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Genetics Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are gametes?

A

Reproductive cells: sperm and egg cells.

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2
Q

Why are gametes haploid?

A

Because they contain half the amount of chromosomes of normal cells.

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3
Q

What happens at fertilisation?

A

A male gamete fuses with a female gamete to produce a fertilised egg, also known as a zygote.

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4
Q

Why is a zygote diploid?

A

It contains a full set of chromosomes.

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5
Q

How is Meiosis different to Mitosis?

A

It’s different because it doesn’t produce identical cells.

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6
Q

What happens in Meiosis?

A
  • Cell duplicates DNA, one arm of each X-shaped chromosome is an exact copy of the other.
  • In the first division, the chromosomes line up in pairs in the centre of the cell. One chromosome in each pair came from mother/father.
  • The pair are then pulled apart, so each cell only has one copy of each chromosome, some of mother some of father.
  • Mixing genes creates genetic variation
  • In the second division, the chromosome line up again in the centre. The arms are pulled apart, You get four haploid daughter cells - these are gametes, each gamete only has a single set amount of chromosomes. The gametes are genetically different.
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7
Q

What is asexual reproduction?

A

They divide by mitosis - this results in two diploid daughter cells, which are identical to each other and the parent cell.

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8
Q

What is sexual reproduction?

A

This involves meiosis and the production of genetically different haploid gametes, which fuse during fertilisation.

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9
Q

What are the advantages of asexual reproduction?

A
  • Can produce a lot of offspring quickly

- Only one parent is needed

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10
Q

What are the disadvantages of asexual reproduction?

A
  • No genetic variation

- If conditions are unfavourable then whole population may be affected

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11
Q

What are the advantages of sexual reproduction?

A
  • Creates genetic variation
  • If conditions change, some of population with survive
  • Leads to evolution
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12
Q

What are the disadvantages of sexual reproduction?

A
  • It takes more time than asexual reproduction

- Two parents need - this is a problem if individuals are isolated.

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13
Q

DNA stands are made up of repeating units called what?

A

Nucleotides.

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14
Q

What does a nucleotide consist of?

A

One sugar molecule, one phosphate molecule and one `base’.

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15
Q

The sugar and phosphate molecules form a what?

A

Backbone.

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16
Q

What are the four bases?

A

Adenine, thymine, cytosine and guanine. (A, T, C, G).

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17
Q

What is the structure of a DNA molecule?

A

It has two strands coiled together in the shape of a double helix.

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18
Q

What are the complementary base pairs?

A

A and T, C and G.

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19
Q

The complementary base pairs are joined together by what?

A

Weak hydrogen bonds.

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20
Q

What is a chromosome?

A

A long, coiled up molecule of DNA. They are found in the nucleus of eukaryotic cells.

21
Q

What is a gene?

A

A section of DNA on a chromosome that codes for a particular protein.

22
Q

What makes up a genome?

A

All of an organism’s DNA.

23
Q

How do you extract DNA from fruit cells?

A
  • Mash strawberries and then put in beaker containing solution of detergent and salt.
  • The detergent breaks down the cell membranes to release the DNA.
  • The salt will make the DNA stick together.
  • Filter the mixture.
  • Add some ice-cold alcohol to the filtered mixture.
  • The DNA will start to come out of solution as it’s not soluble in cold alcohol. It will appear as stringy white precipitate that can be fished out with a glass rod.
24
Q

DNA controls the production of what?

A

Proteins (protein synthesis).

25
Q

Proteins are made up of chains of molecules called what?

A

Amino acids.

26
Q

What is a base triplet?

A

Each amino acids is coded for by a sequence of three bases in the gene.

27
Q

Proteins are made in two stages, what are they?

A

Transcription and translation.

28
Q

What is transcription?

A
  • RNA polymerase binds to region of non-coding DNA in front of a gene
  • The two strands unzip and the RNA polymerase moves along one of the strands of the DNA
  • It uses the coding DNA in the gene as a template to make the mRNA. Base pairing between the DNA and RNA ensures that the mRNA is complementary to the gene
  • Once made the mRNA molecule moves out of the nucleus and joins with a ribosome.
29
Q

What is translation?

A
  • Amino acids are brought to the ribosome by another RNA molecule called transfer RNA (tRNA).
  • The order in which the amino acids are brought to the ribosome matches the order of the base triplets in mRNA. Base triplets in mRNA are also known as codons.
  • Part of the tRNA’s structure is called and anticodon - it is complementary to the codon for the amino acid. The pairing of the codon and anticodon makes sure that the amino acids are brought to the ribosome in the correct order.
  • The amino acids are joined together by the ribosome. This makes polypeptide (protein).
30
Q

What is a mutation?

A

It is a rare, random change to an organism’s DNA base sequence that can be inherited.

31
Q

If a mutation happens in a gene, it produces what?

A

A genetic variant.

32
Q

How can a genetic variant affect the phenotype of an organism?

A

It may code for a different sequence of amino acids, which may change the shape of the final protein and so it’s activity. The activity of an enzyme might increase/decrease/stop which could affect the characteristics of an organism.

33
Q

What did Mendel’s pea plant experiment show?

A
  • Characteristics in plants are determined by hereditary units
  • These units are passed on to offspring unchanged from both parents, one unit from each
  • These units can be dominant or recessive
34
Q

What is an allele?

A

Alleles are different forms of a gene.

35
Q

What does heterozygous mean?

A

Individuals who are heterozygous for a certain gene carry two different alleles.

36
Q

What does homozygous mean?

A

Individuals who are homozygous for a certain gene carry two copies of the same allele.

37
Q

What is monohybrid inheritance?

A

The inheritance of a single characteristic.

38
Q

What genetic diagrams can be used to show monohybrid inheritance?

A

Monohybrid cross, Punnett square and Family pedigrees.

39
Q

What chromosomes do males have?

A

XY.

40
Q

What chromosomes do females have?

A

XX.

41
Q

How are sex-linked disorders inherited?

A

They are inherited as sex-linked disorders are located on a sex chromosome.

42
Q

What are the four blood types?

A

A, B, O and AB.

43
Q

How can you have an AB blood type?

A

This is because A and B are co-dominant with each other - this means one allele isn’t dominant over the other.

44
Q

Why is blood type O rare?

A

Blood type O is a recessive allele so you need two of them to be present.

45
Q

What is genetic variation?

A

Different characteristics as a result of mutation and sexual reproduction.

46
Q

What is environmental variation?

A

Different characteristics caused by an organism’s environment (acquired characteristics).

47
Q

Both genetic and environmental variations lead to what?

A

Differences in phenotype.

48
Q

What is the Human Genome Project?

A

The big idea was to find every single human gene.

49
Q

What are the medical applications of the HGP?

A
  • Prediction and prevention of disease
  • Testing and treatment of inherited disorders
  • New and better medicines

Biology (10 decks)

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