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A2 Biology > Modern Genetics > Flashcards

Modern Genetics Flashcards

1
Q

What is a genome?

A

Complete set of genes or genetic material present in a cell of an organism

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2
Q

What does the genome include?

A

DNA in the nucleus

DNA in mitochondria and chloroplast

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3
Q

What is needed for the polymerise chain reaction (PCR)?

A

The DNA fragment to be copied

Primers

Nucleotides

DNA polymerase from thermophilic bacteria

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4
Q

What is the machine used for PCR called?

A

Thermocycler

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5
Q

4 stages of PCR:

A

1) heat to 95* o break the hydrogen bonds and separate the 2 stands of DNA
2) cool to 55* so primers will join with the complementary base pairs at the end of each DNA strand. DNA polymerase will attach
3) heat to 72* which is the optimum temp for DNA polymerase which adds complementary nucleotides along each DNA strand
4) As the process is repeated the number of DNA strands increases exponentially

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6
Q

The danger method of DNA sequencing using PCR: what materials are needed in each of the 4 samples?

A

All materials for PCR (including 4 normal nucleotides) and a different dideoxynucleotide

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7
Q

The danger method of DNA sequencing using PCR: what will happen to the primer?

A

It will be marked eg fluorescent

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8
Q

The danger method of DNA sequencing using PCR: what is the effect of the dideoxynucleotide?

A

As each one is put through PCR the addition of a dideoxynucleotide to the sequence means no more nucleotides can bind due to the missing oxygen and added phosphate groups- the sequence will end

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9
Q

The danger method of DNA sequencing using PCR: what do you do after completion of PCR?

A

A sample from each tube is taken to be separated with gel- DNA is neg so moves to pos- shortest will move furthest and a sequence will be read

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10
Q

Uses of DNA sequencing

A
  • predicting the protein in an organism for uses in medicine
  • disease management
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11
Q

What is full genome sequencing?

A

Sequencing mitochondrial or chloroplast DNA as well as nuclear DNA

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12
Q

Uses of full genome sequencing

A

Comparisons that can determine evolutionary relationships and differing responses to medical treatments

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13
Q

Where are minisatelites found and what do they contain?

A

Found within introns and contain core nucleotide sequences

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14
Q

How do minisatelites vary between individuals? What are they used for?

A

Vary in number of repeats used for genetic fingerprinting

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15
Q

How do you avoid getting 2 individuals with the same minisatelites when genetic fingerprinting?

A

Choose minisatelites with the most variation

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16
Q

Stages of genetic fingerprinting: collection

A

Same of tissue containing DNA to be analysed

17
Q

Stages of genetic fingerprinting: extraction

A

Sample mixed with phenol and chloroform then centrifuged so proteins precipitate out. DNA is precipitated out of water later using ethanol

18
Q

Stages of genetic fingerprinting: digestion

A

Restriction enzymes cut DNA close to minisatelites regions so they keep original length

19
Q

Stages of genetic fingerprinting: separation (and process of denaturation and southern blotting)

A

Fragments are separated by size by gel electrophoresis- denaturation= gel soaked in alkaline solution to separate DNA into single strands .
DNA is transferred to a nylon membrane using blotting paper to draw it up out of the gel by capillary action

20
Q

Stages of genetic fingerprinting: hybridisation

A

The membrane is immersed in a solution of labelled DNA probes that hybridise with chosen core sequences the unbound probes are washed off and the membrane is dried

21
Q

Stages of genetic fingerprinting: development

A

X Ray film placed over membrane- membrane is dogged in areas where radiation is present producing an autoradiograph. Bands are the DNA fingerprint to be compared

22
Q

Stages of genetic fingerprinting: order of the stages

A 
Collection 
Extraction 
Digestion 
Separation 
Hybridisation
Development
23
Q

When is a gene expressed?

A

When a gene is switched on it is transcribed into an mRNA strand then translated into a protein- if a gene is present on DNA but not mRNA then the gene is not expressed in that cell

24
Q

How can you determine which genes are expressed

A

A gene probe can be used to determine the presence of a gene in dna and mRNA
If the gene is present on dna but not mRNA then the gene is not expressed in that cell

25
Q

2 ways of locating a specific gene

A

Dna probe- short section of dna that has been labelled
Dna is of a known sequence corresponding to the gene being looked for
An rna probe shows if it is expressed

26
Q

What is gene regulation?

A

Mechanisms that are used by cells to increase or decrease the production of specific gene products

27
Q

Gene regulation: transcriptional control transcription factors

A

Proteins that bind to the dna in the nucleus and affect the process of transcribing the genetic material by preventing or stimulating

28
Q

Gene regulation: transcriptional control relationship between histones and dna

A

Dna coils around histones due to opposite charges to form chromatin

29
Q

Gene regulation: transcriptional control histones modification: acetylation

A

Reduction in histone positive charge- loosely wrapped dna which is available for transcription factors to bind

30
Q

Gene regulation: transcriptional control histone modification: methylation

A

Increase in histone positive change more attraction so tightly coiled and switched off

31
Q

Gene regulation: transcriptional control euchromatin

A

Active dna that is loosely wrapped and available for transcription

32
Q

Gene regulation: transcriptional control heterochromatin

A

Silent dna that is tightly bound and switched off

33
Q

Gene regulation: transcriptional control dna methylation

A

Changes arrangement if dna molecule and prevents transcription

34
Q

Gene regulation: transcriptional control:

Rna editing

A

Splicing using spliceosomes
Non coding RNA can act on histones
Mutations can occur in RNA

35
Q

Gene regulation: translational control of degradation

A

If mRNA lasts longer before degradation more protein can be produced

36
Q

Gene regulation: translational control inhibitory proteins

A

Can bind to mRNA which prevents it binding to a ribosome

37
Q

Gene regulation: translational control activation of initiation factors

A

Aids the binding of mRNA to a ribosome

38
Q

Gene regulation: post translational control

A

Addition of non protein groups eg lipids

Folding and formation of bonds

39
Q

Gene regulation: post transcriptional control RNA splicing

A

Exons joined together by spliceosomes which may join exons in a variety of ways so a single gene may produce serveral versions of functional mRNA transcribed from the same section of dna
Several different phenotypes

A2 Biology (19 decks)

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