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CELLS
Chapter 3
CELL THEORY
 Cells
are the building blocks of
plants and animals.
 Cells are the smallest functioning
units of life.
 Cells are produced through the
division of preexisting cells.
 Each cell maintains homeostasis.
CYTOLOGY
 Cyto
– cells
 -ology – study of
 The study of the structure (anatomy) and
function (physiology) of cells.
 Methods of study:
 Light
microscopy – magnifies ~1000x
 Light micrograph is a photo taken from this
 Electron microscopy – uses beams of
electrons
Cell Anatomy
 Cells
are surrounded by extracellular fluid
 In most tissues, fluid is called interstitial fluid
 The inside of each cell is enclosed by the
cell membrane
 Within the cell membrane is contained the
cytoplasm
 This
contains all the organelles, or cellular
structures, and the cytosol, or the cell fluid
 The
cytoplasm also surrounds the nucleus
Cell Membrane
Plasma Membrane
 Structure:
 Phospholipid
bilayer
 Hydrophilic heads
outside
 Hydrophobic tails in
 Function:
 Physical
isolation
 Regulate exchange
 Sensitivity
 Structural support
 selectively
permeable
Organelles w/ & w/o
Membranes
Membrane Enclosed
Nonmembraneous
 endoplasmic
 cytoskeleton
reticulum
 Golgi apparatus
 lysosomes
 peroxisomes
 mitochondria
 nucleus
 microvilli
 centrioles
 cillia
 flagella
 ribosomes
 proteasomes
Membrane-Enclosed
Endoplasmic reticulum
 Structure:
 Network
of
membranes
 Connects to and
 Surrounds the nuclear
envelope
 Smooth ER (no
ribosomes; lipids and
carbohydrates made)
 Rough ER (ribosomes;
protein synthesis)
 Function:
 Synthesis
 Regions
make
proteins, lipids, and
carbohydrates
 Storage
 Transport
 Detoxification
 Toxins are absorbed
and neutralized
Membrane-Enclosed
Golgi apparatus
 Structure:
 5-6
flat membrane
disks, per set
 Contain enzymes
 Function:
 Modify
and package
secretions
 secretory vesicles
 Renew and modify
cell membrane
 membrane renewal
vesicles
 Package enzymes for
use in cytosol
 lysosomes
Membrane-Enclosed
lysosomes
 Structure:
 vesicle
 filled
with enzymes
 Function:
 Catabolic
process
 Return nutrients to
the cytosol
 Disease defense thru
endocytosis
 autolysis “suicide
packets”
Membrane-Enclosed
peroxisomes
 Structure:
 Carry
different
lysosomes
 Grow and subdivide
to create new ones
 Function:
 Absorb
and break
down organic
compounds
 More present in
more metabolically
active cells
 Produce free
radicals – ions that
have unpaired
electrons
Membrane-Enclosed
mitochondria
 Structure:
 Double-membrane
 Inner
membrane has
folds, or cristae
 Internal fluid of
mitochondria is
called the matrix
 Function:
 Provide
energy
 Puts energy in ATP
form – an energy
storing bond
 aerobic metabolism
Membrane-Enclosed
nucleus
 Structure:
 Has
nuclear
envelope around it
 envelope/
membrane is
phospholipid bilayer
 there are nuclear
pores in the nuclear
envelope (RNA
passes through this)
 Has nucleoplasm
 Function:
 Stores
info to control
synthesis of proteins
 Controls the cell’s
function
 Chemically
communicates with
cytosol through pores
No Membrane
ribosome
 Structure:
 No
membrane
 Has an activation
site/ processing
portion
 Function:
 aid
in protein
synthesis
 Participates in
transcription –
copying genetic
information