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Origin and Diversity of Life > Microorganisms > Flashcards

Microorganisms Flashcards

1
Q

Essential features of virus

A
  • outer protein coat
  • inner coiled genome
  • genome is either DNA or RNA
  • lack ribosomes so cannot reproduce themselves
  • proteins are synthesised of host ribosomes
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2
Q

Capsid

A
  • made from repeated subunits called capsomeres
  • capsomeres self assemble in geometrical way
  • coding for single unit minimises genome size
  • simplest structures are icosahedral and helical
  • must contain surface exposed viral proteins on surface to recognise host receptor
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3
Q

Enveloped virus

A
  • viruses released from the cell by budding are usually surrounded by membrane derived from the host membrane
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4
Q

Non-enveloped virus

A
  • viruses released by lysis are usually naked protein capsids
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5
Q

Viral life cycle

A
  • virus binds to host cell via receptor
  • virus is taken up by cell and capsid disassembles
  • replication proteins produced in host ribosomes
  • viral genome is replicated, capsid reassembles, new virus produced
  • virus released through cell membrane or lysis
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6
Q

Bacteriophage

A
  • virus that infect bacteria

- have syringe like tail to inject genomes into host cell

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7
Q

Lysis

A
  • phage DNA is replicated
  • phage proteins synthesised
  • progeny phage are assembled
  • cell breaks open
  • mature phage released
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8
Q

Lysogeny

A
  • recombination takes place between phage DNA and bacterial DNA
  • phsge DNA is replicated with bacterial DNA and transmitted to bacterial progeny
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9
Q

+ sense RNA

A

every viral genome must be transcribed into mRNA+ for virus proteins to be made by the host cell

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10
Q

Stromatolites

A
  • layered microbial communities

- found in shallow warm water

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11
Q

Prokaryote shape

A
  • coccodial eg. Streptococcus
  • bacterial rods eg. E.coli
  • helical bacteria that produces anibiotics eg. Streptomycetes
  • small square archaon eg. Haloquadratum walsbyi
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12
Q

Bacterial cell

A
  • DNA is contained in circular chromosome
  • often have small circles of additional DNA called plasmids
  • have cell wall and plasma membrane made of peptidoglycan
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13
Q

Gram staining

A
  • used in bacterial ID
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14
Q

Gram positive

A
  • purple
  • thick layer of peptidoglycan
  • can form endospores, which are specialised for survival and dispersal
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15
Q

Gram negative

A
  • pink
  • thin layer of peptidoglycan
  • has outer membrane with polysaccharide chains
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16
Q

Growth of bacterial cells

A
  • swimming cells attracted to food bearing surfaces
  • cells settle on surface and move in large groups until suitable location is found
  • cells attach firmly to surface and form microcolony
    colonies form biofilm
    cells on top of biofilm are released, grow flagella, and find new location
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17
Q

DNA transfer by conjugation

A
  • DNA from donor cell transferred to adjacent recipient cell
  • pilus tethers donor to recipient and brings cells together
  • DNA passes through small opening when cells are alligned
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18
Q

DNA transfer through transformation

A
  • DNA released into environment by dead cells

- DNA taken up by recipient cell

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19
Q

DNA transfer though transduction

A
  • DNA is transferred from donor cell to recipient by a virus
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20
Q

DNA transfer of bacteria to plants

A
  • bacteria enter plant through wound
  • section of Ti plasmid is inserted to plant genome
  • Ti genes cause host cell to divide and form tumour
  • compounds that bacteria can metabolise are produced
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21
Q

Isolates

A
  • what bacteria are initially named as

- group of similar isolates forms a species

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22
Q

Archaea

A
  • known as Archaeabacteria
  • organisation is similar to bacteria
  • cell wall is never made from peptidoglycan
    ribosomes and polymerases are simpler versions of eukaryotes
  • unique cell membranes and metabolic pathways
23
Q

Extreme helophiles

A
  • aerobic

- grows in saturated salt solution

24
Q

Methanogens

A
  • anaerobic
  • produce methane
  • distributed in oxygen free environments
25
Q

Thermoacidophiles

A
  • grow at temperatures above 80
  • usually found in high acidic conditions
  • sulfur based metabolism
26
Q

Microbiome

A
  • microbial community found in a particular environment

- can be characterised through sequencing bulk samples (metagenomics)

27
Q

Contents of Eukaryotic cell

A
  • cytoskeleton
  • nuclear membrane
  • nucleus
  • endoplasmic reticulum
  • golgi apparatus
  • mitochondrion
  • plasma membrane
28
Q

