Cell Biology (AQA)

• All living things are made out of cells.
• Cells can either be prokaryotic or eukaryotic.
• The nucleus contains the genetic material that controls the cell's activities.
• Cytoplasm is a gel-like substance in which most of the chemical reactions takes place.
• The cell membrane holds the cell together and controls which substances can go in and out of the cell.
• Plant cell wall is made up of cellulose.
• The permanent vacuole of the plant cell contains cell sap (solution made up of sugar and salts)
• Photosynthesis occurs in the chloroplasts
• chloroplasts contain a green pigment called chlorophyll, which absorbs sunlight for photosynthesis
• Bacterial cells don't have a nucleus. They have a singular circular strand of DNA that floats freely in the cytoplasm.
• magnification = image size / real size
• the function of the sperm cell is to get male DNA to the female DNA
• the sperm cell has a long tail & a streamlined head to help it swim to the egg
• sperm cells have lots of mitochondria
• sperm cells also have enzymes in its head to digest the egg cell membrane.
• The function of the nerve cell is to carry electrical signals from one part of the body to another
• nerve cells are long in structure and have branched connections at their ends to connect to other nerve cells. This creates a network throughout the body
• function of muscle cells is to contract quickly
• muscle cells are long and contain lots of mitochondria to generate the energy needed for contraction
• chromosomes contain genetic information
• the nucleus contains all of the genetic material in the form of chromosomes
• chromosomes are coiled up lengths of DNA molecules
• stem cells can divided into different types of cells based on the given instructions
• stem cells are found in early embryos and are found in bone marrow for adults
• embryonic stem cells are used to make insulin-producing cells for people with diabetes
• embryonic stem cells can also produce nerve cells for paralysed people
• stem cells in plants are found in the meristems
• stem cells can be used to make clones of whole plants quickly & cheaply
• stem cells can also be used by farmers to grow crops with their desired features
• Diffusion is the net-movement of particles from a region of higher concentration to a region of lower concentration
• diffusion only occurs in solutions & gases
• the bigger the concentration gradient, the faster the rate of diffusion
• the larger the surface area of the membrane, the faster the rate of diffusion
• Osmosis is the net-movement of water particles from a region of higher concentration to a region of lower concentration, through a partially permeable membrane.
• a partially permeable membrane is a membrane with very small holes in it
• active transport is the movement of substances from a region of lower concentration to a region of higher concentration, against a concentration gradient