Cells

And

Cellular Transport

Where does the name “cell” come from?

• “Cells” were named by Englishman Robert Hooke in 1665.

• He observed that cork wood looked like monk’s cells in a monastery.

The Cell Theory

1. The cell is the basic unit of structure and function.

2. All organisms are made of one or more cells.

3. All cells come from pre-existing cells.

This is the human Herpes Virus!

Exceptions to the Cell Theory

1. Viruses!! They have DNA and/or RNA inside a protein shell. They are capable of reproduction inside another living cell, but not on their own.

2. Mitochondria and chloroplasts have their own DNA and can reproduce inside a cell.

3. Obviously….the first cell.

Levels of Organization…ContinuedOrgans

Organ Systems

Organism

Types of CellsProkaryotic Cells• The first and most

primitive cells

• Lack a nucleus and other membrane bound organelles (mitochondria, etc)

• Bacteria are the ONLY prokaryotes

Eukaryotic Cells• Most organisms have

eukaryotic cells (ex: all plant and animal cells!)

• All genetic material is contained in a nucleus

• Have many membrane bound organelles

1.

2.

3.

4.

5.

6.

7.8.

9.

10.

11.

12.

13.

1.

2.

3.

4.

5.

6.

7.

8.9.

10.

11.

12.

Lysosome13.

14.

Cell Organelle FunctionsCell Membrane: provides a barrier between the cell

and the environment.Vacuole: stores water, minerals and sometimes

food.Lysosome: a sac of digestive juices (acts like a

stomach).Mitochondria: where cellular respiration takes

place, our energy comes from here!Golgi Bodies: “packages” cell material, wraps a

membrane around protiens and materials made in the cells.

Cell Organelle FunctionsCentrioles: (ONLY in animal cells) help the cell

undergo cellular division, or mitosis.Cytoplasm: jelly like material that fills in the extra

space in a cell, also where most of our chemical rxns occur.

Ribosomes: site of protein production.Endoplasmic Reticulum (ER): Transports materials

around the cell.Nuclear Membrane: separates the nucleus from the

rest of the cell.

Cell Organelle Functions

Nucleolus: dense part of a nucleus, where RNA is made.

Nucleus: stores DNA, controls most cellular activities.

Cell Wall: rigid structure around the outside of plant cells to give them structure and support.

Chloroplast: site of photosynthesis, makes sugar molecules using sunlight, water and carbon dioxide.

The Cell Membrane

Also called:

The Lipid Bi-Layer, Fluid Mosaic Model,

And

The Plasma Membrane

Cell membranes are “semi-permeable” because they allow some molecules to pass

through, while others cannot.

A barrier that separates a cell from its surroundings.

Components of the Cell Membrane

MOVIE

Just the lipids!

The lipid bilayer consists of two (bi) layers of phospholipids.

The ____________ heads point to the outside and the ____________ tails point to the inside of the membrane.

Various _________ molecules are embedded in the membrane as well

Membrane Facts!

hydrophilichydrophobic

proteins

Cell Membrane Cross Section

This is the Lipid Bilayer. Why does this name fit?

This is one of many kinds on proteins embedded in the membrane.

Membrane Proteins

Marker Proteins: They are like a “name tag” for the cell.

Membrane Proteins

Continued…Channel Proteins: These proteins reach through the membrane to both sides. It allows specific molecules to pass from one side of the membrane to the other.

YouTube - Cell membrane animation

Transport Proteins: Proteins that physically move molecules across the membrane. There are a variety of types!

Cellular Transport

Cellular Transport

• Passive Transport does NOT require cellular energy (ATP)

• Moves molecules from high to low concentration

• Active Transport DOES require ATP

Diffusion

The movement of molecules from an area of HIGH concentration to an area of LOW concentration.

The direction of diffusion is called the concentration gradient.

This is a form of passive transport.

_________ molecules CANNOT diffuse, regardless of concentration gradient!

LARGE

What types of molecules can NOT diffuse??

Even though all molecules seem small to us, they do vary in size a lot!

Large molecules can NOT cross the cell membrane!

Large molecules must rely on active transport.

Cellular Transport

• Passive Transport does NOT require cellular energy (ATP)

• Moves molecules from high to low concentration

Examples:• Diffusion

• Active Transport DOES require ATP

OsmosisOsmosis is a special name for the diffusion of ________ across a semi-permeable membrane.

Because this requires NO ATP, it is called _____________.

WATER

Passive transport

Water always moves from low to high SOLUTE

concentration. This is osmosis!

•If a cell is placed in a solution with a LOWER concentration of solute, it will _________ (water will _________ the cell)

•If a cell is placed in a solution with a HIGHER concentration of solute, it will _________ (water will _________ the cell)

swellenter

shrivelleave

Cellular Transport

• Passive Transport does NOT require cellular engery (ATP)

• Moves molecules from high to low concentration

Examples:• Diffusion• Osmosis

• Active Transport DOES require ATP

PhagocytosisThis is “cell eating”. A cell engulfs (or wraps itself around) a food particle thus creating a food vacuole.

This is a type of ACTIVE TRANSPORT!

Clip

Cellular Transport

• Passive Transport does NOT require cellular engery (ATP)

• Moves molecules from high to low concentration

Examples:• Diffusion• Osmosis

• Active Transport DOES require ATP

Examples:• Phagocytosis

PinocytosisThis is “cell drinking”. The cell membrane pinches inward (like a pin poking a hole) and creates a vacuole of dissolved particles.

This is a type of ACTIVE TRANSPORT!

Clip

Cellular Transport

• Passive Transport does NOT require cellular engery (ATP)

• Moves molecules from high to low concentration

Examples:• Diffusion• Osmosis

• Active Transport DOES require ATP

Examples:• Phagocytosis• Pinocytosis

Membrane Proteins Using Cellular Energy: The proteins we learned about in the membrane

sometimes require energy!

Cellular Transport

• Passive Transport does NOT require cellular energy (ATP)

Examples:• Diffusion• Facilitated Diffusion• Osmosis

• Active Transport DOES require ATP

Examples:• Phagocytosis• Pinocytosis• Use of membrane

proteins (ex: transport proteins)

Moving Molecules Against the Concentration Gradient

•The sodium ions are more highly concentrated on the inside of the cell.

•With the help of ATP, the sodium ions are still pumped back into the cell (against the concentration gradient).

This is like moving against the flow of traffic!

It takes ENERGY!

Cellular Transport

• Passive Transport does NOT require cellular energy ATP)

Examples:• Diffusion• Facilitated Diffusion• Osmosis

• Active Transport DOES require ATP

Examples:

• Phagocytosis

• Pinocytosis

• Use of membrane proteins (carrier proteins, etc)

• Moving molecules from low to high concentration