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