1. Chapter 1: Cell Structure
National 5 Biology - Unit 1 Cell Biology
National 5 Biology
Unit 1: Cell Biology
Chapter 1: Cell Structure
4/17/2017
Mrs Smith

2. National 5 Biology - Unit 1 Cell Biology National 5 Biology
Learning Intentions
By the end of this chapter, you should be able to describe cell structure
- Specifically be able to discuss - Cell ultrastructure and functions to include: cell wall, mitochondrion, chloroplast, cell membrane, cytoplasm, vacuole, nucleus, ribosome and plasmid.
- You should also be able to describe the ultrastructure by using examples from typical plant, animal, fungi and bacterial cells.
Explain fungal structure in terms of similarity to plant and animal cells but with a different cell wall structure. (Cell wall structure in fungal and bacterial cells is different from plant cells, ie chitin not cellulose)
Bacterial structure description should include the absence of organelles (no nucleus, mitochondria vacuole or chloroplasts) and a different cell wall structure to plant and fungal cells.
Bacterial structure should also include a description of there chromosomes and plasmid.
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Mrs Smith

3. CELLS ARE THE STARTING POINT!
All living organisms on Earth are divided into cells. The main concept of cell theory is that cells are the basic structural unit for all organisms. Nothing smaller than a cell can lead to independent life.
Cells are small compartments that hold the biological equipment necessary to keep an organism alive and successful. Living things may be single-celled or they may be very complex such as a human being.
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Mrs Smith

4. Plant Cells – Can be viewed under the microscope
Below are examples of plant cells viewed under the microscope
Some of a plant cells parts can be seen clearly when mounted in water (see below)
Other cell structures that are not so obvious can often be shown up more clearly by the addition of a STAIN (dye). Iodine solution can be used on onion cells to stain the nuclei.
Elodea leaf cells in water
Onion leaf cells in iodine solution
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Mrs Smith

5. Using stains with the microscope.
Stains can be used to make cells more visible under the microscope, e.g. Iodine solution.
Onion skin: 2 pieces were taken from the bottom layer of an onion and placed on 2 different slides.
With one, some iodine was placed n the slide to see the different layers, The other slide was left unstained.
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Mrs Smith

6. Onion Cell Lab Instructions.
Add 2 drops of iodine to the centre of a glass slide. Be careful! Iodine can stain your clothes.
Take a small piece of onion. Use tweezers to peel off the skin from the underside (the rough, white side) of the onion. Throw the rest of the onion piece away.
Carefully lay the onion skin flat in the centre of the slide on top of the iodine.
Add 2 drops of iodine to the top of the onion skin.
Stand a thin glass cover slip on its edge near the onion skin, next to the drop of iodine.
Slowly lower the other side of the cover slip until it covers the onion skin completely. If there are air bubbles, gently tap on the glass to “chase” them out.
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Mrs Smith

7. Draw what you see. Why are there no chloroplasts in onion cells?
Iodine Solution with air bubbles
Chloroplasts are absent from onion skin cells because it grows underground in the darkness (so what would be the point?)
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Mrs Smith

8. This is what our Onion cell looked like!
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9. Plant Cell (Pond weed). Lab Instructions
Tear off one small leaf/stem from the plants in the fish tank.
Add one drop of tap water to the slide.
Stand a thin glass cover slip on its edge near the leaf, next to the drop of water.
Slowly lower the other side of the cover slip until it covers the leaf completely. Make sure there are no air bubbles.
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Mrs Smith

10. Draw what you see.
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11. National 5 Biology - Unit 1 Cell Biology
While some cells do look different, all cells have these three basic features.
nucleus
cytoplasm
cell membrane
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12. The Nucleus Controls the cell’s activities
Controls all the chemical reactions inside the cell
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13. is selectively permeable and controls what
The Cell Membrane
The cell membrane
is selectively permeable and controls what
substances may enter
and leave the cell.
Cell membrane
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14. The Cytoplasm It is a jelly like material
All the chemical reactions taking place in the cell occur here
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15. ORGANELLES - Continued
Organelles are tiny structures (such as chloroplasts) that are:
Present in a cells cytoplasm as discrete units normally surrounded by a membrane.
Responsible for a specialised function (such as photosynthesis
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Mrs Smith

16. Ultrastructure
Cell structure is actually way more complicated than we have been teaching you……
There are even smaller structures in a cell. These minute structures cannot be seen with a normal light microscope. They can only bee seen using a more sophisticated piece of equipment called the electron microscope.
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Mrs Smith

17. Cooperative activity Cell race
20 minutes max!
Cooperative activity
Cell race
Your group will be issued with four different cell diagrams and four different descriptions as well as your own summary sheet.
Read each description carefully.
Match up each description with the correct cell.
Copy each cell picture into your jotter
Using all of the descriptions complete your table with a general function for each of the cell parts you have identified.
Complete the table by stating which of the cell parts are present in each cell type.
You have finished the cell race only when every member of the group has completed their own diagram and table and this has been checked by your teacher so assign group tasks wisely and remember to include everybody.
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Mrs Smith

