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Biology GCSE > 2.3 - DNA and inheritance > Flashcards

2.3 - DNA and inheritance Flashcards

1
Q

What is DNA?

A

larger complex polymer, made up of two strands forming a double helix. It determines the characteristics of an organism.

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2
Q

What is a Gene?

A

A small section of DNA on a chrom. codes for particular sequence of amino acids –> make protein

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3
Q

What are Alleles?

A

Different variations of the same gene

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4
Q

What is a genotype?

A

The alleles an organism has for a particular characteristic

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5
Q

What is a phenotype?

A

Visible characteristics of an organism as a result of its genes ( blue eyes)

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6
Q

What is a dominant allele?

A

Only need one copy of allele for characteristic/feature. 2 copies also give.

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7
Q

What is a recessive allele?

A

Only expressed if two are present and doesn’t have dominant allele of that gene

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8
Q

What does Homozygous mean?

A

Same allele ( AA / aa)

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9
Q

What does Heterozygous mean?

A

Different alleles (Aa)

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10
Q

What is a double helix?

A

The shape of DNA molecule, 2 strands twisted together in a spiral

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11
Q

What is the ‘backbone’ of each DNA strand made of?

A

Alternating phosphate and sugar molecules with paired chemicals between each strand called bases

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12
Q

What are the names of the four bases?

A

Thymine - T
Adenine - A
Guanine - G
Cytosine - C

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13
Q

Which bases are in complementary pairing with one another?

A

Thymine - Adenine

Guanine - Cytosine

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14
Q

What is determined by the order bases are found inside a gene?

A

The order of amino acids they code for, which creates a specific protein

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15
Q

The sequence of every amino acid in a protein is determined by the _______

A

triplet code, which is a code of 3 bases. Each specific amino acid will have a triplet code of different bases

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16
Q

What do punnet square’s calculate?

A

the probability of different combinations occurring at offspring

17
Q

What is selfing?

A

Where pollen from one plant lands on the stigma of the same plant - self pollinating it.

18
Q

Which chromosome pair determines your sex?

A

23rd pair

19
Q

What should the chromosome for a male look like?

A

XY (Different size chromosomes)

20
Q

What should the chromosome for a female look like?

A

XX (Same size chromosomes)

21
Q

What is genetic (DNA) profiling?

A

Cutting a sample of DNA into fragments and separating the fragments by size, possible to make a characteristic profile of DNA.

22
Q

In what circumstance can genetic profiling be used?

A

Help solve crimes as the suspect may have left a sample of body tissue at crime scene

23
Q

How do you produce a DNA fingerprint?

A

Isolation - separate the DNA from other tissues.
Fragmentation - use an enzyme to break the DNA into short lengths.
Separation - pass an electric current across a layer of gel which has DNA fragments at one end. The fragments will move different distances across the gel. Called gel electrophoresis.
Comparison - match pattern of fragments on the gel with other samples of DNA.

24
Q

What are the advantage’s of genetic profiling?

A

DNA evidence is reliable.
Everyone’s DNA is different but identical twins.
DNA profiles find paternity.
DNA profiles used identify genetic disorders early.
DNA profiles used to place suspects at a crime scene.

25
Q

What are the disadvantage’s of genetic profiling?

A

Stored DNA could be stolen.
Insurance, loan companies could get hold of your DNA find diseases and refuse your business because of it.
Storage of DNA profiles is invasion of your privacy.
Possible to plant DNA at crime scene giving false evidence.

26
Q

What is genetic engineering?

A

Involves taking genes from one organism and placing them into the genome of another

27
Q

What are the disadvantages of genetic engineering?

A

Crops are given advantage to suit environment

Crops create there own insecticide or herbicide resistant

28
Q

What are the disadvantages of genetic profiling?

A

The escape of pollen from modified crops could lead to modification of other crops. ‘Super Weeds’ might be created (herbicide resistant weeds).
Fears about effects on body of eating modified crops.

Biology GCSE (11 decks)

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