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Higher Biology > DNA and The Genome > Flashcards

DNA and The Genome Flashcards

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1
Q

Describe a nucleotide and a long chain of nucleotides.

A

Made of a deoxyribose sugar, phosphate and base. Long chain of nucleotides joined together by sugar phosphate backbone and is called polynucleotides.

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2
Q

What is the base pairing rule?

A

Adenine pairs with Thymine

Cytosine pairs with Guanine

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3
Q

What kind of structure does DNA have?

A

Hydrogen bonds. Double stranded anti parallel structure with the deoxyribose sugar at the 3’ end and the phosphate at the 5’ end. Forms a double helix.

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4
Q

What is a prokaryote?

A
  • doesn’t have a nucleus
  • single double stranded circular chromosomes in the cytoplasm
  • plasmid (carries non-essential genes)
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5
Q

What is a eukaryote?

A
  • has a nucleus
  • several linear chromosomes in nucleus
  • mitochondrial and chloroplast DNA (extra DNA out with the nucleus)
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6
Q

Is yeast a eukaryote or a prokaryote?

A

Eukaryote even though it has a circular plasmid.

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7
Q

What is mitochondrial DNA?

A
  • circular double stranded DNA
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8
Q

What is chloroplast DNA?

A
  • circular double stranded DNA
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9
Q

How is DNA organised?

A

DNA in the linear chromosomes of the nucleus of eukaryotes is tightly coiled and packaged with proteins.

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10
Q

What model does DNA replicate by?

A

Semi conservative model

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11
Q

What are the requirements for DNA replication?

A

Original DNA template, supply of DNA nucleotides, primers, enzymes (DNA polymerase, helicase, ligase), supply of ATP

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12
Q

What does DNA helicase do?

A

unzips the double-stranded DNA molecule

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13
Q

What does DNA polymerase do?

A

controls formation of sugar-phosphate bond and attaches free nucleotides to the DNA strand

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14
Q

What does DNA ligase do?

A

seals any gaps between nucleotides

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15
Q

Rule for Replication

A

DNA polymerase can only join nucleotides to the 3’ end of a growing strand

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16
Q

What is the leading and lagging strand?

A

One strand will be replicated continuously (leading) and the other in fragments (lagging) because of replication rule

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17
Q

Replication of Leading Strand

A
  1. Hydrogen bonds break and DNA unzips
  2. DNA primer attaches
  3. DNA polymerase attaches free nucleotides to 3’ end
  4. Continuous process until strand is copied
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18
Q

Replication of Lagging Strand

A
  1. Hydrogen bonds break and DNA unzips
  2. Many DNA primers attach along strand
  3. Discontinuous process so fragments joined by ligase
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19
Q

What does PCR stand for and what is it used for?

A

Polymerase Chain Reaction

amplifies specific sections of DNA

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20
Q

Temperatures and Process of PCR

A

95 degrees- DNA strands separate
50-60- primers bind
72- heat tolerant DNA polymerase replicates
Repeat many times- amplify region of DNA

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21
Q

Nucleotides shapes

A 
Circle= phosphate
Pentagon= deoxyribose sugar 
Rectangle= base
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22
Q

polypeptides=

A

another word for protein

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23
Q

codon=

A

3 bases

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24
Q

genome=

A

all the DNA an organism has

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25
Q

Differences between RNA and DNA

A 
RNA= single-stranded, DNA= double stranded
R= ribose sugar, D= deoxyribose sugar
R= uracil, D= thymine
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26
Q

What is transcription?

A

Synthesis of mRNA from section of DNA (gene), starting from part of DNA called the promoter (start codon). mRNA then carries genetic code from DNA in nucleus to ribosomes (where proteins made).

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27
Q

Process of Transcription

A
  1. DNA untwists + unzips as hydrogen bonds btwn bases break
  2. RNA polymerase add nucleotides onto 3’ end of sense strand following base pairing rules
  3. RNA polymerase join ribose sugars to phosphate group using strong chemical bonds
  4. Formation of molecule stops when stop codon reached. Molecule produced= primary transcript
  5. RNA splicing occurs where sections not needed for final protein removed from primary transcript
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28
Q

What is gene expression controlled by?

A

regulation of transcription and translation

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29
Q

exons=

A

coding regions

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30
Q

introns=

A

non-coding regions

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31
Q

What occurs in RNA splicing? Where does mature transcript go afterwards?

A

Introns are removed and exons are spliced together to form a continuous sequence= mature transcript → leaves nucleus to travel to ribosomes in cytoplasm (translation)

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32
Q

What is translation?

A

mRNA is turned into a polypeptide by tRNA at the ribosome

33
Q

Process of Translation

A
  1. mRNA molecule attaches to a ribosome
  2. tRNA molecules transport specific amino acids to ribosome
  3. each mRNA codon codes for specific amino acid
  4. triplet codon mRNA + anticodons translate gentic code into sequence of amino acids
  5. peptide bonds form btwn adjacent amino acids= polypetide
  6. used tRNA molecules exit ribosome + collect another specific amino acid
  7. start + stop codons signal start + end of translation
34
Q

What can occur in post-translational modification of a protein?

A

cutting and combing polypeptide chains or by adding phosphate or carbohydrate groups to the protein

35
Q

How is a phenotype determined?

