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Genetics 1 and 2 Flashcards

1
Q

What was the hershey-chase experiment?

A

labelled protein capsule or DNA of virus with radioactive phosphorus - looked at which one passed on the radioactivity during multiplication = DNA

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2
Q

Describe the work of Mendel

A

worked on pea plants, bred them to be pure with different characteristics, then crossed them,

Discovered dominant and recessive alleles

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3
Q

What are Mendel’s 4 rules

A
  1. There are alternative forms of genes - alleles
  2. For each heritable trait an organism has 2 genes, one from each parent
  3. A sperm or egg only carries one allele for each trait
  4. When the two genes of a pair are different alleles, one is fully expressed whilst the other has no noticeable effect
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4
Q

What is the ratio in a double dom to double rec cross

A

All dom.

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5
Q

What is the ratio in a second gen cross of double dom to double rec?

A

3:1

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6
Q

What is the ratio for crossing heterozygotes with 2 phenotypes?

A

9:3:3:1

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7
Q

What are some examples of mendelian disease?

A 
Phenylketonia 
Huntington's 
Achondroplasia 
Cystic Fibrosis 
Sickle Cell disease
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8
Q

What is the basis that all Mendelian genetics work on?

A

Random assortment of genes into the gametes

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9
Q

What did Thomas Morgan Hunts discover

A

the effect of non-independent assortment of alleles i.e. genes that are linked and so not sorted randomly into alleles
(discovered in flies with red eyes and grey bodies - WT, and mutants with white eyes and black bodies)

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10
Q

What is the distance between genes called

A

recombination frequency

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11
Q

How is linkage analysis done?

A

Lod (logarithm of the odds) score with tests to compare the likelihood that 2 loci are linked vs the likelihoood that they are unlinked

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12
Q

What is incomplete dominance? Give and example.

A

Where the alleles share dominance e.g. blood groups

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13
Q

Describe the molecular makeup of DNA.

A

DNA = base (purine or pyramidine) + sugar + phosphate

purines - adenine and guanine
Pyrimidines - cytosine, uracil and thymine

Sugars - ribose (OH) or deoxyribose (H)

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14
Q

Which base pair is strongest?

A

GC - has 3 H bonds instead of the 2 that AT has

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15
Q

Briefly describe the makeup of chromosomes

A

DNA double helix –> nucleosome, chromatin, looped into heterochromatin which forms the compacted chromosome

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16
Q

What is chromosome aneuploidy

A

having the wrong number of chromosomes

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17
Q

what are the 3 trisomies that are compatible with life?

A

21 (downs), 13 (pataus), 18 (edwards)

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18
Q

What is the most common monosomy?

A

X because one copy of female X chromosome is silenced

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19
Q

What can cause chromosome aneuploidies?

A

non- disjunction of meiosis or mitosis

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20
Q

What is a possible cause of apparent genetic defect that actually isn’t genetic?

A

disfunction of splicing

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21
Q

What are the 5 basic types of mutation?

A

missense (base substitution leading to swapping of amino acid)

silent (base substiution but still get same protien due to triplet code/wobble base pair)

Frameshift insertion (base insertion leads to reading of triplet code one base out of sync)

deletion (base or amino acid deletion)

Chain termination mutation (addition of stop codon)

22
Q

What is the average gene length?

A

3000 bases

23
Q

How long is the dystrophin gene?

A

2.4 mill bases

24
Q

how much of the genome is protein coding?

25
What is a gene?
any interval along the chromosomal DNA that is transcribed into a function RNA molecule or that is then transcribed into a functional protein
26
lnc RNA genes?
transcribed but not translated
27
antisense RNA?
transcribed from the mRNA
28
pseudogenes
RNA gone back into DNA
29
What are examples of autosomal dominant genetic disorders?
Huntingtons, Marfans, achondroplasia
30
What are examples of autosomal recessive disorders?
cycstic fibrosis, sickle cell anaemia, alkaptonuria
31
Why are recessive disorders not wiped out?
Because they tend themselves to advantages in other areas e.g. CF carriers are more cholera tolerant and SC anaemia carriers are resistant to malaria
32
What is cytogenetic analysis?
looking for changes in karyotype to determine what is causing the disease e.g. balanced translocations, duplications, deletions, inversions, non-disjunctions, aneuplodies
33
What is mitochondrial inheritance?
looking into the mitochondrial DNA
34
What does mtDNA tell you?
maternal line - mtDNA degraded in sperm
35
What is the problem with mtDNA
variability within cells | varibility between cells - best obsevered in post-mitotic cells such as muscles and neurons
36
What does methylation if DNA do?
represses transcription
37
What does cytosination of DNA do?
promotes transcription
38
What does acetylation of histones do?
Unravells the chromosome for reading
39
What can adenosine deaminase do?
edit RNA
40
What are restriction endonucleases?
Cut DNA to form palindromic sticky ends
41
What does DNA ligase do?
Stick DNA back together
42
What is reFLP?
Creating libraries of DNA, then southern blot to detect which one is a mutant protein (which one is lost) Northern blot for RNA to supplement Use a probe to find the mutation on the chromosome by putting back in situ
43
What are cDNA libraries
Using reverse transcriptase to create libraries of DNA
44
What are vectors?
things to splice DNA into plasmids, yeast artificial chromosomes
45
Sange sequencing?
DNA polymerase adds tagged terminal nucleotides onto a DNA primer Use capillary sequencing to work out order up to 600bp
46
PCR?
Amplification of DNA using known primers to create complimentary strands
47
Hybridisation microarray assay?
look for hybridisation between different fluorescent probes on microarrays, find which sequences are present
48
Genome wide association studies?
looking at population level to find SNPs and tell if they are disease causing or just natural variance
49
Next gen sequencing
short reads but intensive depth | can read whole genome
50
Which trinucleotide repeat causes huntingtons?
CAG - as numbers increase the classification and disease status alter

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