UNIT 4: Membranes Flashcards
1
Q
Passive transport
A
- Does not require energy as it “moves with the flow”
- Molecules move from high [ ] to low [ ]
2
Q
Facilitated diffusion
A
- Use of proteins acting as channels to pass materials through membranes
- Act of passive transport as it goes from high [] to low [ ]
3
Q
Simple diffusion
A
- Act of passive transport as it does not require energy
- often crosses over oxygen gas and hydrogen gas
4
Q
Active transport
A
- Require energy as substances move from low [ ] to high [ ]
- ATP powers active transport to force molecules against flow by energizing protein channel
5
Q
Endocytosis
A
When a cell fuses with molecules its taking in to bring it inside; fusing often forms vesicles
6
Q
Exocytosis
A
- Can be used to get rid of cell waste
- Important for getting valuable materials out
7
Q
Plant cell walls
A
Large carbohydrates are important for making plant cell walls
8
Q
Fluid mosaic model
A
- Fluid applies movement
- Consist of a fluid lipid bi-layer in which
proteins are embedded and float freely - Membranes are not rigid
- Self-sealing and selective permeable
9
Q
Peripheral proteins
A
- Are on top or below the phospholipid bi-layer and usually won’t go through
- Loosely attached as their generally not stuck
- Act as enzymes or can attach to cytoskeleton and help with cell shape
- Can have a carb attached to it making it a glycoprotein
10
Q
Integral proteins
A
- Goes through the phospholipid bi-layer to act as a pathway for large molecules; such as glucose
- Peripheral proteins can sit on them
- Can have a carb attached to it making it a glycoprotein
- Multi-pass proteins & single-pass proteins
- Receptors relay signals between cell’s external & internal environments
- glycoproteins form the identification system that allows cells to recognize each other and interact
11
Q
Phospholipids
A
- Can have a carb attached to it, making it a glycolipid
- in an aqueous solution are clustered together by the Hydrophobic Effect
- Micelle (One phospolipid layer)
- Liposome (phospolipid bi-layer)
- Amphipathic
- Constantly moving
12
Q
Functions of biological membranes
A
- Protects the cell
- Helps the cell maintain its shape
- Maintains cell homeostasis by allowing certain substances to get in/out of the cell
- Acts in organization of reaction sequences (Contains enzyme systems/pathways for
energy transformation) (Contains specific recognition sites for extracellular signals)
13
Q
Proteins
A
- Confer specificity and perform a variety of functions
- Glycoproteins contain covalently bound carbohydrate
- Lipoproteins contain lipid, bound to the protein
- Constantly moving
14
Q
Membrane asymmetry
A
- Outer monolayer
- Inner (cytosylic) monolayer
15
Q
Sterols
A
- Another lipid component of cell membrane
- Amphipathic properties
- Maintains integrity of the membrane
- OH in cholesterol is near hydrophilic head
16
Q
Membrane fluidity
A
- depends on how densely individual lipid molecules can pack together and Influenced by three major factors; composition, temp and sterol content
- Composition: As tail saturation and length increase, fluidity decreases
- More freedom to move, more fluidity
- Temperature: As temp increases melting point can be reached and lipids melt (very fluid), freezing means less movement and less fluid
- Membrane not as responsive
- Sterol content: Maintains constant membrane fluidity despite changes in temp and degree of fatty acid saturation
17
Q
Flip flop movement
A
- One monolayer to another
- Very rare and slow
- requires specific enzymes
18
Q
Viscious
A
- Lateral movement
- Very fast
- Saturated hydrocarbon tails
- Flip flop movement; rare and slow
19
Q
Fluid
A
Unsaturated hydrocarbon tails with kinks
20
Q
Single pass proteins
A
Polypeptide chain crosses the lipid bi-layer as a single alpha helix
- Non polar amino acids are hydrophobic
- Polar and charged amino acids are hydrophilic
