B13 - Gene expression

Question 1

gene expression

Answer 1

-gene codes for a protein that is synthesised in the cell

Question 2

non coding parts of dna

Question 3

each gene controls

Answer 3

-synthesis of many proteins

Question 4

variations in genes

Answer 4

affects how genes are expressed (phenotype)

Question 5

phenotype

Answer 5

-the physical appearance or biochemistry of an organism

Question 6

mutation

Answer 6

• changes in existing genes = new form of genes
  -usually harmless

Question 7

mutation can

Answer 7

-change a protein produced/shape
-so it loses its function
-or produce a more efficient protein

Question 8

mutations in non coding DNA

Answer 8

-may not affect the phenotype
-can affect which genes are on/off

Question 9

changing genes that are expressed =

Answer 9

changes phenotype

Question 10

alleles

Answer 10

different forms of genes
-codes for diff proteins
-combination of these are inherited characteristic

Question 11

homozygote

Answer 11

an individual with two identical alleles for a characteristic

Question 12

homozygote eg

Answer 12

BB
bb

Question 13

heterozygote

Answer 13

an individual with a different alleles for a charcateristic

Question 14

heterozygote eg

Answer 14

Bb

Question 15

genotype

Answer 15

alleles present or genetic makeup of an individual
-regarding a particular characteristic

Question 16

genotype eg

Answer 16

BB, Bb, bb

Question 17

phenotype affects

Answer 17

physical appearance

Question 18

genetic cross

Answer 18

-consider potential offspring that might result from two known parents

Question 19

A dominant disease genotype

Answer 19

BB Bb not bb

Question 20

Recessive disease genotype

Answer 20

bb
carriers = Bb
not = BB

Question 21

dominant gene in phenotype

Answer 21

always expressed
-even if only one copy is present

Question 22

recessive allele is expressed

Answer 22

only when 2 copies are present

Question 23

sex determination

Answer 23

determines sex of offsring

Question 24

female chrmosome

Answer 24

XX

Question 25

male chromosome

Answer 25

XY Y is very small and carries fewer genes

Question 26

sex chromosome process

Answer 26

cells undergo meiosis to form gametes -one sex chromosome goes into each gamete -egge cells al have X sperm cells half = Y and half = X

Question 27

other 22 chromosome structure

Answer 27

similarly shaped -control general body charcteristic

Question 28

inherited disorders

Answer 28

results of change in bases or coding of genes -passed down from parents

Question 29

polydactyly

Answer 29

babies are born with extra finger or toes -caused by the dominant allele

Question 30

chances for heterozygous to pass polydactyly on

Answer 30

50%

Question 31

chances for homosygous to pass polydactyly on

Answer 31

100%

Question 32

cystic fibrosis

Answer 32

-mucus made by cells = thick -lungs become clogged -pancreas cannot secret enzymes as tubes are blocked -infertility

Question 33

treatment for cystic fibrosis

Answer 33

-physiotherapy antibiotics -enzymes are replaced but no cure

Question 34

cystic fibrosis caused by

Answer 34

recessive gene -must be inherited by both parents -carriers have no symptoms

Question 35

genetic engineering

Answer 35

replace faulty genes with healthy genes

Question 36

screening embryos

Answer 36

-harvest eggs from individual

Question 37

Amniocentesis takes place at

Answer 37

15-16 weeks

Question 38

Amniocentesis

Answer 38

fluid is screened as it contains fetal cells

Question 39

Chorionic villus takes place between

Answer 39

10-12 weeks

Question 40

Chorionic villus

Answer 40

sampling embryonic cells from tissue of placenta

Question 41

screening IVF

Answer 41

-embryos are tested before implanted

Question 42

pros of screening

Answer 42

parents are able to decide to prepare or terminate pregnancy

Question 43

Concerns of screening

Answer 43

-increase risk of miscarriage - false results -ethical/religious concerns -expensive -rise in designer babies = parents choose phenotype