Cell Structure
& Function
Cell Theory
All living things are made up of cells.
Cells are the smallest working units of all
living things.
All cells come from preexisting cells through
cell division.
Definition of Cell
A cell is the smallest unit that is
capable of performing life
functions.
Prokaryotic
Do not have
structures
surrounded by
membranes
Few internal
structures
One-celled
organisms, Bacteria
Eukaryotic
Contain
surrounded by membranes
Most living organisms
Parts of the Cell
All working together so that the
cell can grow, work, repair, and
reproduce
Surrounding the Cell
• Outer membrane of cell that controls movement
in and out of the cell
• Double layer
Functions of Plasma Membrane
Protective barrier
Regulate transport in & out of
cell
Allow cell recognition
Receptor proteins function in cell
communication
Contains the cytoplasm (fluid in
cell)
Provide a binding site for
enzymes
Homeostasis
• Cells must keep the proper
concentration of nutrients and water
and eliminate wastes.
• The plasma membrane is
– it will allow some things
to pass through, while blocking other
things.
Structure of the Plasma
Membrane
Lipid bilayer – two sheets of
– Found around the cell, the nucleus,
vacuoles, mitochondria, and chloroplasts.
– Embedded with
proteins and
strengthened
with cholesterol
molecules.
.
What is a
?
It’s a pair of fatty acid chains and a
phosphate group attached to a glycerol
backbone.
Polar (
) phosphate heads
face out & the nonpolar (
)
fatty acids hang inside.
Membrane Proteins
Determine what
particles can pass
through the membrane.
Serve as
(may
speed reactions).
Act as
that are recognized by
chemicals and molecules from the inside
and the outside of the cell (the immune
system).
structure & support
Polar
nonpolar
identification
Receptors, enzymes, crossing
(outside the cell)
(inside the cell)
Nucleus
Directs cell activities
Contains genetic
material - DNA
Separated from cytoplasm by nuclear
membrane • Surrounds nucleus
• Made of two layers
• Openings allow material to
enter and leave nucleus
Inside the nucleus
Made of DNA
Contain instructions for
traits & characteristics
Contains RNA to build
proteins
Endoplasmic Reticulum
Smooth type:
&
synthesis &
breakdown (lipid metabolism); lacks ribosomes
Rough type: the cell’s
ribosomes embedded in surface
factory;
Ribosomes
Each cell contains
thousands
Found on ribosomes &
floating throughout the cell
Mitochondria
chemical reactions breaking
down fats & carbohydrates
Controls level of water and
other materials in cell
Recycles and decomposes
proteins, fats, and
carbohydrates
Golgi Bodies
Proof reads proteins & makes minor
corrections
Move materials within the cell
Move materials out of the cell
Lysosomes
‘Digests’proteins, fats, and
carbohydrates
Transports undigested
material to cell membrane
for removal
Cell breaks down if
lysosome explodes
Hydrolytic
enzymes
Vacuoles
Also used for digestion,
and waste removal
Contains water solution
Help plants maintain shape
Cytoplasm
Gel-like mixture mostly water
Protects & stabilizes
organelles
Surrounded by cell
membrane
Cells break down food
sources i.e. glucose,
fats, and protein
&release their stored
energy.
Produce energy storage
molecules called ATP –
adenosine triphosphate.
is required
for these processes.
Includes
, the
breakdown of glucose,
and
.
Some bacteria and yeast
are examples of
anaerobes.
Occurs in the cytoplasm.
Breaks down
2 molecules of
carbon structures)
(3-
2
molecules are
formed.
2
energy shuttles are
also formed.
Pyruvate can be metabolized by:
or
Alcoholic Fermentation produces
ethyl alcohol and CO2
Lactic acid fermentation produces
lactic acid.
Requires oxygen.
Most organisms are aerobes.
Equation for Aerobic respiration:
If O2 is present following
glycolysis, pyruvate is
modified and enters the
mitochondria.
Here food is broken down
completely into CO2.
Energy storage molecules like
NADH and ATP are produced.
Energy carriers like
NADH drop off
electrons
Energy
from
electrons
ATP
ATP
ATP
As the electrons “fall” to
oxygen energy is stored
in a payload of ATP.
Oxygen picks up
electrons and hydrogen
ions to form water.
O2
H 2O
ATP is the cells
.
such as
metabolism, transport, and
movement is powered by
the
.
Ribose – a 5-carbon sugar
Adenine – a N-base
3 phosphate groups
ATP is constantly being used and remade in
the cell.
Energy is released or stored by breaking or
making a phosphate bond.
Summary of Cellular Respiration
Respiration
Process
Where
Process
Occurs
Anaerobic
Glycolysis &
Cytoplasm
Fermentation
Aerobic Krebs
Cycle and
Mitochondrion
Electron
Transport
Net Gain of
ATP
Per Glucose
2 ATP
36 ATP
Phospholipid
Bilayer
&
transport mechanisms
move molecules across the membrane
Passive
Active
Requires
Molecules move
from area of
concentration
Diffusion is a
process which means
no energy is used to
make the molecules
move, they have a
natural
Molecules will randomly move through the
pores in
.
concentration of solute 
concentration of solute
Some
do not
extend through the
membrane.
They bond and drag
molecules through
the lipid bilayer and
release them on the
opposite side.
Other
change
shape to move
materials across
the cell
membrane
Along the concentration gradient
Diffusion of
across a membrane
Moves from HIGH
water potential (
) to LOW
water potential (
)
Solution
NO NET MOVEMENT OF
H2O (equal amounts
entering & leaving)
Solution
Solution
Requires energy or
Moves materials from
concentration
to
concentration gradient
moving things out.
Molecules are moved out of
the cell by vesicles that
fuse with the plasma
membrane.
Active Transport
This is how many
hormones are secreted.
moving things in
Pinocytosis
Most common form of
endocytosis.
Takes in molecules
dissolved in H2O.
Phagocytosis
Ingestion of solid particles by
endocytosis
Fuses with lysosomes and the
material is degraded