Chapter 2 The Functioning Cell Grade 8 Science

The Cell Organelles Xmps&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: Diffusion Osmosis Active 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 process The 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 O 2 diffuses into the blood and CO 2 diffuses out. Diffusion is AKA Passive transport. 7QsDs8ZRMI

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 No NRG is required for this process Osmosis 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 O 2 to form packages of NRG called ATP.

Cellular Respiration 2 bi-products of this process are CO 2 and H 2 O. The CO 2 will be released by the vacuoles. H 2 O will be used in the cell.

Cellular Respiration C 6 H 12 O 6 + O 2 CO 2 + H 2 O + ATP

Photosynthesis The reverse process is called photosynthesis, which occurs in plant cells only. Photosynthesis: CO 2 + H 2 O C 6 H 12 O 6 + O 2 sunlight

TOPIC 2.3 How Cells Reproduce Mitosis:

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.