18. Animal Cell
Animal cells are bounded by a cell membrane that controls entry and exit of substances. The cytoplasm is the “factory” part of the animal cell in which chemical reactions take place to manufacture various substances. The nucleus holds the DNA molecules (chromosomes) that are composed of sections called genes. Gene code for the making of proteins that control the activity of the cell. Embedded in the cytoplasm are mitochondria- sausage shaped structures with a smooth outer membrane and a folded inner membrane. It is in the mitochondria that aerobic respiration (respiration that uses oxygen) takes place. Also in the cytoplasm of animal cells free or attached to membranes are ribosomes- small spherical structures that are where protein molecules are created using instructions supplied from the DNA in the nucleus.
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Mrs Smith

19. Plant Cell
Plant cells are bounded by a cell wall made of cellulose fibres that forms a rigid box that although permeable to all but the largest molecules provides support for the cell and the plant as a whole. To the inside of the cell wall is the cell membrane that controls entry and exit of substances and is composed of proteins and phospholipids. The cytoplasm is the “factory” part of the plant cell in which chemical reactions take place to manufacture various substances. The nucleus holds the DNA molecules (chromosomes) that are composed of sections called genes. Genes code for the making of proteins that control the activity of the cell. Embedded in the cytoplasm are mitochondria- sausage shaped structures with a smooth outer membrane and a folded inner membrane. It is in the mitochondria that aerobic respiration (respiration that uses oxygen) takes place. Also in the cytoplasm of plant cells free or attached to membranes are ribosomes- small spherical structures that are where protein molecules are created using instructions supplied from the DNA in the nucleus. Chloroplasts are the site of photosynthesis in green plant cells. Vacuoles are fluid filled sac containing cell sap which are important in controlling water balance within the cell.
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Mrs Smith

20. Fungal Cell
Fungal cells are bounded by a cell wall made of chitin that forms a rigid box that provides support for the cell. To the inside of the cell wall is the cell membrane that controls entry and exit of substances and is composed of proteins and phospholipids. The cytoplasm is the “factory” part of the fungal cell in which chemical reactions take place to manufacture various substances. The nucleus is the control centre of the cell. It holds the DNA molecules (chromosomes) that are composed of sections called genes. Gene codes for the making of proteins that control the activity of the cell. Embedded in the cytoplasm are mitochondria- sausage shaped structures with a smooth outer membrane and a folded inner membrane. It is in the mitochondria that aerobic respiration (respiration that uses oxygen) takes place. Also in the cytoplasm of fungal cells free or attached to membranes are ribosomes- small spherical structures that are where protein molecules are created using instructions supplied from the DNA in the nucleus. Vacuoles are fluid filled sac containing cell sap which are important in controlling water balance within the cell.
4/17/2017
Mrs Smith

21. Bacterial Cell
Bacterial cells are bounded by a cell wall made of peptidoglycan that forms a rigid box that provides support for the cell. To the inside of the cell wall is the cell membrane that controls entry and exit of substances and is composed of proteins and phospholipids. The cytoplasm is the “factory” part of the bacterial cell in which chemical reactions take place to manufacture various substances. In a bacterial cell the DNA is free in the cytoplasm usually in one large mass. The DNA is composed of sections called genes. Genes code for the making of proteins that control the activity of the cell. In bacterial cells smaller circles of DNA called plasmids are found. Plasmids are freely exchanged between bacterial cells and are now used in “genetic engineering”. Also free in the cytoplasm of bacterial cells are ribosomes- structures that are where protein molecules are created using instructions supplied from the DNA.
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Mrs Smith

22. Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes No Yes Yes
Structure
Function
In animal cell?
In plant cell?
In fungal cell?
In bacterial
cell?
cell membrane
cytoplasm
nucleus
mitochondrion
ribosome
cell wall
vacuole
chloroplast
Holds cell contents and controls entry and exit of substances.
Yes
Yes
Yes
Yes
Cell’s “factory” –chemical reactions occur here.
Yes
Yes
Yes
Yes
Contains DNA which holds the information to make proteins which control the activity of the cell.
Yes
Yes
Yes No
Site of aerobic respiration.
Yes
Yes
Yes No
Manufacture of protein using instructions from DNA.
Yes
Yes
Yes
Yes
Rigid box gives organism support.
Yes- cellulose
Yes- chitin
Yes- peptidoglycan No
Fluid filled sac No
Yes
Yes No
Site of photosynthesis where carbohydrate is made. No
Yes No No
plasmid
Ring of DNA exchanged readily between cells. No No No
Yes
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23. Cells have differences in structure
Close examination of 4 types of cells sown below show they have some features in common but also differ from one another in other ways.
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24. Animal Cell Structure
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25. Animal Cell Structure
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26. ciliated epithelial cells
Example animal cells
nerve cell
blood cells
ciliated epithelial cells
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sperm and egg cells

