Cells Notes

Name: ______( ) Class: 1 ____ Date: ______

1.  Cells

·  Our body is made up of cells.

·  The largest cell is the ostrich egg

·  The smallest cell is the bacterium cell.

·  The longest cell is the nerve cell.

·  Unicellular organisms are made up of one cell.

·  Multicellular organisms are made up of many cells.

·  The microscope is an instrument used to help us visualize cells.

2.  What’s in a cell?

Part / Purpose / Plant / Animal
Cell membrane / It is selectively permeable to control movement of substances into and out of the cell. / √ / √
Cellulose cell wall / Provides support for plant cell. / √ / X
Cytoplasm / Fills the cell and contains substances needed for reactions in the cell. / √ / √
Nucleus / Contains genetic material.
Directs activities of the cell.
Controls cell division and growth. / √ / √
Mitochondrion
(one)
Mitochondria (many) / Cellular respiration / √ / √
Chloroplast / Contains chlorophyll and is the site of photosynthesis. / √ / X
Part / Purpose / Plant / Animal
Vacuole / Storage compartment for water, sugars and pigments. / √
Large, central / √
Small, numerous
Ribosome / Produces protein from a set of genetic instructions / √ / √

Animal cells

Plant cells

3.  Cells in a multicellular organism

·  In a multicellular organism, cells become specialized for a specific function.

·  As a cell specializes, its shape and contents change such that it becomes more efficient at its function.

Different types of cells

Red blood cell / / Biconcave-shaped to carry more oxygen
Nerve cell / / Long and branched to deliver messages
Skin cell / / Flat and close together to form a protective layer
Fat cell / / Large space for storing fat
Muscle cell / / Long with many fibers that can contract and relax

4.  Tissues

·  Cells in plants and animals are grouped together in tissues.

·  A tissue is a group of similar cells that are organized to do a specific job.

·  Examples of tissues are:

Animal tissues

-  Muscle tissue : Contract and so allowing them to move a bone/organ.

-  Nerve tissue : Carry electrical impulses from one part of the body to another.

-  Epithelial tissue : Protect the structures beneath them. E.g. skin

-  Connective tissue : Join all parts of the organism. E.g. tendons and ligaments, bones, blood.

-  Epithelial tissue : (Also known as epithelium). Protect the skin from injury.

Plant tissues

-  Epidermal tissue : (also known as epidermis). Single layer of tightly packed cells covering and protecting the young parts of the plant.

-  Xylem tissue : Transport water and dissolved mineral salts from the roots to the leaf.

-  Phloem tissue : Transport water and dissolved mineral salts from the leaf to other parts of the plant.

-  Photosynthetic tissue : (also known as mesophyll). For plants to carry out photosynthesis.

5.  Organs

·  Tissues work together to form an organ.

·  An organ is made of different tissues working together to perform a particular function.

·  Examples of organs are

-  Heart : contains muscle, nerve, epithelial and connective tissue.

-  Leaf : contains photosynthetic, xylem, phloem and epidermal tissue

6.  Organ systems

·  Different organs and tissues work together to form an organ system.

·  Examples of organ systems are:

Animal systems

-  Respiratory system : takes in oxygen from the surroundings and releases carbon dioxide and water vapour

-  Digestive system : breaks down the food we eat into simpler substances so that it can be absorbed by the blood.

-  Nervous system : controls our actions, ensures all the parts of our body work smoothly together and enables us to respond to changes.

-  Blood circulatory system : carries food, oxygen and water to various parts of the body and carries wastes away to be removed.

-  Skeletal system : supports our body, gives us shape, protects our organs and enables movement.

-  Reproductive system : enables reproduction of organism.

Plant systems

-  Shoot system : provide support, enables photosynthesis and reproduction.

-  Root system : provides plant with a supply of water and minerals

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