A

It is determined by the proteins produced as the result of gene expression, influenced by intra- and extra- cellular environmental factors.

36
Q

What is the benefit of RNA splicing?

A

one gene can produce many different proteins depending on which segments are treated as introns and exons

37
Q

Protein shape

A

3d- peptide bonds, folded polypeptide chains, hydrogen bonds

38
Q

mutations=

A

changes in the genome which are random, spontaneous and very rare

39
Q

mutant=

A

an organism whose phenotype has been altered by a mutation

40
Q

What are the types of mutations?

A

point mutations, chromosome structure mutatuons, polyploidy

41
Q

What are the 3 main types of point mutations?

A
  • deletion- one base pair has been removed
  • insertion- an extra base has been added
  • substitution- one base has been swapped for another
42
Q

What are the types of substitution?

A
  • silent- same amino acid coded for
  • nonsense- stop codon coded for (protein synthesis halted)
  • neutral- similar amino acid coded for (little- no effect on protein)
  • missense- different amino acid coded for ( synthesised protein function altered)
  • splice site mutation
43
Q

What is a point mutation?

A

involves change in order of the base pair of a gene

44
Q

What is a splice site mutation?

A

RNA splicing removes introns + joins exons together, mutations at start/end → one or more introns not being removed from mRNA → translation of protein that does not function properly

45
Q

What are the types of chromosome structural mutations?

A

Deletion- drastic effect as genes are lost
Inversion- reverses normal sequence of genes → formation of nonviable gametes
Translocation- transfer of genes from another chromosome which is not its matching partner → problems during pairing of chromosomes to nonviable gametes

46
Q

What is the importance of gene duplication in evolution?

A

Duplication of genes produces second copy of gene that is free from natural selection, additional gene can be altered (mutation) without affecting OG genes function → confer advantage by increasing fitness + chance of survival

47
Q

What is a polyploidy mutation?

A

the duplication of all the chromosomes → extra sets of chromosomes

48
Q

Importance of polyploidy in food crops=

A

polyploidy crops= larger and increased seed and fruit size (economic importance)

49
Q

Importance of polyploidy in evolution=

A

polyploidy= increase in genetic diversity

50
Q

What is evolution?

A

the gradual change in the characteristics of the population of organisms over successive generations as a result of variation in the population’s genes

51
Q

What are the two types of gene transfer?

A
  1. Vertical transfer of genetic material- from parent to offspring as a result of sexual/asexual reproduction
  2. Horizontal gene transfer- genetic material passed from one cell to another (occurs mostly in prokaryotes and viruses)
52
Q

What is natural selection?

A

the non random increase in frequency of DNA sequences that increase survival

53
Q

genetic drift=

A

the random increase or decrease in frequency of genetic sequences

54
Q

stabilising selection=

A

mean is unchanged but selection favours middle value

55
Q

directional selction=

A

selection favours either low or high value which changes mean value

56
Q

disruptive selection=

A

selection favours both extreme high and low so 2 means arise

57
Q

What is sexual selection?

A

the non-random increase in the frequency of DNA sequences that increase reproduction

58
Q

How does sexual selection operate?

A
  1. male to male competition

2. female choice

59
Q

Why does genetic drift occur?

A
  1. sampling error
  2. neutral mutations
  3. founder effect
60
Q

founder effect=

A

if a population becomes isolated and is not large enough to contain the entire gene pool, gene frequencies will be different in that one

61
Q

What is speciation?

A

the formation of new biological species

62
Q

What are the two types of speciation?

A

allopatric and sympatric

63
Q

allopatric speciation=

A

when gene flow between two or more populations is prevented by a geographical barrier

64
Q

sympatric speciation=

A

when two or more populations live in close proximity in same environment but become genetically isolated because of behavioural or ecological barrier or polyploidy

65
Q

What is a hybrid zone?

A

an environment may contain several subpopulations of a species that can’t all interbreed- only breed with neighbour

66
Q

What does the comparison of genomes show?

A

many genes are highly conserved (similar) across different organisms

67
Q

What is required to compare sequence data?

A

computer and bioinformatics

68
Q

Main events in evolution

A

last universal ancestor, prokaryotes, prokaryotes able to photosynthesise, eukaryotes, multicellular organisms

69
Q

How can the main events in evolution be determined?

A

sequence data and fossil evidence

70
Q

In pharmacogenetics, what can you do after getting your genome?

A

predict which medicines and which dosages will be most effective

71
Q

What is cellular differentiation?

A

the process by which a cell develops more specialised functions by expressing the genes characteristic for that type of cell

72
Q

omnipotent stem cells=

A

adult stem cells

73
Q

pluripotent stem cells=

A

embryonic stem cells

74
Q

Roles of proteins

A
  1. Structural- muscle
  2. Signalling- hormones and recptors
  3. Catalytic- enzymes
  4. Immunological- antibodies
75
Q

Fibrous proteins

A

keratin, silk, collagen

76
Q

Globular proteins

A

structural proteins, enzymes, hormones

77
Q

stem cell research

A

gain information about how cell processes occur (cell growth, gene expression/regulation)

78
Q

Stem cells can be used as _ to study _

A

model cells

how diseases develop and drug testing

Higher Biology (3 decks)

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