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Higher Biology > DNA and the genome > Flashcards

DNA and the genome Flashcards

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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
mRNA is transcribed from DNA in the ________and____________ into proteins by ribosomes in the cytoplasm.
mRNA is transcribed from DNA in the nucleus and translated into proteins by ribosomes in the cytoplasm.
26
What are each triplet of bases on the mRNA molecule called and what do they code for?
Each triplet of bases on the mRNA molecule is called a codon and codes for a specific amino acid.
27
What does transfer RNA fold due to? What does each tRNA molecule carry? What does a tRNA molecule have?
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.
28
What 2 things form the ribosome?
Ribosomal RNA (rRNA) and proteins form the ribosome.
29
RNA polymerase moves along DNA .....
RNA polymerase moves along DNA unwinding the double helix and breaking the hydrogen bonds between the bases.
30
RNA polymerase synthesises a primary....
RNA polymerase synthesises a primary transcript of mRNA from RNA nucleotides by complementary base pairing.
31
What is uracil complementary to?
Uracil in RNA is complementary to adenine.
32
What does RNA splicing form?
RNA splicing forms a mature mRNA transcript.
33
What are the introns of the primary transcript
The introns of the primary transcript are non-coding regions and are removed.
34
The exons are _________ and are joined together to form the ____________-
The exons are coding regions and are joined together to form the mature transcript.
35
The order of the exons is ________ during splicing.
The order of the exons is unchanged during splicing.
36
Where does translation begin and end?
Translation begins at a start codon and ends at a stop codon.
37
What do Anticodons do?
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.
38
What does each tRNA do when the polypeptide is formed?
Each tRNA then leaves the ribosome as the polypeptide is formed.
39
Different mature mRNA transcripts are produced from the__________
Different mature mRNA transcripts are produced from the same primary transcript depending on which exons are retained.
40
How is the phenotype determined?
Phenotype is determined by the proteins produced as the result of gene expression.
41
What is cellular differentiation?
Cellular differentiation is the process by which a cell expresses certain genes to produce proteins characteristic for that type of cell.
42
Differentiation into specialised cells from meristems in plants; embryonic and___________ stem cells in animals.
Differentiation into specialised cells from meristems in plants; embryonic and tissue (adult) stem cells in animals.
43
What are meristems?
Meristems are regions of unspecialised cells in plants that can divide (self-renew) and/or differentiate.
44
What type of cells are stem cells?
Stem cells are unspecialised cells in animals that can divide (self-renew) and/or differentiate.
45
What can cells in the very early embryo do?
Cells in the very early embryo can differentiate into all the cell types that make up the organism and so are pluripotent.
46
Why can all the genes in embryonic stem cell be switched on?
All the genes in embryonic stem cells can be switched on so these cells can differentiate into any type of cell.
47
What are tissue stem cells involved in? 3 examples.
Tissue stem cells are involved in the growth, repair and renewal of the cells found in that tissue.
48
What are tissue stem cells described as being? Why are they called this? Give an example.
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
Therapeutic uses involve the repair of what 3 things?
Therapeutic uses involve the repair of damaged or diseased organs or tissues.
50
The therapeutic uses of stem cells should be exemplified by how they are used in what 2 things?
The therapeutic uses of stem cells should be exemplified by how they are used in corneal repair and the regeneration of damaged skin.
51
What does research using stem cells involve stem cells being used as?
Research uses involve stem cells being used as model cells to study how diseases develop or being used for drug testing.
52
What can stem cell from the embryo do under the right conditions in the lab?
Stem cells from the embryo can self-renew, under the right conditions, in the lab.
53
What does stem cell research provide?
Stem cell research provides information on how cell processes such as cell growth, differentiation and gene regulation work.
54
What can use of embryonic stem cells offer?
Use of embryonic stem cells can offer effective treatments for disease and injury; however, it involves destruction of embryos.
55
What is the genome?
The genome of an organism is its entire hereditary information encoded in DNA.
56
What is a genome made up of?
A genome is made up of genes and other DNA sequences that do not code for proteins.
57
What do most of the eukaryotic genome consist of?
Most of the eukaryotic genome consists of non-coding sequences.
