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Biology > SB3 - Genetics > Flashcards

SB3 - Genetics Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is sexual reproduction?

A

Involves the joining of male and female gametes

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2
Q

What gametes join together in sexual reproduction of flowering plants?

A

Pollen & egg cells

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3
Q

How many chromosomes does a normal cell have?

A

46

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4
Q

How many chromosomes does a gamete have?

A

23

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5
Q

How is variation produced in sexual reproduction?

A

The genetic information from each parent is mixed

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6
Q

What is asexual reproduction?

A

Involves one parent with no gametes joining

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7
Q

What process does Asexual reproduction use?

A

Mitosis

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8
Q

Why does asexual reproduction produce clones?

A

As there is no mixing of genetic information

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9
Q

What are the advantages of Sexual reproduction?

A
  • Produces variation in offspring
  • Allows us to use selective breeding
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10
Q

How is sexual reproduction allowing animals to produce variation in offspring an advantage?

A
  • Means that if the environment changes it is likely that an organism in the species will have a survival advantage
  • Variation decreases the chance of the whole species becoming extinct
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11
Q

How is sexual reproduction allowing animals to use selective breeding an advantage?

A
  • Organisms with different desirable characteristics can be bred to produce offspring
  • Speeds up natural selection
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12
Q

What are the disadvantages of Sexual reproduction?

A
  • Time and energy are needed to find a mate
  • It is not possible for an isolated individual
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13
Q

What are the advantages of asexual reproduction?

A
  • Only one parent is needed
  • Uses less energy + is faster
  • Favourable conditions - lots of identical offspring can be produced
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14
Q

How does asexual reproduction use less energy?

A

As organisms don’t need to find a mate

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15
Q

What are the disadvantages of asexual reproduction?

A
  • It does not lead to variation in a population
  • The species may only be suited to one habitat
  • Disease may affect all the individuals in a population
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16
Q

What is meiosis used to produce?

A

Haploid gametes

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17
Q

What is meiosis?

A

Reduction division in a cell in which the chromosome number is halved from diploid to haploid

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18
Q

What is DNA?

A

The material inside the nucleus of cells, carrying the genetic information of a living being

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19
Q

What is DNA made up of?

A

Nucleotides

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20
Q

What is a nucleotide made out of?

A
  • Sugar
  • Bases
  • Phosphate group
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21
Q

What is the double helix held together by?

A

Weak hydrogen bonds between complementary base pairs

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22
Q

How are weak hydrogen bonds formed between bases?

A

Parts of DNA bases have slight electrical charges

A slightly negative charged part of one bases attracts a slightly positive part of another base = weak hydrogen bond

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23
Q

How many hydrogen bonds does Cytosine & Guanine produce?

A

3 hydrogen bonds

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24
Q

How many hydrogen bonds does Adenine & Thymine produce?

A

2

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25
Q

What does Adenine pair with?

A

Thymine

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26
Q

What does Guanine pair with?

A

Cytosine

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27
Q

What shape is DNA?

A

Double helix

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28
Q

What important information does DNA carry?

A

Genetic code - determines characteristics of a living organism

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29
Q

What type of molecule is DNA?

A

A polymer

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30
Q

What does the order of different bases form?

A

Genetic code

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31
Q

What is a gene?

A

A short section of DNA

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32
Q

What does each gene code for?

A

Many amino acids, which are joined together to make a specific protein

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33
Q

How many types of amino acids are there?

A

20

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34
Q

What is a genome?

A

All of the DNA in an organism

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35
Q

What are the aims of the Human genome project?

A
  • To work out the order or sequence of all the three billion base pairs in the human genome
  • To identify all the genes
  • To develop faster methods for sequencing DNA
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36
Q

What has the Human genome project helped us understand the human body?

A
  • Improved our understanding of the genes
    linked to different types of disease
  • Treatment of inherited disorders
  • Tracing human migration patterns from the past
37
Q

Core practical: Extracting DNA

Describe the method you would use to extract DNA from a fruit?

A

1) Gently mix together some cold water, some salt and washing up liquid. Gently heat this mixture at a high temp for 5-10 minutes

2) Peel the skins of a fruit and chop into small pieces. Pulverise the fruit.

3) Add the solution from Step 1 to the fruit

4) Filter the solution using a few sheets of kitchen paper and a sieve. Pour the filtrate into a test tube

5) Add some pineapple juice to the filtrate and allow to rest for a few minutes

6) Add a few teaspoons of cold ethanol to the solution and wait a few minutes

38
Q

Core practical: Extracting DNA

Why do we add ethanol?

A

Ethanol causes the DNA to precipitate out of the solution

39
Q

Core practical: Extracting DNA

What is the expected observation of this practical?

A

A white mass should precipitate at the top of the tube after 10 minutes (this is the DNA)

40
Q

Core practical: Extracting DNA

Why do we add a protease enzyme solution / pineapple juice?

A

This breaks down the proteins attached to the DNA - helps us to see it more clearly

41
Q

How many bases code for an amino acid?

A

3

42
Q

What determines what type of protein is produced?

A

The different types and order of amino acids
—>Therefore it is the order of bases in DNA that determine which proteins are produced

43
Q

What are the steps that make up protein synthesis?

A
  • Transcription
  • Translation
44
Q

What is a polypeptide chain?

A

Amino acid sequences

45
Q

What are some uses of proteins?

