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Cytoplasm
HONORS ANATOMY &
PHYSIOLOGY
Cytoplasm
 material between plasma membrane&
nucleus
 site of most cellular activity
 3 elements
1. Cytosol
2. Organelles
3. Inclusions
Cytosol
 viscous, semitransparent fluid in
which other elements in cytoplasm are
suspended
 complex mixture of:
 water
 proteins
 salts
 Sugars
 other
solutes
Organelles
 specialized cellular compartments or
structures
 each has specific function
Organelles
 non-membranous:
 cytoskeleton
 ribosome
Endomembrane System
 membranes allow inside to differ from
cytoplasm
 membranous:
 mitochondria,
Ers, Golgi, lysosomes,
peroxisomes
 intermembrane system: connections
between ERs, nucleus
Mitochondria
structure
 dbl membrane
 inner
membrane has
enzymes used in etransport chain
 matrix w/in ↑
enzymes for citric
acid cycle
Function
 aerobic cellular
respiration 
ATP
Mitochondria
Ribosomes
Structure
Function
 proteins + rRNA
 translation part of
 2 subunits
 large
 small
protein synthesis
Ribosomes
Endoplasmic Reticulum
 extensive system of interconnected
tubes & parallel membranes enclosing
fluid-filled cavities called cisterns
 continuous with outer membrane of
nuclear envelope
1. Smooth ER
2. Rough ER
Smooth ER
Structure
 continuous with
RER
 enzymes (integral
proteins)
Function
 metabolize lipids
 synthesize cholesterol &




lipoproteins
synthesize steroid
hormones
absorb, synthesize, &
transport fats
detoxify drugs, cancercausing chemicals
glycogen  free glucose
SER
RER
Structure
Function
 ribosomes stud surface
 synthesize all proteins
of membrane
 proteins made on these
ribosomes thread way
into cisterns
 proteins then enclosed
in vesicles  Golgi
exported from cell
 makes membranes
RER
Golgi Apparatus
Structure
Function
 stacked & flattened
 modifies,,
membranous sacs
 associated with
numerous vesicles
concentrates, &
packages proteins
&lipids destined for
export
 packages enzymes into
vesicles  lysosomes,
peroxisomes
Peroxisomes
Structure
Function
 “peroxide bodies”
 detoxify harmful
 membranous sacs
substances (many in
liver& kidney)
 breakdown &
synthesize fatty acids
containing enzymes
 ex: oxidases, catalases
 made in ER
Lysosome
Structure
 spherical, membranous
organelles containing
activated digestive
enzymes in acid pH
 many found in cells
that phagocytize
 plasma membrane has
H+ pumps
Function
 enzymes digest all




molecules
H+ pumps maintains
normal pH in cytosol
degrade worn out
organelles
glycogen  glucose
breakdown nonuseful
tissues
Tay-Sachs
 1 enzyme missing in lysosmes of nerve
cells  buildup of glycolipid 
lysosomes swell with undigested lipids
 interferes with normal nervous
system functioning  death in early
childhood
Cytoskeleton
 “cell skeleton”
 network of protein rods thru cytosol
 supports cell structure
 allows cell movement
 Types:
1. Microfilaments
2. Intermediate Filaments
3. Microtubules
Microfilaments
Structure
Function
 made of actin
 strengthens cell surface
 “web” just inside
 transmit force during
plasma membrane of
all cells
movement & shape
changes
 works with myosin 
muscle contractions &
formation of cleavage
furrow in cytokinesis
Intermediate Filaments
Structure
Function
 tough, insoluble
 resist pulling forces
protein fibers
 most stable &
permanent of the 3
 attach to
desmosomes
exerted on cell
Microtubules
Structure
Function
 hollow tubes made of
 determine overall
protein tubulin
 most radiate from
centrosome
 very dynamic: selfassemble/dissemble
 have associated proteins
that help organelles
move in cytoplasm
shape of cell
 distribute organelles
 https://www.youtube.c
om/watch?v=4TGDPot
bJV4
Centrosomes
Structure
Function
 made of paired
 generates & organizes
centrioles: barrelshaped organelles
oriented @ rt angles to
each other
microtubules
 organizes mitotic
spindle
Cilia
Structure
Function
 whip-like, motile
 as beat in unison
cellular extensions
 found in large #s on
surface of cell
 9 paired microtubules
runs length of cilium
mucus/particles swept
over surface of cell
http://www.zoology.ubc.ca/courses/bio33
2/Images/Cilia/Cil3/cilium.gif
Flagella
Structure
Function
 cell projections formed
 propels entire cell
by centrioles
 longer than cilia
 only human cell with
flagella is the sperm
 9 + 2 pattern of
microtubules
http://worms.zoology.wisc.edu/dd2/echin
o/fert/sperm/sperm.html
Microvilli
Structure
Function
 minute projections of
 ↑ surface area
plasma membrane on
cell surface
 found on surface of
absorptive cells
 have core of
microfilaments (actin)
Nucleus
Structure
Function
 dbl membrane
 houses chromosomes
 ~5 µm in diameter
 shape conforms to cell




