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Higher Biology > DNA and the genome > Flashcards

DNA and the genome Flashcards

1
Q

What is the structure of DNA?
What does DNA contain?

A

Double stranded antiparallel structure, with deoxyribose and phosphate at 3’ and 5’ ends of each strand respectively, forming a double helix.

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2
Q

What do Prokaryotes contain?

A

Prokaryotes have a single circular chromosome and smaller circular plasmids.

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3
Q

What do Eukaryotes contain?

A

Eukaryotes all have linear chromosomes, in the nucleus, which are tightly coiled and packaged with associated proteins.

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4
Q

What are the associated proteins called?

A

The associated proteins are called histones.

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5
Q

What chromosomes do Eukaryotes contain and where are they found?

A

Eukaryotes contain circular chromosomes in their mitochondria and chloroplasts.

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6
Q

What is yeast a special example of?

A

Yeast is a special example of a eukaryote as it also has plasmids.

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7
Q

What happens prior to cell division?

A

Prior to cell division, DNA is replicated by a DNA polymerase.

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8
Q

What does DNA polymerase need to start replication?

A

DNA polymerase needs primers to start replication.

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9
Q

What is a primer?

A

A primer is a short strand of nucleotides which binds to the 3’ end of the template DNA strand allowing polymerase to add DNA nucleotides.

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10
Q

What does DNA polymerase add?

A

DNA polymerase adds DNA nucleotides, using complementary base pairing, to the deoxyribose (3’) end of the new DNA strand which is forming.

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11
Q

DNA is unwound and….

A

DNA is unwound and hydrogen bonds between bases are broken to form two template strands.

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12
Q

DNA polymerase can only add DNA nucleotides in one direction resulting in…

A

DNA polymerase can only add DNA nucleotides in one direction resulting in the leading strand being replicated continuously and the lagging strand replicated in fragments.

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13
Q

Fragments of DNA are joined together by what?

A

Fragments of DNA are joined together by ligase.

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14
Q

PCR amplifies DNA using what?

A

(PCR) amplifies DNA using complementary primers for specific target sequences.

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15
Q

In PCR, primers are short strands of nucleotides which are…

A

In PCR, primers are short strands of nucleotides which are complementary to specific target sequences at the two ends of the region of DNA to be amplified.

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16
Q

What does repeated cycles of heating and cooling do?

A

Repeated cycles of heating and cooling amplify the target region of DNA.

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17
Q

What is DNA heated to? To separate the strands?

A

DNA is heated to between 92 and 98 °C to separate the strands.

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18
Q

What is it then cooled down to to allow primers to bind to target sequences?

A

It is then cooled to between 50 and 65 °C to allow primers to bind to target sequences.

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19
Q

What is it then heated to for heat tolerant DNA polymerase to replicate the region of DNA for heat-tolerant DNA polymerase to replicate the region of DNA.

A

It is then heated to between 70 and 80 °C for heat-tolerant DNA polymerase to replicate the region of DNA for heat-tolerant DNA polymerase to replicate the region of DNA.

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20
Q

What can PCR do to help solve crimes?

A

PCR can amplify DNA to help solve crimes, settle paternity suits and diagnose genetic disorders.

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21
Q

Only a fraction of the genes in a cell are……

A

Only a fraction of the genes in a cell are expressed.

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22
Q

What does transcription and translation involve?
What 3 types of RNA?

A

Transcription and translation involves three types of RNA (mRNA, tRNA and rRNA).

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23
Q

What is RNA?

A

RNA is single stranded and is composed of nucleotides containing ribose sugar, phosphate and one of four bases: cytosine, guanine, adenine and uracil.

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24
Q

What does Messenger RNA carry?

A

Messenger RNA (mRNA) carries a copy of the DNA code from the nucleus to the ribosome.

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25
Q

mRNA is transcribed from DNA in the ________and____________ into proteins by ribosomes in the cytoplasm.

A

mRNA is transcribed from DNA in the nucleus and translated into proteins by ribosomes in the cytoplasm.

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26
Q

What are each triplet of bases on the mRNA molecule called and what do they code for?

A

Each triplet of bases on the mRNA molecule is called a codon and codes for a specific amino acid.

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27
Q

What does transfer RNA fold due to?
What does each tRNA molecule carry?
What does a tRNA molecule have?

A

Transfer RNA (tRNA) folds due to complementary base pairing. Each tRNA molecule carries its specific amino acid to the ribosome. A tRNA molecule has an anticodon (an exposed triplet of bases) at one end and an attachment site for a specific amino acid at the other end.

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28
Q

What 2 things form the ribosome?

A

Ribosomal RNA (rRNA) and proteins form the ribosome.

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29
Q

RNA polymerase moves along DNA …..

A

RNA polymerase moves along DNA unwinding the double helix and breaking the hydrogen bonds between the bases.

