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Biology > 4 - Genetic information > Flashcards

4 - Genetic information Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

The fixed position occupied by a gene on a DNA molecule

A

Locus

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2
Q

How is a gene code for a polypeptide?

A

Nucleotide sequence in triplets which codes for the primary structure of the polypeptide chain

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3
Q

Exon

A

Triplet sequence coding for a polypeptide

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4
Q

How is a phosphodiester bond formed between 2 nucleotides in DNA?

A

Condensation reaction between deoxyribose + phosphate, catalysed by DNA polymerase

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5
Q

Where is a non-coding base sequence positioned?

A

Between genes

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6
Q

3 Ways in which the structure of the chromosome may differ along its length, resulting in more stain binding in some areas

A

Differences in base sequences

Differences in histone

Differences in supercoiling

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7
Q

Homologous chromosomes

A

2 chromosomes which carry the same genes

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8
Q

Intron

A

Non-coding region of DNA

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9
Q

What does tRNA have that mRNA does not?

A

Hydrogen bonds
Amino acid binding site
Anticodon

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10
Q

What does mRNA have that tRNA does not?

A

Codon

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11
Q

What is the difference in shape of mRNA and tRNA?

A

mRNA - linear

tRNA - clover leaf shaped

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12
Q

What is the difference in structure between mRNA and pre-mRNA? Why?

A

mRNA has fewer nucleotides because of splicing

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13
Q

How is one amino acid added to a polypeptide chain during translation?

A

tRNA brings specific amino acid
(tRNA) anticodon binds to (mRNA) codon
Amino acids joined via condensation reaction

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14
Q

How is mRNA produced from an exposed template strand of DNA?

A

Free RNA nucleotides form complementary base pairs

Phosphodiester bonds form
by action of RNA polymerase

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15
Q

How is mRNA formed by transcription in eukaryotes?

A

Hydrogen bonds break between bases

1 DNA strand acts as a template

Free nucleotides align by complementary base pairing
Uracil instead of thymine in RNA

RNA polymerase joins nucleotides, forming phosphodiester bonds

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16
Q

Splicing

A

removing introns from pre-mRNA to form mRNA

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17
Q

How is a polypeptide formed by translation of mRNA?

A

mRNA attaches to ribosomes
Anticodons bind to complementary codons
tRNA brings specific amino acid
Peptide bonds formed using ATP
tRNA released
Ribosomes moves along mRNA to form polypeptide

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18
Q

Proteome

A

The full range of proteins a cell can code for

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19
Q

Transcription

A

conversion of DNA –> RNA

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20
Q

Translation

A

The converssion of RNA –> proteins

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21
Q

What enzyme breaks the hydrogen bonds between the 2 strands?

A

RNA polymerase

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22
Q

Outline Transcription

A

mRNA associates with ribosome which frinds the start codon

tRNA brings specific amino acid

Ribosome fits 2 codons (codon-anticodon)

amino acids joined by peptide bonds

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23
Q

Types of mutation

A

Substitution
Deletion
Polyploidy
Non-disjunction

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24
Q

Substitution

A

When one nucleotide in the base sequence is replaced by another one

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25
Q

Deletion

A

A single nucleotide is lost, causing a frameshift

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26
Q

Addition

A

A nucleotide is added, causing a frameshift

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27
Q

Polyploidy

A

An individul has 3 or more sets of chromosomes

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28
Q

Non-disjunction

A

Chromosomes fail to seperate properly in Meisosis

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29
Q

Independent Assortment

A

Meiosis I - homologous chromosomes line up in random pairs

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30
Q

Crossing Over

A

When pairs of chromosomes line up, they can exchange some of their genetic material

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31
Q

Meiosis I

A

Homologous chromosomes line up

Crossing over at the chiasmata

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32
Q

Meiosis II

A

Chromatids seperate, producing 4 haploid daughter cells

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33
Q

Mutagenic agent

A

A factor that increases the rate of mutations

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34
Q

Causes of genetic diversity

A

Independent segregation

Crossing over

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35
Q

Why might a mutation have no effect on the individual

A

Genetic code is degenerate

Mutation on Intron

No effect on tertiary structure

New allele is recessive

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36
Q

How might a mutation have a positive effect

A

Changes to properties of protein lead to greater reproductive success or greater chances of survival

