Exam 2 Bacteria & Archaea 9/28 Flashcards

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1
Q

Bacteria can take many different shapes

A

Spherical (s. coccus, pl. cocci)
Rod-shaped (s. bacillus, pl. bacilli)
Comma-shaped (s. vibrio, pl. vibrios)
Spiral (s. spirillum, pl. spirilla)
Pleiomorphic (varied shapes)

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2
Q

Vibiancy

A

Dormancy mechanism caused by stress, lowering metabolism to sleeping state

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3
Q

Bacteria can also assume multicellular organizations

A

Hyphae (branching filaments of cells)
Mycelia (tufts of hyphae)
Trichomes (smooth, unbranched chains of cells)

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4
Q

Size of bacteria can vary greatly

A

Usually smaller than eukaryal cells

SMALL eukaryal cells are usually >5 μm in diameter

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5
Q

The cytoplasm

A

Liquid/gel environment where all metabolic and functional activity occurs

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6
Q

The Nucleoid (nuclear region)

A

irregularly shaped region in bacteria and archaea

usually not membrane bound (few exceptions)

location of chromosome and associated proteins

supercoiling

nucleoid proteins (HU)

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7
Q

Plasmids

A

extrachromosomal DNA

exist and replicate independently of chromosome

episomes

contain few genes that are non-essential

May exist in many copies in cell

Inherited stably during cell division

Can be lost during cell division

Classification of plasmids based on mode of existence, spread, and function

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8
Q

Ribosomes

A

complex structures

entire ribosome
*bacterial and archaea ribosome = 70S
*eukaryotic (80S) S = Svedburg unit

^*(note: eukaryotic are slightly larger than bacterial and archaea ribosomes)

bacterial and archaeal ribosomal RNA
16S small subunit = 30S
23S and 5S in large subunit = 50S
archaea have additional 5.8S in large subunit (also seen in eukaryotic large subunit)

proteins vary

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9
Q

The cytoplasm

What else is in the cytoplasm of bacterial cells?

A

A stew of macromolecules

Inclusion bodies may also be present
Polyhydroxybutyrate granules
Sulfur globules
Gas vesicles
Carboxysomes
Magnetosomes

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10
Q

Inclusions

A

Common in all cells

granules of organic or inorganic material

some are enclosed by a single-layered membrane

storage of nutrients, metabolic end products, energy, building blocks

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11
Q

Magnetosomes

A
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12
Q

bacterial cytoskeleton

A

The cytoskeleton is a series of internal proteins
Keeping everything in the cell
Move things to the right locations in cells.

Some cytoskeleton proteins are involved in cell wall synthesis during cell division (FtsZ and MreB).

Other cytoskeletal proteins are involved in moving internal items (e.g., plasmids, magnetosomes).

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13
Q

Bacterial Cell Envelope

A

Plasma membrane
Cell wall
Layers outside the cell wall

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14
Q

The plasma membrane

A

ALL cells have a plasma membrane (PM).

Interior/exterior

Usually composed of a phospholipid bilayer with embedded proteins

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15
Q

Plasma Membrane Functions

A

encompasses the cytoplasm

selectively permeable barrier

interacts with external environment

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16
Q

Bacterial Lipids

A

The PM may have sterol molecules called “hopanoids” in it to help with stability across temperature ranges

17
Q

Membrane Proteins

A

peripheral
- loosely connected to membrane
- easily removed
- Make up 20 – 30% of membrane proteins

integral
- amphipathic
- Carbohydrates often attached
- carry out important functions
- Can move laterally in the membrane
- may exist as microdomains (patchwork)

18
Q

Membrane Proteins Functions

A

ATP production/energy production

Transportation through the membrane

19
Q

The plasma membrane: getting things in

A

O2 and CO2 - diffuse across readily

H2O – aquaporins

Osmosis is the flow of water across the PM toward the side with a higher solute concentration.

20
Q

How do organisms take up nutrients?

A

Microbes can only take in dissolved particles across a selectively permeable membrane

Must be able to take up specific molecules

Must concentrate nutrients against a gradient

microorganisms have developed a number of different transport mechanisms to accomplish this
facilitated diffusion – all microorganisms
active transport – all microorganisms
group translocation – Bacteria and Archaea
endocytosis – Eukarya only

21
Q

Passive Diffusion

A

molecules move from a region of higher concentration to one of lower concentration between the cell’s interior and the exterior

Not energy dependent

The rate of diffusion depends on the concentration gradient

H2O, O2, and CO2 often move across membranes this way

22
Q

Facilitated Diffusion

A

similar to passive diffusion

movement of molecules is not energy dependent

direction of movement is from high concentration to low concentration

size of concentration gradient impacts rate of uptake

differs from passive diffusion

uses membrane bound specific carrier molecules

smaller concentration gradient is required for significant uptake of molecules

A concentration gradient spanning the membrane drives the movement of molecules

Is reversible depending on concentration of molecules

The gradient can be maintained by transforming the transported nutrient into another compound

effectively transports glycerol, sugars, and amino acids

more prominent in eukaryotic cells than in bacteria or archaea

No energy required

Not useful to bacteria and Archaea that live in environments with low concentrations of nutrients

23
Q

rate of facilitated
diffusion

A

rate of facilitated
diffusion increases
more rapidly and
at a lower
concentration

diffusion rate
reaches a plateau
when carrier
becomes
saturated

24
Q

Active Transport

A

energy-dependent process

move molecules against a gradient

concentrates molecules inside cell

involves specific carrier proteins (permeases)

25
Q

Types of Active Transport

A

3 types: Primary, Secondary, Group Translocation

Primary Active Transporters (ABC Transporters) – use energy provided by ATP hydrolysis to move substances against a conc gradient

Secondary Active transporters (major facilitator superfamily MFS Transporters) – couple the potential energy of ion gradients to transport substances

26
Q

ABC Transporters

A

primary active transporters use ATP

ATP-binding cassette transporters

observed in Bacteria, Archaea, and eukaryotes

Consist of :
2 hydrophobic membrane spanning transporter proteins
2 cytoplasmic associated ATP-binding domains

Considered to be uniport – transports one molecule at a time

27
Q

ABC Transporter Function

A

Leads to ATP hydrolysis which provides energy for opening channel and movement of solute

28
Q

Secondary Active Transport

A

major facilitator superfamily (MFS)

uses ion gradients to co-transport substances
symport - two substances both move in the same direction
transport of lactose using lactose permease in E. coli transports lactose and a proton simultaneously into the cell

antiport - two substances move in opposite directions
transport of sugars and amino acids in E. coli while pumping sodium out