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269 > Genetics 1 and 2 > Flashcards

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?

A

1.5 %

25
Q

What is a gene?

A

any interval along the chromosomal DNA that is transcribed into a function RNA molecule or that is then transcribed into a functional protein

26
Q

lnc RNA genes?

A

transcribed but not translated

27
Q

antisense RNA?

A

transcribed from the mRNA

28
Q

pseudogenes

A

RNA gone back into DNA

29
Q

What are examples of autosomal dominant genetic disorders?

A

Huntingtons, Marfans, achondroplasia

30
Q

What are examples of autosomal recessive disorders?

A

cycstic fibrosis, sickle cell anaemia, alkaptonuria

31
Q

Why are recessive disorders not wiped out?

A

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
Q

What is cytogenetic analysis?

A

looking for changes in karyotype to determine what is causing the disease e.g. balanced translocations, duplications, deletions, inversions, non-disjunctions, aneuplodies

33
Q

What is mitochondrial inheritance?

A

looking into the mitochondrial DNA

34
Q

What does mtDNA tell you?

A

maternal line - mtDNA degraded in sperm

35
Q

What is the problem with mtDNA

A

variability within cells

varibility between cells - best obsevered in post-mitotic cells such as muscles and neurons

36
Q

What does methylation if DNA do?

A

represses transcription

37
Q

What does cytosination of DNA do?

A

promotes transcription

38
Q

What does acetylation of histones do?

A

Unravells the chromosome for reading

39
Q

What can adenosine deaminase do?

A

edit RNA

40
Q

What are restriction endonucleases?

A

Cut DNA to form palindromic sticky ends

41
Q

What does DNA ligase do?

A

Stick DNA back together

42
Q

What is reFLP?

A

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
Q

What are cDNA libraries

A

Using reverse transcriptase to create libraries of DNA

44
Q

What are vectors?

A

things to splice DNA into

plasmids, yeast artificial chromosomes

45
Q

Sange sequencing?

A

DNA polymerase adds tagged terminal nucleotides onto a DNA primer
Use capillary sequencing to work out order up to 600bp

46
Q

PCR?

A

Amplification of DNA using known primers to create complimentary strands

47
Q

Hybridisation microarray assay?

A

look for hybridisation between different fluorescent probes on microarrays, find which sequences are present

48
Q

Genome wide association studies?

A

looking at population level to find SNPs and tell if they are disease causing or just natural variance

49
Q

Next gen sequencing

A

short reads but intensive depth

can read whole genome

50
Q

Which trinucleotide repeat causes huntingtons?

A

CAG - as numbers increase the classification and disease status alter

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