The document discusses the parts of the cell. It begins by stating that the cell is the basic unit of life and is composed of a nucleus and cytoplasm. The nucleus contains DNA and RNA, and the cytoplasm functions in absorption and cell duplication. The document then describes the major cell organelles - the cell membrane, mitochondria, ribosomes, endoplasmic reticulum, Golgi complex, lysosomes, centrioles, and microtubules - and their specific functions in transport, energy production, protein synthesis, modification and transport, waste digestion, and cell structure and division.

1. Parts of the Cell
Oral Histology and Embryology Lecture
Dr. Jojo Quinitio

2. Learning Outcomes
• At the end of the lecture, the student must be able to
1. Describe a typical cell.
2. Enumerate and describe the functions of the different cell organelles
3. Explain the two types of cellular junctions
4. Compare and contrast the two types of cellular division: mitosis and meiosis
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3.  The cell is the basic structural, functional and biological unit of all known living
organisms
 Cells with similar characteristics of form and function are grouped together to form a
tissue
 Tissues bond together to form an organ (independent body part that performs a
specific function or functions)
Example: heart, liver, skin, stomach
 Organs can function together as a system
Example: the heart, arteries, veins, capillaries make up the cardiovascular system
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4.  The cell is composed of a nucleus and cytoplasm
 The nucleus contains the DNA (deoxyribonucleic acid) and RNA
(ribonucleic acid) which are the fundamental structures of life
 The cytoplasm functions in absorption and cell duplication
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7. 1. Cell membrane (plasma membrane)
 Surrounds the cell and serves as a selective barrier that regulates transport of
substances in and out of the cell
 Membrane is composed of phospholipids and proteins
 Phospholipids – regulate the diffusion of substances in and out of the cell (gate
keeper)
 Proteins – receptors for specific hormones, neurotransmitters and antibodies
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8. 2. Cytoplasm
• Includes the semi-fluid portion contained inside the cell membrane
called the cytosol
• The cytosol uses the raw materials brought into the cell to produce
energy; it also functions in the excretion of waste products
3. Organelles
• The major organelles of the cell are the nucleus, mitochondria,
ribosomes, endoplasmic reticulum, Golgi complex, lysosomes and
cytoskeleton
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9. A. Nucleus
 The largest and densest organelle in the cell
 Nucleus is found in all cells except in mature red blood cells
 Ordinarily a cell has a single nucleus; some cells are binucleate such as the cardiac muscle
cells or parenchymal liver cells; other cells are multinucleated such as the osteoclasts and
skeletal muscle cells
 The main nucleic acid in the nucleus is the DNA and it appears as diffused stippling called
chromatin when viewed in the microscope
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 The nucleus is important in the
production of DNA and RNA
 DNA contains genetic information
in the cell while RNA carries
information from the DNA to the
cytoplasm where protein
synthesis occurs
 the nucleus also contains from 1
to 4 nucleoli which produces the
RNA

11. B. Mitochondria
 Most numerous organelles in the cell
 “Power plants” of the cell – important in generating energy for the cell
 Major source of adenosine triphosphate (ATP) and are the site of many
metabolic reactions
 Adenosine triphosphate (ATP) – provides energy to drive many
processes in living cells
 Most of a cell’s energy comes from the mitochondria by 2 pathways of
aerobic respiration:
 Kreb’s cycle
 Hydrogen pathway
 The mitochondria also helps balance the concentration of water,
calcium and other ions in the cytoplasm
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12. C. Ribosomes
 Function as “protein factories” for the cell
 They are found in the cytoplasm, attached to the membrane of the
endoplasmic reticulum or inside the mitochondria
D. Endoplasmic reticulum
 These are channels connected to the nuclear membrane whose functions
are modification, storage, segregation and transport of proteins inside and
outside the cell
 2 types: smooth ER (doesn’t contain ribosomes) and rough ER (contains
ribosomes)
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13. E. Golgi complex
 Once the newly created protein has been modified by the ER, it is transferred to the
Golgi complex for segregation, packaging and transport of protein compounds
 The Golgi complex wraps these proteins into vesicles and releases it outside the cell
– exocytosis
 Examples of proteins produced by the cell include hormones, enzymes and other
secretory products such as mucus for salivary glands
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14. F. Lysosomes
 Function is to digest waste and foreign materials which occurs during
phagocytosis
 Lysosomes contain enzymes which help digest these materials; main enzyme
found in lysosomes is hyaluronidase
 Lysosomes are found in all cells except in red blood cells; they are prominent
in macrophages and leukocytes
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15. G. Centrioles
 Short cylinders found near the nucleus
 They have an important role in forming the mitotic spindle during cell
division or replication
H. Microtubules
 Small tubular structures in the cytoplasm that are composed of the protein
tubulin
 Microtubules help maintain the shape of the cell and are important
elements in cilia and flagella and in the mitotic spindles for cell division
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