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Biology > Year 11 Term 2 > Flashcards

Year 11 Term 2 Flashcards

1
Q

What does genetic engineering involve

A

Changing the genetic material of an organism

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2
Q

What is the first step of genetic engineering

A

Insulin gene is cut out of DNA by an enzyme and plasmid is taken out of bacterium and split open by a restriction enzyme

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3
Q

What’s a restriction enzyme

A

They recognise specific sequences of DNA and cut the DNA at these points. The cut leaves one of the DNA strands with unpaired bases, this is called a sticky end

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4
Q

What is the second step of genetic enginerring

A

The insulin gene is inserted into plasmid by another enzyme, then this plasmid is taken up by the bacterium. The bacteria then multiplies many times, the insulin gene is switched on and the insulin is harvested

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5
Q

What are other examples of genetic engineering

A

Genes can be cut out of the DNA of one plant and inserted into rice genes, enzymes are still used in this process

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6
Q

In animals, plants and microbes, when does genetic modification usually take place

A

Genes are often transferred at early stage of development so that the organism develops with the desired characteristics

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7
Q

GM of golden rice

A

Genes in the pathway for better carotene production are obtained and introduced to the white rice genome, resulting in golden rice which increases the vitamin A content almost 25 fold

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8
Q

Arguments for GM (genetically modified) crops

A 
Higher crop yields
Can be resistant to herbicides
Reduces pesticide use
Safe for human consumption
Preserves habitats as less land needed to grow crops
Better shelf life
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9
Q

Arguments against GM cops

A

Unknown long term health risks
Could affect wildlife as killing weeds
Increasing yields means a distribution problem
GM crops are often infertile

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10
Q

What is another name for meiosis

A

Reduction division

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11
Q

Where is the only place meiosis occurs

A

Only in the cells of the reproductive organs and produces gametes (sex cells) in the ovaries and testes or then anther and ovule of a plant

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12
Q

What does haploid mean

A

Half the number of chromosomes

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13
Q

What does diploid mean

A

Full sets of chromosomes e.g. 46 or 23 pairs

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14
Q

Why do gametes only have one copy of each chromosome

A

So that when gametes fuse at fertilisation, the zygote has the normal amount of chromosomes. The zygote then divides by mitosis to produce more cells that differentiate as the embryo develops

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15
Q

What happens during meiosis

A

Chromosomes replicate then shorten and thicken. The pairs line up at centre of cell and spindles attach these pairs separate into 2 new cells and nucleus reforms, spindles attach to the duplicates of chromosomes and are pulled apart into separate cells

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16
Q

What is left at the end of meiosis

A

4 new cells have formed each having 2 chromosomes (23) they are haploid cells and each one contains different genetic material to the others

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17
Q

What is asexual reproduction

A

Only 1 parent, no fusion of gametes so offspring genetically identical, happens by mitosis, only genetic variation is random mutations

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18
Q

What are the several types of asexual reproduction

A

Binary fission (bacteria)
Production of spores (fungi)
Strawberry (runners)
Potato (tuber)

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19
Q

What is sexual reproduction

A

Mixing of genetic info from 2 organisms, offspring genetically different to parents, male and female gametes produced by meiosis fuse, nuclei of cells are haploid and unite at fertilisation forming diploid zygote

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20
Q

Ads and Disads of sexual reproduction

A

Increases chance of survival if circumstances change, there is genetic variation however a partner needs to be found

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21
Q

Ads and Disads of asexual reproduction

A

Only needs 1 parent, no time/energy wasted finding a mate, produces large amount rapidly however susceptible to disease and no genetic variation

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22
Q

Malaria sexual and asexual reproduction

A

Malaria caused by parasite that’s spread by mosquitoes. The parasite reproduces sexually when it’s in the mosquito and asexually when it’s in the human host

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23
Q

Fungus sexual and asexual reproduction

A

These fungus species release spores which can become new fungi when land in a suitable place. a.s produced spores form genetically identical fungi to parent fungus. s produced spores introduce variation and produced in response to a change in the environment, increasing the chance of the fungi surviving the change

