The human genome and diseases

Question 1

how can mutations occur

Answer 1

1. inherited
2. acquired

Question 2

what are mutations

Answer 2

permanent changes to the DNA sequence

Question 3

what are inherited mutations called

Answer 3

germline mutations

Question 4

how are germline mutations passed on

Answer 4

through gametes via eggs and sperms

Question 5

how can mutations be acquired

Answer 5

through somatic cells

Question 6

how are mutations acquired by somatic cells

Answer 6

1. if DNA gets damaged
2. DNA is copied incorrectly

Question 7

are somatic mutations inheritable

Answer 7

no - are not passed onto the next generation

Question 8

what is the driving force for evolution

Answer 8

genetic variation/mutation

Question 9

what type of effects can mutations have on an organism

Answer 9

1. beneficial effect
2. no effect
3. deletion effect - damaging/harmful

Question 10

what type of effect does most mutations have

Answer 10

no effect at all

Question 11

what can the outcome of mutations depend on

Answer 11

1. environmental effects such as diet or exposure to toxins
2. other genes (regarding genetic background)

Question 12

why can mutations on a single gene have different effects

Answer 12

due to alleles

Question 13

what are the 2 ways in thinking of mutations

Answer 13

1. dominant vs recessive
2. loss of function vs gain of function

Question 14

what does it mean regarding humans being diploid

Answer 14

they have 2 copies of each of their genes
- one maternal
- one paternal

Question 15

what type of mutations can occur (regarding alleles)

Answer 15

1. heterozygous
2. homozygous

Question 16

what are heterozygous mutations

Answer 16

one mutant and one wildtype allele

Question 17

what are homozygous mutations

Answer 17

both alleles are mutant

Question 18

what is a dominant mutation

Answer 18

on that causes a phenotype when heterozygous - is in every genration and only needs one mutant allele to appear

Question 19

what is a recessive mutation

Answer 19

one that causes a phenotype when homozygous - skips a generation and requires individuals to have both alleles in order to appear

Question 20

what does a mutation have to do in order to have a phenotype

Answer 20

has to affect the function of the gene

Question 21

what does loss of function mean in regards to mutations

Answer 21

a mutation breaks a gene to cause it not work or work as normal

Question 22

is loss of function usually dominant or recessive

Answer 22

often recessive - because a normal copy of the gene exist in the other chromosome which can replace the lost function

Question 23

what does gain of function mean in regards to mutations

Answer 23

a mutation can cause a gene to work too well or do something unexpected

Question 24

is gain of function usually dominant or recessive

Answer 24

often dominant - because having an allele that works too well or does something its not supposed to = can not be replaced by the normal copy of the gene

Question 25

what is an X linked mutation

Answer 25

the gene responsible for the mutation is on the X chromosome

Question 26

what can we determine when we examine the inheritance pattern of an allele

Answer 26

1. dominant vs recessive 2. if it is: - X linked - Y linked - Autosomal

Question 27

how does X linked mutation affect females

Answer 27

- they have a 50% of getting it and will be carriers regardless

Question 28

how does X linked mutations affect males

Answer 28

- fathers can not pass it on to sons (no male to male transition) - most often affects males as they only have one X chromosome therefore if they do have it they will express it

Question 29

what are Y linked mutations

Answer 29

the gene responsible for the mutation is on the Y chromosome

Question 30

how does Y linked mutations affect females

Answer 30

no effect - don't have an Y chromosome

Question 31

how does Y linked mutations affect males

Answer 31

- only affects males as they have XY - father to son transmission

Question 32

are Y linked mutations dominant or recessive

Answer 32

always dominant as the affected male will pass it down to his son and only one Y chromosome is present

Question 33

what are autosomal linked mutations

Answer 33

affected alleles are on the autosomes and not the sex chromosomes

Question 34

how are males and females affected by autosomal linked mutations

Answer 34

males and females are affected equally

Question 35

what are polygenic disorders

Answer 35

involve several genes acting together or environmental factors interacting with genes ( lifestyle choices)

Question 36

what are some examples of polygenic disorders

Answer 36

- obesity - diabetes - Rheumatoid arthritis - gout - bipolar disorder

Question 37

why are genes associated with polygenic disorders hard to identify

Answer 37

due to the complex interplay of multiple genes, environmental factors, and the small individual effects of each gene. This complexity makes it hard to pinpoint specific genes and predict individual risk, especially compared to monogenic disorders where a single gene mutation is responsible for the disease

Question 38

if you have a disease related variation - does it mean you will get the disease

Answer 38

no - such disease come through a combination of variations and the environment most diseases are probabilistic not deterministic