fundamentals of genetics, prokaryote genetics

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49 Terms

1
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what are some simple mendelian traits

red hair- fair skin, freckles, higher vitamin absorption capacity, lower melanin conc., higher risk melanoma, cleft chin, dimples, freckles, albinism

2
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what are the 2 types albinism?

oculocutaneous Albinism (7 subtypes), ocular Albinism- autosomal recessive

3
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what enzyme is affected by type 1 OCA?

tyrosinase (stops melanin biosynthesis)

4
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what does an x-linked gene affect more?

if reccessive-men, if dominant-women

5
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XX people can be homozygous or heterozygous for x-linked traits, what are XY people?

hemizygous

6
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what is an example of polygynous traits

colour of bell peppers (chlorophyll & carotenoids)

7
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what is an example of incomplete dominance?

colour of petals in snapdragons (pink, white or red)

8
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what is an example of co-dominance?

blood type (humans)

9
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how do you determine if a trait is mendelian or non?

genotype, not phenotype

10
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what is the dual effect of A^y agouti gene?

dominant effect on coat colour (yellow) & recessive effect on viability (if mouse has 2 A^y copies, will die)

11
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what is the 2 gene trait in Labradors?

coat colour - B & E= black, bb & E=choc, B & ee or bb & ee=yellow (ee is epistatic)

12
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what is pedigree analysis?

analysing inheritance of traits within a family, useful in identifying mutant alleles underlying many human disorders

13
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14
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name a disease that is autosomal dominant (humans)?

huntingtons

15
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name an autosomal recessive disease (humans)

cystic fibrosis

16
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what are some x-linked recessive disorders?

red-green colour blindness, haemophila

17
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what is an example of an x-linked dominant disease?

familial vitamin D-resistant rickets

18
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what are the 3 types single nucleotide change, causing mutations?

silent (no change in protein sequence), missense (change aa sequence), nonsense (creates stop codon)

19
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what 4 ways to further understand a newly discovered gene?

screens, candidate approach-educated guess, biochemical, genetic

20
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what are 2 of many ways epistatic alleles can affect other alleles?

masks the effect of one or more other loci, modifies effect of one or more other loci, epistasis= interaction at phenotypic level of organisation

21
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what does penetrance mean in mutants?

the percentage of individuals with a given allele who exhibit the phenotype associated with that allele

22
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what causes incomplete penetrance?

interacting genes in the rest of the genome- uncharacterised modifiers (e.g. warts on Hippo gene), influence of the environment-epigenetics

23
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what is an example of a more recent endosymbiont?

Wolbachia in 70% arthropod species, oft maternally inherited just like mitochondria

24
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what are the two states of prions?

normal [PRION-], altered [PRION+] -can bite [PRION-] to create 2 [PRION+]→ an aggregate

25
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do prions change shape by altering DNA?

no- through change in folding, prions can transmit between and within cells

26
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in what kingdom did prions evolve?

fungi- to program distinct metabolic states, e.g. under environmental stress→ chaperones convert all [PRION+] to [PRION-]

27
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what is a biofilm?

when prokaryote cells aggregate to cells with different mutually supportive functions (resembles complex tissues)

28
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what is syntrophic consortia?

share metabolites, perform particular biochemical tasks, e.g. in gums & teeth

29
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how big are prokaryotic chromosomes?

between ~2 & 12Mbp, usually only one in the prokaryote cell

30
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how big are prokaryotic plasmids usually?

~2 to 500Kbp

31
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what is pGO1?

a plasmid found in hospital infection (cont. resistance to Quaternary ammonium compounds AKA hospital disinfectant)

32
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what percentage of plasmids are conjunctive? what are transfer genes called?

~25% and they’re called tra or trs

33
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what are recipient & donor plasmids called?

recipient= -, donor= +, at the end the minus cell is converted to a plus cell

34
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what are transposable elements?

genes that can be transposed from 1 location to another

35
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what are 2 ways transposable elements can work?

copy, cut & paste (through transposase enzymes)= an insertion sequence, sometimes 2 pairs of insertion sequences are transferred alongside a gene in-between= a transposon gene (Tn)

36
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how can homologous recombination in prokaryotes work?

if insertion sequences homologous= during crossover- can be inserted or excised (termed an episomal plasmid- if also conjugative, will place an oriT in chromosome)

37
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what are Hfr strain cells?

integrated conjugative plasmids, hfr=high frequency of recombination, has an oriT inserted into its chromosome allowing it to transfer a copy of chromosome

38
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what is transduction?

chromosomal DNA moved via prokaryotic viruses (accidental package of host chromosomal DNA in newly synthesised capsids)

39
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what does a virion consist of?

protein coat (CAPSID) & nucleic acid

40
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what are the 6 stages of bacteriophage life cycles?

  1. virion attaches

  2. injection of viral nucleic acid

  3. nucleic acid replication

  4. viral capsid synthesis

  5. viral assembly/ packaging

  6. cell lysis and virion release

41
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what is transformation?

deliberate uptake of DNA from external environment, only 1-2% can be competent

42
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how can E.coli be turned competent?

treating with metal ions such as Ca2+

43
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what is a mobilome?

mobile DNA sequences in prokaryotes, not the same as genome

44
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how do cells that can become competent use quorum sensing?

detect other cells of the same species→ restricts DNA transfer to just same species (recognise a 11 base signal sequence), some leaking does still occur

45
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what are some examples of prokaryotic immune responses?

restriction endonucleases by cutting at a commonly occurring short sequence (DNA methylase modifies host cell DNA preventing it from being digested)

46
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how would you describe the yeast 2micron plasmid?

entirely sacred, usually just 4 genes, can be used for genetic engineering

47
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what are double minutes?

circular fragments of unstable chromosomal DNA in some human cancer cells, encode oncogenes

48
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what are some natural examples of conjugation into eukaryotes?

A. tumefactions have a conjugative plasmids (Ti) into plants→ causes proliferation

49
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what are some ways of conjugation artificially?

transfection (uses modified adenovirus & retrovirus genomes), lipid mediated, electroporation, microinjection