cells

• the cell is the basic structural and functional unit of living organisms
• unicellular- one cell
• multicellular- many cells
• plant and animal cells are made u of structures called organelles
• organelles are specialised structures in cells that carry out one or more vital functions
• organelles are found within the cytoplasm of the cell and are surrounded by either one or two membranes
• protoplasm- cytoplasm and nucleus
• The cells that make up a multicellular organism cannot live independently.
• there are five levels of organization in multicellular organisms: (smallest to largest)

  1. Cell
  2. Tissue
  3. Organ
  4. Organ System
  5. Organism
• The cell theory:

  • All organisms are made up of cells
  • The cell is the basic unit of life in all living things
  • All cells come from existing cells
• Organelles are structures that enable the cell to live, grow and reproduce.
• cell membrane - supports and protects the cell, controls what goes in and out
• lysosome - contains digestive enzymes that destroy damaged organelles and invaders
• cytoplasm - jelly-like fluid that surrounds and protects the organelles
• nucleus - control centre of the cell that contains the DNA
• nuclear membrane - surrounds the nucleus
• nucleolus - structure in the nucleus that makes ribosomes
• vacuole - stores food and water
• Golgi body - processes and packages materials for cell
• mitochondria - power house of the cell. breaks down food to produce energy in the form of ATP
• rough endoplasmic reticulum - builds and transports substances through the cell. has ribosomes on it
• smooth endoplasmic reticulum - builds and transports substances through the cell. does not have ribosomes
• ribosome - helps make protein for cell
• cell wall - gives shape and protection to plant cells
• chloroplast - changes sunlight into sugar for plant cells. contains a green pigment called chlorophyll
• nucleoid - single, long, coiled loop of DNA. controls all cellular activities
• plasmid - small, circular piece of DNA
• flagellum - long, whip-like projection. aids in movement of bacterial cells
• capsule - slimy outer covering found in some bacteria. protects the cell
• Cells in multicellular organisms become specialised to carry out all essential life processes efficiently. Specialized cells are better able to carry out their specific functions
• Tissues - groups of specialised cells working together to carry out a specific function.
• diffusion is the net movement of molecules from an area of high concentration to an area of low concentration until the particles are evenly distributed.
• osmosis is the movement of water molecules through a differentially permeable membrane from a solution containing a lot of water molecules, to a solution containing fewer water molecules.
• the cell membrane is differentially permeable
• during active transport particles move against a concentration gradient. energy produced in respiration is used to move the particles through the membranes from areas of lower concentration to areas of higher concentration.
• Active transport is important as it allows cells to accumulate high concentrations of important substances e.g glucose, amino acids and ions