variation, genetics & inheritance (paper 2) TOPIC 6

Question 1

variation definition

Answer 1

differences in the characteristics of individuals in a population

Question 2

what do all variants arise from

Answer 2

mutations

Question 3

define genetic variation

Answer 3

characters determined by the genes we inherit from parents

Question 4

give some examples of genetic variations

Answer 4

• eye colour
• blood group

Question 5

what do our genes control

Answer 5

the development of our characteristics

Question 6

define environmental variation

Answer 6

charcateristics that can be altered or changed by lifestyle

Question 7

give some examples of some environmental variation

Answer 7

• tattoos
• scars

Question 8

what ar ethe two different categories of variation that can be represented on a graph

Answer 8

• continuous
• discontinuos

Question 9

define mutation

Answer 9

a change in the DNA base sequence

Question 10

what is the effect of a CGT nucleotide rather than CTT

Answer 10

a different amino acid is coded

Question 11

if a protein is mutated and it is an enzyme, why might this mutation stop it from functioned

Answer 11

it can lead to a different shaped active site, which is complimentry

Question 12

what is the name of A

Answer 12

base

Question 13

what is the name of B

Answer 13

sugar

Question 14

what is the name of C

Answer 14

phosphate

Question 15

what are the names of the 4 different types of bases

Answer 15

• C
• T
• A
• G

Question 16

which bases pair with which in a DNA structure

Answer 16

• C pairs with G
• A pairs with T

Question 17

what is the name given to the structure of DNA

Answer 17

double helix

Question 18

what is the name of this whole diagram

Answer 18

nucleotide

Question 19

define a gene

Answer 19

a sequence of DNA that codes for a specific sequence of amino acids

Question 20

define an allele

Answer 20

different forms (varients) of a single gene

Question 21

define genotype

Answer 21

the combination of allelels of a single gene

Question 22

define phenotype

Answer 22

an organisms appearance or characteristic

Question 23

define homozygous

Answer 23

having two identical alleles for a particular gene (BB or bb)

Question 24

define heterozygous

Answer 24

having two different alleles for a particular gene (Bb or bB)

Question 25

in which organelle are proteins made

Answer 25

ribosomes

Question 26

how many bases code for one amino acid

Answer 26

3

Question 27

what is embryo screening

Answer 27

when the embryo is tested during the course of pregnancy to detect inherited diseases

Question 28

name a condition embryos may be screened for

Answer 28

cystic fibrosis

Question 29

what are some of the ethical issue with embryo screening

Answer 29

- can result in abortions - miscarridge risk increases - embryo's cannot give consent - parents may choose genetic makeup of child

Question 30

is DNA an example of a polermer yes or no

Answer 30

yes

Question 31

what does DNA stand for

Answer 31

deoxyribonucleic acid

Question 32

what is the genetic material inside a nucleus called

Answer 32

DNA

Question 33

what are chromosomes

Answer 33

the structures the DNA is contained

Question 34

what is a genome

Answer 34

the entire genetic material of an organism

Question 35

how many chormosomes in a human nucleus

Answer 35

46 chromosomes

Question 36

explain what is meant by 'the gene is expressed'

Answer 36

when a gene codes for a protein that is synthsised in the cell

Question 37

describe the steps of protein synthesis

Answer 37

- the DNA molecule is too big to leave the nucleus - a template is made - the template leaves via a nuclear pore because it is small enough - template goes out to a ribosome in the cytoplasm - carrier molecules attach to the template in order - when chain is complete, detaches from ribosome and folds to a specific shape

Question 38

what are proteins synthesised on

Answer 38

ribosomes

Question 39

what is the template determined by

Answer 39

the sequence of bases in the DNA molecule

Question 40

what do carrier molecules do in protein synthesis

Answer 40

bring specific amino acids to the chain

Question 41

why does the protein chain fold into a unique shape

Answer 41

it enables it to carry out its function

Question 42

define mutation

Answer 42

a change in the base sequence of a section of DNA coding for a specific trait

Question 43

what is the effect of a mutation

Answer 43

- it may change the amino acid sequence of a protein - this changes its shape of the active site - and it may be non functional

Question 44

what does non-coding DNA do

Answer 44

switch genes on and off

Question 45

what does coding DNA do

Answer 45

code for specific proteins

Question 46

which allele is always expressed: dominant or recessive

Answer 46

dominant

Question 47

when is a dominate allele expressed

Answer 47

all the time even when only one copy is present

Question 48

when is a recessive allele expressed

Answer 48

when 2 copies of the allele is present

Question 49

what do you use to determine allele combinations for an offspring for one gene only

Answer 49

a punnett grid

Question 50

does a punnett grid determine alleles for all the genes

Answer 50

no only one

Question 51

what are the two inherited disorders we study

Answer 51

- polydactyly - cyctic fibrosis

Question 52

what is polydactyly

Answer 52

having extra toes or finger

Question 53

what type of allele is polydactyly caused by

Answer 53

a dominant allele

Question 54

what is cystic fibrosis

Answer 54

a disorder of cell membranes

Question 55

what type of allele is cystis fibrosis caused by

Answer 55

two recessive alleles

Question 56

what are people called that have one recessive allele of a disease

Answer 56

a carrier

Question 57

what procedure can be carried to see if an offspring will have an inherited disorder like cystic fibrosis

Answer 57

embryo screening

Question 58

what are the female sex chromosomes

Answer 58

XX (the same)

Question 59

what are the male sex chromosomes

Answer 59

XY (different)

Question 60

what are the two methods for embryo screening (do not need to know fully just in case of reference)

Answer 60

- aminocentisis = fluid from around feotus - chorionic villus spampling = sample of tissue from placenta

Question 61

what are the advantages of embryo screening

Answer 61

- doctors can determine if the child will have an illness or disease - it prepares parents - allows parents to decide to have children or not

Question 62

what are the disadvantage of embryo screening

Answer 62

- can result in unborn child being aborted - can cause miscarridge - expensive - goes against religious beliefs