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30
Q

RNA polymerase synthesises a primary….

A

RNA polymerase synthesises a primary transcript of mRNA from RNA nucleotides by complementary base pairing.

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31
Q

What is uracil complementary to?

A

Uracil in RNA is complementary to adenine.

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32
Q

What does RNA splicing form?

A

RNA splicing forms a mature mRNA transcript.

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33
Q

What are the introns of the primary transcript

A

The introns of the primary transcript are non-coding regions and are removed.

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34
Q

The exons are _________ and are joined together to form the ____________-

A

The exons are coding regions and are joined together to form the mature transcript.

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35
Q

The order of the exons is ________ during splicing.

A

The order of the exons is unchanged during splicing.

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36
Q

Where does translation begin and end?

A

Translation begins at a start codon and ends at a stop codon.

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37
Q

What do Anticodons do?

A

Anticodons bond to codons by complementary base pairing, translating the genetic code into a sequence of amino acids. Peptide bonds join the amino acids together.

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38
Q

What does each tRNA do when the polypeptide is formed?

A

Each tRNA then leaves the ribosome as the polypeptide is formed.

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39
Q

Different mature mRNA transcripts are produced from the__________

A

Different mature mRNA transcripts are produced from the same primary transcript depending on which exons are retained.

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40
Q

How is the phenotype determined?

A

Phenotype is determined by the proteins produced as the result of gene expression.

41
Q

What is cellular differentiation?

A

Cellular differentiation is the process by which a cell expresses certain genes to produce proteins characteristic for that type of cell.

42
Q

Differentiation into specialised cells from meristems in plants; embryonic and___________ stem cells in animals.

A

Differentiation into specialised cells from meristems in plants; embryonic and tissue (adult) stem cells in animals.

43
Q

What are meristems?

A

Meristems are regions of unspecialised cells in plants that can divide (self-renew) and/or differentiate.

44
Q

What type of cells are stem cells?

A

Stem cells are unspecialised cells in animals that can divide (self-renew) and/or differentiate.

45
Q

What can cells in the very early embryo do?

A

Cells in the very early embryo can differentiate into all the cell types that make up the organism and so are pluripotent.

46
Q

Why can all the genes in embryonic stem cell be switched on?

A

All the genes in embryonic stem cells can be switched on so these cells can differentiate into any type of cell.

47
Q

What are tissue stem cells involved in?
3 examples.

A

Tissue stem cells are involved in the growth, repair and renewal of the cells found in that tissue.

48
Q

What are tissue stem cells described as being? Why are they called this?
Give an example.

A

Tissue stem cells are multipotent as they can differentiate into all of the types of cell found in a particular tissue type. For example, blood stem cells located in bone marrow can give rise to all types of blood cell.

49
Q

Therapeutic uses involve the repair of what 3 things?

A

Therapeutic uses involve the repair of damaged or diseased organs or tissues.

50
Q

The therapeutic uses of stem cells should be exemplified by how they are used in what 2 things?

A

The therapeutic uses of stem cells should be exemplified by how they are used in corneal repair and the regeneration of damaged skin.

51
Q

What does research using stem cells involve stem cells being used as?

A

Research uses involve stem cells being used as model cells to study how diseases develop or being used for drug testing.

52
Q

What can stem cell from the embryo do under the right conditions in the lab?

A

Stem cells from the embryo can self-renew, under the right conditions, in the lab.

53
Q

What does stem cell research provide?

A

Stem cell research provides information on how cell processes such as cell growth, differentiation and gene regulation work.

54
Q

What can use of embryonic stem cells offer?

A

Use of embryonic stem cells can offer effective treatments for disease and injury; however, it involves destruction of embryos.

55
Q

What is the genome?

A

The genome of an organism is its entire hereditary information encoded in DNA.

56
Q

What is a genome made up of?

A

A genome is made up of genes and other DNA sequences that do not code for proteins.

57
Q

What do most of the eukaryotic genome consist of?

A

Most of the eukaryotic genome consists of non-coding sequences.

58
Q

What forms of RNA are tRNA and rRNA?

A

tRNA and rRNA are non-translated forms of RNA.

59
Q

What are mutations?

A

Mutations are changes in the DNA that can result in no protein or an altered protein being synthesised.

60
Q

What does a single gene mutation involve?

A

Single gene mutations involve the alteration of a DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides.

61
Q

What are the 3 Nucleotide substitutions?

A

Nucleotide substitutions — missense, nonsense and splice-site mutations.

62
Q

What do missense mutations result in?

A

Missense mutations result in one amino acid being changed for another. This may result in a non-functional protein or have little effect on the protein.

63
Q

What do nonsense mutations result in?

A

Nonsense mutations result in a premature stop codon being produced which results in a shorter protein.

64
Q

What do splice site mutations result in?

