Cells

CELL STRUCTURES AND CELL FUNCTIONS 


Learning outcomes:
- Explain that the basic unit of all living things is the cell.
- Identify structure and state the function of the main organelles in the cell such as nucleus, nucleus membrane, chromatin, cytoplasm, vacuole, mitochondria, ER, ribosomes, Golgi apparatus, lysosomes, chloroplast, cell wall.
- Identify the main organelles from diagrams
- Compare and contrast plant and animal cells.

Cell Theory
- All living things are made out of cells
- Cells are the smallest working units of all living things.
- All cells come from re-existing cells through cell division.

Definition of cell
A cell is the smallest that is capable of performing life functions.

Example of cells
- Amoeba Proteus
- Plant stem
- Bacteria
- Nerve cell
- Red blood cell

Two types of cells
- Prokaryotic
- Eukaryotic

Prokaryotic
- Do not have organelles (specialized structure in cells) surrounded by membranes
- Few internal structures
- One celled organisms eg. Bacteria

Eukaryotic
- Contain organelles surrounded by membranes
- Most living organisms eg plant, animal, fungi                                              

Cell wall
- Most commonly found in plant cells and bacteria
- Surrounds the cell membrane
- Rigid structure that maintains the shape, supports and protects cells
- Permeable to small molecules and small proteins only.

Surrounding the cell

Membrane
- Selectively permeable membrane of cell that controls movement of substances in and out of the cell
- Do NOT say semi permeable, the correct term is selectively permeable or partially permeable

Nucleus
- Contain chromatins that control cell activities
- Chromatin contain DNA which is genetic material
- DNA contain instructions for traits and characteristics and to carry out the cell’s function
- Separated from cytoplasm by nuclear membrane

Cytoplasm
- Gel like mixture
- Surrounded by cell membrane
- Contains organelles

Mitochondria
- Referred to as the “powerhouse” of the cell
- The food with eat is transformed into energy (ATP) for the cell and our bodies
- Produces molecules

Endoplasmic Reticulum
- An interconnected network of tubes and vesicles
- Synthesis of proteins, fats, steroid
- Transports materials around in a cell
- Smooth type: lack ribosomes
- Rough type: ribosomes embedded in surface

Ribosomes
- Each cell contains thousands of ribosomes
- Make proteins
- Found on endoplasmic reticulum and floating throughout the cell

Golgi Bodies
- Works closely with the ER
- Primary Function is to process and package complex molecules such as proteins and fats that are made by the cell
- Brings these products to the surface of the cell where they can be secreted
- Other secretions include hormones, antibodies and enzymes
- Use the term: Golgi apparatus

Lysosome
- Contain digestive enzymes
- Digest excess or worn-out organelles, food particles and engulf bacteria or viruses
- Also help repair worn-out plasma membrane
- They also provide sugars, amino acids and bases which are the foundation of macromolecules
- Cell breaks down if lysosome explodes