KAAP309 Lecture Notes - Lecture 3: Aica Ribonucleotide, Resting Potential, Fluid Compartments
18 May 2018
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Chapter 3: Cells A
I. Overview
A. Plasma membrane: structure
B. Plasma membrane: transport
C. Resting membrane potential
D. Cell-environment interactions
E. Cytoplasm
F. Nucleus
G. Cell growth and reproduction
H. Extracellular materials
I. Developmental aspects
II. Do exercise scientists need to think about cells?
A. eerise i a pill
B. AMPK and PPARδ agonists are exercise mimetics
C. AICAR activates intracellular pathways that are also activated by exercise
D. Mice taking AICAR look like mice on exercise
E. Mice on AICAR plus exercise are supermice
III. Types of cells
A. Cells that connect body parts, form linings, or transport gases
1. Erythrocytes
2. Fibroblasts
3. Epithelial cells
B. Cells that move organs and body parts
1. Skeletal muscle cell
2. Smooth muscle cells
C. Cell that stores nutrients: fat cell
D. Cell that fights disease: macrophage
E. Cells that gathers information and control body functions: nerve cell
F. Cell of reproduction: sperm
IV. Generalized cell
A. All cells have some common structures and functions
B. Human cells have three basic parts:
1. Plasma membrane: flexible outer boundary
a) Bimolecular layer of lipids and proteins in a constantly changing
fluid mosaic
b) Plays a dynamic role in cellular activity
c) Separates intracellular fluid from extracellular fluid
i. Interstitial fluid = ECF that surrounds cells
d) Membrane proteins
i. Integral proteins
• Firmly inserted into the membrane
• Function includes: transport proteins (channels
and carriers), enzymes, or receptors
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ii. Peripheral proteins
• Loosely attached to integral proteins
• Include filaments on intracellular surface and
glycoproteins on extracellular surface
• Functions include: enzymes, motor proteins, cell-
to-cell links, provide support on intracellular
surface, and form glycocalyx
2. Cytoplasm: intracellular fluid containing organelles
3. Nucleus: control center
a) Except for RBC
V. Membrane Junctions
A. Three types:
1. Tight junction: impermeable junctions prevent molecules from passing
through the intracellular space
2. Desmosome: anchoring junctions bind adjacent cells together and help
from an internal tension-reducing network of fibers
3. Gap junction: communicating junctions allow ions and small molecules
to pass from one cell to the next for intracellular communications
VI. Membrane transport
A. Plasma membranes are selectively permeable: some molecules easily pass
through the membrane, others do not
B. Types of transport
1. Passive process
a) No cellular energy (ATP) required
b) Kinetic energy
c) Substance moves down its concentration gradient
d) Types of passive processes:
i. Simple diffusion: nonpolar lipid-soluble (hydrophobic)
substances diffuse directly through the phospholipid
bilayer
ii. Facilitated diffusion: certain lipophobic molecules
(glucose, amino acids, and ions) use carrier proteins or
channel proteins, both of which:
• Exhibit specificity (selectivity)
• Are saturable; rate is determined by number of
carriers or channels
• Can be regulated in terms of activity and quantity
iii. Carrier-mediated facilitated diffusion: via a protein carrier
specific for one chemical; binding of substrate causes
shape change in transport protein
iv. Channel meditated-facilitated diffusion: through a
channel protein; mostly ions selected on basis of size and
charge
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v. Osmosis
• Movement of solvent (water) across a selectively
permeable membrane
• Water diffuses through plasma membranes
through the lipid bilayer and through water
channels called aquaporins
• When osmosis occurs, water enters or leaves a
cell
• Change in cell volume disrupts cell function
2. Active processes
a) Energy (ATP) required to move solutes across a living plasma
membrane
b) Occurs only in living cell membranes
c) Types of active processes:
i. Active transport
• Requires carrier proteins (solute pumps)
• Moves solutes against a concentration gradient
• Primary active transport
I. Energy from breadown of ATP causes shape
hage i trasport protei to pup
molecules across the membrane
II. Sodium-potassium pump
• Secondary active transport
I. Energy stores in ionic gradients is used
indirectly to drive transport of other solutes
II. Always involves cotransport – transport of
more than one substance at a time
ii. Vesicular transport
• Transport of large particles, macromolecules, and
fluids across plasma membranes
• Requires cellular energy (ATP)
• Exocytosis: transport out of cell
• Endocytosis: transport into cell (receptor
mediated)
• Transcytosis: transport into, across, and then out
of the cell
• Vesicular transport within a cell
VII. Tonicity
A. Tonicity: How much dissolved material there is in a solution. Tonicity
determines whether a solution will make cells shrink or swell.
B. Isotonic: A solution with the same solute concentration as the inside of a normal
cell
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Document Summary
Chapter 3: cells a: plasma membrane: structure, plasma membrane: transport, resting membrane potential, cell-environment interactions, cytoplasm, nucleus, cell growth and reproduction, extracellular materials, developmental aspects. Interstitial fluid = ecf that surrounds cells: membrane proteins. Integral proteins: firmly inserted into the membrane, function includes: transport proteins (channels and carriers), enzymes, or receptors. Peripheral proteins: loosely attached to integral proteins. Simple diffusion: nonpolar lipid-soluble (hydrophobic) substances diffuse directly through the phospholipid bilayer. Carrier-mediated facilitated diffusion: via a protein carrier specific for one chemical; binding of substrate causes shape change in transport protein. Active transport: requires carrier proteins (solute pumps, moves solutes against a concentration gradient, primary active transport. Energy from breadown of atp causes shape (cid:272)ha(cid:374)ge i(cid:374) tra(cid:374)sport protei(cid:374) to (cid:862)pu(cid:373)p(cid:863) molecules across the membrane. Energy stores in ionic gradients is used indirectly to drive transport of other solutes. Always involves cotransport transport of more than one substance at a time. Tonicity: tonicity: how much dissolved material there is in a solution.
