Genetics 1

Question 1

gene expression

Answer 1

transcription: helicase split DNA, mRNA formed by RNA polymerase
translation: mRNA to ribosome, tRNA comp base pairing with 3 base coding region bringing correct AA - form protein
Post-trans mod: give 3D structure and prepare for role - ER anad Golgi

Question 2

insertion

Answer 2

addition of base

Question 3

deletion

Answer 3

removal of base

Question 4

substitution

Answer 4

base switched for another

Question 5

dublication

Answer 5

dna abnormally copied one or more times

Question 6

frameshift

Answer 6

addition/loss of bases = changes in genes reading frame

Question 7

repeat expansion

Answer 7

nucleotide repeats - short DNA sequences repeated multiple times in row eg trinucleotide repeat
repeat expansions - mutation increases the number of times the DAN is repeated eg huntingtons

Question 8

point mutation

Answer 8

missense - sub of 1 AA for another
nonsense - formation of stop
silent - altered codon corresponds to same AA

Question 9

where are mutations more important

Answer 9

coding region

= defective protein

Question 10

sickle cell

Answer 10

mutation of glutamic acid to valine

valine higher affinity to itself than O2 - hydrophobic

Question 11

risk of passing on sickle cell

Answer 11

depends on mother
recessive
mother trait = 50% chance affected
mother normal = no chance affected - could be carrier

Question 12

CF

Answer 12

loss of chloride ion transporter
common monogenic conditions in Caucasian
pancraetin insufficiency
need enzyme replacement
thick mucous
pul secretions = bronchiectasis
failure to thrive in children = lung transplant

Question 13

mutation of CF

Answer 13

changeF508

Question 14

inheritance of CF

Answer 14

autosomal recessive

Question 15

Tay sachs disease

Answer 15

at 5 months

weaker, hypotonic, hyperreflexic, seizures, not responsive to visual stimuli, MRI showed macrocephaly

Question 16

marfan’s syndrome

Answer 16

early diastolic murmer
tall
wide arm span
loss of function of Fibrillin-1 gene on chromosome 7

Question 17

mutation in Marfan’s

Answer 17

loss of function - normally recessive

here they are dominant - no protein can be made - null mutation

Question 18

huntingtons

Answer 18

CAG chain repeats
autosomal dominant
trinucleotide repeat expansion
anticipation - a longer repeat = earlier onset of symptoms

Question 19

CAG repeats

Answer 19

6-26 normal
27-35 - intermediate - rarely cause disease
>27 unstable, expand with future generations
>36 repeats - threshold for disease
36-39 variable penetrance
>40 full penetrance