Topic 1 : Cells

• Ribosomes are responsible for protein synthesis in the cell.
• The nucleus stores genetic material and controls the cell's activities.
• A cell is the basic structural, functional and biological unit of life. Hence, it is the smallest unit of life.
• Cell membrane - regulates what enters or leaves the cell, protects the cell from damage, allows communication between cells
• Cells contain small structures called organelles inside them to carry out their functions
• The cell membrane is semi-permeable, which means it only allows some substances to pass through
• Cytoplasm is a jelly-like material that contains nutrients, salts and organelles.
• Cytoplasm is the site of chemical reactions.
• The Mitochondria is the powerhouse of all cells , which is where most energy is released.
• Mitochondrias are organelles that contains enzymes for respiration.
• Enzymes are proteins that function as a biological catalyst, which means they speed up chemical reactions
• The cell wall, chloroplast and vacuole are only present in plant cells.
• DNA is the actual instructions inside the chromosome stored in a long molecule.
• The cell wall provides structure and protection to the cell and is made out of cellulose
• The cell wall prevents the cell from bursting when it takes large volumes of water.
• Chloroplast is an organelle that contains green pigment called chlorophyll, which absorbs light energy for photosynthesis.
• Chloroplast contains enzymes needed for photosynthesis
• Ribosomes are small round structures that are either attached to membranes or lie freely in cytoplasm
• Bacteria is the simplest form of true living organisms.
• The vacuole is filled with cell sap to help keep the cell swollen using turgor pressure to keep the cell in shape.
• Cell sap contains water, minerals and dissolved nutrients
• The cell membrane is made up of fats and proteins
• The figure below shows all the basic parts of a microscope

  
• Bacteria cells are small with no more than 0.01mm in length. They can only be seen under high magnification of a microscope.
• Animal cells do not contain chloroplasts or mitochondria because they cannot make their own food from sunlight like plants. Instead animal cells rely on eating other organisms to get energy.
• The bacteria cell wall is made up of a mixture of proteins, sugars and lipids called peptidoglycan
• Bacteria cytoplasm contains glycogen (carbohydrate food store), lipids (fat as food stores) and ribosomes.
• Each bacterial cell contains a single chromosome made up of DNA.
• Plant cells have a rigid cell wall which gives them shape and support. The cell wall also protects the plant cell against pathogens.
• A plant cell has a large central vacuole that takes up most of the volume inside the cell. It acts as a storage area for water, nutrients and waste products.
• Bacteria DNA has no nuclear membrane
• When a bacteria reproduces, it's called binary fission
• Bacteria plasmids are small double stranded units of DNA, usually circular but sometimes linear that exists independent of the chromosome
• Each bacterial plasmids carries only a few genes and is capable of self- replication. They come in many different sizes and are used for many different purposes in biotechnology.
• Bacteria consists of a few shapes such as bacillius, coccus and spirillus
• In unicellular organisms, a cell must be able to carry out all functions
• Ribosomes make proteins from amino acids
• In multicellular organisms, cells are usually modified to carry out that one main function
• The appearance of the cell will vary depending on what the main function is
• Differentiation is the process by which a cell that is less specialized develops into a more specialized cell type