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: Biology 6. G

eneticsSection 1: DNA

1 The genetic material in the nucleus of a cell is….

DNA

2 Describe the structure of DNA. A polymer made up of two strands forming a double helix.

3 Name the structure within which DNA is contained.

Chromosomes.

4 What is a gene? A small section of DNA on a chromosome.

5 What is the function of a gene? To code for a particular sequence of amino acids in order to make a specific protein.

6 What is a genome? The entire genetic material of an organism.

7State 3 ways in which understanding of the human genome will be important.

1. To search for genes linked to different types of disease2. To understand and treat inherited disorders3. To trace early human migration patterns

Section 1: DNA – Triple Only

8 Name the three parts of a DNA molecule.

A phosphate group, a sugar molecule and a nucleotide base

9 Name the four nucleotides found in DNA.

Adenine, thymine, guanine and cytosine

10 How many bases code for a particular amino acid?

3

11 What is a set of three nucleotide bases called?

A codon

12 Which cell organelle synthesises proteins?

Ribosomes.

13 How is the protein sequence correctly assembled?

Using a template molecule from the DNA.

14 What brings specific amino acids to the ribosomes?

Carrier molecules.

15When the protein chain is complete, what process aids it to form its unique shape?

Folding.

16Name three uses of proteins in the body.

1. Enzymes2. Hormones3. Structural proteins e.g. collagen

17 What is a change in the DNA sequence called?

A mutation.

18Name three potential consequences for a protein of a mutation.

1. No change or a slight change so no effect on the protein2. Altered protein, so an enzyme may stop working3. Mutation within a non-coding region nearby to a gene

may affect the expression (production) of a protein

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: Biology 6. G

enetics 2Section 2: Sexual & Asexual Reproduction

19By which cell division type does asexual reproduction rely on?

Mitosis

20 How are gametes formed? Meiosis

21How is a gamete different from a normal body cell?

Half genetic information

22Name the structure formed by fertilisation (fusion of male and female gametes).

Zygote

23State one difference between asexual and sexual reproduction.

A: no fertilisation/genetically identical offspring; S: fertilisation/genetic variation

24 Name the gametes in plants. Egg + Pollen

25 Name the organ that produces egg cells. Ovaries

26 Name the organ that produces sperm cells. Testes

27How many divisions do a cell undergo in meiosis?

Twice

28Name the process where a sperm and an egg cell fuse together.

Fertilisation

29How many chromosomes are there in a human gamete?

23

30 Define 'gametes'. Sex cells

31 Name the gametes in animals. Sperm + Egg

32 Describe the cells produced by meiosis. 4 cells, genetically different.

33 Describe the cells produced by mitosis. 2 cells, genetically identical (clones).

34

State the three key steps in meiosis. 1. Copies of the DNA are made.2. The cell divides twice to form 4 gametes, each

with a single set of chromosomes.3. All 4 cells are genetically different from each

other.

35 When a new cell is formed through fertilisation, how does it divide?

Mitosis.

MITO

SIS vs. MEIO

SIS

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: Biology 6. G

enetics 3Section 3: The Mechanism of Inheritance

36 What is a chromosome? A thread-like structure which contains coiled up DNA and proteins.

37 What is an allele? A different version of a gene.

38 What does the term “dominant” mean? The individual only needs one copy of this allele for its phenotype to be seen.

39 What does the term “recessive” mean? The individual needs two copies of this allele for its phenotype to be seen.

40 What does the term “homozygous” mean? The individual has two identical alleles for this gene.

41 What does the term “heterozygous” mean? The individual has two different alleles for this gene.

42 What is a genotype? The genetic makeup of an organism for a particular gene (e.g. RR).

43 What is a phenotype? The displayed characteristic due to the interactions between alleles (e.g. red flowers).

44 How many pairs of chromosomes does an ordinary human body cell have?

23

45 How many pairs of chromosomes determine the sex of the individual?

1

46 What is the genotype of a female? XX

47 What is the genotype of a male? XY

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enetics 4Section 4: Inherited Conditions

48 What is polydactyly? A condition that causes the individual to have extra fingers or toes.

49 Is polydactyly a dominant or recessive condition?

Dominant.

50 State the genotype(s) that would result in polydactyly.

PP or Pp (homozygous dominant or heterozygous for this gene).

51 What is cystic fibrosis? A condition which causes sticky mucus to build up in the lungs.

52 Is cystic fibrosis a dominant or recessive condition?

Recessive.

53 State the genotype(s) that would result in cystic fibrosis.

cc (homozygous recessive).

54 State one method of screening embryos. Amniocentesis/Chorionic villus sampling/IVF

55 State one concern of screening embryos. Causing miscarriage/Ethical concerns/Inaccurate results/Expensive

56 State one benefit of embryo screening. Know if child will have disorder/Able to decide if proceed with pregnancy or abortion

57 Genes determine the phenotype of an organism – true or false?

False – the environment also plays a role.

Section 5: The Discoverers of Inheritance – Triple Only

58Name the person who first discovered inherited characteristics are determined by 'units' passed on unchanged.

Gregor Mendel

59 Why were Mendel's ideas of inheritance not accepted during his time?

As chromosomes were not discovered/seen yet

60 Who published the double helix structure of DNA?

Watson and Crick

61 Watson and Crick used whose work to find out the structure of DNA?

Franklin and Wilkins (but without Franklin's permission)

Polydactyly