• Look at the following images, what are some similarities and differences between the cells?

Name the two different types of cells

1. Prokaryotic Cells

2. Eukaryotic Cells

Unit 3: Cells

Objective: To be able to compare and contrast the differences between Prokaryotic and Eukaryotic Cells.

The Cell Theory• All living things are composed

of cells (unicellular or multicellular).

• Cells are the basic units of structure and function in living things.

• New cells are produced from existing cells.

Types of Cells• Two kinds of cells depending on whether they have a

nucleus

Prokaryote Eukaryote

Prokaryotes

The ONLY prokaryotes in the world are BACTERIA.

Prokaryotes• Genetic material

(DNA) is notcontained in a nucleus, it is free floating

PRO = No Nucleus

• Usually small and simple

What is the most important thing to remember about

Prokaryotes?

Eukaryotes• Includes protists, fungi,

plants and animals.

Eu = You

• Usually larger and more complex than prokaryotes.

• May be unicellular like an amoeba or multicellular like a plant or human.

Eukaryotes

• Contains a NUCLEUS, to hold genetic information

• Contains dozens of specialized structures called organelles.

What is the most important thing to remember about

Eukaryotes?

• You have 3 minutes to complete your Venn Diagram on Prokaryotic cells and Eukaryotic cells, then check your answers with your neighbor.

Types of Cells• Two kinds of cells depending on whether they have a

nucleus

Prokaryote Eukaryote

• No nucleus• Cells smaller• All have a cell

wall

• Nucleus• Cells larger• Organelles• Some have a cell

wall (plants)

• cells• DNA• Cell membrane• ribosomes

Eukaryotic Cell Structure

(a.k.a organelles)Objective : To be able to identify

organelles within a Eukaryotic cell

and their function.

What is an organelle?

• An organelle is a membrane bound structure that carries out specific activities for the cell (think of them as little organs with certain jobs to do).

• All organelles reside (live and float around in) the cytoplasm.

You need to know the following Organelles

associated with Animal and Plant Cells.

Discuss H.W. Cell Membrane Cell Wall Nucleus Cytoplasm Mitochondria Golgi Complex Ribosomes Smooth ER Rough ER Vacuole Lysosome Chloroplasts Cytoskeleton (not an organelle but important)

Every cell is enclosed by a

Cell Membrane

• Function:

o Regulates what enters and leaves the cell

o Provides protection and support

Nucleus – The control center• Function:

o Contains almost all of the cells DNA for coding proteins and other molecules

o DNA is found on chromosomes which contain genetic information.

Nucleus-The control center• Structure:

• Surrounded by a double membrane called a nuclear envelope. It allows materials (RNA, proteins, etc) in and out of the nucleus.

• Small internal region called a nucleolus where ribosomes are made.

Ribosomes(not an organelle, but important)

• Function:

Site of protein assembly (synthesizes proteins)

• Structure:

Small pieces of RNA and protein found throughout the cell, and on the Rough E.R.

No membrane present.

Endoplasmic ReticulumFunction:

• Site where lipid parts of cell membrane are made, along with proteins. Transports materials throughout the cell. Sends ribosomes to the Golgi Complex.

Structure:

• Rough ER-has ribosomes on surface to assemble proteins (attached to the nucleus)

• Smooth ER-NO ribosomes on surface

Do Now: Answer the following Questions.

• What is the function of the cell membrane?

• Do animals, plants, or both have a cell membrane?

• What does a plant have surrounding the cell in addition to a cell membrane?

Cell Membrane FunctionObjective: To be able to understand the

function of the cell membrane as it relates to diffusion, osmosis, and active

transport.

Copyright Pearson Prentice Hall

Cell MembraneCell Membrane

Outside of

cell

Cell

membrane

Inside of cell

(cytoplasm)Protein

channel

Proteins

Lipid bilayer

Carbohydrate

chains

Functions• Regulates what goes in and out of a cell• Maintains homeostasisCharacteristics• Lipid bilayer that carries a charge• Protein channels to help move material across the cell membrane

Copyright Pearson Prentice Hall

Cell MembraneCell Membrane

Outside of

cell

Cell

membrane

Inside of cell

(cytoplasm)Protein

channel

Proteins

Lipid bilayer

Carbohydrate

chains

Materials enter or leave a cell by:• Passive Transport (Diffusion)• Active Transport

We will discuss this further in a couple slides….

