1.1 CELLS

WHAT ARE CELLS??????

•Cells are the basic unit of life

•All living things are made up of cells

•Each cell contains small parts called ORGANELLES which have special functions to maintain all life processes such as:

a) intake of nutrients e) exchange of gasesb) movement f) waste removalc) growth g) reproductiond) response to stimuli

•There are two types of cells: Animal cells and Plant cells•Plant and animal cells have some organelles in common, others vary

ANIMAL CELL

Cytosol

Cytoplasm refers to the jelly-like material with organelles in it.

If the organelles were removed, the soluble part that would be left is called the cytosol. It consists mainly of water with dissolved substances that organelles need to survive

The nucleus is the control center of the cell. It is the largest organelle in the cell and it contains the DNA of the cell. The DNA of all cells is made up of chromosomes.  DNA (Deoxyribonucleic Acid) contains all the information for cells to live, perform their functions and reproduce. 

Inside the nucleus is another organelle called the nucleolus. The nucleolus is responsible for making ribosomes.

Nucleus

MitochondriaMitochondria are the powerhouses of the cell.

Convert the energy in food molecules into chemical energy cells can use Every type of cell has a different amount of mitochondria. There are more mitochondria in cells that have to perform lots of work, for example- your leg muscle cells, heart muscle cells etc. Other cells need less energy to do their work and have less mitochondria.

Endoplasmic reticulum (ER)- It is a network of membranes throughout the cytoplasm of the cell. There are two types of ER.

When ribosomes are attached it is called rough ER and smooth ER when there are no ribosomes attached. 

The rough endoplasmic reticulum is where most protein synthesis occurs in the cell. The function of the smooth endoplasmic reticulum is to synthesize lipids (fats) in the cell.

                                                    

                                        

It is organelle in the cell that is responsible for modifying, sorting and correctly packaging the proteins produced in the ER so that they can be delivered to other parts of the cell or outside of the cell.   

Golgi complex/apparatus

Cell Membrane

– A protective barrier around the cell – Is made of a double layer of lipids

– Lipids are fat like substance that DO NOT dissolve in water

– It is designed to allow different substances to move through it

• How do substances move through the cell membrane? a) Osmosis – water moves from a high concentration to

a low concentrationB) Diffusion- When a dissolved substance moves from a high concentration to a low concentration

The fluid mosaic model

•In this model the cell membrane is seen as a bilayer of phospholipids (fat molecules) in which protein molecules are embedded.

•The cell membrane is the gate keeper of the cell. It controls the movement of substances into and out of the cell.

                      This term literally means "small vessel". This organelle helps store and transport products produced by the cell.

Some vesicles deliver materials to parts of the cell and others transport materials outside the cell in a process called exocytosis

Vesicles

•function as the cell's clean up system.

•digest bacteria or damaged organelles and recycle the proteins and lipids from them for use elsewhere in the cell

Lysosomes

Cytoskeleton

• All cells have a cytoskeleton

• Made of protein filaments

• Helps keep the cell’s shape

•Within an animal cells only

•The two centrioles are arranged such that one is perpendicular to the other.

•During animal cell division, the centrioles are responsible for making the "spindle" which separating replicated (copied) chromosomes.

Centrioles

•are thread-like projections of certain cells that beat in a regular fashion to create currents that sweep materials along

                                         

Cilia

•may extend to the rear of a cell and push it forward by snakelike wriggling, or it may stick out in front and draw a cell along.

Flagella

PLANT CELL

A rigid frame around the cell that provide strength

Only in plant cells

                      

•The cell organelle in which photosynthesis takes place. Light energy of the sun is converted into chemical energy. • Chloroplasts are found only in plant cells not animal cells•Chloroplasts contain tiny pigments called chlorophylls. Chlorophylls are responsible for trapping the light energy from the sun and give plants their green colour.

Chloroplast

• are storage organelles in cells. •may store water, waste products, food, and other cellular materials. •In plant cells, the vacuole may take up most of the cell's volume.

Vacuoles

Differences between Animal & Plant cells.

Feature Animal Cells Plant Cells

PhotosynthesisNo chloroplasts

Chloroplasts capture light energy

Vacuole Size

Small Large

Cell Division

Have centrioles to make spindle fibers

Cell walls

No cell walls Cell walls are present

LysosomesPresent Are not present

No centrioles

HOMEWORK:

p. 16 #1-3, 5

Worksheet: Colour the cell parts the appropriate colour and answer the questions