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Building a phenotype - lectures > Small Is Beautiful - Lecture > Flashcards

Small Is Beautiful - Lecture Flashcards

1
Q

Smallest bacterium identified to date

A

Candidatus action Marina minuta

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2
Q

Mycoplasma

A

X

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3
Q

Average size of a spherical bacterium

A

0.5-2 micrometres

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4
Q

Why cant bacteria get any smaller?

A

Need enough volume to accommodate genetic resources

Machinery needed to express genes and housekeep proteins/biochemicals

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5
Q

Smaller cell means (SA:V)

A

Higher SA:V ratio

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6
Q

As cell size increases the SA:V …

A

Decreases

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7
Q

What happens if a cell gets too big?

A

Not enough material can cross the membrane fast enough to suffice what’s needed now the volume has increased.

Then the cell must divide into smaller cells with more favourable SA:V

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8
Q

What is the importance of SA:V?

A

How fast a cell can grow depends on the rate at which it can exchange waste products and nutrients with the environment. If it has a higher SA:V it can do this quicker.

A large population of small cells can be better supported than a population of large cells.

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9
Q

Example of giant bacteria (big but with huge energetic cost)

A

E. Fishelsoni (found in the guts of surgeon fish)

  • extreme polyploidy (possessing more than two complete sets of chromosomes)
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10
Q

Advantage of being an extremely small bacteria

A

Enormous SA:V which may be advantageous to obtain nutrients in resource deficient habitats

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11
Q

Disadvantages of being an extremely small bacteria

A

Genome very small - genes encoding enzymes for core metabolic pathways are not present - metabolically limited lifestyle (evolutionarily limited)

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12
Q

What are the three major functions of the cytoplasmic membrane?

A
  1. Permeability barrier - highly impermeable and most subastances carried in or out are carried by transport proteins
  2. Protein anchor
  3. Energy conservation and consumption - membrane involved in creating proton motive force and electrochemical gradients
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13
Q

Three ways a substance can be transported through a cell membrane

A
  1. Simple diffusion
  2. Facilitated diffusion
  3. Active transport
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14
Q

Simple diffusion example

A

Small non-polar molecules such as oxygen or carbon dioxide

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15
Q

Facilitated diffusion example

A

Larger charged molecules such as chloride or sodium ions

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16
Q

Binary fission definition

A

Asexual reproduction in unicellular prokaryotic organisms by separation of the body into two new bodies

17
Q

6 steps of binary fission

A
  1. Cell elongates
  2. Bacterial genome replicates + any plasmids also replicate
  3. Duplicated DNA separates and moves towards poles as the cell elongates
  4. Cleavage furrow forms
  5. Cell wall forms in cleavage furrow
  6. Two identical daughter cells are formed
18
Q

4 main differences between mitosis and binary fission

MMPD

A

Mitosis in multicellular organisms, BF in unicellular organisms

Mitosis has mitotic spindles, BF does not

Mitosis has subphases (prophase, metaphase, telophase, anaphase), BF does not

DNA replication occurs in S phase in mitosis, in BF it occurs at the same time as binary fission

19
Q

Three reasons binary fission is decent

A

Only one parent required to reproduce

Rapid division

Daughter cells are clones of parent cells

20
Q

Photoautotroph

A

Uses light as an energy source

Can fix carbon from non biological sources

21
Q

Photoheterotroph

A

Using light as energy source

Organism must obtain carbon from biological sources

22
Q

Chemoautotroph

A

Organism uses chemical reactions as energy source

Organism can fix carbon from a non-biological source

23
Q

Chemoheterotroph

A

Organism uses chemical reactions as an energy source

Organism can obtain carbon from biological sources

24
Q

Prefix for energy form light

Prefix for energy form chemical reactions

A

Photo

Chemo

25
Q

Autotroph

A

Organism produces own food using light, water, carbon dioxide or other chemicals
(Producer)

26
Q

Heterotroph

A

Organism eats other plants and animals for energy and nutrients

27
Q

Most prokaryotes are …

A

Chemoheterotrophs

Many break down organic waste/play roles as decomposers etc

28
Q

What are photoautotrophs important in?

A

Aquatic ecosystems

29
Q

What are cardinal temperatures?

A

Minimum temperature below which growth isn’t possible

Optimum temperature at which growth is most rapid

Maximum temperature at which growth is not possible

30
Q

Four broad classes of microorganisms based on optimum growth temperatures

A

Psychrophile
Mesophile
Thermophile
Hyperthermophile

31
Q

Talk about mesophiles (4 things)

A
  1. Widespread - found in digestive tract of animals, terrestrial and aquatic environments, temperate and tropical latitudes
  2. E. Coli is a typical mesophile
  3. Majority of bacteria associated with humans are mesophiles
  4. Optimum temperature = 39 degrees
32
Q

Talk about psychrophiles (3 things)

A
  1. Optimal = 15 degrees or lower
  2. Found in constantly cold environments
  3. Often grow in dense masses within and under sea ice in polar regions
33
Q

Psychrophile enzymes

A

Produces enzymes that function optimal in colder temperatures

34
Q

Psychrophile membrane

A

Membrane remains du toon despite cold temperatures because it’s semi fluid state is maintained by membrane having a higher content of unsaturated and shorter fatty acid chains

35
Q

Psychrophile cold shock protein

A

Type of molecular chaperone which can maintain cold- sensitive proteins in an active form

36
Q

Psychrophile cryoprotectants

A

Cryoprotectants help prevent formation of ice crystals which can puncture the cytoplasmic membrane

Eg. Antifreeze proteins, glycerol, exopolysaccharide cell surface slime (creates slime layers that offer protection).

37
Q

Thermophile (3 things)

A
  • Optimum temperature 45-80 degrees
  • found in hot springs, deep sea hydrothermal vents, decaying plant matter
  • source of thermos table enzymes used in PCR
38
Q

Hyperthermophile

A
  • Optimum temperature exceeding 80 degrees

- most tolerant known = methanopyrus (archaea capable of growth up to 122 degrees)

39
Q

Further thoughts slide

A

What is the significance of finding extremophilic prokaryotes?

What might be the consequences of this diversity for life of earth?

Could we live without prokaryotes?

Building a phenotype - lectures (36 decks)

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