Genetics

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  • Created by: ShanayHS
  • Created on: 07-05-18 21:39
What is a solenoid
A secondary form of chromatin, formed of cylindrical coiled dna.
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Describe the physiological structure of haemoglobin
It is comprised of four subunits - a2b2. The alpha subunits are made from 141 aa, compared to the beta which is made of 146 aa. The genes responsible are HBA1 and HBB.
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What is the cause of sickle cell anaemia
Codon for glutamate mutated to valine, to produce HBS instead of HBB.
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List the type of chromosomal mutations
Deletion, Insertion, Translocation, Inversion
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Name two ways of acquiring mutations
Inheritance through germ line cells, acquisition through mutations in somatic cells
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Name five types of DNA damage
Abasic site, cross link formation, modified base,ssb, dsb
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How can ionisation cause dsb
Ionisation of a water molecule results in the production of a hydroxyl free radical. This free radical proceeds to attack the phosphate sugar backbone of a dna strand, leading to the formation of ssb.
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How do DSBs arise
When two ssb are within close approximations of each other.
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Name the effect of DSBs
Repairing DSBs leads to further mutations, which can be toxic to the cell ( cytotoxic).
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Name two dominant diseases associated with mutations
Achondroplasia ( Problem with cartilage/ muscle formation ) and Huntingtons disease ( Nerve problem )
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What gene is responsible for Achondroplasia
FGFR3
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What is the cause of Huntingtons disease
Repeated expansion of glutamate on dna strand.
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What are the molecular steps to developing cancer.
Normal cell -- > Hyperproliferation -- > Adenoma --> Carcinoma
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What is the Ames test
The Ames test is a test used to identify the presence of mutations. An enzyme is mutated in salmonella, that prevents it from producing histidine, making it his-. If this enzyme is reverse mutated on the agar jelly it will become his+ .
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What is the colour change experienced in the Ames test
Green to yellow
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What is the reversion mutation frequency equation.
reverted colonies/ total amount of cells plated
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Name two methods of new generation sequencing
Illumina and Ion torrent
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What is an ortholog
shared characteristics from a common ancester
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What is an paralog
A gene that is related to another gene in the same organism by descent from a single ancestral gene that was duplicated
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What is the structural unit of a nucleosome
octamer ( H2A, H2B, H3,H4 x2) attached to the H1 histone
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What is the frequency of cutting equation
unique number/ total number of combinations
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What is the equation for recombinaton frequency
number of recombinants / total progeny ( n ) * 100
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What are the consequences of meiosis
> Constant number of chromosomes > Genetic diversity
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Name an example of a disease sex typed on the x chromosome.
Haemohilia
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Define the term '' hemizygous ''
The allele of a disease is found only on one chromosome, only present in males.
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Name the type of numerical abnormalities which can occur with chromosomes
Polyploid ( 3n e.g trisomy ) and Aneuploidy ( 3n-1 )
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What is karyotyping
The act of organising chromosomes
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Name one cause of polyploid chromosomes.
Anaphase lag
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Name one cause of aneuploid chromosomes.
non-disjunction during anaphase
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Name the structural abnormalities undergone by chromosomes
Balance, Inversion, Insertion, Deletion and Isochromosomes
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How is the prokaryote chromosome organised
Into loop domains
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Name some roles of bacterial plasmids
Bacterial resistance, symbiosis and virulence
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Name the stages in genetic exchange
Conjugation, Transduction and Transformation
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Describe the action of type 2 nucleases
Acts in a two fold rotational symmetrical manner ( recognize palindrome sites ), cuts at 4 to 8 base pair and leaves complimentary sticky ends.
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How do you know that your cells have successfully transformed
Check for antibiotic resistance
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Why are genome libraries important
Check genes of interest and accurate clones
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Describe the blue white screening process.
Lac z codes for b-galactosidase. B- galactosidase converts x-gal, which shows as a colour change from colourless to blue. Dna inserted in lac Z inactivates it, so no x-gal is produced.
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Name three useful cloning vectors
Plasmid, Lambda phage and cosmid
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How many clones of a genetic library should be sequenced
genome size / dna insert size
