1. INTRODUCTION TO CELLS
Topic 1.1
IB Biology
Miss Werba

2. ULTRASTRUCTURE OF CELLS
TOPIC 1 – CELL BIOLOGY
1.1
INTRODUCTION TO CELLS
1.2
ULTRASTRUCTURE OF CELLS
1.3
MEMBRANE STRUCTURE
1.4
MEMBRANE TRANSPORT
1.5
THE ORIGIN OF CELLS
1.6 CELL DIVISION
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3. THINGS TO COVER U.1 U.2 U.3 U.4 U.5 U.6 U.7 A.1 A.2 A.3 Statement
Guidance
U.1
Cell theory
U.2
Characteristics of living things
Name and explain nutrition, metabolism, growth, response, excretion, homeostasis and reproduction.
U.3
SA:Vol ratio and cell size
U.4
Emergent properties in multicellular organisms
U.5
Cell differentiation
U.6
Selective gene expression
U.7
Stem cells
A.1
Questioning cell theory using atypical examples - eg. Striated muscle, giant algae, aseptate fungal hyphae
A.2
Investigating unicellular organisms - eg. Paramecium and Chlorella
A.3
Stem cell therapy - eg. Stargardt’s disease, burn treatment, leukaemia
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4. THINGS TO COVER A.4 S.1 IM.1 NOS 3.1 4.5 Statement Guidance
Ethics of stem cell therapy
S.1
Practical 1 - Using a light microscope to investigate the structure of cells and tissues, with drawing of cells.
Calculations of magnification of images and actual size of cells.
Use scale bars to indicate actual size in drawings.
IM.1
Stem cell research collaboration
NOS
3.1
Looking for trends & discrepancies
4.5
Ethical implications of research
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5. CELL THEORY

6. CELL THEORY All living organisms are made of cells
U.1
CELL THEORY
All living organisms are made of cells
Cells are the smallest units of life
All cells come from pre-existing cells
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7. U.1
U.5
U.7
CELL THEORY
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8. U.1
U.5
U.7
CELL THEORY
Evidence:
With the invention of microscopes (Janssen) scientists could see cells (Hooke, Leeuwenhoek)
Louis Pasteur demonstrated that cells couldn’t grow in sterile conditions (disproved abiogenesis)
Organelles (structures within cells) and viruses cannot carry out all of the characteristics of other living things
Cell division is visible under a microscope
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9. NOS.3.1
CELL THEORY
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10. Looking for trends and discrepancies
NOS.3.1
CELL THEORY
Looking for trends and discrepancies
Although most organisms conform to cell theory, there are exceptions.
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11. CELL THEORY Exceptions to the cell theory: Striated muscle
Erythrocytes (red blood cells)
Giant algae
Aseptate fungal hyphae
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12. CELL THEORY Striated muscle:
Skeletal muscle is composed of muscle fibres that are larger than a single cell.
The muscle fibres are multinucleated, containing several hundred nuclei.
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13. CELL THEORY Erythrocytes (red blood cells):
U.1
A.1
CELL THEORY
Erythrocytes (red blood cells):
Once they have matured, they lose their nucleus.
This prevents them from carrying out many cell functions from this point of their life cycle.
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14. CELL THEORY Giant algae:
U.1
A.1
CELL THEORY
Giant algae:
The single cells of some large algae are undifferentiated, remaining in a “stem cell”-like state.
They form chains so that they can form larger structures.
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15. CELL THEORY Aseptate fungal hyphae: Hyphae are long threads.
In aseptate or nonseptate hyphae, these threads have multiple nuclei, but the cells are not separated by cell walls.
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16. FUNCTIONS OF LIFE

17. FUNCTIONS OF LIFE MRS C GREN
Unicellular organisms carry out all the functions of life:
Movement
Respiration
Sensitivity or stimulus response
Composed of cells
Growth
Reproduction
Excretion
Nutrition
MRS C GREN
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18. FUNCTIONS OF LIFE MR H GREN
Unicellular organisms carry out all the functions of life:
Metabolism
Response
Homeostasis
Growth
Reproduction
Excretion
Nutrition
MR H GREN
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19. U.2
FUNCTIONS OF LIFE
Unicellular organisms carry out all the functions of life:
Metabolism – carry out reactions to generate organic molecules
Response – monitor stimuli and are capable of reacting
Homeostasis – maintain internal environment within narrow limits
Growth
Reproduction – can produce viable offspring
Excretion – waste products of metabolism are disposed of
Nutrition – obtains food either through photosynthesis or ingestion
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20. FUNCTIONS OF LIFE Examples to learn: Paramecium Chlorella U.2 A.2
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21. FUNCTIONS OF LIFE Paramecium:
Unicellular organisms in the kingdom of Protista
Small but visible with the naked eye (~ μm)
They are ciliates, meaning that they are surrounded by tiny hair-like structures
Cilia are used to waft food particles towards their oral groove
Use contractile vacuoles to respond to changing salinity in their environment
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22. FUNCTIONS OF LIFE Chlorella: Unicellular plant
Spherical in shape, ~2-10 μm in diameter
Come together in large numbers to form algae.
Contains chloroplasts, allowing it to photosynthesise.
Photosynthesis provides the energy and minerals to multiply rapidly.
It reproduces asexually, producing 4 organisms each time.
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23. Cell size

