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(a) Chemical level: a molecule in
the membrane that encloses a cell
(b) Cellular level: a cell
in the stomach lining
(c) Tissue level: layers of
tissue in the stomach wall
(d) Organ level:
the stomach
(e) Body system
level: the digestive
system
(f) Organism level
Recall basic cell physiology
This class I will assume you know the basic
functions of these structures:
Smooth and rough endoplasmic reticulum
Golgi
Peroxisomes
Lysosomes
Mitochondria
Basic structure of the plasma membrane
Gazing into a cell….
Peroxisome
Nucleus
Lysosome
Golgi
Cristae
Glycolysis can occur with or without oxygen
Yet, aerobic respiration yields more energy from
glucose and occurs in the mitochondria
Chemical reactions for energy
Citric acid cycle
Glycolysis
Electron transport chain
Cytosol
Making ATP
First, glycolysis – then either:
Aerobic Pathway
Anaerobic Pathway
Citric acid cycle
Electron transport chain
Fermentation
Within the mitochondria...
Pyruvate enters
mitochondria
 Citric Acid Cycle
matrix
 Electron Transport
Inner membrane (cristae)
Pyruvate
Acetyl-CoA
Citric Acid
CO2
(or Krebs)
Cycle
ATP
CO2
Where does weight ‘go’ when
someone loses weight?
Electron Transport Chain
High energy electrons taken
from hydrogen are
transferred through a series of
carriers on inner membrane
 ATP Synthase w/in cristae
 32 ATP formed
Free radicals from ETC
A by-product of ETC is the production of
abnormal versions of O2 (O2-, O2--)
These molecules are highly reactive and
produce “free radicals”, which contribute
to aging and some diseases.
Energy Harvest
Glycolysis (from one glucose)
2 ATP
2 NADH (makes 4 ATP in ETC)
Citric Acid Cycle
2 ATP plus NADH, FADH2 for ETC
Electron Transport Chain
28 ATP by oxidative phosphorylation
Anaerobic conditions
Aerobic conditions
Lactic acid myth
Lactic acid (really lactate) isn’t the cause of
muscle fatigue and soreness
Lactate leaves muscle, enters blood and is
used elsewhere for ATP production (using
O2 )
Lactate threshold
Interval training uses periods of training above
and below the L threshold. High intensity
portions stimulate your body to produce
enzymes that speed the use of lactate fuel
(MCT1 carrier protein)
Plasma membrane of cells
oligosaccharide
groups
phospholipid
cholesterol
EXTRACELLULAR ENVIRONMENT
(cytoskeletal
proteins beneath
the plasma
membrane)
ADHESION
PROTEIN
open
channel
protein
gated
channel
protein
(open)
gated
channel
protein
(closed)
TRANSPORT
PROTEINS





active
transport
protein
RECEPTOR
PROTEIN
CYTOPLASM
Receptor sites (ex: endocrine sites)
Cell adhesion (CAM) grips neighbor cell
Channels for ions, small molecules
Carrier proteins
Attach to cytoskeleton
RECOGNITION
PROTEIN
Membrane receptors
Binding to the receptor will:
 Open or close channels for ions (Na+,
K+, Ca++)
 Transfer a signal to 2nd messenger to
trigger events in the cell
2nd messenger system

will activate an enzyme
Other cell adhesions
Extracellular matrix - Biological “glue.” 3
protein fibers are interwoven in this matrix:
collagen, elastin, fibronectin. Secreted by
cells
Desmosomes – “Rivets” to anchor adjacent
cells that are not touching
Other cell adhesions
Tight junctions – Epithelium cells
form tight seal at points of contact
Gap junctions - Small tunnels connect
cells
open channel
proteins
gated channel
proteins
transport protein
transport protein with binding site for
a specific substance (the solute)
Passive
transport
(facilitated
diffusion)
protein has 2
different
conformations
high solute concentration
Concentration
gradient
phosphorylation
required
Active
Transport
Direction
of transport
Membrane (permeable to water only)
Side 1
Side 2
Solute can’t move to
side 1 down its gradient
but water moves
H2 O
Side 1
Water and solute
concentrations now
equal
Side 2
Membrane (permeable to H2O)
Side 1
Solute can’t move to
side 1 down its gradient
Side 2
H2 O
Pure water
Gradients still exist
Osmosis is balanced
by hydrostatic
pressure
Side 1
Side 2
Hydrostatic
(fluid)
pressure
difference
Osmosis
Hydrostatic
pressure
Isotonic Hypotonic Hypertonic