Topic 3 - Genetics Flashcards Preview

Edexcel GCSE Biology > Topic 3 - Genetics > Flashcards

Flashcards in Topic 3 - Genetics Deck (68):
1

Which structures are found inside the nucleus?


chromsomes

2

Which substance forms a long strand in each chromosome?

DNA

3

How do body cells make copies of themselves?

cell division, mitosis

4

How many chromosomes are there in a human body cell nucleus?

46

5

What happens in fertilisation?

two gametes fuse

6

What is the name of the cell formed in fertilisation?

zygote, fertilised egg cell

7

Which term means producing more of the same kind of organism?

reproduction

8

What is the name of the human male gamete?

sperm cell

9

The DNA strand in a chromosome contains sections that carry instructions for characteristics. What are these sections called?

genes

10

What molecule forms the genome of an organism?

DNA

11

Where are genes found?

[in sections of DNA] on chromosomes

12

What does a gene carry the instructions for?

making a protein

13

A protein is made by linking together smaller molecules. What are these smaller molecules called?

amino acids

14

What is any molecule made of repeating units called?

a polymer

15

A human cell contains 46 strands of DNA. Is it diploid or haploid?

diploid

16

Are the cells produced by meiosis haploid or diploid?

haploid

17

Are the cells produced by mitosis haploid or diploid?

diploid

18

What shape is DNA?

a double helix

19

What is a chromosome made out of?

DNA and proteins [to package the DNA]

20

What shape is a DNA molecule?

double helix


21

What part of a DNA strand contains the instructions for a protein?

gene

22

What are the letters of the bases that form the DNA code?

A,C,T and G

23

How do these bases pair up in DNA?

A with T, C with G

24

Apart from bases, what other parts are needed in a DNA molecule?

phosphate group, sugar

25

What is one phosphate group, one sugar and one base called?

nucleotide

26

Why is DNA a polymer?

It is made of many nucleotides joined in a chain.

27

Give an example of a protein.

any example. E.g. an enzyme

28

How is the active site of an enzyme formed?

by folding of protein/polypeptide/amino acid chains

29

Why are proteins polymers?

They are made of many amino acids joined in a chain.

30

Triple only- What molecule is produced in transcription?

mRNA or messenger RNA

31

Triple only- What base does mRNA contain that DNA does not?

uracil

32

Triple only-What is the name of the enzyme that allows transcription to occur?

RNA polymerase

33

Triple only-The mRNA nucleotides fit together with the nucleotides on the DNA template strand. What word describes bases that fit together?

complementary

34

Triple only- Where does transcription occur in a cell?

nucleus

35

Triple only-Where does translation occur in a cell?

cytoplasm

36

Triple only-What has to bind to an mRNA molecule for translation to occur?

ribosome

37

Triple only-What molecule carries amino acids to the mRNA in the ribosome?

tRNA

38

Triple only- What has to happen to the polypeptide for an enzyme in order for it to become a functional enzyme?

It has to fold

39

How many bases does a codon contain?

three

40

Triple only-What does each codon contain the code for?

the addition of a particular amino acid to the polypeptide chain

41

Triple only-What is the name of the process in which the genetic code is used to make a polypeptide?

translation

42

A change in the bases of a gene creates a genetic variant. What is this sort of change called?

mutation

43

Triple only-What does translation produce?

a polypeptide

44

Triple only- Why might a mutation in a codon not cause a change in the polypeptide produced?

It does not affect the amino acid that is coded for.

45

Triple only- Why can a difference of a single amino acid change how a protein functions?

It can interfere with the way the polypeptide chain(s) fold(s).

46

Triple only- What has to bind to an mRNA molecule for translation to occur?

ribosome

47

Triple only- Why might a mutation in the non-coding region before a gene cause an increase in the production of a certain protein?

The mutation causes RNA polymerase to bind better.

48

What is an organism’s phenotype?

its observed characteristics

49

What are different versions of the same gene called?

alleles

50

What sort of variation do alleles cause in organisms?

genetic variation

51

When we consider one gene, what word is used to say that both alleles are the same?

homozygous

52

If a dominant allele has the letter A, how would you show that an organism is heterozygous?

Aa

53

What word describes the characteristics caused by the alleles of a gene?

phenotype

54

What word describes the alleles of a gene found in an organism?

genotype

55

What word describes an allele that only has an effect if an organism has two copies?

recessive

56

A genotype is written QQ. What does this tell you?

It is homozygous for the dominant allele.

57

What is a probability?

the chance of an event occurring

58

If the occurrence of an event has a probability of 1, what does this mean?

It is certain to occur.

59

Triple only- What is monohybrid inheritance?

inheritance of alleles of one gene

60

Triple only- In monohybrid inheritance, what is the theoretical probability of parents who are both heterozygous for a gene producing an offspring that is also heterozygous for the gene?

probability 50 per cent or half

61

Triple only- In monohybrid inheritance, what is the theoretical ratio of dominant to recessive phenotypes produced by parents who are both heterozygous for the characteristic?

03:01

62

Triple only- What letters are used to describe the different human blood groups?

A, B, O

63

How can we show the possible inheritance of alleles by offspring from their parents?

genetic diagram, Punnett square

64

Which type of diagram is used to show the inheritance of a characteristic through different generations in a family?

family pedigree

65

If the genotype for one gene of a rabbit is Bb, where B is the allele for brown coat and b the allele for black coat, what is the rabbit’s phenotype?

brown

66

What are the possible allele combinations of offspring from heterozygous parents who are both Aa for a gene?

AA, Aa and aa

67

A human egg cell that contains an X sex chromosome is fertilised by a sperm cell containing a Y sex chromosome. What will be the sex of the baby that develops?

male

68

What is the theoretical probability of a couple having a baby boy?

probability 50 per cent or half