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24
Q

What does DNA stand for

A

Deoxyribonucleic acid

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25
Q

What is DNA made up from

A

Is a polymer made from 4 different nucleotides, each nucleotide consists of a common sugar and phosphate group with 1 of 4 different bases attached to the sugar, A, T, C, G

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26
Q

Where is DNA found

A

In chromosomes

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27
Q

What is a gene

A

A small section of DNA on a chromosome. Each gene codes for a particular sequence of amino acids to make a specific protein

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28
Q

What is the sequence of 3 bases

A

It’s the code for a particular amino acid. The order of the bases controls the order in which amino acids are assembled to produce a particular protein

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29
Q

Double helix shape of DNA

A

The 2 sides of the ladder are made of alternating sugar molecules and phosphate groups
The rungs of the ladder are made of chemicals called bases, each base is attached to sugar molecule of the side (or backbone) of the DNA

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30
Q

How many types of amino acids are there

A

There are 20 amino acids but can be put together in many different orders to make thousands of different proteins

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31
Q

What is the genome of an organism

A

It’s the entire genetic material of that organism

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32
Q

What has studying the whole human genome allowed us to do

A

The search for genes linked to different types of disease
The understanding and treatment of inherited disorders
Tracing human migration patterns from the past

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33
Q

How are proteins formed

A

The sequences of bases from DNA is copied to form a messenger molecule which leaves the nucleus and moves to ribosome in the cytoplasm of the cell. Carrier molecules bring specific amino acids to the ribosome and attach to the messenger molecule in order determined by sequence of bases. Amino acids are formed together to form protein

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34
Q

Hair protein

A

Keratin, a fibrous structural protein

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35
Q

Muscle protein

A

Actin, forms filaments in muscles

36
Q

What is a muation

A

A random change in an organisms DNA

37
Q

When do mutations occur

A

All the time often due to a mistake in copying DNA before the cell divides

38
Q

Are mutations beneficial

A

Yes, they can be and are one of the driving forces of evolution

39
Q

How can the chance of mutation be increased

A

By exposure to some chemicals or radiation

40
Q

How do mutations change the sequence of DNA bases in a gene

A

One of the amino acids may be substituted with another which may change intermolecular forces between amino acids so the protein may change shape and if it’s an enzyme then enzyme and substrate won’t fit so will lose function

41
Q

Non-coding DNA

A

Not all parts of DNA code for proteins. Non-coding DNA can switch genes on and off, so variation in these areas if DNA may affect how genes are expressed

42
Q

Genes and charcteristics

A

Genes you inherit from parents control your characteristics, most of which are due to multiple genes interacting rather than a single gene but some are controlled by single gene such as fur colour in mice

43
Q

What’s an allele

A

A different form of a particular gene

44
Q

Why do other cells (not gametes) have 2 alleles, one on each chromosome of a pair

A

Because we inherit half of our alleles from our mother (in the egg) and half from our father (in the sperm)

45
Q

Dominant

A

An allele that is always expressed in the phenotype, even when only copy is present. It;s represented by a capital letter

46
Q

Homozygous

A

When an organism has two alleles for a particular gene that are the same e.g. AA or aa

47
Q

Genotype

A

The alleles (letters) present for a particular gene in a organism

48
Q

Chromosome

A

Thread-like structure in the cell nucleus made of a molecule of DNA which carried genes

49
Q

Recessive

A

An allele that’s only expressed in the phenotype if two copies are present (and therefore no dominant allele present) It’s represented by a lowercase letter

50
Q

Hetrozygous

A

When an organism has two alleles for a particular gene that are different e.g. Aa

51
Q

Phenotype

A

That characteristics that is shown or expressed

52
Q

What do genetic diagrams allow you to do

A

Allow you to see how certain characteristics are inherited. You cross (breed together) two parents

53
Q

What is polydactyly

A

Inherited disorder where born with extra fingers or toes

not life-threatening

54
Q

What causes polydactyly

A

Caused by dominant allele so can be inherited if just one parent carries defective allele. The parent with the allele will also have conditions since it’s dominant

55
Q

What is cystic fibrosis

A

Inherited disorder of cell membranes, results in body producing lots of thick mucus in air passages of lungs (makes breathing difficult) and in the pancreas

