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300802 Biodiversity > Chapter 28: Prokaryotes > Flashcards

Chapter 28: Prokaryotes Flashcards

0
Q

Microfossils

A

Fossilised forms of microscopic life

Oldest are 3.5 billion years

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1
Q

First cells:

A

Oldest: 3.5 billion years old

Microfossils - indicate prokaryotes were first cells

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2
Q

Stromatolites

A

Combination of sedimentary deposits and precipitated material held in place by cyanobacteria.

2.7 billion years old.

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3
Q

Do domains of prokaryotes include:

A

Bacteria + Archaea

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4
Q

Bacteria & Archaea (what are the differences?)

A

Plasma membrane
Cell Wall
DNA replication
Gene Expression

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5
Q

Archaea (habitat)

A

Extremophiles

Live in hot springs (extreme env.)

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6
Q

Prokaryotes (habitat)

A

Live everywhere eukaryotes do

Also able to thrive in places no eukaryote could live

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7
Q

Prokaryotes (differ from eukaryotes)

A

They are:
Unicellular
Cell size vary
Chromosomes - no membrane bounded nuclei. Single circular chromosome made of DNA
Cell division & genetic recombination - binary fission
Internal compartmentalisation (none)
Flagella - simple; single fibre of protein flagellin
Metabolic diversity

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8
Q

Prokaryotic Taxonomy (characteristics once used to classify prokaryotes)

A
  1. Photosynthetic or non
  2. Motile/nonmotile
  3. Unicellular, colony forming or filamentous
  4. Formation of spores or division by transverse binary fission
  5. Importance as human pathogens or not
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9
Q

Prokaryotic cell wall:

A

Complex

Many layers

Peptidoglycan (polymer unique to bacteria)

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10
Q

Two types of bacteria:

A

Can be identified using staining process:

Gram stain

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11
Q

Gram Stain

A

Gram-positive

Gram-negative

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12
Q

Gram-positive bacteria

A

Have thicker peptidoglycan wall

Stain purple colour

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13
Q

Gram-negative bacteria

A

More common

Contain less peptidoglycan

Do not retain purple coloured dye

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14
Q

Prokaryotic cell structure (3 basic shapes):

A

Bacillus - rod
Coccus - spherical
Spirillum - helical

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15
Q

Cell Surface Structures

A

Bacterial cell walls: peptidoglycan

Archaea cell walls: pseudomurein

16
Q

Capsule

A

Present in some bacteria - additional gelatinous layer
Allow bacteria adhere to smooth surfaces & develop into structures: ‘biofilm’

Capsule inhibits human protective response and antimicrobial agents

17
Q

S-layer

A

Present in some bacteria + archaea

An additional protein or glycoprotein layer forming rigid paracrystalline surface - ‘S-layer’

18
Q

Endospores

A

Some prokaryotes able to form endospores
Develop a thick wall around genome and a small portion of cytoplasm

Resistant to environmental stress, esp. heat

19
Q

Prokaryotes (internal)

A

Internal membranes: complex

Nucleoid region: lack nuclei, only containing single circular chromosome. DNA located in nucleoid

Ribosomes: smaller than eukaryotes, differ in protein & RNA content

20
Q

Prokaryotic Metabolism

A

Acquire carbon & energy in four different ways:

Autotrophs (photo/chemolitho - autotrophs) and Heterotrophs (photo/chemo - heterotrophs)

21
Q

Autotrophs - obtain carbon from inorganic CO2

A

Photoautotrophs - energy from the Sun

Chemolithoautotrophs - obtain energy from oxidizing inorganic substances
e.g. nitrifiers

22
Q

Nitrifiers

A

Chemolithoautotrophs

Oxidize ammonia or nitrate to obtain energy, producing nitrate
Nitrate taken up by plants

Process called nitrification

23
Q

Heterotrophs - from organic molecules

A

Photoheterotrophs: light is used as energy source but obtain organic carbon made from other organisms

Chemoheterotrophs: obtain both carbon and energy from organic molecules
e.g. human beings

24
Q

Symbiosis

A

Ecological relationship between different species living in direct contact with each other

25
Q

Mutualism

A

Both parties benefit

e.g. nitrogen fixing bacteria on plant roots

26
Q

Commensalism

A

One organism benefits and the other is unharmed/unaffected

27
Q

Parasitism

A

One organism benefits and the other is harmed

28
Q

Sexually transmitted diseases

A 
Mostly are bacterial:
STDs
Gonorrhea 
Syphilis 
Chlamydia("silent STD" - no symptoms until infection established)
29
Q

Beneficial prokaryotes

A

Decomposers (carried out by prokaryotes and fungi) - release a dead organism’s chemicals to the environment

Fixation

30
Q

Nitrogen fixer reduce N2 to NH3

three associations

A

Anabaena - in aquatic environments, nitrogen carried out by these cyanobacteria

Rhizobium - in plant roots in soils

Frankia - in plant roots in soil

31
Q

Bioremediation

A

Bacteria used for this process:

removal of pollutants from water, air and soil

32
Q

Current classification of prokaryotes is based on:

A

sequencing of proteins, DNA and RNA

33
Q

Prokaryotic DNA is located:

A

nucleoid region

34
Q

Not a characteristic of ALL prokaryotes:

A

cell walls constructed of peptidoglycan.

300802 Biodiversity (8 decks)

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