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37
Q

Where is prokaryotic DNA located

A

In the cytoplasm as they have no nucleus

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38
Q

Coiling of prokaryotic DNA

A

Supercooling - condenses circular chromosomes so that they can fit inside the cell

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39
Q

Length of prokaryotic DNA

A

Chromosomes are short

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40
Q

Eukaryotic DNA

A

Histone-bound

In Nucleus

Homologous pairs

Long and linear

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41
Q

How are the presence of DNA in mitochondria and chloroplasts explained?

A

Endosymbiotic theory

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42
Q

Endosymbiotic theory

A

States that bacterial cells were engulfed by a larger cell during evolution

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43
Q

Process of endosymbiotic theory

A

The bacteria and host cell formed a beneficial symbiotic relationship

The bacterial cells became incorporated into the larger cell to become organelles

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44
Q

What were the bacterial cells incorporated into host cells thought to become?

A

Mitochondria and chloroplasts

45
Q

Why is is thought that mitochondria and chloroplasts were once free-living bacteria?

A

When they were free-living bacteria, they needed their own DNA to survive

This explains why there is still some DNA in mitochondria and chloroplasts

46
Q

Role of mitochondrial DNA

A

Encodes enzymes used in respiration

47
Q

Role of chloroplast DNA

A

Encodes enzymes used in photosynthesis

48
Q

What encodes a specific amino acid?

A

Codon

49
Q

Role of mRNA

A

The base sequence in a gene is made into a polypeptide by copying DNA into mRNA

mRNA is then copied into the corresponding polypeptide

50
Q

Functional RNA

A

Some genes encode a function RNA molecule instead of a polypeptide

Functional RNA are necessary for protein synthesis

51
Q

Transfer RNA

A

Helps find the correct amino acids for a specific codon

52
Q

Ribosomal RNA

A

Part of a ribosome, centre of protein synthesis

53
Q

Codon

A

3 bases that encode a specific amino acid

54
Q

What happens when a gene is translated for protein synthesis?

A

The introns are removed from the sequence

55
Q

Features of the genetic code

A

Universal

Non-overlapping

Degenerate

56
Q

Genetic code as degenerate

A

Some amino acids are encoded by more than one codon

This is because there are 64 possible triplet codons and only 20 amino acids

57
Q

Genetic code as non-overlapping

A

No overlap between triplet codes

58
Q

Genetic code as universal

A

The same 4 bases are used in the DNA of every organism

The same codons encode the same amino acid in every organism

Codons in DNA are transcribed into mRNA and translated into amino acids in every organism

59
Q

Genome

A

Complete set of genes in an individuals DNA

60
Q

Proteome

A

Full range of proteins an individual can produce

61
Q

2 processes involved in synthesizing protein from a base sequence

A

Transcription

Translation

62
Q

How is mRNA produced?

A

Transcribed from DNA in the nucleus to produce single stranded RNA

mRNA strand in complementary to the DNA base sequence

63
Q

Where does mRNA travel?

A

From the nucleus to the ribosomes in the cytoplasm

64
Q

Role of ribosomes in synthesising polypeptide

A

Translate mRNA into amino acids and synthesised the polypeptide

65
Q

tRNA - Shape and role

A

Forms a clover-like shape and is vital for translation

tRNA reads the mRNA codons and brings the corresponding amino acid into the tibosomes

66
Q

Why is it important that the correct amino acid is brought to the ribosomes by tRNA?

A

So that the protein is assembled correctly

67
Q

tRNA anticodon

A

Complementary to a specific mRNA codon

The amino acid that corresponds to a specific anticodon binds to a specific attachment site on the tRNA molecule

68
Q

RNA polymerase

A

Enzyme which allows transcription to take place

Binds to the locus of the gene to be transcribed

69
Q

What happens when RNA polymerase binds to DNA?

A

The hydrogen bonds between adjacent nucleotides break

DNA strands separate

Bases of target gene are exposed

70
Q

How are free-floating nucleotides binded to the template strand in transcription?

