Chapter 2

The Functioning Cell

Grade 8 Science

The Cell Organelles

http://www.cellsalive.com/

http://www.youtube.com/watch?v=Fzj6TRnXmps&feature=related

* Every living cell, plant and animal has a cell membrane.

* For a cell to remain healthy, it must perform life functions-growth, response, excretion, exchange of gases, and nutrition. (Mr. Green)

i) Permeable: a cell membrane that allows all substances to pass through.

ii) Selectively permeable: A membrane that is selective, and only allow certain substances to enter and leave.

iii) Impermeable: a cell membrane that allows no substances to pass through.

Topic 2.1: The Cell Membrane

The cell membrane is selectively permeable.

The Cell Membrane

Cell membranes may range from impermeable to permeable.

Most are selectively or semi-permeable

The Cell Membrane

The function of the cell membrane is to control which substances enter or leave the cell.

The Cell Membrane

The structure is such that only certain substances can pass through.

The Cell Membrane

Movement of substances into and out of the cell is done in 3 ways:

DiffusionOsmosisActive Transport

Diffusion

A spreading out process.

Occurs due to the random movement of particles in a liquid or a gas.

Diffusion

No NRG is required for this processThe particles spread from a region of higher concentration to a region of lower concentration.

Diffusion

Patch medicines use this process. Example some heart medications, band-aids and many other “slow release” medications.

Diffusion

In the lungs O2 diffuses into the blood and CO2

diffuses out.Diffusion is AKA Passive transport.

http://www.youtube.com/watch?v=H7QsDs8ZRMI

Vocabulary Review

A solvent is a fluid (liquid or gas) that dissolves solute (a solid, liquid or gas) resulting in a solution. The most common solvent is water.

Vocabulary Review

Osmosis

Osmosis: the movement of water molecules from an area of high concentration to an area of low concentration.

Osmosis

Osmosis is the diffusion of water down its concentration gradient.

Osmosis http://www.youtube.com/watch?v=VVORi8Bqlss&feature=related

No NRG is required for this processOsmosis is AKA Passive Transport

Hypertonic Solutions:

Hypertonic Solutions: contain a high concentration of solute. When a cell is placed in a hypertonic solution, (salt water) the water diffuses out of the cell, causing the cell to shrivel.

A Hypotonic solution

A Hypotonic solution would cause the cell to explode!

An isotonic solution

An isotonic solution is when there is equilibrium or balance and the cell is very happy!

Active Transport

Active transport is the pumping of molecules through a membrane against their concentration gradient.

Active Transport

Carrier Proteins embedded in the cell membrane will act as ‘tunnels’ to move specific substances such as glucose.

Active Transport

This process does require NRG.

It will move molecules from a low concentration to a high concentration!

The Cell Membrane

WOW! That was cool!

Topic 2.2 How Cells Get Energy

* These notes are only an outline to assist you to explore further and make your own comprehensive notes.

The Mitochondria

Food is an energy source.

Ex. Computer - electricity

Ex. Animal- “cheeseburger”

Ex. Plant- Glucose

Topic 2.2 How Cells Get Energy

Mitochondria: “The Power House of the cell.”

This is the organelle where cellular respiration occurs

The Mitochondria

NRG produced in the mitochondria is used by the other organelles so they can perform their functions (do their jobs).

The Mitochondria

NRG is also required for vital life functions such as growth and reproduction.

(MR. GREEN)

Cellular Respiration

A chemical reaction in all living cells that will release stored NRG.

Cells will use glucose and O2 to form packages of NRG called ATP.

Cellular Respiration

2 bi-products of this process are CO2 and H2O.

The CO2 will be released by the vacuoles.

H2O will be used in the cell.

Cellular Respiration

C6H12O6 + O2 CO2 + H2O +ATP

Photosynthesis

The reverse process is called photosynthesis, which occurs in plant cells only.

Photosynthesis:

CO2 + H2O C6H12O6 + O2 sunlight

TOPIC 2.3How Cells Reproduce

Mitosis:

http://www.cellsalive.com/mitosis.htm

A: Mitosis

MITOSIS

MITOSIS: (cell Division, cell reproduction)

The process where a parent cell divides it’s contents and duplicates it’s genetic material to make 2 daughter cells. The rate of mitosis varies, depending on the cell type.

MITOSIS

Ex. Bacteria cells reproduce every 20 min.Ex. Red Blood Cells reproduce every 120 days.Ex. Liver cells reproduce every 200 days.

MITOSIS

A. Regeneration: When cells divide to replace or repair old, damaged or lost cells.

Ex: the Hydra

Ex: broken bone in animals

Ex: Bark repair on damaged trees. (Plant)

MITOSIS

Cells have a life cycle: divide-grow-die.

Different cells divide at different rates-

Ex. Your body produces approx. 1 million RBC per second!!!

B: Cancer Cells

B. Cancer Cells: Mitosis gone wild! When cells begin to divide and spread in an uncontrolled way. Factors that are known to cause this to occur are called carcinogens.

Carcinogens

Ex. Asbestos- lung Cancer Ex. Smoking- lung Cancer Ex. Pesticides- Lung Cancer Ex. Ultraviolet Radiation- skin Cancer

Cancer

Would you believe that cancer cells were once healthy cells? It’s just that suddenly, they stopped listening to the body. They started to grow out of control and crowd out some of the healthy cells nearby, which can cause big problems.

Cancer Treatments

a. Chemotherapy: chemicals are used to kill the Ca. Cells while leaving the healthy cells intact.

Cancer Treatments

b. Radiation Therapy: Using high energy particles to kill Cancer cells.

Cancer Treatments

c. Gene Therapy: (New) altering the genes that cause the cells to divide uncontrollably.

Cancer Treatments

d. Alternative Methods: such as herbal and natural techniques to help boost the immune system.