CBG Lecture 1: Prokaryotes and Eukaryotes Flashcards

1
Q

what is an UTR

A

untranslated region, found at 3’ and 5’ mRNA

targeting sequences that are temporal and spatial: how long and where mRNA should stay/go

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2
Q

how to change DNA code from plus sense to - sense

A

leave labels but reverse the letters, the complementary base pair

eg. 5’ CGT 3’ DNA (+) as written
1. swap labels and reverse: 5’ TGC 3’
2. complementary base pair 5’ ACG 3’

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3
Q

how many possible codons are there

A

64 - 3 stop, 61 aa coding, start codings

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4
Q

what is the central dogma of biology

A

sequential info in protein cant flow back to nucleic acid
TRANSLATION IS IRREVERSIBLE
phenotype back to protein is irreversible
no such thing as an anti ribosome

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5
Q

what is a prion

A

an infectious agent composed of protein in a misfolded form. there is no nucleic acid element to their structure
prions disease
(protein and infection)

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6
Q

what are planctomycetes

A

a phylum of aquatic bacteria that tend to enclose tehir nuclear material within a double membrane

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7
Q

what is reverse transcription

A

RNA back to DNA

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8
Q

what are planctomycetes

A

a phylum of aquatic bacteria that tend to enclose their nuclear material within a double membrane

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9
Q

compare nucleus and time of arising in proks and eukaryotes

A

o PROK: no nucleus, arose 3000MYA

EUKS: nucleus, arose 1500MYA

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10
Q

outline prokaryotic cell structure

A

simple cell structure, naked DNA with a simple path from DNA to proteins
circular chromosome in nucleoid (area within the cytoplasm holding the DNA)
only essential organelles: ribosome, mitochondria
rotating flagellum
binary fission
small and diffusion limited:1micrometre
have plasmalemma
have pilli
have capsule

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11
Q

what is a nucleoid

where found

A

area within the cytoplasm holding the DNA

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12
Q

what can prokaryotes be divided into

A

bacteria and archaea

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13
Q

what subdivision of prok’s is related closer to eukaryotes

A

archaea

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14
Q

outline PROK’s molecular biology

A
'junk' free genome (most is transcribed and translated)
nacked DNA lacking histones
one RNAP using sigma factor
tRNAi formylmethionine start codon
small 70s ribosomes
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15
Q

what is S (wrt. ribosome size)

A

sedimentation coefficient in Svedbergs

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16
Q

outline EUKARY’s cell structure

A

linear chromosomes in nucleus - with ssSNA ends (telomeres)
complex endomembranes and endosymbionts
prominent cytoskeleton and up-down flagellum (9+2 tubulin rubbing)
complex mitotic division (using microtubule tracks)
large cytplasmic screening 100micrometre

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17
Q

outline eukaryotic molecular biology

A
junk in genome
dna bound by histones into nucleosomes
3 RNAPs using TBP (TATA binding protein)
tRNAiMETHIONINE start codon
large 80s ribosomes
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18
Q

what size ribosomes present in EUKS

A

80s

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19
Q

how does DNA packaging in EUKS compare to PROKS

A

no DNA packaging in PROKS, but DNA bound by histones into nucleosomes in EUKS

20
Q

what tRNAi start codon do EUKS use

A

methionine

21
Q

what tRNAi start codon do PROKS use

A

formylmethionine

22
Q

what RNAPs do EUKS use? and use what initiate transcription

A

3 type RNAPS and TBP (TATA binding protein)

23
Q

what RNAPs do PROKS use? and use what initiate transcription

A

one type RNAP use sigma factor

24
Q

what did Woese propose

A

3 domains of life based on rDNA sequences - bacteria, archaea, eukarya
the prokaryotes are not a monophyletic group and are sometimes split into archaeabacteria and eubacteria
archaea are a polyphyletic group

25
Q

what is rDNA

A

the DNA that encodes rRNA - these genes tend to be highly conserved and mutate rather slowly becaUSE theyre so essential to the cell

26
Q

why did Woese base domain theory on rDNA

A

because the genes encoded tend to be highly conserved and mutate rather slowly, as they are essential to the cell

27
Q

what grp (phylogenetically) are archaea

A

polyphyletic group

28
Q

what relation exists between archaea and eukaryotes

A

archaea are eukaryotes in a bacterium’s clothing

29
Q

why are archaea said to be eukaryotes in a bacterium’s clothing

A

they have a prokaryotic cell structure (no nucleus/no endosymbionts/no skeleton) but they have eukaryotic molecular biology (histone bound DNA, tRNAmet start codon, RNAP using TBP)

30
Q

give example of an archaea

A

halobacterium

31
Q

what did Margulis propose

A

that eukaryotes contain endosymbionts of bacterial origin

  • -> Mitochondria (proteobacteria : Rickettsia)
  • -> Plastids (cyanobacteria)

the mitochondria merged from the bacteria line into the eukaryotic line, hence the commonalities between them

32
Q

why is it not sensible to say that archaea are more closely related to eukaryotes than bacreria

A

due to gene transfer from the endosymbiont to the host nucleus. if you look at individual genes, some of the eukaryotic genes are of clearly (proteo/cyano-)bacteria origin: the eukaryotic genome is loads of genes from different sourcesa

33
Q

what is the following archaea feature more similar to BACTERIA or EUK??
aa attached to initiator tRNA

A

eukaryote

34
Q

what is the following archaea feature more similar to BACTERIA or EUK??
start codon identification by ribosome

A

bacteria

35
Q

what is the following archaea feature more similar to BACTERIA or EUK??
binding of RNAP to promoter

A

euk

36
Q

what is the following archaea feature more similar to BACTERIA or EUK??
number of different RNAPs

A

bacteria

37
Q

what is the following archaea feature more similar to BACTERIA or EUK??
cytoskeletal architecture and composition

A

bacteria

38
Q

what is the following archaea feature more similar to BACTERIA or EUK??
dna packaging

A

eukaryotes

39
Q

what is the following archaea feature more similar to BACTERIA or EUK??presence/absence of introns

A

absence of introns - bac

40
Q

what is the following archaea feature more similar to BACTERIA or EUK??
no. rRNAs in large subunit

A

bacteria

41
Q

how does flagellum of bacteria move?

give an exception

A

movement by PMF

Oscillatoria: use gliding for movement, lack flagellum

42
Q

how does flagellum of EUKS move?

A

rotating flagellum-structurally similar to bacterium but analogous

43
Q

what is max size bacteria can grow? why not bigger?

A

1 micrometre

size is limited by the fact they rely on diffusion for nutrients and survival so cant grow bigger

44
Q

why can eukaryotic cells be bigger than archaea/bac

A

the cytoskeleton allows mixing up of the cytosol which means substances can be transported intracellularly easily
therefore can grow bigger
also, cytoskeleton forms a framework for movement of organelles

45
Q

what is ENCODE

A

Encyclopedia of DNA Elements
30 research papers, decade long project
hypothesized that around 80% of genome serves a biochemical purpose

46
Q

what were the main outcomes of the ENCODE project

A

showed DNA bases not only define proteins but

  1. specify landing spots for proteins that influence gene activity
  2. strands of RNA have many roles
  3. places where chemicals