Biology - Topic 3 - Genetics Flashcards Preview

GCSE Science Edexcel Combined > Biology - Topic 3 - Genetics > Flashcards

Flashcards in Biology - Topic 3 - Genetics Deck (50):
1

Which structures are found inside the nucleus?

chromosomes

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 would happen to the number of chromosomes in a zygote if two body cells were used in fertilisation?

it would have twice the number it should

11

How many chromosomes does a human gametecontain?

23

12

Where are genes found?

(in sections of DNA) on chromosomes

13

What does a gene carry the instructions for?

making a protein

14

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

amino acids

15

What is any molecule made of repeating units called?

a polymer

16

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

diploid

17

Are the cells produced by meiosis haploid or diploid?

haploid

18

Are the cells produced by mitosis haploid or diploid?

diploid

19

What shape is DNA?

double helix

20

What is a chromosome made out of?

DNA and proteins (to package the DNA)

21

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

A, C, T and G

22

How do the bases pair up in DNA?

A with T, C with G

23

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

phosphate group, sugar

24

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

nucleotide

25

How is the active site of an enzyme formed?

by folding of protein/polypeptide/amino acid chains

26

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

mutation

27

What is an organism’s phenotype?

its observable characteristics

28

What are different versions of the same genecalled?

alleles

29

What sort of variation do alleles cause in organisms?

genetic variation

30

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

homozygous

31

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

Aa

32

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

genotype

33

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

recessive

34

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

It is homozygous for the dominant allele.

35

What is monohybrid inheritance?

inheritance of alleles of one gene

36

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

genetic diagram, Punnett square

37

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

family pedigree

38

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

39

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

AA, Aa and aa

40

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

41

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

50% or 0.5

42

Name the four bases in DNA.

adenine, thymine, cytosine, guanine

43

Why can DNA be matched to the person it came from?

Everybody has a slightly different orders of bases in their DNA.

44

Is human eye colour coded for by one gene or many genes?

many

45

One gene codes for the cell membrane protein CFTR. There are many alleles for the CFTR gene. How many alleles do you have for the CFTR gene in one of your body cells?

two

46

A mutation of the CFTR gene can lead to the disorder cystic fibrosis. What is a mutation?

a change in the order of bases that form the gene

47

Cystic fibrosis is an inherited disorder. What does that mean?

It is passed from parent to offspring in the genes in a gamete.

48

What research, finished in 2003, was the first effort to map a complete human genome?

Human Genome Project

49

How could a map of a person’s genome help identify diseases they might develop?

Some alleles show an increased risk for the person of developing a genetic disorder.

50

How could a map of a person’s genome identify which medicines they should be given?

Some alleles affect how well medicines work in the body, including problems they can cause.