Biology

• Animal and plant cells are eukaryotic cells
• eukaryotic cells include DNA that forms chromosomes contained within a nucleus
• animal cell has a cell membrane, nucleus, mitochondria, ribosomes and a cytoplasm
• plant cell has a cell membrane, nucleu, mitochondria, ribosomes, cytoplasm, vacuole, chloroplasts and a cell wall
• plant cell - square diagram that has bigger walls with a smaller inner but a lot of nothing
• animal cell - circular and has fewer things inside it
• cell membrane: controls the movement of substances in and out of a cell
• nucleus: contains DNA
• mitochondria is where the energy is released through respiration
• ribosomes: site of protein synthesis
• cytoplasm is a jelly like substance where chemical reactions happen
• a vacuole contains cell sap
• chloroplasts: contain chlorophyll to absorb light energy for photosynthesis
• cell wall: made of cellulose, which strengthens the cell
• bacteria cells are single celled, have no nucleus, contain small rings of DNA called plasmids and they are smaller than eukaryotic cells
• cell membrane is in all 3 cell types
• cytoplasm is in all 3 cell types
• nucleus is in animal and plant cells
• only plant cells and bacteria have a cell wall
• chloroplasts are only in plant cells
• vacuole is only in plant cells
• the DNA is free in the cytoplasm in bacteria cells
• plasmids are in bacteria cells
• light microscopes are used to form images
• light microscopes allow living samples to be viewed
• light microscopes are relatively cheap
• light microscopes have low magnification
• light microscopes have low resolution
• electron microscopes use a beam of electrons to form images
• electron microscopes mean samples cannot be living
• electron microscopes are expensive
• electron microscopes have high magnification
• electron microscopes have high resolution
• to calculate magnification of an image is image size

  magnification= ———————

  actual size
• electron microscopes allow you to see sub cellular structures (ribosomes) that are too small to be seen with a light microscope
• the specialised cells are: sperm, red blood, muscle, nerve, root hair and palisade cells
• the sperm cell fertilises an egg and has a tail to swim
• the red blood cell transports oxygen around the body and has no nucleus so has more room to carry oxygen
• the muscle cells contracts and relaxes to allow movement. it contains protein fibre which contract to make the cells shorter
• the nerve cell carries electical impulses around the body and has dendrites to make connections with other neurones or effectors