B2- cells tissues and organs

Animal and plant cells

• all living things are made of cells
• a cell is very small and can only be seen with a microscope
• a cell contains: a nucleus- to control the cells activities and holds genetic material
• cytoplasm- to control the cells chemical reactions
• cell membrane- to allow substances to leave and enter the cell
• mitochondria- to release energy by areobic respiration
• ribosomes- to proteinsynthesis
• plant cells also have; a cell wall- made of cellulose to give it a ridgid shape
• chroplasts containing chlorophyll- to photosynthesise
• permenant vacuole- containing sap

bacteria and yeast

• bacteria cells have a cell membrane and a cell wall surrounded by cytoplasm
• bacteria cells have NO nucleus so genetic material is in the cytoplasm
• when bacteria multiplies it forms a colonie that can be seen with the naked eye
• yeast cells have a nucleus surrounded by cytoplasm cell wall and cell membrane
• yeast cells are single cell organisms

specialised cells

• as an organism matures each cell develops into a particular type which is more suited to its role
• muscle cells have lots of mitochondria for energy production
• gland cells have lots of ribosomes to release enzymes
• sperm cells have a long tail to swim
• root hair cells increase the surface area so it can absorb more water

diffusion

• molecules of liquids and gases move around quickly because of energy they have
• dissolved subtances can move into and out of cells by diffusion
• diffusion is the spreading out of the particles of a gas or any solution
• the net movement (the overall direction of flow) is determined by the concentration of particles on each side of the cell membrane
• particles move from high concentration to low concentration because there is more room for them to spread out
• the larger to differenc in concentration gradient the faster the rate…