Cytoskeleton

A
  • enables cells to change shape and remodel quickly
29
Q

Nuclear membrane

A
  • separates transcription and translation
  • vesicles budding off from membranes transport materials into the cell (endocytosis) and release materials out of the cell (exocytosis)
30
Q

Mitochondria

A
  • surrounded by double membrane
  • inner membrane folded into cristae to increase surface area
  • small molecules transported from cytoplasm to matrix and oxidised to CO2
  • ADP transferred from cytoplasm to matrix, phosphorylated, and released back to cytoplasm
31
Q

Origin of mitochondria

A
  • mitochondria are said to be derived from Rickettsia-like parasites
  • are bacterial in origin
  • have own small chromosome
  • ribosome sequence resembles those in Rickettsia
  • Rickettsia take up ATP, use energy, export ADP (opposite from mitochondria)
32
Q

Origin of Eukaryotes from Prokaryotes

A
  • eukaryotic cells evolved from ancestral archaeon and later incorporated proteobacterial cell which became the mitochondria
  • supported by discovery of Lokiarchaeota, which resembles eukaryotic cell without mitochondria
33
Q

Excavates

A
  • contains many parasites of human pathogens

- eg. trypanosomes and euglena

34
Q

Stramenopiles, Alveolates, Rhizarians

A
  • stamenopiles include diatoms

- have silica shell call frostrule

35
Q

Ciliates

A
  • alveolate
  • large complex cells
  • often have mouth and gullet
  • surface covered in short flagella which beat in unison (cilia)
  • two nuclei per cell; macronucleus for transcription; micronucleus for reproduction
  • includes paramecium
36
Q

Apicomplexans

A
  • alveolate
  • parasitic
  • complex multi host lifecycle
  • eg. plasmodium
37
Q

Archaeplastids

A
  • are plants
38
Q

Amoebozoans

A
  • cytoskeleton allows eukaryotic cell to engulf another

- include Myxomycetes, radiolarians, foraminiferns, dicteyostelids

39
Q

Myxomycetes

A
  • haploid amoebas engulf smaller prey
  • fuse to form diploid structure, grows into giant plasmodium and forms many nuclei
  • conditions deteriorate, fruiting bodies form to create haploid spores for dispersal
40
Q

Radiolarians

A
  • large aquatic silica skeleton

- long slender pseudopodia supported by microtubules

41
Q

Foraminiferans

A
  • calcium carbonate shell

- long slender pseudopodia which form mesh like network

42
Q

Dicteyostelids

A
  • haploid amoebas grow and reproduce as solitary organisms
  • can mate to form diploid macrocyst, undergoes meiosis to produce haploid amoebas
  • conditions deteriorate, pheromones released, amoebas join to form multicellular slug
  • slug locates suitable location to produce fruiting bodies to make and disperse haploid spores
43
Q

Steps of complex multicellularity evolution

A
  • cells stick together by signalling to eachother
  • gap junctions allow materials to be exchanged
  • bulk flow, where vascular organs carry nutrients, water, blood etc.
44
Q

Opisthokonts

A
  • complex multicellularity evolved multiple times

- choanoflagellates, red algae, green algae, brown algae, fungal fruiting bodies, slime mould fruiting bodies

45
Q

Fungi

A
  • belong to opisthokonts, are heterotrophs
46
Q

Hyphae

A

threads that form underground network called mycelium, which have many nuclei per cell

47
Q

Chitrids

A

flagellated spores, cell wall made of chitin, some form mycelium, decomposers or parasites

48
Q

Zygomycetes

A

simple moulds, haploid hyphae reproduce through haploid spores produced in sporangium, parasites of insects
- diploid cells undergo meiosis to form ascus with four ascospores

49
Q

Basidiomycetes

A

largest most complex fungi, short lived haploid hyphae fuse to form dikaryotic hyphae called secondary mycelium
- reproduce by production of basidiocarps where nuclear fission and meiosis occur

50
Q

Lichens

A

symbiosis between fungi and algae

51
Q

Fungus like microbes

A
  • have cell walls
  • cylindrical hyphae forming branched mycelium
  • reproduces by spores
  • spores often swim
  • cell walls not made from chitin
52
Q

Fungus like organism examples

A
  • opisthokonts - true fungi
    Amoebozoans - myxomycetes and dictostelids
    stramenopiles
53
Q

Oomycetes

A
  • spores are diploid
  • zoospores germinate and form diploid mycelium
  • sexual reproduction through gametes
54
Q

Myxobacteria

A
  • gram negative bacteria
  • glide over surfaces in packs
  • food is scarce, releases signals, aggregate and form fruiting body

Origin and Diversity of Life (3 decks)

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