BIOL 121 Chp 3 pt1: Plasma Membrane Structure and Function
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Transcript of BIOL 121 Chp 3 pt1: Plasma Membrane Structure and Function
1
The Cellular Level of
Organiza3on Part 1: Membrane
Structure & Transport
BIOL 121: A&P I
Chapter 3
Rob Swatski Associate Professor of Biology
HACC – York Campus Text
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Flagellum Chroma.n
Nuclear pore
Nuclear envelope
Nucleolus
Glycogen granules
CYTOPLASM (cytosol plus organelles except the nucleus)
Rough endoplasmic re.culum (ER)
Membrane-‐bound ribosome
Golgi complex
Microfilament
Sec.onal view
Cytoskeleton:
Microtubule
Microfilament
Intermediate filament
Microvilli
Centrosome: Pericentriolar material
Centrioles
PLASMA MEMBRANE
Secretory vesicle
Lysosome
Smooth endoplasmic re.culum (ER)
Peroxisome
Mitochondrion
Microtubule
Cilium
Proteasome
Free ribosomes
NUCLEUS:
3
Main Parts of a Cell
Plasma membrane Cytoplasm Nucleus
4
5
Plasma Membrane
6
Phospholipids
Cell structure & func.on
Plasma membrane
Amphipathic 7
8
Head
Polar
Hydrophilic
Glycerol & phosphate
Tails
Nonpolar
Hydrophobic
2 FaZy acids
Phospholipid Structure
9
10
11
Permeable
12
Impermeable
13 Semipermeable
14
Ion Channel
Carrier
Receptor
Membrane Proteins
More Membrane Proteins! 15
Enzyme
Linker
Cell-‐iden.ty marker (Glycoprotein)
Extracellular fluid Plasma membrane Cytosol
Ion channel (integral) Forms a pore through which a specific ion can flow to get across membrane. Most plasma membranes include specific channels for several common ions.
Pore
Carrier (integral) Transports a specific substance across membrane by undergoing a change in shape. For example, amino acids, needed to synthesize new proteins, enter body cells via carriers. Carrier proteins are also known as transporters.
Receptor (integral) Recognizes specific ligand and alters cell's func.on in some way. For example, an.diure.c hormone binds to receptors in the kidneys and changes the water permeability of certain plasma membranes.
Enzyme (integral and peripheral) Catalyzes reac.on inside or outside cell (depending on which direc.on the ac.ve site faces). For example, lactase protruding from epithelial cells lining your small intes.ne splits the disaccharide lactose in the milk you drink.
Linker (integral and peripheral) Anchors filaments inside and outside the plasma membrane, providing structural stability and shape for the cell. May also par.cipate in movement of the cell or link two cells together.
Cell iden3ty marker (glycoprotein) Dis.nguishes your cells from anyone else's (unless you are an iden.cal twin). An important class of such markers are the major histocompa3bility (MHC) proteins.
MHC protein
Products Substrate
Ligand
Substance to be transported
Ion
17
Concentra3on gradient
Electrochemical Gradient
18
Membrane Transport
Passive Ac.ve Vesicular
19
20
Passive Transport
Beginning (a)
Intermediate (b)
Equilibrium (c)
Diffusion
22 Diffusion
23
Factors Influencing Diffusion Rate
24
Simple Diffusion
Channel-‐Mediated Facilitated Diffusion
25
26
Carrier-‐Mediated Facilitated Diffusion
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28
Osmosis
29
30
Tonicity
Isotonic Hypotonic Hypertonic
31
32
Isotonic
33
Hypotonic
34
Hypertonic
35
Ac3ve Transport
Needs ATP
Transports against gradient
Ions, AA, glu
Primary and Secondary Ac.ve Transport
ATP
Primary Ac3ve Transport: Na+-‐ K+ pump
36
37
Na+ gradient
Extracellular fluid Na+/K+ ATPase 3 Na+ expelled 2K+
2 K+ imported ADP
ATP 3 Na+
K+ gradient
Cytosol
P
P
1 2 3 4
1 2 3 4
3 sodium ions (Na+) from the cytosol bind to the inside surface of the sodium–potassium pump.
Na+ binding triggers ATP to bind to the pump and be split into ADP and P (phosphate). The energy from ATP splijng causes the protein to change shape, which moves the Na+ to the outside.
2 potassium ions (K+) land to the outside surface of the pump and cause the P to be released.
The release of the P causes the pump to return to its original shape, which moves the K+ into the cell.
Primary Ac3ve Transport: Na+-‐ K+ pump -‐ REVIEW
Secondary Ac3ve Transport: Symporters
39
Secondary Ac3ve Transport: An3porters
40
Vesicular Transport: Endocytosis
Phagocytosis Receptor-‐Mediated Endocytosis
Bulk-‐Phase Endocytosis (Pinocytosis)
41
Phagocytosis
42
43
Phagocytosis
44
Receptor-‐Mediated Endocytosis
Bulk-‐Phase Endocytosis (Pinocytosis) 45
46
Transcytosis
Vesicular transport
Endocytosis, intracellular transport, exocytosis
Exocytosis
Secretory vesicles
Enzymes, hormones, NT’s,
wastes
47