CELL BIOLOGY
CELL STRUCTURE
&
FUNCTION
Chapter 4
CELL (Plasma) MEMBRANE
• Holds contents
inside
CELL MEMBRANE
• Controls what enters and leaves cell
FLUID MOSAIC MODEL
Image from: http://bio.winona.msus.edu/berg/ILLUST/memb-mod.jpg
CELL MEMBRANES are mainly
PHOSPHOLIPIDS
POLAR HEAD“hydrophillic”
2 NON-POLAR TAILS“hydrophobic”
WATER INSIDE CELL
Water
WATER OUTSIDE CELL
Cell membranes form because
the hydrophobic tails are trying to
stay away from water!
CELL MEMBRANE
BILAYER
Made of PHOSPHOLIPIDS
& PROTEINS
MEMBRANE
PROTEINS
Image modified from:
http://bio.winona.msus.edu/berg/ILLUST/Bil&mem3.jpg
PERIPHERAL
_______________
stick only on the
SURFACE of
the membrane
Can be on inside or outside of cell
MEMBRANE PROTEINS
INTEGRAL
______________
proteins that stick
into the membrane
Can go part way
OR
all the way through
Image modified from:
http://bio.winona.msus.edu/berg/ILLUST/Bil&mem3.jpg
OTHER MOLECULES in
MEMBRANES
GLYCOPROTEINS
_____________________
Proteins with
carbohydrates attached
Function in cell recognition
Organ donors
Foreign invader ID
OTHER MOLECULES in
MEMBRANES
STEROIDS
_____________________
Lipids made with carbon rings
STRUCTURAL
Fit between hydrophobic tails
of phospholipids
SELECTIVELY PERMEABLE
“Semi-permeable”
Let’s some kinds
of molecules
pass through,
but keeps
others OUT!
Passive Transport
• Moves from an area
of greater
concentration. to
and area of lesser
concentration
• Move “down a
concentration
gradient”
Passive Transport - Osmosis
• Moves water from
area where it is
most pure to area
where it is less pure
• Hypotonic
• Hypertonic
• Isotonic
(Equilibrium)
Osmosis
• Hypertonic = less
pure (more solute)
• Hypotonic = more
pure (less solute)
• Isotonic = equal
Passive Transport – Ion Channels
• Integral proteins
form channels that
allow substances to
pass through
Passive Transport – Facilitative
Diffusion
• Proteins “carry”
substances across
the cell membrane
Active transport - endocytosis
• Movement of large
substances into the
cell
Active Transport - exocytosis
• Large particles
leave the cell
CYTOPLASM =
cytosol + organelles
CYTOSOL
_______________
Fluid portion of
the cytoplasm
ORGANELLES
_________________
small structures
with a special
function
CYTOSKELETON
= the support system of the
cell
A. Microtubules
B. microfilaments
NUCLEUS =
the “control
center” of the cell
NUCLEUS
A. Contains genetic material
CHROMATIN
(DNA & proteins)
Thin form of DNA
CHROMOSOMES
(DNA & proteins)
Thick form of DNA
NUCLEUS
B. Surrounded by a
nuclear envelope
1. contains pores
for materials to
enter and leave the
nucleus
NUCLEUS
C. Contains the
nucleolus = area of
densely-packed DNA
1. makes ribosomes
MITOCHONDRIA = the
“powerhouse” of the cell
A. Converts glucose
into ATP
1. occurs during the
process of respiration
MITOCHONDRIA
2. Reaction occurs on
the inner membrane of
the mitochondria known
as the cristae
Increases surface area for more
chemical reactions to happen
MITOCHONDRIA
B. Contains its own
DNA = mtDNA
1. mother is only
person to pass
mtDNA to offspring
-used to identify bodies
Jesse James
Ribososmes = make proteins(attach
amino acids into long chains)
A. Some ribosomes are found floating
in the cytoplasm
- make proteins for inside the cell
B. Some ribosomes are found attached
to endoplasmic reticulum
- make proteins for outside of cell
ROUGH ENDOPLASMIC
RETICULUM (ER)
= carries proteins
through the cell
(highway system)
ROUGH ENDOPLASMIC
RETICULUM (ER)
A. Has ribosomes
attached
SMOOTH ENDOPLASMIC
RETICULUM (ER) = detoxifies the cell
A. Has no ribosomes
attached
CENTRIOLES =
• Appear during cell
division to pull
chromosomes apart
CENTRIOLES
GOLGI BODY
(APPARATUS) =
• “Packaging
centers” of the
cell
•Packages molecules for
transport out of cell. Puts
proteins into vesicles.
All the cell membranes
interconnect
It’s ALL connected!
VACUOLES
• Storage for
enzymes and
waste
LYSOSOMES =
Contain enzymes use to
help break down food or
break down tissues
Peroxisomes = bags of enzymes used
to help break down chemicals
A. Used to break
down hydrogen
peroxide in cells
Cilia/Flagella= move the cell or move
substances past the cell
• Many
• short
* one or two
* long
How are
Bacteria and Plant Cells
Different from Animal
Cells?
WHICH IS BIGGER?
Plant
cell
Small
Animal
Cell
Bacteria
Smaller
Smallest
2 KINDS OF CELLS
__________________
PROKARYOTES
“No nucleus or membrane bound organelles”
They have a cell membrane around outside.
No membranes around their DNA
NO organelles surrounded by membranes inside
EXAMPLE: Bacteria
BACTERIA
• No nuclear membrane
• No membrane bound
organelles
• Cell wall
• Single loop of DNA
• Few organelles
2 KINDS OF CELLS
EUKARYOTES
_________________
“Nucleus with membrane bound organelles”
They have a cell membrane around outside.
They have a nuclear membrane around their DNA and
organelles surrounded by membranes inside
EXAMPLE: Animal & plant cells
CELL WALL
Supports and
protects cell
Outside of
cell membrane
Made of cellulose
Different than bacteria cell wall
Plasmodesmata
• Connect adjacent
plant cells
Plasmodesmata
Vacuole
• large
• Water –filled
• Provides support for
the plant (turgor)
Chloroplasts
• Green pigment
• Most numerous
Chromoplast
• Additional pigments
(red, orange, yellow)
Leucoplasts
• Store starch
PLANT CELLS
•
•
•
•
Cell wall
Plastids
Bigger vacuoles
No centrioles
2 KINDS OF ORGANISMS
_____________________
AUTOTROPHS
Can make their own food
Example:
Green Plants
__________________
2 KINDS OF ORGANISMS
HETEROTROPHS
_____________________
Can’t make their own food
Get energy by eating other
organisms
Animals & YOU
Examples: ________________
ALL LIVING THINGS
ARE MADE OF…..
CELLS
____________
CELL WALL
Supports and
protects cell
Outside of
cell membrane
Made of different
molecules than plant cell wall
CHLOROPLASTS
• Use energy from
sun to make
glucose for food
CHLOROPLASTS
• Surrounded by
DOUBLE
membrane
• Thylakoid stacks
contain enzymes for
photosynthesis
•Contain own DNA
VACUOLES
Storage for
enzymes and
waste
Vacuoles are
much larger
in plants
NO
CENTRIOLES
in Plants