58
What forms of RNA are tRNA and rRNA?
tRNA and rRNA are non-translated forms of RNA.
59
What are mutations?
Mutations are changes in the DNA that can result in no protein or an altered protein being synthesised.
60
What does a single gene mutation involve?
Single gene mutations involve the alteration of a DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides.
61
What are the 3 Nucleotide substitutions?
Nucleotide substitutions — missense, nonsense and splice-site mutations.
62
What do missense mutations result in?
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
What do nonsense mutations result in?
Nonsense mutations result in a premature stop codon being produced which results in a shorter protein.
64
What do splice site mutations result in?
Splice-site mutations result in some introns being retained and/or some exons not being included in the mature transcript.
65
What do nucleotide insertions or deletions result in?
Nucleotide insertions or deletions result in frame-shift mutations.
66
What do frame shift mutations cause?
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
name the 4 types of chromosome structure mutations
Chromosome structure mutations — duplication, deletion, inversion and translocation.
68
What is duplication?
Duplication is where a section of a chromosome is added from its homologous partner.
69
What is deletion?
Deletion is where a section of a chromosome is removed.
70
What is Inversion?
Inversion is where a section of chromosome is reversed.
71
What is translocation?
Translocation is where a section of a chromosome is added to a chromosome, not its homologous partner.
72
What does duplication allow?
Duplication allows potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce its protein.
73
What is evolution?
Evolution — the changes in organisms over generations as a result of genomic variations.
74
What is natural selection?
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
The changes in phenotype frequency as a result of what 3 selections?
The changes in phenotype frequency as a result of stabilising, directional and disruptive selection.
76
What happens in stabilisation selection?
In stabilising selection, an average phenotype is selected for and extremes of the phenotype range are selected against.
77
What happens in directional selection?
In directional selection, one extreme of the phenotype range is selected for.
78
What happens in disruptive selection?
In disruptive selection, two or more phenotypes are selected for.
79
Natural selection is more rapid in....
Natural selection is more rapid in prokaryotes.
80
What can prokaryotes exchange resulting in faster evolutionary change than in organisms that only use vertical transfer?
Prokaryotes can exchange genetic material horizontally, resulting in faster evolutionary change than in organisms that only use vertical transfer.
81
What is horizontal gene transfer?
Horizontal gene transfer is where genes are transferred between individuals in the same generation.
82
What is vertical gene transfer?
Vertical gene transfer is where genes are transferred from parent to offspring as a result of sexual or asexual reproduction.
83
What is speciation?
Speciation is the generation of new biological species by evolution as a result of isolation, mutation and selection.
84
What is a "species"
A species is a group of organisms capable of interbreeding and producing fertile offspring, and which does not normally breed with other groups.
85
What is the importance of isolation barriers?
The importance of isolation barriers in preventing gene flow between sub-populations during speciation.
86
What do Geographical Barriers lead to and behavioural or ecological barriers?
Geographical barriers lead to allopatric speciation and behavioural or ecological barriers lead to sympatric speciation.
87
What is required to compare sequence data?
To compare sequence data, computer and statistical analyses (bioinformatics) are required.
88
What does comparison of genomes reveal?
Comparison of genomes reveals that many genes are highly conserved across different organisms.
89
What are important models for research?
Many genomes have been sequenced, particularly of disease-causing organisms, pest species and species that are important model organisms for research.
90
How can the sequence of events be determined?
The sequence of events can be determined using sequence data and fossil evidence.
91
Definition of Phylogenetics
Phylogenetics is the study of evolutionary history and relationships.
92
What does comparison of sequences provide?
Comparison of sequences provides evidence of the three domains of life — bacteria, archaea and eukaryotes.
93
What is sequence data used to study?
Use of sequence data to study the evolutionary relatedness among groups of organisms.
94
What is sequence divergence used for?
Sequence divergence is used to estimate time since lineages diverged.
95
Why are sequence data and fossil evidence used?
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
What are molecular clocks use for?
Molecular clocks are used to show when species diverged during evolution.
97
What do molecular clocks assume?
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
What is Pharmacogenetics the use of?
Pharmacogenetics is the use of genome information in the choice of drugs.
99
What can an individuals personal genome sequence be used for?
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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