shape
3 regions:
nuclear envelope
nucleoli
chromatin
(DNA) making it the
control center of cell
Nuclear Envelope
Structure
Function
 selectively permeable dbl
 gives shape to nucleus
membrane with nuclear
pores
 outer membrane
continuous with RER
 inner membrane lined
with rod-shaped proteins
that give shape to nucleus
 pores: complex of proteins
 pores allow transport
route for substance
in/out of nucleus
 encloses nucleoplasm
(jelly-like similar to
cytoplasm)
Nucleolus
Structure
Function
 dark staining spherical
 assemble ribosomal
bodies w/in nucleus
subunits  combine
rRNA with proteins
Chromatin
Structure
 bumpy threads
weaving thru
nucleoplasm
 30% DNA
 60% histones (proteins
which package and
regulate DNA
 10% RNA
Function
 genome
 codes
for proteins
Chromosomes
Structure
Function
 DNA
 Codes for proteins
 Telomeres : DNA at
 protects chromosome
either end of
chromosome
coding portion acting
like “bumpers”
Other Roles of DNA
 Iintrons (parts of pre-mRNA that stay in
the nucleus) have role as other RNAs
 antisense
RNAs: can block translation
 microRNAs: supress certain mRNAs made by
certain exons
 riboswitches: folded RNAs that code for protein
that include an on or off switch responding to
metabolic changes in their immediate
environment (change in environment induces
change in configuration  stopping or starting
protein translation)
Degradation of Organelles
 autophagy: “self-eating”
 cell debris swept into vesicles
(autophagosomes)  lysosomes for
digestion
 rate increases in cell stress
 anoxia,
high temp, lack of growth factors
 can lead to apoptosis (programmed cell
death)
Ubiquitins
 proteins that mark other proteins no
longer being used by cell for
destruction
 once marked  hydrolyzed by
proteosomes (giant waste disposal
complexes)  recycle a.a. and release
ubiquitins
Extracellular Material (ECM)
 any substance contributing to body
mass found outside cells
1. Body Fluids
2. Cellular Secretions
Body Fluids
interstitial fluid
2. plasma
3. cerebrospinal fluid
1.
Cellular Secretions
 gastric juices
 bile
 mucus
 sweat
 serous fluid
Extracellular Matrix
 most abundant ECM = “cell glue”
 secreted by cells
 jellylike substance
 proteins + polysaccharides
Apoptosis
 programmed cell death
 common in developing embryo:
 especially in nervous system
 carves out digits in developing hands, feet
Hyperplasia
 accelerated division of cells
Atrophy
 decrease in size of an organ or body
tissue
 loss
of normal stimulation
muscles that
lose their nerve supply atrophy
& waste away
Cell Aging
 still a mystery
 wear-and tear theory
 mitochondrial theory
 progressive disorders in immune
system
 genetic theory: telomere clock