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BIOLOGY SUMMARY

CELLSMODULE 2

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MODULE 2Cells

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TOPIC 1Structure of Eukaryotic Cells • Eukaryotic cells: 20-100ųm diameter & structure

• Structure/function of: ○ Nucleus and nucleolus ○ Nuclear envelope ○ Rough and smooth endoplasmic reticula ○ Golgi apparatus ○ Ribosomes ○ Mitochondria ○ Lysosomes ○ Chloroplasts ○ Cell surface membrane ○ Centrioles ○ Flagella vs cilia

• Tissue = group of specialised cells ○ Epithelia ○ Cartilage ○ Muscle ○ Xylem/Phloem

• Organ = group of tissues with a combined function • Organ system = group of related organs • Specialised cells

○ Erythrocytes: max oxygen capacity ○ Neutrophils: lots of lysosomes ○ Epithelial cells: smooth/mucous ○ Sperm cells: cover large distances ○ Palisade cells: lots of chloroplasts ○ Root hair cells: large surface area ○ Guard cells: open/close

• Specialised tissues ○ Squamous epithelia ○ Ciliated epithelia ○ Cartilage ○ Muscle ○ Phloem ○ Xylem

TOPIC 2Structure of Prokaryotic Cells and Viruses • Prokaryotic cells: 0.5-1ųm diameter • Features of prokaryotes

○ Only one membrane (cell surface) ○ Peptidoglycan cell wall

○ Smaller ribosomes ○ DNA free in cytoplasm; plasmids ○ ATP production in cell surface membrane ○ Capable of anaerobic respiration

• Structure of a virus ○ Acellular and non-living ○ RNA ○ Capsid, attachment proteins

TOPIC 3Methods of Studying Cells • 1mm = 1000ųm; 1ųm = 1000nm • Light microscopy:

Advantages Disadvantages • Wide range of specimens

can be observed • Specimens can be alive • Specimens can be whole,

or embedded in wax ten sectioned

• Non-coloured specimens must be stained for specific organelles or molecules

• Relatively low resolution does not give detailed information

• Electron microscopy:

Advantages Disadvantages

• Produces detailed images of the structures inside cells

• SEM produces detailed 3D images showing contour of cells

• Electron beams deflected in air, so sample must be in a vacuum

• Samples must be dead • Extremely expensive • Large piece of

equipment • Use requires a high

degree of skill and training

• magnification = image size ÷ object size • Magnification vs resolution • Fractionation and cetrifugation

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