Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MICR3330 > 2 - Plasma membrane > Flashcards

2 - Plasma membrane Flashcards

1
Q

Cell envelope

A

Outermost part of the prokaryotic cell (outer membrane, cell wall and plasma membrane)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What colour does gram positive stain

A

Purple (two ps) / monoderms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What colour does gram negative stain

A

Pink (one p) / diderms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Functions of cell envelope

A
  • provides rigidity and structure
  • prevents osmotic lysis
  • encloses the cell contents
  • includes receptors for responding
    to external conditions
  • includes motility and attachment structures
  • critical to evolution
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Phospholipid bilayer

A
  • Have polar (hydrophilic) and non polar (hydrophobic) end
  • Outer surfaces are hydrophilic, interior is hydrophobic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Bacterial lipids

A
  • Bacterial membranes differ from
    eukaryotic membranes in lacking sterols
    such as cholesterol
  • Have sterol like molecules called hopanoids
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Hopanoids

A
  • Help stabilise membrane, increase bacterial survival under stress
  • Most abundant biological molecule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Peripheral proteins

A

Loosely connected to membrane, easy to remove, soluble in water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Integral proteins

A

Not easily extracted, insoluble, amphipathic (hydrophilic and hydrophobic ends)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Function of integral proteins

A
  • Transport
  • Energy production
  • Exposed regions allow cell to interact with environment (via carbohydrate side chains)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Fluid mosaic model

A
  • Proteins float in lipid bilayer, free to move laterally
  • Membrane lipids homogeneously distributed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why are aspects of fluid mosaic model now being questioned

A

Due to existence of functional membrane microdomains (FFM)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Flotillins

A

Function to assemble large protein complexes invloved in specific cellular processes (e.g. protein secretion, cell wall metabolism)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Membrane protein synthesis

A
  • Begins in the cytoplasm
  • A peptide leader sequence binds to the membrane at sites determined by specific docking proteins
  • The protein is threaded into the membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Functions of plasma membrane

A
  • Selectively permeable osmotic barrier
  • Controls movement of chemicals to and from the cell
  • The site of many important cellular processes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Selectively permeable osmotic barrier

A

Retains cell contents and prevents leakage of important cell chemicals

17
Q

Controls movement of chemicals to and from the cell

A
  • Has specific transport systems for nutrient uptake, waste excretion, and secretion of enzymes
18
Q

The site of many important cellular processes

A
  • Assembly and synthesis of cell membrane lipids
  • Assembly and secretion of extracellular proteins
  • Energy generation
19
Q

Plasma membrane transport

A
  • Some chemicals diffuse into and out of the cell (no energy required)
  • Some chemicals must be transported (energy required)
  • Transport occurs against a concentration gradient
20
Q

Five transport processes in bacterial cells (2 types of diffusion, 3 types of active transport)

A
  • Passive diffusion
  • Facilitated diffusion
  • Active transport (Primary, Secondary, Group translocation)
21
Q

Passive diffusion

A
  • Molecules move from a region of higher concentration to one of lower concentration (down concentration gradient)
  • Rate depends on size of concentration gradient between inside and outside cell
  • Only small, neutral or weakly charged molecules can diffuse across PM
22
Q

Channel proteins

A

Form pores in membranes through which substances can pass

23
Q

Carrier proteins (permeases)

A

Carry substances across membranes (more substrate specific)

24
Q

Facilitated diffusion

A
  • Diffusion across the plasma membrane is aided by a channel protein or carrier proteins
  • ATP is not required
  • Continues until inside = outside
  • Can become saturated (reaches plateau)
  • Rate of diffusion depends on size of concentration gradient
  • Rate increases much more rapidly than passive diffusion
25
Q

Carrier mediated facilitated diffusion

A

Solute binding permease triggers conformational change and transport

26
Q

Active transport

A
  • Transport of non-diffusible chemicals against a concentration gradient with input of energy
  • Typically involves specific integral membrane permeases and substrate binding proteins
  • Driven by ATP or proton motive force
27
Q

Primary active transport

A
  • Mediated by carriers such as ABC transporters
  • Use ATP move substances against a concentration gradient without modifying them
  • Uniporters (move a single molecule across membrane)
28
Q

ABC transporters

A

ATP Binding Cassette

29
Q

Steps of primary active transport

A
  1. Solute-binding protein binds
    substrate and attaches to the
    transporter
  2. ATP hydrolysis releases energy at the transporter complex
  3. Substrate is transported through pore
30
Q

Secondary active transport

A
  • Couples the potential energy of ion gradients to move substances against a concentration gradient without modifying them
  • Cotransporters (moves two substances simultaneously)
31
Q

Symporters

A

Move both substances in the same direction

32
Q

Antiporters

A

Move two substances in opposite directions

33
Q

Example of antiport permease transport

A
  • Na+ transport in E.coli
  • Helps E. coli grow under quite high salt conditions
34
Q

Group translocation

A
  • Molecule is chemically modified as it is transported into cell
  • Phosphorylated by a sugar phosphotransferase system (PTS)
  • Involves several enzymes transferring phosphate to the sugar (phosphorelay system)
  • Only found in prokaryotes
35
Q

What is the phosphate donor in group translocation

A
  • Phosphoenolpyruvate (PEP)
  • A high energy molecule that can be used to make ATP, but here its energy is used to fuel transport
36
Q

Benefits of phosphorelay system

A
  • Phosphorylated sugar cannot diffuse back out of the cell
  • Group translocation allows nutrient uptake under conditions where the membrane is deenergised and ion coupled sugar transport is failing.

MICR3330 (29 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions