to be recessive

Answer 14

-> first few generation of mutants will not show phenotype as hidden in heterozygotes

Question 15

Deteering bacterial mutations:

Answer 15

1) Bacteria spread on original plate
2) Grows into colonies
3) Stamped onto penicillin - containing place using helmet pad (?)
4) Only resistant colonies survived with new mutation

• This experiment showed that mutations were spontaneous - not caused by the penicillin

Question 16

Mutations in Maize

Answer 16

• Every corn normal is a seed
  -> Endosperm
  -> Triploid - 2 female + 1 male
  CC x cc
  Purple white

should be Ccc - all purple
The presence of a white normal shows mutation

Question 17

Mutations in Mice

Answer 17

aa bb cc ++ ++ X ++ ++ ++ dd ee
f1: all a+ b+ c+ d+ e+

If mutation at locus C
a+ b+ cc d+ e+
= mouse with cc coat colour

• Used to test effect of mutagens today
• Can find patches of mutant coat colour on mice

Question 18

Work on mutation rates by looking at (?) pedigrees and working out number of new mutations

Answer 18

~ 60 new mutations in every child from parents

Question 19

Direct detection mutations in a tumour using FISH

Answer 19

.

Question 20

Genetic heterogeneity - polydactyl

Answer 20

• > extra fingers

- > most similar looking mu(?) but don’t count

Question 21

Phoemela (?)

Answer 21

• cleft hand mutation
• environmentally induced
• Phenocopy - copies a genetic mutation

Question 22

Barbara Malintock -

Answer 22

• Showed particular genes that were harmless in one line, caused mutations in another line

f2:
9/16 A- D- black; D+ has no effect on A
3/16 A- dd black
3/16 aa D- dotted: D+ allele mutates a
1/16 aa dd white

-Dotted locus was moving around

Genomic instability - damages other genes
-> intrinsic

Question 23

Variation in per-base (?) mutation rates

Answer 23

Higher rate in bigger genomes

Higher Eukaryotes - 10^-11 - 10^-9
Prokaryotes 10^-10 - 10^-8
RNA virus 10^-5 - 10^-4

Up to 500,000 DNA modification per day
-> We have repair enzymes to fix these

Question 24

Warner Syndrome

Answer 24

promature ageing due to DNA repair failure

more common in Asia

Question 25

Ionising radiation:

Answer 25

UV, X-Ray, Gamma