Cells

Animal Cells

Nucleus - Genetic Material

Cytoplasm - where most chemical reactions happen, enzymes to control these.

Cell membrance - holds cell together, controls what goes in and out

Mitochondria - most reactions for aerobic respiration

Ribosomes - proteins are synthesized

Plant cells

Cell wall - rigid structure, cellulose, supports and strengthens cell e.g. algae

Permanent vacuole - stores cell sap

Chloroplasts - contain chlorophyll (which absorbs light for photosynthesis), where photosynthesis occurs

Bacterial cells

Cytoplasm and cell membrance, surrounded by a cell wall

Single circular strand of DNA

Can have plasmids (small rings of DNA)

Microscopy

Light microscopes

Use light and lenses to magnify an image

Let us see cells and large subcellular structures e.g. nuclei

Electron Microscopes

Electrons to form an image

Migher magnification

Higher resolution (ability to distinguish between two points)

Let us see smaller things in more detail e.g. internal structure of mitochondria

Preparing a slide for a light microscope

1)Add a drop of water to the middle of a clean slide

2)Peel off some epidermal tissue from a layer of onion

3)Place the epidermal tissue on the slide (in the water)

4)Add a drop of iodine, stains are used to highlight objects by giving colour to them.

Observing the specimen

5)Place a cover slip on top

1)Clip the slide onto the stage and select the lowest-powered objective lens

2)Use the coarse adjustment know to move the stage to just below the lens

3)Use the coarse adjustment knob to move the stage downwards until the image is roughly in focus

4)Use the fine adjustment knob to adjust the focus until you get a clear image of what's on the slide.

5)If you need a greater magnification swap to a higher-powered objective lens and refocus

Cell Differentiation and Specialisation