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Cytology
be used in the future to deal with the Exercise 1.10
conditions that require transplanting,
such as kidney transplanting. 1. Explain the features that are found
in both, prokaryotic and eukaryotic
(d) It helps in the future treatment of cancer cells.
patients by enabling measurement 2. Using examples, explain the concept
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of the cancer progress at cellular of cell differentiation.
level, where the cytopathologists 3. Explain why cell differentiation is
term ‘grade’ is used as a marker to generally referred to as a cellular
determine how the differentiated cell division of labour.
in a tumor is. 4. Explain the importance of cell
differentiation to animals and plants.
Activity 1.3: Observation of a
specialised root hair cell
1.4 The organic constituents
Materials (biochemistry) of cells
Onion roots, surgical blade, iodine
solution, petri dish, dropper, light The cells are composed of water, inorganic
microscope, and microscope slides ions and organic molecules (carbon-
containing compounds). Water is the most
Procedure abundant molecule of the cell, constituting
(a) Take the onion root, and use a surgical about 70% of the total mass. It also interacts
blade to cut it transversely into very with other molecules or constituents in the
thin slices. cell. The organic components of the cells
(b) Put a slice on the petri dish, and add include: Carbohydrates, proteins, lipids,
one drop of iodine solution using a enzymes, nucleic acids and regulatory
dropper. substances such as hormones and vitamins.
(c) Transfer the stained slice to the
microscope slide. 1.4.1 Carbohydrates
(d) Observe the stained slice under a
light microscope. Task 1.4
Search for text and simulations from
Questions the library and internet sources and
1. What conclusion can you make prepare a brief report about:
from what you have observed? (a) properties of carbohydrates
2. What are the features that (b) biochemical tests.
characterise a specialised onion
cell? Carbohydrates are among the fundamental
classes of macromolecules found in living
organisms. These are molecules which
Safety precautions
contain the carbonyl compound (aldehyde
Observe safety precautions when working and ketone derivatives). They are primary
with sharp objects, such as knife and products of photosynthesis, and energy
surgical blade. providing substrates for various organisms,
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