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GCSE AQA Biology > Topic 6- Inheritance, Variation and Evolution > Flashcards

Topic 6- Inheritance, Variation and Evolution Flashcards

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1
Q

What does DNA stand for?

A

Deoxyribonucleic acid.

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2
Q

What is DNA?

A

It’s the chemical that all of the genetic material in a cell is made up from.

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3
Q

What does DNA contain?

A

Coded information- basically all the instruction to put an organism together and make it work.

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4
Q

What does your DNA determine?

A

The inherited characteristics you have.

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5
Q

Where is DNA found in?

A

The nucleus of animal and plant cells, in really long structures called chromosomes.

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6
Q

What do chromosomes normally come in?

A

Pairs

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7
Q

Describe DNA.

A

It is a polymer. It’s made up of 2 strands coiled together in the shape of a double helix.

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8
Q

What is a gene?

A

A small section of DNA found on a chromosome.

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9
Q

What does each gene code for?

A

A particular sequence of amino acids which are put together to make a specific protein.

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10
Q

How many amino acids are used?

A

Only 20 amino acids are used, but they make up thousands of different proteins.

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11
Q

What do genes tell cells to do?

A

Genes tell cells in what order to put the amino acids together.

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12
Q

Give another thing DNA determines.

A

What proteins the cells produce, e.g. haemoglobin, keratin. This in turn determines what type of cell it is, e.g. red blood cell, skin cell.

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13
Q

What is genome?

A

It is the entire set of genetic material in an organism.

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14
Q

What is understanding the human genome important for?

A

Science and medicine.

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15
Q

Why is understanding the human genome important? (1)

A

Genes linked to diseases can be identified. This helps us better understand inherited diseases, so we can develop effective treatments.

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16
Q

Why is understanding the human genome important? (2)

A

Tiny differences in people’s genomes can be studied. This helps us trace the migration patterns of past human populations

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17
Q

What are DNA strands?

A

They are polymers made up of lots of repeating units called nucleotides.

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18
Q

What are nucleotides?

A

Repeating units

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19
Q

What does each nucleotide consist of?

A

A sugar, a phosphate group and one ‘base’.

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20
Q

What forms a ‘backbone’ to the DNA strands?

A

The sugar and phosphate groups in the nucleotides.

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21
Q

Which 4 different bases joins to each sugar?

A

A, T, C, G

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22
Q

What does each base link to?

A

Each base links to a base on the opposite strand in the helix.

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23
Q

Give 2 examples of complementary base pairing.

A
  1. A always pairs up with T

2. C always pairs up with G

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24
Q

What decides the order of amino acids in a protein?

A

It’s the order of bases in a gene that decides the order of amino acids in a protein.

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25
Q

What does each amino acid code for?

A

Each amino acid is coded for by a sequence of 3 bases in the gene.

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26
Q

What do amino acids joined together make?

A

Various proteins, depending on the order of the gene’s bases.

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27
Q

What do non-coding parts of DNA do?

A

Switch genes on and off, so they can control whether or not a gene is expressed.

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28
Q

Where are proteins made?

A

In the cell cytoplasm on tiny structures called ribosomes.

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29
Q

What do ribosomes use to make proteins?

A

The code in the DNA.

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30
Q

Why can’t DNA move out of the nucleus?

A

Because it’s really big.

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31
Q

How do the ribosomes make proteins? (1)

A

The cells need to get the code from the DNA to the ribosome.

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32
Q

How do the ribosomes make proteins? (2)

A

This is done by using a molecule called mRNA- which is made by copying the code from DNA.

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33
Q

How do the ribosomes make proteins? (3)

A

The mRNA acts as a messenger between the DNA and the ribosomes- it carries the code between the two.

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34
Q

How do the ribosomes make proteins? (4)

A

The correct amino acids are brought to the ribosomes in the correct order by carrier molecules.

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35
Q

How can a protein perform the task it’s meant to do?

A

When a chain of amino acids has been assembled, it folds into a unique shape which allows the protein to perform the task it’s meant to do.

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36
Q

Give 3 examples of types of proteins.

A
  1. Enzymes
  2. Hormones
  3. Structural proteins
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37
Q

When does a gene mutate?

A

Occasionally

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38
Q

What is a mutation?

A

It is a random change in an organism’s DNA. They can sometimes be inherited.

39
Q

How does a mutation occur?

A

Continuously, they can occur spontaneously.

40
Q

What increases the chances of mutation?

A

By exposure to certain substances or some types of radiation.

41
Q

What can mutations do?

A

Change the sequence of the DNA bases in a gene, which produces a genetic variant.

42
Q

What is a genetic variant?

A

A different form of the gene.

43
Q

What can mutations to a gene sometimes lead to?

A

Changes in the protein that it codes for.

44
Q

What effects do most mutations have?

A

Very little or no effect on the protein.

45
Q

What effect do some mutations have?

A

Some will change it to such a small extent that its function or appearance is unaffected.

46
Q

What affect do some mutations have? (2)

A

It can seriously affect a protein. Sometimes, the mutation will code for an altered protein with a change in its shape. This could affect its ability to perform its function.

47
Q

What happens if there is a mutation in the non-coding DNA?

A

It can alter how genes are expressed.

48
Q

Give 3 types of mutations.

A
  1. Insertions
  2. Deletions
  3. Substitutions
49
Q

What are insertions?

