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Variation And Inheritance Flashcards

0
Q

What do chromosome threads carry

A

Genes

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1
Q

Where are chromosomes

A

In the nucleus

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2
Q

How many chromosomes do gametes carry

A

One

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3
Q

The nuclei of male and female sex cells contain

A

One set of genes

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4
Q

Offspring carry how many genes

A

2

One set from each parent

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5
Q

2 main reasons of variation between individuals of the same kind of organism

A

Genes

Environmental

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6
Q

Asexual reproduction. Variation?

A

No.
Does not involve fusion of the gametes
Genetically identical to single parent
Clones

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7
Q

Sexual reproduction. Variation?

A

Yes
Fusion of gametes
Mixing of genetic information

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8
Q

Why is sexual reproduction important

A

Leads to variation

Natural selection can occur so we can evolve

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9
Q

How many pairs of chromosomes do human beings have

A

23 pairs

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10
Q

Sex chromosomes (how many and what does a male and female look like)

A

1 pair of sex chromosomes
XX= female
XY= male

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11
Q

2 types of genes

A

Dominant

Recessive

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12
Q

Phenotype

A

Physical appearance of the genes characteristic

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13
Q

Genotype

A

The genetic makeup

Eg DD or Dd

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14
Q

Homozygous

A

Both alleles the same

Eg DD or dd

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15
Q

Heterozygous

A

The two alleles are different

Eg Dd

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16
Q

Monohybrid inheritance

A

The inheritance of a single characteristic controlled by a pair of alleles

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17
Q

Who observed clear patterns of inheritance on pea plants

A

Gregory Mendel

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18
Q

Chromosomes are made of…

A

DNA (deoxyriboneucleic acid)

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19
Q

What is the structure of DNA

A

Double helix

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20
Q

What are genes

A

Short sections of DNA

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21
Q

How many compounds are in DNA and what are they called

A

4 called bases

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22
Q

What does each gene contain

A

Code to make a specific protein

23
Q

How many bases control the code for an amino acid

24
Squares of dominant and recessive
Punnett squares
25
What is polydactyly
A genetic condition where you have extra fingers/toes
26
What allele is polydactyly caused by
Dominant allele
27
What is cystic fibrosis
An inherited disorder which affects the cell membranes and causes the production of thick sticky mucus. Affects lungs especially
28
What allele causes cystic fibrosis
Recessive
29
Can parents who don't have cystic fibrosis still have kids with the disease
Yes. The parents are called carriers
30
What type of allele causes sickle cell anaemia
Recessive
31
What does the recessive gene of sickle cell anaemia do
Affects the shape of the red blood cells so they cannot carry oxygen efficiently & they block capillaries causing pain
32
Sickle cell homozygous
Don't usually survive
33
Heterozygous sickle cell
Some blood cells affected | But does give them protection from the malaria parasite
34
Homozygous not sickle cell
The majority of the population | However they are at risk of malaria
35
Down's syndrome is caused by
A mistake during meiosis when a cell has too many chromosomes So there is an extra chromosome 21
36
What is a gene probe
A probe that will bind to a particular damaged gene or chromosome
37
How does a gene probe work
Has a fluorescent chemical on the end Probe is added to a mixture containing the DNA sample from the embryo UV light is used to detect the probe If the probe has attached to the faulty allele it fluoresces
38
Concerns over embryo foetus screening
Risk of miscarriage False positives/negatives (reliable?) Decisions about terminating pregnancy
39
Positives about embryo screening
May give parents more choices / time to prepare for baby with special needs
40
3 ways to take cells from developing foetus'
Chorionic villus sampling- transcervical Chorionic villus sampling- transabdominal Amniocentesis
41
Clones
Offspring produced by asexual reproduction that are genetically identical to its parent organism
42
2 ways of cloning plants
Cuttings Tissue culture (Take a tissue sample from parent plant. Tissue grown in agar with nutrients and plant hormones. Equals many tiny identical plants. Plant clones planted and grown)
43
Why might you clone an animal or plant
High quality | Eg resistance, yield
44
How to clone animals
Embryo transplants
45
Embryo transplants explain
Embryo with unspecialised cells split into smaller groups of cells Transplant into host mother Sometimes genetically modified
46
Adult cell cloning
Adult cell of parent animal eg skin cell Nucleus removed and added into a mature ovum whose nucleus has been removed Mild electric shock = cells divide forming embryo Embryo transplanted into womb of host mother Clone of original born
47
Advantages of adult cell cloning
Yield increased. Eg genetically engineered lambs = special protein in milk = uses in medicine Save from extinction
48
Disadvantages of adult cell cloning
Ethics Limits variation in population so doesn't help natural selection Clone humans in future?
49
Genetic engineering
A technique for changing the genetic information of a cell
50
Explain how genetic engineering works
Gene is cut out of chromosome using an enzyme Gene is then placed into another chromosome of a different organism A vector (carrier) such as a plasmids or virus may be used to transfer the gene
51
Why do GM crops produce a higher yield
Because they often make their own pesticide dorm are herbicide resistant
52
Explain the manufacture of genetically modified insulin
Human cell with insulin gene Insulin gene is cut out of DNA using an enzyme. Bacteria with a ring of DNA called a plasmid Plasmid taken out of bacteria and split open using enzyme. Insulin gene inserted into plasmid using another enzyme. Plasmid with insulin producing gene is taken up by bacterium Bacterium multiplies many times, insulin produced and harvested form human injection.
53
Advantages of genetic technology
Herds with useful characteristics Adult cell cloning of copies of the best adapted animals Faulty gene = genetic disorder. Can be fixed with genetic engineering (in future) Medical drugs produced Higher yield of crops = more food per square metre
54
Disadvantages of genetic technology
Farmers have to buy GM seeds every year as crops are infertile Accidentally introducing genes into wild flowers Insects which aren't pests? Eating GM crops? Human health Ethical Long term?

Biology (23 decks)

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