Cell Structure and Function
Two Basic Cell Types:
Prokaryotic vs. Eukaryotic Cells
Two Basic Types
• Remember….cells are the basic unit of life for
ALL living things.
• There are two basic types of cells:
1. Prokaryotic cells – found in bacteria
2. Eukaryotic cells – found in protists, fungi, plants
and animals
As we discuss the differences between Eukaryotic and
Prokaryotes fill in you concept map.
Prokaryotes
Eukaryotes
Nut-Nucleus
same
No Nut-No
Nucleus
Characteristics Shared
ONLY WRITE THE BOLDED WORDS IN VENN DIAGRAM
• same basic functions
• Plasma membrane to control what enters and
leaves the cell
• “Filled” with cytoplasm
• Contain ribosomes to make protein
• Contain DNA
What Makes Eukaryotic Cells
Different?
ONLY WRITE THE BOLDED WORDS IN VENN DIAGRAM
• Much larger
• Much more complex
• Contain a nucleus to house the genetic material (DNA)
• Linear DNA packaged into chromatin found inside the
nucleus
• Contains organelles-specialized structures in the
cytoplasm
• Not all have a cell wall
What Makes Prokaryotic Cells
Different?
ONLY WRITE THE BOLDED WORDS IN VENN DIAGRAM
•
•
•
•
•
•
Much smaller
Less complex
No nucleus
Circular DNA that is found in the cytoplasm
No organelles found in the cytoplasm
Surrounded by a cell wall
Eukaryotic Cells
What does size have to do with it?
• Prokaryotic cells are much smaller than
eukaryotic cells. Why?
– Smaller surface area to volume allows nutrients to
easily and quickly reach inner parts of the cell.
– Eukaryotic cells are larger and can not pass
nutrients as quickly. They require specialized
organelles to:
• carry out metabolism
• provides energy
• transport chemicals throughout the cell
Why do we call them cells?
• In 1665, Robert Hooke was the first to view
cells from cork (dead plant material).
• He called them “cells” because they looked
like tiny rooms.
Cell Theory
1. All living things are made of CELLS
2. CELLS are the basic units of structure and
function in living things
3. New CELLS are produced from existing CELLS
About Cell Membranes
1.All cells have a cell
membrane
2.Functions:
a.Controls what enters and
exits the cell to maintain
an internal balance called
homeostasis
b.Provides protection and
support for the cell
TEM picture of a
real cell membrane.
3.Structure of cell membrane
Lipid Bilayer -2 layers of
phospholipids
a.Phosphate head is polar
(water loving)
b.Fatty acid tails non-polar
(water fearing)
c.Proteins embedded in
membrane
Phospholipid
Lipid Bilayer
• 4. Cell membranes have pores (holes) in it
a.Selectively permeable: Allows some molecules
in and keeps other molecules out
b.The structure helps it be selective!
Pores
Polar heads Fluid Mosaic
love water
Model of the
& dissolve. cell membrane
Non-polar
tails hide
from water.
Carbohydrate cell
markers
Proteins
Membrane
movement
animation
Label the cell membrane in your notes
Outside of cell
Proteins
Lipid
Bilayer
Transport
Protein
Animations
of membrane
Go to structure
Section:
Carbohydrate
chains
Phospholipids
Inside of cell
(cytoplasm)
•Animations of Active
Transport & Passive
Transport
Types of Cellular Transport
•
Passive Transport
cell doesn’t use energy
1. Diffusion
2. Facilitated Diffusion
3. Osmosis
•
Weeee!!
!
high
low
Active Transport
cell does use energy
1. Protein Pumps
2. Endocytosis
3. Exocytosis
This is
gonna
be hard
work!!
high
low
Passive Transport
•
•
•
cell uses no energy
molecules move randomly
Molecules spread out from an area of high
concentration to an area of low
concentration.
• (HighLow)
•
Three types:
3 Types of Passive Transport
1. Diffusion
2. Facilitative Diffusion – diffusion with the
help of transport proteins
3. Osmosis – diffusion of water
Passive Transport:
1. Diffusion
Simple Diffusion
Animation
1. Diffusion: random movement of
particles from an area of high
concentration to an area of low
concentration.