A

They are where a new base is inserted into the DNA base sequence where it shouldn’t be.

50
Q

What can an insertion change?

A

It changes the way the groups of three bases are ‘read’, which can change the amino acids that they code for.

51
Q

How can an insertion change more than 1 amino acid?

A

The have a knock- on effect on the bases further on in the sequence.

52
Q

What are deletions?

A

They are where a random base is deleted from the DNA base sequence.

53
Q

What do deletions do?

A

They change the way that the base sequence is ‘read’ and have knock- on effects further down the sequence.

54
Q

What are substitutions?

A

They are when a random base in the DNA base sequence is changed to a different base.

55
Q

What is sexual reproduction?

A

It is where genetic material from 2 organisms is combined to produce offspring which are genetically different to either parent.

56
Q

What does a mother and a father produce in sexual reproduction?

A

They produce gametes by meiosis- e.g. egg and sperm cells in animals.

57
Q

How many chromosomes are there in gamete?

A

23 chromosomes

58
Q

What is fertilisation?

A

When the egg and the sperm cell fuse together to form a cell with the full number of chromosomes.

59
Q

What does the mixture of genetic information produce?

A

Variation

60
Q

Describe asexual reproduction.

A

There’s only one parent. There’s no fusion of gametes no mixing of chromosomes and no genetic variation between parent and offspring.

61
Q

Describe the offspring in asexual reproduction.

A

The offspring are genetically identical to the parent- they’re clones.

62
Q

Give an example of a living thing which reproduces asexually/.

A

Bacteria

63
Q

What is cystic fibrosis?

A

It is a genetic disorder of the cell membranes.

64
Q

What is the result of cystic fibrosis?

A

It results in the body producing a lot of thick sticky mucus in the air passages and in the pancreas.

65
Q

What allele causes cystic fibrosis?

A

A recessive allele, ‘f’, carried by about 1 person in 25.

66
Q

What is polydactyly?

A

It is a genetic disorder where a baby’s born with extra finders or toes.

67
Q

What allele causes polydactyly?

A

Dominate allele

68
Q

What does IVF stand for?

A

In vitro fertilisation

69
Q

What happens during IVF?

A

Embryos are fertilised in a laboratory, and then implanted into the mother’s womb.

70
Q

What can you do with an embryo before implanting it during IVF?

A

It’s possible to remove a cell from each embryo and analyse its genes. Many genetic disorders can be detected this way.

71
Q

Give another way of testing for disorders.

A

It’s also possible to get DNA from an embryo in the womb and test that for disorders.

72
Q

Give an argument for embryonic screening (1).

A

It will help to stop people suffering.

73
Q

Give an argument for embryonic screening (2)

A

Treating disorders costs the Government (and the taxpayers) a lot of money.

74
Q

Give an argument for embryonic screening (3)

A

There are laws to stop it going too far. At the moment parents cannot even select the sex of their baby.

75
Q

Give an argument against embryonic screening (1).

A

It implies that people with genetic problems are ‘undesirable’- this could increase prejudice.

76
Q

Give an argument against embryonic screening (2).

A

Screening is expensive.

77
Q

Give an argument against embryonic screening (3)

A

There may come a point where everyone wants to screen their embryos so they can pick the most ‘desirable’ one.

78
Q

How did Carl Linnaeus group living things in the 1700’s?

A

According to their characteristics and the structures that make them up.

79
Q

Describe the Linnaean system.

A

Living things are first divided into kingdoms. The kingdoms are then subdivided into smaller and smaller groups.

80
Q

Give 6 subdivisions of kingdoms (in order).

A
  1. Phylum
  2. Class
  3. Order
  4. Family
  5. Genus
  6. Species
81
Q

How were scientists able to put forward new models of classification?

A
  1. Knowledge of the biochemical processes taking place inside organisms developed.
  2. Microscopes improved.
82
Q

What did Carl Woese propose in 1990?

A

Three-domain system

83
Q

How did Carl Woese know that some species are not closely related?

A

Using evidence gathered from new chemical analysis techniques such as RNA sequence analysis.

84
Q

Give examples of the 3 domains in the three- domain system.

A
  1. Archaea
  2. Bacteria
  3. Eukaryota
85
Q

What does the Eukaryota domain include?

A

It includes a broad range of organisms including fungi, plants, animals and protists.

86
Q

What does the Bacteria domain contain?

A

True bacteria like E. coil. There are biochemical differences between the Bacteria domain and the Eukaryota domain.

87
Q

What did the organisms in the Archaea domain were once thought to be?

A

Primitive bacteria

88
Q

What are the organisms in Archaea?

A

They’re different type of prokaryotic cell.

89
Q

Where were Archaea organisms once found in?

A

Extreme places such as hot springs and salt lakes.

90
Q

Describe the binomial system.

A

The first part refers to the genus that the organism belongs to. The second part refers to the species.

91
Q

What information does the first part of the binomial system give?

A

It gives you information on the organism’s ancestry.

92
Q

How is the binomial system able to avoid potential confusion?

A

The scientists in different countries or who speak different languages all refer to a particular species by the same name.

93
Q

What does an evolutionary tree show? (1)

A

It shows how scientists think different species are related to each other.

94
Q

What does an evolutionary tree show? (2)

A

They show common ancestors and relationships between species.

GCSE AQA Biology (7 decks)

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