B1 Cells
Microscopes
Magnification = eyepiece lens x objective lens
magnification = size of object/size of real object
Resolution is the ability to distinguish between two different points
resolving power affects how much detail a microscope shows
Animal Cells
nucleus - controls all activities of the cell and is surrounded by nuclear membrane, contains genes that carry instructions for making new proteins needed to build new cells
cytoplasm - a liquid gel in which organelles are suspended and where most of the chemical reactions for life take place
cell membrane - controls the passage of substances such as glucose and mineral ions into the cell
mitochondria - structures in the cytoplasm where aerobic respiration takes place, releasing energy, very small
ribosomes - site of protein synthesis
Plant Cells
All the features of an animal cell
Cell Wall - made of cellulose that strengthens and supports the cell
Chloroplasts - found in all the green parts of a plant, contain chlorophyll(absorbs light for photosynthesis)
Permanent Vacuole - space in cytoplasm filled with cell sap, keeps the cell rigid to support the plant
Eukaryotic and Prokaryotic Cells
Eukaryotic cells have a membrane, cytoplasm and genetic material enclosed in a nucleus
Prokaryotic cells are 1-2 orders of magnitude smaller than eukaryotes, prokaryotic cells may also contain extra small rings of DNA called plasmids which code very specific features such as antibiotic resistance
Bacteria are prokaryotic cells, they have a cell wall but not made of cellulose, in prokaryotes, the genetic material is not enclosed in a nucleus, it is a single DNA loop in the cytoplasm.
Some bacteria have a protective slime capsule which is protective, some types of bacterium have at least one flagellum - a long protein strand used to propel the bacteria around
Specialisation in animals
Nerve Cells
Lots of dendrites to make connections to other nerves
Axon carries nerve impulse from one place to another
Nerve endings(synapses) use transmitter chemicals which requires lots of mitochondria
Muscle Cells
Contain special proteins that slide over each other to allow fibres to contract
Contain many mitochondria to transfer energy needed for chemical reactions as cells contract and relax
Store glycogen, a chemical that can be broken down and used in cellular respiration
Sperm Cells
A long tail propels the sperm as it needs to move a long distance quickly
Many mitochondria needed for the tail
Acrosome(tip) stores digestive enzymes for breaking down the outer layers of the egg
Large nucleus contains genetic information to be passed on
Specialisation in plants
Root hair cells
Large SA for water to move into the cell
Large permanent vacuole that speeds up the movement of water by osmosis
Many mitochondria that transfer energy needed for active transport of mineral ions into the cell
Photosynthetic Cells
Contain specialised green structures - chloroplasts that trap light needed for photosynthesis
Positioned in layers in leaves to absorb maximum light
Large permanent vacuole keeps cell rigid as a result of osmosis
Xylem Cells
Alive when formed but a special chemical called lignin builds up in spirals in cell walls, the cell dies and forms long hollow tubes
Spirals of lignin make them very strong and help them withstand the pressure of water moving up the plant
Phloem Cells
Cell walls between cells break down to form sieve plates that allow water to move freely up and down tubes to where is needed
Lose a lot of internal structure but are supported by companion cells, mitochondria of the companion cells transfer energy needed to move dissolved food up and down the plant