1. CELL
S.S.MOORTHY SEMENCHALAM
M.Sc. Comm Health (Occ Health) UKM
B.HSc. Nursing (Aust)
Dip Med Sc. (Moh)
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2. Learning Outcomes
At the end of this session, the students will be able to:
• Define cell and organelle
• State the function of each organelles
• List generalizes cells
– Nucleus
– Mitochondria
– Golgi apparatus
– Ribosome
– Lysosome
– Rough and smooth endoplasmic reticulum
• Understand the cell membrane transportation across cell
membrane
• Discuss cell division – mitosis and meiosis
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3. Cell Theory – 4 basic Concepts
• Cell is the basic unit of structure and function of all
living organisms
• The activity of an organism depends on both the
individual and collective activity of its cells
• The biochemical activities of cells are determined
by their specific sub-cellular structures
• Continuity of life has a cellular basis (cells come
from cells)
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4. Structure of a Generalized Cell
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5. Terminology
The Cytoplasm is the viscous, semi-fluid (gel-like) matter between
the cell membrane and the nucleus
The aqueous or watery component of the cytoplasm is the Cytosol,
which includes ions and soluble macromolecules
The insoluble constituents of the cytoplasm include the Organelles
and the Cytoskeleton
The space outside cells is called the Interstitium. The extracellular
fluid is called Interstitial fluid (containing sugars, amino acids,
vitamins, hormones, salts, and waste products.
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6. Plasma Membrane (Cell Membrane)
• Every cell is surrounded by a cell membrane
• It separates the cell’s cytoplasm from its external environment
• It also regulates the passage or transport certain molecules in
and out of the cell, while preventing the passage of others
(“selective semi-permeable membrane”)
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7. Plasma Membrane (Cell Membrane)
• Cell membrane is made of protein and lipid (fatty substance)
molecules, which arranged in a double layer
Head (polar)
- Hydrophilic -
Phospolipid Cell
membrane
Tails (nonpolar)
- Hydrophobic -
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8. Nucleus
• The largest organelles
• It contains the body’s genetic material, which
directs the activities of the cell called genes
(chromosomes)
• Human somatic cells have 46 chromosomes, 23
inherited from each parent.
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10. Mitochondria
• The ‘powerhouses’ of the cell
• Generate most of the ATP ( adenosin triphosphate ) cellular
energy
• Active cells, such as those found in the muscles, liver, and
kidneys, have a large number of mitochondria (high rate ATP
usage)
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11. Golgi apparatus
• Consists of stacks of closely folded flattened
membranous sacs
• It is present in all cells but is larger in those that
synthesis and export protein
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12. Ribosomes
• Tiny granules composed of RNA and protein
• Synthesised protein from amino acid
• Free ribosome's make protein for use within the same cell
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13. Endoplasmic Reticulum (ER)
• Two types: 1) Smooth ER
2) Rough ER
• Smooth ER – synthesises lipids and steroid
hormones. It is also associated with the
detoxification of some drugs
• Rough ER – studded with ribosomes
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15. Lysosomes
• Formed by the Golgi apparatus
• Contain a variety of enzymes involved in breaking down large
molecules (e.g. carbohidrate and protein) into smaller
particles that are either recycled or expelled from the cell as
waste material
• Intracellular digestive system ( destroy cellular debris from
damaged cells)
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16. Cell Membrane Transport
Passive Transport - requires no ATP (energy) input
Diffusion Simple Diffusion
Facilitated Diffusion
Osmosis
Filtration
Active Transport - metabolic energy ATP required
Primary Active Transport
Secondary Active Transport
Vesicular Transport
Exocytosis
Endocytosis
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17. Passive Transport: Diffusion
Diffusion is a physical process whereby molecules of
gases, liquids, or solid particles scatter themselves evenly
through a medium. Molecules are in constant motion
(kinetic energy) and move around in a random fashion,
colliding with other molecules and/or walls of the
container.
Molecules move from areas where they are in higher
concentration to areas where their concentration is lower
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18. Passive Transport: Diffusion
Molecules move
from areas where
they are in higher
concentration to
areas where their
concentration is
lower
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19. Passive Transport: Diffusion
The driving force for diffusion is the kinetic energy
of the particles
The speed or rate of diffusion is influenced by:
Molecular size (the smaller, the faster)
Temperature (the warmer, the faster)
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20. Cell Membrane – Semi-Permeable
The plasma membrane is a selectively permeable barrier.