A

Splice-site mutations result in some introns being retained and/or some exons not being included in the mature transcript.

65
Q

What do nucleotide insertions or deletions result in?

A

Nucleotide insertions or deletions result in frame-shift mutations.

66
Q

What do frame shift mutations cause?

A

Frame-shift mutations cause all of the codons and all of the amino acids after the mutation to be changed. This has a major effect on the structure of the protein produced.

67
Q

name the 4 types of chromosome structure mutations

A

Chromosome structure mutations — duplication, deletion, inversion and translocation.

68
Q

What is duplication?

A

Duplication is where a section of a chromosome is added from its homologous partner.

69
Q

What is deletion?

A

Deletion is where a section of a chromosome is removed.

70
Q

What is Inversion?

A

Inversion is where a section of chromosome is reversed.

71
Q

What is translocation?

A

Translocation is where a section of a chromosome is added to a chromosome, not its homologous partner.

72
Q

What does duplication allow?

A

Duplication allows potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce its protein.

73
Q

What is evolution?

A

Evolution — the changes in organisms over generations as a result of genomic variations.

74
Q

What is natural selection?

A

Natural selection is the non-random increase in frequency of DNA sequences that increase survival and the non-random reduction in the frequency of deleterious sequences.

75
Q

The changes in phenotype frequency as a result of what 3 selections?

A

The changes in phenotype frequency as a result of stabilising, directional and disruptive selection.

76
Q

What happens in stabilisation selection?

A

In stabilising selection, an average phenotype is selected for and extremes of the phenotype range are selected against.

77
Q

What happens in directional selection?

A

In directional selection, one extreme of the phenotype range is selected for.

78
Q

What happens in disruptive selection?

A

In disruptive selection, two or more phenotypes are selected for.

79
Q

Natural selection is more rapid in….

A

Natural selection is more rapid in prokaryotes.

80
Q

What can prokaryotes exchange resulting in faster evolutionary change than in organisms that only use vertical transfer?

A

Prokaryotes can exchange genetic material horizontally, resulting in faster evolutionary change than in organisms that only use vertical transfer.

81
Q

What is horizontal gene transfer?

A

Horizontal gene transfer is where genes are transferred between individuals in the same generation.

82
Q

What is vertical gene transfer?

A

Vertical gene transfer is where genes are transferred from parent to offspring as a result of sexual or asexual reproduction.

83
Q

What is speciation?

A

Speciation is the generation of new biological species by evolution as a result of isolation, mutation and selection.

84
Q

What is a “species”

A

A species is a group of organisms capable of interbreeding and producing fertile offspring, and which does not normally breed with other groups.

85
Q

What is the importance of isolation barriers?

A

The importance of isolation barriers in preventing gene flow between sub-populations during speciation.

86
Q

What do Geographical Barriers lead to and behavioural or ecological barriers?

A

Geographical barriers lead to allopatric speciation and behavioural or ecological barriers lead to sympatric speciation.

87
Q

What is required to compare sequence data?

A

To compare sequence data, computer and statistical analyses (bioinformatics) are required.

88
Q

What does comparison of genomes reveal?

A

Comparison of genomes reveals that many genes are highly conserved across different organisms.

89
Q

What are important models for research?

A

Many genomes have been sequenced, particularly of disease-causing organisms, pest species and species that are important model organisms for research.

90
Q

How can the sequence of events be determined?

A

The sequence of events can be determined using sequence data and fossil evidence.

91
Q

Definition of Phylogenetics

A

Phylogenetics is the study of evolutionary history and relationships.

92
Q

What does comparison of sequences provide?

A

Comparison of sequences provides evidence of the three domains of life — bacteria, archaea and eukaryotes.

93
Q

What is sequence data used to study?

A

Use of sequence data to study the evolutionary relatedness among groups of organisms.

94
Q

What is sequence divergence used for?

A

Sequence divergence is used to estimate time since lineages diverged.

95
Q

Why are sequence data and fossil evidence used?

A

Use of sequence data and fossil evidence to determine the main sequence of events in evolution of life: cells, last universal ancestor, prokaryotes, photosynthetic organisms, eukaryotes, multicellularity, animals, vertebrates, land plants.

96
Q

What are molecular clocks use for?

A

Molecular clocks are used to show when species diverged during evolution.

97
Q

What do molecular clocks assume?

A

Molecular clocks assume a constant mutation rate and show differences in DNA sequences or amino acid sequences. Therefore differences in sequence data between species indicate the time of divergence from a common ancestor.

98
Q

What is Pharmacogenetics the use of?

A

Pharmacogenetics is the use of genome information in the choice of drugs.

99
Q

What can an individuals personal genome sequence be used for?

A

An individual’s personal genome sequence can be used to select the most effective drugs and dosage to treat their disease (personalised medicine).

Higher Biology (3 decks)

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