24. CELL SIZE Use your logic to put these in the correct order!
Bacteria
Cell membrane thickness
Cells
Molecules
Organelles
Virus
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25. CELL SIZE Relative sizes
U.3
S.1
CELL SIZE Relative sizes
Cells (<100 μm) - generally plant cells are larger than animal cells
Organelles (<10 μm)
Bacteria (1μm)
Virus (100nm)
Cell membrane thickness (10nm)
Molecules (1nm)
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26. CELL SIZE Relative sizes
2.1.4
CELL SIZE Relative sizes
Watch this!
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27. CELL SIZE Magnification
2.1.5
CELL SIZE Magnification
Measurements need to be in the same units!
1mm =1000μm
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28. U.2
A.2
CELL SIZE
Paramecium:
Use the MIA formula triangle to calculate the magnification of the paramecium shown in this image:
9.4cm
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29. U.2
A.2
CELL SIZE
Paramecium:
Use the MIA formula triangle to calculate the magnification of the paramecium shown in this image:
M = ?
I = 94mm
A = 162μm = 0.162mm
M = I ÷ A = 580x
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30. U.2
A.2
CELL SIZE
Chlorella:
Use the MIA formula triangle to calculate the magnification of the Chlorella shown in this image:
1.0cm
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31. U.2
A.2
CELL SIZE
Chlorella:
Use the MIA formula triangle to calculate the magnification of the chlorella shown in this image:
M = ?
I = 10mm
A = 4μm = 0.004mm
M = I ÷ A = 2500x
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32. CELL SIZE Chlorella: Bonus Q:
Could this organism have been viewed under a light microscope?
Answer:
No. Maximum resolution of light microscopes is usually x.
It would have needed to have been an electron microscope.
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33. CELL SIZE Erythrocyte:
U.2
A.2
CELL SIZE
Erythrocyte:
Use the scale bar provided to determine the size of this red blood cell.
Then calculate the magnification of this image.
HINT: use equivalent fractions first, and then the formula triangle
6.6cm
1.0cm
1.0μm
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34. CELL SIZE M = ? I = 66000μm, A = 6.6μm M = I ÷ A = 10000x Erythrocyte:
U.2
A.2
CELL SIZE
Erythrocyte:
M = ?
I = 66000μm, A = 6.6μm
M = I ÷ A = 10000x
6.6cm
1.0μm
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35. CELL SIZE Magnification – sample questions
A red blood cell is 8μm in diameter. If drawn 100 times larger than its actual size, what diameter will the drawing be in mm?
If a mitochondrion has a length of 5µm and a student’s drawing of the mitochondrion is 10mm, what is the magnification of the drawing?
If a Sequoia sempervirens tree is 100m tall and a drawing of it is 100mm tall, what is the magnification of the drawing?
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36. CELL SIZE Magnification – sample answers
U.2
A.2
CELL SIZE Magnification – sample answers
0.8 mm
×2000
×0.001
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37. CELL SIZE Limitations Cells cannot grow indefinitely.
U.3
CELL SIZE Limitations
Cells cannot grow indefinitely.
They reach a maximum size and then they may divide.
If a cell becomes too large, it would develop problems.
These problems may include….?
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38. U.3
CELL SIZE Limitations
The rate of metabolism varies with a cell’s volume
The rate of molecular exchange varies with a cell’s surface area
When a cell grows, volume grows quicker than surface area and the cell must divide or die
Many cells contains structures to increase the ratio of their surface area to their volume (SA:Vol ratio)
eg. microvilli
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39. BECOMING MULTICELLULAR