27. Plant Cell Ultrastructure
Cellulose
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28. Plant Cell Structure THEY ALSO HAVE MITOCHONDRIA AND RIBOSOMES
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29. Example Plant Cells root hair cells onion epidermal cells xylem cells
phloem cells
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leaf cells
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30. Fungal Cell Ultrastructure
chitin
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31. Fungal Cell Ultrastructure
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32. Example fungal Cells Penicillium notatum yeast cells
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mushroom mycelial cells
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Fusarium mycelial cells

33. Bacterial Cell Ultrastructure
Peptoglycan
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34. Bacterial Cell Ultrastructure
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35. Example Bacterial Cells
Eschericia coli
Rhizobium
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Cholera bacteria

36. Cell Rap
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37. The Cell Song
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38. Cell Structure Notes
All living things are composed of one or more _______ , the basic unit of life. The cells of green plants, animals and fungi have several structures in common, including a ________, and mitochondria. ___________ cells lack a cell wall and store genetic material within _________. Only green plants contain __________, but all cells contain ribosomes, a cell membrane and cytoplasm. The cell’s activities are controlled by the nucleus. A plant cell is __________ by the cell wall and its cell _____ is stored in its vacuole.
cells
nucleus
Bacterial
plasmids
chloroplasts
supported
sap
Bacterial Cells Supported Nucleus Plasmids Chloroplasts Sap
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Mrs Smith

39. Activity – Measuring cell sizes
Cells cannot be seen without the aid of a microscope.
They are so small that we used units called micrometers (μm) or microns to measure them
There are 1000 microns in 1 millimetre.
YOU MUST BE ABLE TO MOVE BETWEEN THESE DIFFERENT UNITS> MAKE SURE YOU PRACTISE CONVERTING ONE TO THE OTHER.
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Mrs Smith

40. Measuring cell sizes
We can estimate the sizes of cells by knowing the diameter of the field of view.
e.g. If the field of view is 2mm which is 2000μm and there are 8 cells streching from one side to the other, then each cell must be 250μm (2000/8)
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Mrs Smith

41. Activity – Measuring cell sizes
2mm (field of view)/ 5 (no. of cells lengthwise across field of view) = 0.4mm
2mm (field of view)/ 10 (no. of cells up and down in field of view) = 0.2mm
0.4
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0.2
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42. Activity – Measuring cell sizes
This cell is 25mm in the diagram.
What is the actual size of the cell?
0.0625mm
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Mrs Smith

43. Activity – Measuring cell sizes
This cell is 20mm in the diagram.
What is the actual size of the cell?
0.05mm
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Mrs Smith

44. Task TYK
Complete questions 1 – 4. Torrance p5
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Mrs Smith

45. Task TYK Complete questions 1 – 4. Torrance p5 Cells (1)
A) Cell membrane, mitochondria, nucleus, ribosome's. (4)
B) Cell wall, chloroplasts, large central vacuole (3).
Chloroplast for photosynthesis, nucleus for control of cell activities, cell membrane for control of movement of substances onto and out of cell, mitochondrion for aerobic respiration (4).
A) 1 millimetre = 1000 micrometers (1)
B) 1 micrometer = millimetres (1).
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Mrs Smith

46. Quick test
How is the cell wall of a plant cell different from that of a yeast cell?
Name two cell structures that cannot be seen with a light microscope.
What features do yeast and p[lant cells have in common?
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Mrs Smith

47. National 5 Biology - Unit 1 Cell Biology
Answers
How is the cell wall of a plant cell different from that of a yeast cell?
Plant cell wall is made of cellulose, yeast cell wall is made of chitin.
Name two cell structures that cannot be seen with a light microscope.
Ribosomes and mitochondria.
What features do yeast and plant cells have in common?
Cell wall, nucleus, cytoplasm, cell membrane, ribosomes, mitochondria and vacuole.
4/17/2017
Mrs Smith

48. Have we achieve our learning Intentions
National 5 Biology - Unit 1 Cell Biology
National 5 Biology
Have we achieve our learning Intentions
By the end of this chapter, you should be able to describe cell structure
- Specifically be able to discuss - Cell ultrastructure and functions to include: cell wall, mitochondrion, chloroplast, cell membrane, cytoplasm, vacuole, nucleus, ribosome and plasmid.
- You should also be able to describe the ultrastructure by using examples from typical plant, animal, fungi and bacterial cells.
Explain fungal structure in terms of similarity to plant and animal cells but with a different cell wall structure. (Cell wall structure in fungal and bacterial cells is different from plant cells, ie chitin not cellulose)
Bacterial structure description should include the absence of organelles (no nucleus, mitochondria vacuole or chloroplasts) and a different cell wall structure to plant and fungal cells.
Bacterial structure should also include a description of there chromosomes and plasmid.
4/17/2017
Mrs Smith