cell

1. HUMAN ANATOMY & PHYSIOLOGY/D.PHARM/BULU/SIPS/2017.
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CELL
Syllabus: - Structure of cell, function of its components with special reference to
mitochondria and microsomes.
Questions: - (OSBP)
1. Draw a neat labelled diagram of typical human cell, describe briefly about cell
organelles. (7+8)2007.
2. Define cell, name the organelles of cytoplasm. Write the structure and function of
mitochondria and endoplasmic reticulum. (1+2+12)2010.
3. Define cell. Name the organelles of cytoplasm. Write details on mitosis and
meiosis.(2+2+6)2011.
4. Mitochondria.(5)2014
5. Define cell. Name the organelles of cytoplasm. Write structure & function of
mitochondria. (1+4+10)2015.

2. HUMAN ANATOMY & PHYSIOLOGY/D.PHARM/BULU/SIPS/2017.
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Define:-
 Basic unit of structure and function in living things.
 Smallest independently functioning unit.
Components of the cell:-
 Cell membrane
 Cytoplasm
 Nucleus
1. CELL MEMBRANE
Cell membrane envelopes the cell, it is a thin, pliable elastic structure 7.5 to 10 nanometers
thick.
Composition:-
 Proteins 55%
 Phospholipids 25%
 Cholesterol 13%
 Carbohydrates 3%.
2. CYTOPLASM
Portion of protoplasm that surrounds the nucleus and is peripherally bound by cell
membrane.
Composition
a. Cytosol: - Clear fluid portion of cytoplasm in which inclusions, particles and
organelles are dispersed.
b. Organelles:- Endoplasmic reticulum, Golgi apparatus, Lysosomes,
Mitochondria, Peroxisomes, Ribosomes, Microtubules , Microfilaments.
3. NUCLEUS (CONTROL CENTER OF CELL)
Composition:
a. NUCLEOPLASM: fluid in the nucleus. •
b. CHROMOSOMES: thread like coiled structures (genetic material)
c. NUCLEOLI: one or more small masses present in the nucleus having no limiting
membrane, contain mRNA
FUNCTION: • Control center of cell. • Controls protein synthesis. • Controls cell division.
ORGANELLES OF A CELL
ENDOPLASMIC RETICULUM(ER)
 Network of interconnected tubular and flat vesicular structures.
 Bounded by lipid bilayer membrane that contains large number of proteins.

3. HUMAN ANATOMY & PHYSIOLOGY/D.PHARM/BULU/SIPS/2017.
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 Filled with endoplasmic matrix.
 Vast surface area and multiple enzymes provide machinery for major metabolic
functions.
TYPES:-
1. Rough ER/granular(has ribosomes attached)
 Concerned with protein synthesis.
2. Smooth ER/agranular ( has No ribosomes attached)
 Concerned with lipid synthesis.
GOLGI APPARATUS (GA)
Structure:
 Consists of 4 to 5 layers of flat vesicles closely related to the ER.
 Prominent in secretary cells(those that secrete enzymes and hormones).
Function
It processes substances synthesized by the ER to form Lysosomes & Secretary vesicles.
It packages these products
 Formation of carbohydrates esp. large saccharide polymers bound with small
amounts of proteins e.g. Hyaluronic acid and chondroitin sulphate.

4. HUMAN ANATOMY & PHYSIOLOGY/D.PHARM/BULU/SIPS/2017.
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LYSOSOMES (CELL GARBAGE DISPOSAL SYSTEM)
Structure:
 250 to 750 nanometers in diameter.
 Lipid bilayer outer membrane.
 Filled with a mixture of hydrolytic enzymes (40 different types) all manufactured in
the ER and modified in the GA.
 Organelles formed by breaking off from Golgi apparatus.
Function
 Digestion of food stuff.
 Bactericidal agents e.g. lysozyme and lysoferrin.
 Regression of various tissues
PEROXISOMES
Structure:
 250 to 750 nanometers.
 Bound by lipid bilayer.
 Contain oxidase .
 Formed by budding off from smooth ER.
Function:-Causes the oxidation (detoxification) of poisons and toxins in the cell.

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MITOCHONDRIA (POWER HOUSE OF THE CELL)
Structure:
 Two lipid bilayer.
 Shelves formed by in folding of inner bilayer onto which oxidative enzymes are
attached.
 Mitochondrial cavity filled with gel matrix containing enzymes.
 Variable sizes and shapes.
 Presence of Deoxyribo Nucleic Acid (enables to self replicate).
Function:-
 Formation of high energy compound Adenosine Tri phosphate (ATP).
 Mitochondria have its own cellular DNA and replicates independently of the cell in
which it is found.
MICROFILAMENTS AND MICROTUBULES
FORMATION:
Originate as precursor protein molecules synthesized by ribosomes which polymerize to
form filaments.
Function:
Act as cytoskeleton providing rigid physical structure for certain parts of cell e.g.
 Actin in ectoplasm.
 Contractile machine in muscle cells.
 Microtubules in cilium.
 Centriole and mitotic spindle.

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FUNCTIONS OF CELL
INGESTION
 Diffusion
 Facilitated Diffusion
 Active transport
 Endocytosis
DIGESTION
 Act of Lysosomes
SYNTHESIS
 Granular ER synthesizes proteins.
 Agranular ER synthesizes lipids.
 Golgi apparatus synthesizes Lysosomes and secretary vesicles
 Hyaluronic acid and chondroitin sulphate.
MOVEMENT
 Amoeboid locomotion exhibited by WBC and macrophages
 Ciliary movement exhibited by cilia of ciliated epithelium and flagellum of sperm.
MITOSIS
 Division of somatic cell into two identical daughter cells.
 Mitosis is conventionally divided into five phases: –
 Prophase
 Prometaphase
 Metaphase
 Anaphase
 Telophase
Prophase
 Chromatin condenses, this causes the chromosomes to begin to become visible.
 Centrosomes separate, moving to opposite ends of the nucleus.
 The centrosomes start to form a framework used to separate two sister chromatids
called the mitotic spindle that is made of microtubules.

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Prometaphase
Metaphase
Anaphase

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Telophase
The end