It only allows “selected” substances to pass through.
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21. Passive Membrane Transport: Facilitated
Diffusion
Some molecules,
combine with
protein carriers
move through
transmembrane
protein channels
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22. Passive Membrane Transport: Facilitated
Diffusion
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23. Passive Transport: Osmosis
Osmosis - movement of water across a semi
permeable membrane.
*Driven by a difference in solute concentrations
on the two sides of the membrane.
Osmolarity
- Total concentration of solute particles in a solution
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24. Effect of Membrane Permeability on Diffusion
and Osmosis – Membrane Permeable to Solute
and Water
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25. Solution tonicity
Isotonic – solutions with the same solute
concentration as the cytosol
Hypertonic – solutions having greater solute
concentration than the cytosol
Hypotonic – solutions having lesser solute
concentration than the cytosol
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26. Hypotonic Isotonic Hypertonic
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27. Passive Transport: Filtration
The movement of water and solutes across a
membrane due to some mechanical force, such as blood
pressure and gravity
Pressure gradient pushes solute-containing fluid from a
higher-pressure area to a lower-pressure area
Filtration also occurs in the kidney (glomerulus).
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28. Active Transport
•Process whereby molecules move across the cell
membrane from an area of lower concentration to
an area of higher concentration (against the
concentration gradient)
•Requires the high energy chemical compound
ATP which is supplied by cell metabolism
(adenosine triphosphate)
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29. Vesicular Transport
• Transport of large particles, macromolecules, and fluid
across plasma and intracellular membranes
– Exocytosis – (Exo = out) – moves substance from
the cell interior to the extracellular space
– Endocytosis – (Endo = in) – moves substance from
the outside into the intracellular space
- Phagocytosis (cell eating) – substances engulfed by
the cell membrane are within particles
- Pinocytosis (cell drinking) – substances engulfed by
the cell membrane are in solution
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30. Exocytosis
Hormone secretion, neurotransmitter release,
mucus secretion, ejection (excretion) of wastes
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31. Endocytosis - Phagocytosis
bacteria, cell debris
Phagocytosis – pseudopods extend, engulf solids, and bring them into
the cell (phagosome may fuse with a lysosome → phagolysosome)
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32. Endocytosis - Pinocytosis
Pinocytosis – fluid-phase endocytosis – cell membrane
invaginates (infolds) and brings extracellular fluid and
solutes into the cell
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33. Principle of cell division
• A cell has its own life span
• Eventually cells damage, get worn out and die.
They are replaced by a process of cell division
for growth, repair & replacement.
• Humans have 46 chromosomes (23 pairs).
– 22 pairs somatic (body) chromosomes
– 1 pair is sex chromosomes.
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34. Principle of cell division
• Nuclear division involves 5 main phases:
1) INTERPHASE- Cell is engaged in metabolic activity and
prepare for mitosis / meiosis
2) PROPHASE- Chromatin in the nucleus begins to condense &
become visible. Centrioles begin to move to opposite ends
of the cells
3) METAPHASE- Spindle fibers align the chromosomes along
the middle of the cell nucleus
4) ANAPHASE- Paired chromosomes separate at the
kinetochores and move to opposite side of the cell
5) TELOPHASE- Chromatid arrive at the respective poles, and
cytokinesis (partitioning) begins
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35. Cell division: Mitosis
• Mitosis is a somatic (body) cell division
• A cell undergoes nuclear division and produce 2
identical daughter cells.
• Each daughter cell has the same number and kind
of chromosomes as the original cell (46)
• Somatic cell division replaces dead or injured
cells and adds new ones for tissue growth.
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37. Cell division: Meiosis
• Meiosis is a reproductive cell division( eggs & sperm ).
• A cell undergoes nuclear division and produces 4
identical daughter cells.
• Each daughter cell has half of chromosomes of the
original cell (23)
• Reproductive cell division produces gametes (sperm and
ova)
• Two stages: Meiosis I and Meiosis II
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39. QUESTIONS PLEASE..
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