56
Q

What causes cystic fibrosis

A

Caused by recessive allele which is carried in 1/25 people. As it’s recessive, people who only one copy don’t have the disorder, known as carriers but don’t have syptoms

57
Q

Treatments for cystic fibrosis

A

Physiotherapy and antibiotics (to keep lungs clear), taking enzymes to replace ones made in pancreas
Currently no cure

58
Q

What is embryo screening

A

A way of detecting inherited genetic disorders such as cystic fibrosis in embryos

59
Q

What is pre-implantation genetic diagnosis (PGD)

A

During IVF a cell is removed from embryo and genes analysed so only embryos with healthy alleles are implanted. Faulty ones are destroyed

60
Q

What is chorionic villus sampling (CVS)

A

A sample of cells is taken from placenta at 10-13 weeks and genes analysed. If embryo has an inherited disorder, parents decide whether to terminate pregnancy

61
Q

Arguments for screening

A

Helps to stop people from suffering from inherited disorders which reduces healthcare costs
Gives parent the choice to terminate the pregnancy

62
Q

Arguments against screening

A

May lead to people choosing desired characteristics
Implies those with disorders are ‘undesirables so increases prejudice
Rejected embryos are destroyed which some view as unethical
Very expensive to screen embryos

63
Q

Sex determination

A

23rd pair of chromosomes are the sex chromosomes which determine your sex

64
Q

Male sex chromosomes

A

XY

65
Q

Female sex chromosomes

A

XX

66
Q

What did Mendel cross in the first cross and what were the results

A

Crossed tall pea plant and dwarf pea plant which resulted in all tall pea plants

67
Q

What did Mendel cross in the second cross and what were the results

A

Crossed 2 pea plants from the 1st offspring which resulted in 3 tall pea plants and 1 small pea plant

68
Q

How did Mendel explain the results

A

Characteristics in plants are determined by hereditary units
H.U are passed on to offspring unchanged from both parents, one unit from each prent
H.U can be dominant or recessive

69
Q

Why wasn’t his explanation accepted by other scientists

A

The peers lacked any background knowledge

They didn’t know about genes, chromosomes and DNA

70
Q

When were Mendel’s theories taken seriously

A

early 20th century when scientists realised the similarities between the way that chromosomes and Mendel’s units acted

71
Q

Definition of species

A

A group of living organisms that are able to interbreed to produce fertile offspring

72
Q

What is variation

A

The difference in the characteristics of individuals in a population

73
Q

What may cause variation

A

The genes they have inherited
The condition in which they have developed
A combination of genes and the environment

74
Q

What are mutations

A

They are changes to the sequence of bases in DNA

75
Q

What effect do mutations have on an organisms phenotype

A

Most have no effect on the phenotype, some have a small affect and alter the characteristics slightly, very rarely do mutations result in a new phenotype

76
Q

Definition of evolution

A

A change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species

77
Q

How does natural selection work

A

Variation caused by mutation, so the variant with the advantage will survive and breed, passing on the advantage genes to the next generation

78
Q

Darwin’s theory of evolution

A

He believed in natural selection however was only gradually accepted because it didn’t mention any mutations, genes or DNA he believed the individuals with characteristics most suited to the environment passed them on

79
Q

What was Lamarck’s theory

A

The evolution of animals was caused by the inheritance of acquired characteristics, based on the idea that changes occur in an organisms lifetime can be inherited

80
Q

Creationism

A

Living things were created separately, they did not evolve

81
Q

Theory of intelligent design

A

Life is too complex to have evolved so must have been put together by a higher being

82
Q

Religion

A

Some people may not accept scientific theories because they believe in a creator

83
Q

How are fossils evidence of evolution

A

Fossils show changes over time and some features are similar to present day

84
Q

New species arise as a result of:

A

Isolation
Genetic variation
Natural selection
Speciation

85
Q

What is speciation

A

The development of a new species
Occurs when populations of the same species become so different they can no longer successfully interbreed to produce fertile offspring

86
Q

How does bacteria develop resistance to antibiotics by natural selection

A

Mutations of bacterial pathogens produce new antibiotic resistant strains
Antibiotics kill individual pathogens of the non-resistant strain
Individual resistant pathogens survive and reproduce so pop of resistant strain increases
resistant strain will spread

Biology (16 decks)

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