Cell membranes• Are Selectively permeable

(semi-permeable)• Allowing some

molecules in and keeps other molecules out because they have pores (holes) in it

Types of Cellular Transport

• Passive Transport(High Concentration to Low Concentration)

cell doesn’t use energy1. Diffusion (through the membrane)

2. Facilitated Diffusion (through channels)

3. Osmosis (water moving)

• Active Transport –(Low Concentration to High Concentration)

cell does use energy

- through channels

high

low

This is going to be hard work!!

high

low

Weeee!!!

Copyright Pearson Prentice Hall

Before we can discuss cellular transport, let’s review some terms.

Solution

• A solution is a mixture of two or more substances.

– Examples: Lemonade

– Solute – substance that is dissolved (powder)

– Solvent – material that is dissolving the substance (water, the universal solvent)

Concentration = the mass of solute (mass of powder) in a given volume of solution (volume of water), or mass/volume.

Keep these things in mind when thinking about how materials cross the

cell membrane

• Size if the material (molecule)

• Concentration of material on either side of the cell membrane

Copyright Pearson Prentice Hall

Passive Transport: DiffusionWhat Happens During Diffusion?

• Particles move from high concentration to low concentration (H L)

• When the concentration of the particles is the same throughout a system, the system has reached equilibrium (this is the goal!!)

2 Types of Simple Diffusion

• 1. Simple Diffusion

• Facilitated Diffusion

Copyright Pearson Prentice Hall

Simple Diffusion Through Cell Boundaries – molecules can pass directly through the cell membrane. High to low.

A B C

Time

Diffusion continued…• Some molecules are too large or charged, to

pass through the membrane using simple diffusion.

• How will the cell reach equilibrium with the external environment?

Facilitated diffusion: • Diffusion of specific particles using

protein channels found in the membrane

• Protein channels allow only specific molecules through (large or too charged)

• Still considered a form of passive transport because molecules travel from High to Low

Facilitated

diffusion(Protein channel)

Facilitated Diffusion (High Concentration to Low Concentration)

Copyright Pearson Prentice Hall

Osmosis – a special kind of diffusionWhat is osmosis?

Osmosis the diffusion of water through a selectively permeable membrane (semi-permeable) from an area of high concentration to an area of low concentration

Time

Which way will the water move?

Selectively permeable membrane

Which way will the water move?

Write a definition for the following terms related to osmosis

based on the pictures(Describe which way the

water is moving and why).

• Isotonic -

• Hypertonic -

• Hypotonic -

Q: What are two differences between diffusion and osmosis? Give an example of each.

• 1.

• 2.

Q: What does diffusion, facilitated diffusion, and osmosis all have in common?

Remember there were 2 ways materials enter or leave a cell by:

• Passive Transport (no energy needed)

• Active Transport (energy needed)

Brainstorm: When would a cell need to use energy to transport material across the cell membrane?

Active Transport•The movement of molecules

from an area of low

concentration to an area of

high concentration

•(LOW HIGH)

• Requires the use of energy (ATP)

•Three Types:

1. Protein Pump2. Endocytosis3. Exocytosis

1. Protein Pumps (active transport)

1. Protein Pumps -transport proteins that require energy (ATP) to do work.

EX: Sodium Potassium Pumps (Active Transport using proteins)

Protein changes shape to move molecules: this requires energy!

Endocytosis (Endo=in)

"Cell Eating"

2. Endocytosis: the process in

which a cell takes in bulky material, like a macromolecule.

• Uses energy

• Cell membrane

• folds around food particles

• forms food vacuole & digests food

• This is how white blood cells eat bacteria!

ENDOCYTOSIS

Exocytosis (Ex = exit/out)3. Exocytosis: the process in which

large molecules are released from the cell.

Membrane of the vacuole

surrounding the material fuses

With cell membrane and

releases the material out of the

cell

• Cell changes shape –requires energy• Ex: Hormones or wastes

released from cell