40. BECOMING MULTICELLULAR
Unicellular organisms are in the Kingdom Protoctista (Protists)
They evolved 3-4 billion years ago.
They remained the dominant life form until 600 million years ago.
Unicellular organisms are able to carry out all of the typical cellular processes within their single cell!
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41. BECOMING MULTICELLULAR
Kingdom Plantae, Animalia and Fungi are all composed of eukaryotic cells
They are multicellular organisms – made up of many cells together.
These cells specialise (differentiate) so that all energy in the cell is not taken up by performing all cellular functions.
These cells group into tissues, organs and systems making us far more capable than a single bacterial cell.
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42. CELL DIFFERENTIATION Differentiation:
U.4
U.5
U.6
CELL DIFFERENTIATION
Differentiation:
process by which newly-formed cells specialize as they mature
Cells in multicellular organisms share the same genetic info (cf. cell division, reproduction, formation of blastocyst)
What is different between cells is gene expression
Chemical signals lead to differential gene expression and thus specialization of cells
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43. U.4
U.5
U.6
CELL DIFFERENTIATION
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44. U.4
U.5
U.6
EMERGENT PROPERTIES
The combination of different cell types can give rise to emergent properties in multicellular organisms
Means that the whole organism is greater than the sum of its parts:
because of the varied gene expression
because of the complex interactions between cells
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45. STEM CELLS

46. STEM CELLS Stem cells retain the capacity to divide
U.7
STEM CELLS
Stem cells retain the capacity to divide
They are undifferentiated
They have the ability to differentiate along different pathways
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47. THERAPEUTIC USE OF STEM CELLS
Stem cells have the potential for tissue repair and can theoretically treat a variety of degenerative conditions
In 1968, doctors performed the first successful bone marrow transplant.
Bone marrow contains somatic stem cells. It is transplanted routinely to treat a variety of blood and bone marrow diseases, blood cancers, and immune disorders.
More recently, peripheral blood stem cells (from the blood stream) and umbilical cord stem cells have been used to treat some of the same blood-based diseases.
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48. THERAPEUTIC USE OF STEM CELLS
eg. Stargardt’s disease
a genetic eye disorder
it is a type of macular degeneration affecting the retina at the back of the eye
causes progressive loss of central vision in both eyes
Macula
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49. THERAPEUTIC USE OF STEM CELLS
eg. Stargardt’s disease
recent stem cell research has involved using retinal pigment epithelium (RPE)
can use embryonic stem cells to generate RPE
first human therapeutic trials were conducted in , improving vision in the patients receiving the treatment
Australian researchers are now focusing on the use of IPSCs for the treatment of similar disorders
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50. THERAPEUTIC USE OF STEM CELLS
eg. Stargardt’s disease
Click to read the related article
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51. THERAPEUTIC USE OF STEM CELLS
eg. Parkinson’s Disease, MS, strokes
all involve loss of neurons or other cells in the nervous system
could potentially use stem cells to replace them
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52. THERAPEUTIC USE OF STEM CELLS
eg. Leukaemia
a cancer of white blood cells or leukocytes
chemotherapy is normally used to kill the abnormal cells; however, a bone marrow transplant is needed if it doesn't work.
The patient's existing bone marrow and abnormal leukocytes are first killed using chemotherapy and radiation.
A sample of donor bone marrow containing healthy, matched stem cells is introduced into the patient's bloodstream.
If the transplant is successful, the stem cells will migrate into the patient's bone marrow and begin producing new, healthy leukocytes to replace the abnormal cells.
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53. THERAPEUTIC USE OF STEM CELLS
eg. Burn treatment
Therapeutic cloning can be used to regenerate skin cells in burns victims
Use the nucleus from the required cell to generate new cells with the correct genetic information – eg. skin cells
See Topic 3.5 for detailed process
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54. STEM CELLS
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55. STEM CELLS
Stem cell research has depended on the work of teams of scientists in many countries who share results thereby speeding up the rate of progress.
However, national governments are influenced by local, cultural and religious traditions that impact on the work of scientists and the use of stem cells in therapy.
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56. U.7
A.4
ETHICS OF STEM CELL USE
There is enormous potential in the therapeutic use of these cells.
The source of these cells is no longer limited to embryos, reducing some of the associated ethical concerns – eg. adult SC, umbilical cord SC, IPSC.
Some religious groups support SC research if embryos are not involved.
Some groups still oppose SC research, regardless of where the SC are sourced from, as it goes against the laws of nature.
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59. INTRODUCTION TO CELLS
Q8. Which functions of life are carried out by all unicellular organisms?
Response, homeostasis, growth and photosynthesis
Metabolism, ventilation, reproduction and nutrition
Response, homeostasis, metabolism and growth
Reproduction, ventilation, response and nutrition
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60. INTRODUCTION TO CELLS
Q9. A botanist measures a leaf and finds it is 24 cm long and 8 cm wide. His drawing of the leaf is 4 cm wide. Which was the magnification and length of his drawing, assuming that the proportions of the drawing were correct?
Scale
Length / cm A. x2 48 B. 12 C.
x0.5 D.
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61. INTRODUCTION TO CELLS
Q10. a. Outline the cell theory [2] b. Calculate the magnification of the electron micrograph. [1]
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