Cells

Mr Heffernan

Cells

• What are cells? – Cells are the basic building blocks of living thing.

• Can we see cells with our eyes? – No, we need to use a microscope because they are too

small.• How are new cells formed? – New cells are formed by a process called cell division.

• Do animal and plant cells have the same structure? – No, some of the parts are the same but plant cells have

a cell wall animal cells do not.

Cell Division

• Cells can divide to form two identical cells.

• This process is called Cell Division.

• Cell division allows living things to grow.

• Humans grow from a single cell called a zygote by cell division.

One Cell divides

To form two identical cells

Animal Cells• Animal cells have three main

parts – A cell membrane – A nucleus – Cytoplasm

• The cell membrane is a very thin layer surrounding the cell.

• The nucleus is the control centre of the cell.

• Cytoplasm is a watery fluid between the nucleus and the cell membrane.

Cell membrane

Nucleus

Cytoplasm

Plant Cells

• Plant cells also have a cell membrane, a nucleus and cytoplasm.

• Plant cells also have a cell wall.

• The cell wall is found outside the cell membrane in plant cells.

Cell membrane

Cytoplasm

Nucleus

Cell Wall

Tissues

• Plants and animals contain many different types of cells.

• Cells on the inside of your cheek are very different from red blood cells.

• A group of similar cells which carry out the same function are called Tissues.

Examples of Tissues

• Tissues are a group of cells which carry out the same function

Red blood Cells

Bone CellsCheek Cells

Organs

• A structure that contains two or more tissues working together is called an organ.

• Some examples of organs are ―Lungs―Heart―Brain―Kidneys―Leaves―Roots

Is this what a heart looks like?NO! It looks more like this and it is about the size of your closed fist

Organs 2

Systems

• A system is a number of organs working together.

• Examples of systems in the human body are— The respiratory system— The digestive system— The reproduction

system

For more information on the digestive system follow the link http://www.daviddarling.info/encyclopedia/D/digestive_system.html

Cells Tissues Organs Systems Organisms

Organisms

• An organism is a living thing.• Organisms are composed of a number of

systems.• These systems work together to allow the

organism to function properly and stay alive• Organisms are organised as shown below