Cell Membrane, Diffusion, Osmosis Flashcards
0
Q
Cell membrane functions
A
- separates internal from external environment
- regulates movement of nucleus into & out of cell
- cell-to-cell recognition
- binding site for molecules
- sets up enzymatic sequence
1
Q
Fluid Mosaic Model meaning
A
- fluid: fatty acid tails of phospholipids that make the inner membrane like a light oil
- mosaic: the mosaic-like appearance of proteins scattered outside or within the membrane
2
Q
Cell membrane consists of
A
- phospholipid bilayer with embedded proteins (fluid mosaic model)
- hydrophilic polar heads face towards exterior and interior of the cell
- hydrophobic non-polar fatty acid tails face each other in the middle
3
Q
Cholesterol function
A
- stiffens & strengthens membrane
- helps regulate fluidity of membrane
4
Q
Types of proteins
A
- can be peripheral (attached to outside) or integral (embedded in membrane) proteins
- transport proteins
- receptor proteins
- enzymatic proteins
- cell recognition proteins
5
Q
Transport Proteins
A
- channel proteins: create a pore that allows a particular molecule or ion to cross the membrane
- carrier protein: each type of protein only interacts with one specific molecule to allow it into the cell
Ex. Glucose & amino acids brought in this way
6
Q
Receptor Proteins
A
- bind to hormones
- change protein shape
- trigger cellular responses
7
Q
Enzymatic Proteins
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- catalyze (speed up) metabolic reactions
8
Q
Cell Recognition Proteins
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- have glycoproteins that are unique to each individual
9
Q
Attached carbohydrate chains
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- named for their attachment to the membrane
- glycolipids: attach to phospholipids
- glycoproteins: attach to proteins, involved in cell recognition, unique to individuals
10
Q
Glycocalyx
A
General term used for glycolipid & glycoprotein layer around cell
11
Q
Membrane
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- selectively/differentially permeable (can select what passes though it)
- small, uncharged H2O molecules can pass through, but big or charged molecules need help across
12
Q
Passive Transport
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- one way of passing through membrane
- no ATP
- ex. Facilitated diffusion, osmosis
13
Q
Active Transport
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- one way of passing through the membrane
- needs ATP
- ex: ion pumps, co-transport, endocytosis
14
Q
Diffusion
A
- Molecules move from high [ ] to low [ ] (with the concentration gradient)
- particles move randomly but spread out evenly to achieve equilibrium
- molecules that enter/leave through diffusion are small and/or lipid soluble: oxygen, CO2, alcohol, small lipids
15
Q
Lungs and diffusion
A
- lungs rely on diffusion to add oxygen to the blood and remove CO2
- ie. oxygen diffuses along concentration gradient in the blood
16
Q
Osmosis
A
- diffusion of only water across a selectively permeable membrane
17
Q
Solution
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Contains a solute (solid dissolved in water) and solvent (liquid)
18
Q
3 categories of solutions
A
- isotonic
- hypotonic
- hypertonic
19
Q
Isotonic solutions
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- iso: equal
- solute [ ] equal inside & outside cell
- no net movement of water in or out
- ex. NaCl solution isotonic to blood
20
Q
Hypotonic Solutions
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- hype: low/less
- solute concentration around the cell is less than the cell’s cytoplasm
- water enters cell to balance concentrations (puffy cell-hypotonic)
21
Q
Cell reactions in hypotonic solutions
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- Cytolysis: When animal cells burst (occurs in animal cells but not plant cells due to rigid cell wall)
- plant cells increase turgar pressure
22
Q
Hypertonic solutions
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- hyper: high/greater
- fluid surrounding cell has higher concentration than cell’s cytoplasm
- water leaves the cell (bumpy cell- hypertonic)
23
Q
Reactions of cells in hypertonic solutions
A
- animal cell shrivels “crenation”
- plant cells go through “plasmolysis”
24
Osmoregulation
Animals living on water face an osmotic difference between their cells & surrounding water
25
Freshwater osmoregulation
- salt in body > salt in water
- animals:
- excrete large amounts of water in urine
- contractile vacuoles in single-cell organisms expel water
27
Saltwater osmoregulation
- salt in body less than salt in water...water leaves cells
- animals:
- make their body surfaces less permeable
- pump salts out of blood & back into sea water
- produce very small amount of urine to get rid of metabolic waste (source of water loss)
- drink to replace lost water
- get rid of excess ions by active transport from body fluids back into water