1. Cells
The basic units of life

2. Our learning objectives for this unit are:
By the end of this unit you should be able to 
1- Describe what a cell is.
2-Name some of the important cell organelles and state their jobs.
3-Explain the 3 main difference between an animal cell and a plant cell.
4- Specialized animal and plant cells, with their special jobs and adaptations.
5- cells  tissues  organs organ systems organisms

3. What are cells ?
1- Cells are the Basic ( building) units of EVERY living organisms.
2-Cells are the smallest & the most important part of the body.
3- All living organisms are made of cells.
4-Cells are the basic units
of structure & function
in any living organism.

4. Living organisms can be divided according to the number of cells they’re made of into:
Organisms made of one cell—unicellular organisms
Ex: bacteria
Organisms made of many cells—multi cellular organisms
Ex: plants, animals

5. Cell Parts and Their Functions:
Inside each cell, there are little organs & each of them has a special job to do to keep the cell alive.
Those specialised cell organs( parts) are called … cell organelles—“little organs”

6. Cell membrane All cells have a cell membrane.
The main job of the cell membrane is to determine what goes in and out of the cell.
It also prevents the content of the cell from escaping.

7. How the cell membrane controls what goes in & out of the cell
Cell membranes have tiny holes called “pores”.
These pores let certain small dissolved substances like water, oxygen and carbon dioxide go in and out the cells.
These pores also prevent harmful chemicals from going into the cells.

8. Cytoplasm The liquid inside the cell.
it’s a jelly-like liquid that hold the cell organelles in position ( hold the other cell organelles in their places..
It’s 90% water and the rest is lipids, sugars, proteins and salts.
Most of the important chemical reactions that keep the cell alive happen inside the cytoplasm.

9. Nucleus The control center of the cell.
It’s the most important cell organelle.
Most cells have nuclei (except red blood cells).
the nucleus controls the cell structure & functions.
the nucleus carries the genetic information(DNA) that passes the genetic information from one generation to another.

10. Mitochondria The “powerhouse” of the cell.
Respiration takes place in the mitochondria where glucose & oxygen undergo chemical reactions.
As a result, carbon dioxide, water & energy are released.
This energy is used by the cells for all of the important life processes.

11. Respiration The word equation for respiration is:
The chemical reaction that releases ENERGY from food ( glucose).
The word equation for respiration is:
Glucose+ oxygen  carbon dioxide + water ( energy)
Oxygen  the gas you breathe in
Glucose  product of digestion of carbohydrates

12. Plant cells
Plant cells have several organelles that animal cells DON’T have.
These 3 organelles are:
1-Cholorplasts.
2-Cell wall.
3- Large cell vacuole.

15. Cell wall Made of cellulose( plant starch). It’s non-living.
Non-selective( unlike the cell membrane, can let anything in and out).
Gives the shape of plant cells( oval, round, elongated or rectangular).
Give strength to the cell.

16. NOTE THAT 
Plant cells have a cell wall, then, a cell membrane on their outside.
Animal cells ONLY have a cell membrane on their outside.

17. Large cell vacuole A large space that’s found in plant cells.
It’s filled with a liquid called “cell sap”.
The large vacuole in each plant cell has
important jobs to do:
1- For storage of sugars.
2-To exert pressure on the cytoplasm to keep the cell firm ( strong).

18. Chloroplasts They are filled with chlorophyll.
Chlorophyll is a green pigment that’s necessary for photosynthesis.
This green pigment ( dye) is what absorbs sunlight for photosynthesis.
Chloroplasts are numerous in palisade cells
( cells in the middle of the leaf).

19. A plant cell under the microscope.
The chloroplasts filled with chlorophyll pigment show.

20. Differences between plant & animal cells
Plant cells
Animal cells
1-Have a cell wall and a cell membrane
1-Have a cell membrane ONLY
2-Contain chloroplasts filled with chlorophyll pigment.
Carry out photosynthesis to make their food producers
2-No chloroplasts
Cannot carry out photosynthesis consumers
3-Have a large vacuole.
3-Have no large vacuole.
Have a definite shape
Have no definite shape

21. A plant cell example: Palisade cell
An animal cell example:
liver cell
A plant cell example: Palisade cell

22. Adaptations in cells
Adaptation: is the change of an existing design for a particular task.
Many cells are adapted to perform more specific tasks, some of these cells are:
Animals
Plants
Red blood cells.
Root hair cells.
White blood cells.
Palisade cells
Smooth muscle cells.
Xylem vessels.
Nerve cells.
Ciliated epithelial cells.

23. Red blood cells Biconcave discs( flying saucer shape).
The function of red blood cells is to carry oxygen around the body.
Red blood cells contain hemoglobin.
Hemoglobin is a protein bound with iron. It is what binds to oxygen & carries it around the body.
NOTE:
RBCS DON’T HAVE A NUCLEUS.
to leave enough space for the carrying of as much oxygen as possible.

24. White blood cells
White blood cells have an irregular shape ( not definite).
JOB of white blood cells : TO defend the body against infections.
There are many types of white blood cells:
1- Lymphocytes: produce antibodies to attack harmful bacteria.
2- phagocytes: eat the harmful microorganisms

26. Smooth muscle cells Spindle shaped cells.
They line together forming a muscular tissue around the wall of the oesophagus, stomach & intestines ( organs of the digestive system)
They help to move the food through the digestive system organs.

27. Nerve cells Neurons  Spinal cord  Brain
Nerves are made of nerve cells ( Neurons).
Those cells have long, thread-like extensions that are connected to other nerve cells in the spinal cord.
The nerve cells in the spinal cord are then connected to the nerve cells in the brain.
Neurons  Spinal cord  Brain

28. Ciliated epithelial cells
Cilia are very thin extensions of the cytoplasm.
If cells have one surface covered with cilia, they are called “ciliated cells”.
Cilia can trap dirt & dust.
Cells of the respiratory system , like throat cells & bronchi cells are ciliated to clean the air entering the lungs from dust.

29. Special plant cells
1- Root hair cells: Adaptation: Root hair cells have thin extensions to: 1- Allow them to grow easily between soil particles to anchor the plant better. 2-Give the root a large surface area to absorb water & mineral salts from the soil. 3- Root hair cells DON’T have chloroplasts..but why ???

30. 2-Palisade cells The cells in the middle part of the leaf.
There shape allows them to pack close to each other in the upper side of the leaf.
They form a tissue called palisade mesophyll
Adaptation: palisade cells have a large number of chloroplasts
to help them absorb as much sunlight as they can for photosynthesis.

31. 3-Xylem vessels Tubes that carry water to all parts of the plant.
They are made of dead cells which gives strength to the plant.
Xylem vessels extend from the roots , through the stem and all the way up to the leaves.

32. Cells, tissues, organs & organisms
Organ systems
Living organism

33. Cells  organs organ systems organism
As we studied before, plants have different types of cells.
The palisade cells in the leaf work together to make tissues, these tissues together make the “leaf organ”.
Same thing happens in the root organ, the stem organ and the flowers.
All of these organs together make” the PLANT A living organism”

34. Same for animals
Animals have different kinds of cells in their bodies that group together to form tissues.
These tissues group together to form organs.
These organs group together to form organ systems.
These organ systems group together to form an organism.
Example:
stomach cells  tissues stomach
( an organ, with the other digestive organs)
the digestive system( with the other body systems)
the human body