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How do you screen a genomic library.
Attach the desired dna to a membrane. You then attach dna labelled with a radioactive marker to the membrane so it can hybridise. You then wash the membrane and should see positive results.
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Compare complete and enriched libraries
complete = all dna, genomic library representative of entire genome, enriched - mrna information, abundance of mrna represented by abundance of genome
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How do you make a cDNA library
Isolate RNA, then isolate mRNA from RNA, add reverse transcriptase, ligate into cloning vector
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What is the sanger sequencing method
attain purified dna, add dna primers, dntps etc, add to pcr, place for capillary gas electrophoresis and analyze.
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What are the limits of the sanger sequencing method
It is expensive, time consuming and ineffective
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Name the three stages of illumina sequencing
Tagmentation, amplification and analysis
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What are the specifics of MiSEC
25 million reads per flow cell , takes 2 days
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What are the specifics of HiSEC
3 billion reads per flow cell, takes 3 days
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List types of next generation sequencing
Fast, Highly parallel, Low cost and micro scale
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What stages does gene expression occur in
transcriptional, post-transcriptional and post-translational
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What do regulatory genes do
control gene expression and produce regulatory proteins
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Where do transcription facts at
Activation : upstream of promoter, Repression : on promoter
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Name the parts of the lac operon in order
Regulatory gene, promoter, lac 0, structural genes ( lac z, lac y and lac a )
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Name the key players in the positive control of lac operon.
Adenylyl cyclase, cAMP, CAP-cAMP complex
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What is the two component signal transduction
histidine protein kinase autophosphorylates at the site of a histidine residue. This creates a high energy phosphoryl group that is transferred to aspartate residue. this leads to a conformational change which activates gene expression.
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Explain how translocation, inversion and Duplication mutations occur.
Translocation; segment moves to another chromosome. Inversion: section of genes is inverse within the chromosome. Duplicate : A section of DNA to its homologous chromosome so that it has a repeated section of DNA.
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What three states can a cell with damaged dna enter
Senescence, Apoptosis and Uncontrolled tumour development.
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Name two repair pathways for damaged DNA
Nucleotide excision repair and base excision repair.
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Outline the base excision repair pathway
The wrong base is identified by DNA glycosylase and then removed leaving an abasic site. The abasic site is then repaired via a long or short path consisting of many proteins such as AP polymerase.
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What is cancer driven by ?
Mutation accumulation
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What gene is associated with being more predisposed to develop cancer.
APC gene
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Name one disadvantage of using the Ames test
It cannot account for identifying all mutagens
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What are bacteriophages
Bacterial viruses
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What is the molecular composition of bacteriophages
Protein membrane coat with ''head'' like structure containing nucleic acids
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How can you identify bacteriophages
They can be seen as ''holes'' in the spreaded bacterial lawn as the effects of their lysis can be seen.
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How do lytic bacteriophages work
1.They adsorb to the bacterium 2. they insert their nucleic acid 3.Dna replicates and expresses genes 4. phages are produced and lyse the bacterial cell.
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Name the types of bacteriophages
Lytic and temperate
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How do temperate phages work
1.2.3. nucleic acid has cos ends which ligate to form circular dna 4. site specific recombination occurs at attA and attB mixing both genomes and forming a prophage 5. prophage genes are switched off.
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Name an advantage of each cloning vector
Plasmid - circular, phage lambda - efficient at cloning, cosmid - efficient at cloning
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What is a transposon element.
A section of DNA which can jump from different sections of the genome.
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How do transposons work
The transposon element is removed using transposase and transferred to another section of DNA, in a cut or paste mechanism; This can disrupt gene expression.
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Other cards in this set

Card 2

Front

Describe the physiological structure of haemoglobin

Back

It is comprised of four subunits - a2b2. The alpha subunits are made from 141 aa, compared to the beta which is made of 146 aa. The genes responsible are HBA1 and HBB.

Card 3

Front

What is the cause of sickle cell anaemia

Back

Preview of the front of card 3

Card 4

Front

List the type of chromosomal mutations

Back

Preview of the front of card 4

Card 5

Front

Name two ways of acquiring mutations

Back

Preview of the front of card 5
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