(High to Low)
•
Diffusion continues until all
molecules are evenly spaced
(equilibrium is reached)-Note:
molecules will still move around but
stay spread out.
http://bio.winona.edu/berg/Free.htm
Passive Transport:
2. Facilitated Diffusion A
2. Facilitated diffusion: diffusion
of specific particles through
transport proteins found in
the membrane
a. Transport Proteins are
specific – they “select” only Facilitated
certain molecules to cross
diffusion
the membrane
(Channel
Protein)
b.Transports larger or
charged molecules
Carrier Protein
B
Diffusion
(Lipid
Bilayer)
Passive Transport:
3. Osmosis
Osmosis
animation
• 3.Osmosis: diffusion of
water through a
selectively permeable
membrane
• Water moves from high to
low concentrations
•Water moves freely
through pores.
•Solute (green) to large
to move across.
•
Hypotonic Solution
Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions
Hypotonic: The solution has a lower concentration of
solutes and a higher concentration of water than
inside the cell. (Low solute; High water)
Result: Water moves from the solution to inside the
cell): Cell Swells and bursts open (cytolysis)!
•
Hypertonic Solution
Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions
Hypertonic: The solution has a higher concentration
of solutes and a lower concentration of water than
inside the cell. (High solute; Low water)
shrinks
Result: Water moves from inside the cell into the
solution: Cell shrinks (Plasmolysis)!
•
Isotonic Solution
Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions
Isotonic: The concentration of solutes in the solution
is equal to the concentration of solutes inside the cell.
Result: Water moves equally in both directions and
the cell remains same size! (Dynamic Equilibrium)
What type of solution are these cells in?
A
B
C
Hypertonic
Isotonic
Hypotonic
Osmosis Video
• Osmosis Rap
Osmosis worksheet
Active Transport
•cell uses energy
•actively moves molecules to where they are
needed
•Movement from an area of low concentration
to an area of high concentration
•(Low  High)
•Three Types:
3 Types of Active Tranport
• 1. Protein Pumps
• 2. Endocytosis:
• 3. Exocytosis
Types of Active Transport
1. Protein Pumps transport proteins that
require energy to do
work
•Example: Sodium /
Potassium Pumps
are important in nerve
responses.
Sodium
Potassium Pumps
(Active Transport
using proteins)
Protein changes
shape to move
molecules: this
requires energy!
Types of Active Transport
• 2. Endocytosis: taking bulky
material into a cell
• Uses energy
• Cell membrane in-folds
around food particle
• “cell eating”
• forms food vacuole &
digests food
• This is how white blood
cells eat bacteria!
Types of Active Transport
3. Exocytosis: Forces material
out of cell in bulk
• membrane surrounding the
material fuses with cell
membrane
• Cell changes shape –
requires energy
• EX: Hormones or wastes
released from cell
Endocytosis &
Exocytosis
animations
Exocytosis and Endocytosis


Exocytosis – process of a cell releasing materials
(exiting)
Endocytosis – process of cell taking materials in
(entering)
Exocytosis
How Organisms Deal with
Osmotic Pressure
•
Paramecium
(protist) removing
excess water video
•Bacteria and plants have cell walls that prevent
them from over-expanding. In plants the pressure
exerted on the cell wall is called tugor pressure.
•A protist like paramecium has contractile vacuoles
that collect water flowing in and pump it out to
prevent them from over-expanding.
•Salt water fish pump salt out of their specialized
gills so they do not dehydrate.
•Animal cells are bathed in blood. Kidneys keep the
blood isotonic by remove excess salt and water.
Cellular Transport Review Diagrams
Active Transport Examples
Diffusion/ Facilitated Diffusion
Osmosis
Cell Transport Concept Map
Name
Date
Cell transport involves the
exchange of molecules
through the
Cell membrane
Against the
concentration gradient
(low to high)
Active
transport
requires
ATP:
Energy
Down the
concentration gradient
(high to low)
Passive
transport
large molecules
transported by
small molecules move
through
Proteins
moved by
Endocytosis
in
Diffusion
Exocytosis
out
Small molecules
move through
of water
Larger molecules
move through
Osmosis
examples
Example:
Glucose
Amino acids
Ions
Word Bank:
Active Transport
Passive Transport
Diffusion
Food
Bacteria
Facilitated Diffusion
ATP Energy
Glucose/Amino Acids/Ions
Wastes/Secretions
Example:
Wastes
Secretions
Cell
membrane
Proteins
also called
Cell Membrane (2X) Osmosis
Food/Bacteria
Proteins (2X)
Endocytosis
Exocytosis
Facilitated
Diffusion