A
  • Enzymes
  • Hormones
  • Structural proteins
46
Q

How are proteins used as hormones?

A

They carry messages around the body

47
Q

How are proteins used as structural proteins?

A

They provide structure and are physically strong

48
Q

How are proteins used as enzymes?

A

They act as biological catalysts to speed up chemical reactions occurring in the body

49
Q

What is Transcription?

A

DNA is transcribed and an mRNA molecule is produced

50
Q

What is Translation?

A

mRNA is translated and an amino acid sequence is produced

51
Q

Where does Transcription occur?

A

Nucleus

52
Q

Describe & explain transcription in protein synthesis

A
  • Part of a DNA molecule unwinds
    —> exposes the gene to be transcribed
  • RNA polymerase binds to a region of non-coding DNA just in front of the gene
  • RNA polymerase then makes a complementary copy of the code from the gene
  • mRNA molecule leaves the nucleus via a pore in the nuclear envelope
53
Q

What does it mean for part of a ‘DNA molecule to unwind’ in transcription?

A

The hydrogen bonds between the complementary base pairs break

54
Q

How does ‘RNA polymerase make a complementary copy of the code from the gene’?

A

By building a single-stranded nucleic acid molecule - mRNA

55
Q

What is a polynucleotide?

A

Made up of many nucleotides linked together in a long chain

56
Q

Give some examples of polynucleotides

A
  • DNA
  • RNA
57
Q

What do RNA nucleotides contain instead of thymine?

A

Uracil (U)

58
Q

Describe the structure of an RNA polynucleotide

A
  • Alternating ribose sugars
  • Phosphate groups linked together
  • Nitrogenous bases of each nucleotide projecting out sideways
59
Q

Where does Translation occur in protein synthesis?

A

Cytoplasm

60
Q

Why must DNA first be transcribed into mRNA before it can be translated into a protein?

A

DNA cannot travel out of the nucleus to the ribosomes as it is too big to pass through the nuclear membrane

61
Q

What is a codon?

A

Each triplet of bases on a mRNA molecule

62
Q

Describe & explain translation in protein synthesis

A
  • After leaving the nucleus, the mRNA molecule attaches to a ribosome
  • tRNA molecules bind with their specific amino acids and bring them to the mRNA molecule on the ribosome
  • The anticodon on each tRNA molecule pairs with a complementary codon on the mRNA molecule
  • Peptide bond is then formed between the two amino acids
  • Polypeptide chain is formed
63
Q

What does the ribosome do after the mRNA molecule attaches onto it?

A
  • The ribosome ‘reads’ the code on the mRNA in groups
  • The ribosome translates the sequence of bases into a sequence of amino acids that make up a protein
64
Q

Describe the structure of a tRNA molecule?

A
  • Anticodon on one end
  • A region where specific amino acid can attach at the other end
65
Q

What is an anticodon?

A

A triplet of unpaired bases at one end

66
Q

How many tRNA molecules can fit onto a ribosome at any one time?

A

2

67
Q

What molecules are in the cytoplasm that is useful for protein synthesis?

A
  • tRNA
  • Amino acids specific to the tRNA
68
Q

When does the process translation stop?

A

Until a ‘stop’ codon on the mRNA molecule is reached

69
Q

What does mRNA stand for?

A

messenger RNA

70
Q

What does tRNA stand for?

A

transfer RNA

71
Q

What is a genetic variant?

A

Small changes in the order of bases that make up a strand of DNA

72
Q

What is genotype?

A

Refers to the genes present in the DNA of an individual

73
Q

What is phenotype?

A

Refers to the visible effects of those genes

74
Q

What does non-coding mean?

A

The DNA bases do not code for the production of an amino acid

75
Q

How does genetic variants in the non-coding regions of a gene affect the phenotype?

A

Influences the binding of RNA polymerase and altering the quantity of protein produced

76
Q

Describe & explain how genetic variants in the ‘non-coding’ regions of a gene affect the phenotype?

A
  • If a mutation happens in the non-coding region to which RNA polymerase attaches
    —> Can affect the ability of RNA polymerase to bind to it
  • It can make it difficult for RNA polymerase to bind, less mRNA will be transcribed from the gene and less protein (that the gene codes for) will be produced
77
Q

How does genetic variants in the coding regions of a gene affect the phenotype?

A

The gene may code for a different sequence of amino acids so it’ll alter the activity of the protein produced

78
Q

What are the types of DNA mutations?

A
  • Insertions
  • Substitutions
  • Deletions
79
Q

What is substitutions?

A

One of the bases is changed for another random bas

80
Q

What is insertions?

A

An extra base is inserted into the sequence

81
Q

What is deletions?

A

One of the bases is deleted from the sequence

82
Q

What is the issues with DNA mutations?

(insertion, deletions and substiutions)

A

It may change all the amino acids coded

83
Q

What is an allele?

A

Different forms of a gene

84
Q

What is a dominant allele?

A

Only one (out of the two alleles) is needed for it to be expressed and for the corresponding phenotype to be observed

85
Q

What is a recessive allele?

A

Two copies are needed for it to be expressed and for the corresponding the phenotype to be observed

86
Q

What is homozygous?

A

When both inherited alleles are the same

87
Q

What is heterozygous?

A

When one of the inherited alleles is dominant and the other is recessive

88
Q

What is a chromosome?

A

A structure found in the nucleus which is made up of a long strand of DNA

89
Q
A

Biology (11 decks)

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