A

RNA polymerase

71
Q

What do RNA nucleotides form when binding to template strand?

A

A strand of mRNA complementary to template strand

72
Q

What forms between adjacent nucleotides?

A

Phosphodiesterase bonds in a condensation reaction

73
Q

Role of STOP codon

A

Signals to RNA polymerase to stop separating DNA and producing mRNA

74
Q

What happens when the mRNA strand is separated from the template strand?

A

The hydrogen bonds between the 2 strands of DNA form again and the strands join together

75
Q

What is mRNA used in?

A

Translation

76
Q

Where does translation take place?

A

Cytoplasm

77
Q

How many bases can fit inside a ribosome at any one time?

A

6 bases (2 codons)

78
Q

How is tRNA binded in translation?

A

One molecule of tRNA binds to the first codon in the ribosome

tRNA has an anticodon complementary to a specific codon

Anticodon allows correct tRNA molecule to bind to correct codon

79
Q

How is an amino acid bound to tRNA?

A

ATP

80
Q

When is the polypeptide chain released from the ribosome?

A

When the ribosome reaches a STOP codon

81
Q

Pre-mRNA

A

mRNA before it has been spliced

82
Q

When is pre-mRNA spliced?

A

Before it enters the ribosome for translation

83
Q

Splicing

A

Removes introns from the mRNA

84
Q

Role of RNA polymerase in prokaryotes

A

Catalyses every step of transcription

including the separation of DNA strands and the production of the mRNA strand

85
Q

What do ribosomes translate mRNA into?

A

Amino acids

86
Q

Non-Dysjunction

A

Where chromosomes do not separate properly

87
Q

2 ways of increasing genetic variation in meiosis

A

Crossing over

Independent segregation

88
Q

Crossing over

A

Chromosomes line up at centre of cell in homologous pairs and sections of DNA are swapped between chromosomes

89
Q

Independent segregation

A

The chromosomes in a homologous pairs are randomly separated in meiosis I to produce 2 genetically different daughter cells

90
Q

Random fertilisation

A

Gametes randomly fuse together during sexual reproduction to produce a diploid cell

91
Q

How is genetic diversity in a population increased?

A

Mutations - creation of new alleles

Gene flow - introduction of new alleles by migration

92
Q

Stabalising selection

A

The process where natural selection favours an average phenotype

93
Q

Directional Selection

A

The process where natural selection favours an average phenotype

94
Q

Types of adaptation

A

Behavioural

Physiological

Anatomical

95
Q

Species

A

Organisms that can interbreed to produce fertile offspring

96
Q

How are potential mates of the same species identified?

A

Courtship behaviour

97
Q

Courtship behaviours

A

Complex displays which help an individual to attract a mate

98
Q

Phylogeny

A

Evolutionary relationships between organisms

99
Q

Taxa

A

A group of closely related organisms

100
Q

Stages of the hierarchy

A

Domain
Kingdom
Phylum
Class
Orer
Family
Genus
Species

101
Q

Binomial naming system

A

Consists of the genus and the species of an organism

102
Q

Identifying evolutionary relationships through antibody-antigen interactionsss

A

An organisms antibodies can be isolated with another organisms proteins to see how many antigen-antibody complexes are formed

103
Q

Investigating evolutionary relationships through genome sequencing

A

The more similar the base sequences between organisms, the more closely related they are

104
Q

Ways of determining evolutionary relationships

A

Antibody-antigen complexes

Base sequencing

Amino acid sequencing

105
Q

Species richness

A

The number of species in a habitat or community

106
Q

How do pesticides reduce biodiversity?

A

Direct removal of pests

The species that feed on pests cannot survive

107
Q

How do herbicides reduce biodiversity?

A

Direct removal of plants

Species that feed on the unwanted plants cannot survive

108
Q

How does deforestation reduce biodiversity?

A

Direct removal of species (trees)

Removal of habitats causing species to die

109
Q

Environmental Stewardship Scheme

A

Encourages farmers to balance agriculture with conserving biodiversity

Biology (7 decks)

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