Cell Theory

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  • Topic: Cell, Cellular differentiation, Stem cell
  • Pages : 14 (2659 words )
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  • Published : February 23, 2013
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Topic 2 - Cells
2.1 Cell theory

SL Book: pg.
Lizard book: pg. 1-5,
Green eBook: pg. 9-15

2.1.1 Outline the cell theory (pg. 2, 9-10)
*
2.1.2 Discuss the evidence for cell theory (pg. 3-4, 9-10) *
2.1.3 State that unicellular organisms carry out all the functions of life (pg. 1, 10) *
2.1.4 Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using the appropriate SI unit (pg. 2, 10) *
2.1.5 Calculate the linear magnification of drawings and the actual size of specimens in images of known magnification (practical). (pg. 11-13) *
2.1.6 Explain the importance of the surface area to volume ratio as a factor limiting cell size (pg. 5, 12) *
2.1.7 State that multicellular organisms show emergent properties (pg. 7-8, 12-13) *
2.1.8 Explain that cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others (pg. 7-8, 13) *
2.1.9 State that stem cells retain the capacity to divide and have the ability to differentiate along different pathways (pg. 7-8, 14-15) *
2.1.10 Outline one therapeutic use of stem cells (pg. 7-8, 14-15)

2.1.1 Outline the cell theory

SL Text Book: pg.
HL Lizard Book: pg. 2
Green book: pg. 9-10

To do:
1 Check out further information on ‘Cell Theory’ on Wikipedia 2 Discuss your findings
3 Add notes
4 Summary in note book

The idea behind cell theory is that all living things are made of cells, and cells are the smallest units that can be alive. There are thousands of different kinds of cells, but the biggest division is between cells of the prokaryote kingdom (the bacteria) and those of the other four kingdoms (animals, plants, fungi and protoctista), which are all eukaryotic cells.

Development of this theory progressed during the mid 1600s due to development of the microscope.

The theory states that new cells are formed from other existing cells.

2.1.2 Discuss the evidence for cell theory

SL Text Book: pg.
Lizard book: pg. 3-4
Green book: pg. 9-10

To do:
1 Read the relevant sections in the text books
2 Discuss your findings
3 Add notes
4 Summary in note book
*

2.1.3 State that unicellular organisms carry out all the functions of life

SL Text Book: pg.
HL Lizard book: pg. 1
Green book: pg. 10

To do:
1 List the processes carried out by all living things? 2 Summary in note book

2.1.4 Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using the appropriate SI unit.

SL Text Book: pg.
HL Lizard book: pg. 2
Green book: pg. 10

SI Units
Metres (m)
Centimetres (cm)
Millimetres (mm)
Micrometres (m)
Nanometres (nm)

Conversions
1mm = 1,000m = 1,000,000nm
0.1mm = 100m = 100,000nm

If you get stuck the following website will help you to convert: http://www.cleavebooks.co.uk/scol/ccleng.htm

Molecules
DNA
2nm wide – width kept constant due to specific base pairing. 70,000,000nm (70mm) long

Phospholipid 5nm long

Water Molecule 0.385nm

The general rule would be to say molecules are usually nm in size. Cells and cell organelles are composed of molecules and so molecules are the smallest. Proteins can be very large molecules but remember they are found INSIDE cells or are synthesized inside cells and secreted so they are smaller than cells.

Cell Membrane
10nm wide
This is calculated from the length of 2 phospholids (each which are 5nm).

Viruses
Largest 100nm (think the book is being abit conservative here – the smallpox virus is 300nm) HIV – 100nm
Polio Virus – 30nm

Remember that viruses can infect cells and so they have to be smaller than cells, including bacteria. (Bacteriophages are viruses that infect bacterial cells).

Bacteria
Usually...
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