BASIC CELL PROCESS :

INTEGRATION & COORDINATION

Iskandar

1. CELLS & TISSUES1. CELLS & TISSUES

• CELLULAR• The cell is the basic structural and functional unit of

most living organisms.• Two kinds of cells are : procaryotic and eucaryotic• The cell is composed of cell membrane, cytoplasm

and nucleus.• The cell membrane is a phospholipid bilayer with

embedded proteins that separates the inside of the cell from the extracellular fluid.

• The cytoplasm consists of semigelatinous cytosol with dissolved nutrients, ions wastes, insoluble inclusions and organelles to carry out specific function.

Non membranous organelles include ribosomes, which take part in protein synthesis, vaults of uncertain function and insoluble protein fibers such as actin, myosin, keratin, and tubulin.The cytoskeleton is made of microfilaments, intermediate filament and microtubules. It provides support, aids transport of material within the cell, links cells together, and enable motility in certain cells.Centrosomes are the microtubule-organizing center of the cell. Centrioles aid the movement of chromosome during cell division

• Cilia move fluid or secretions across Cilia move fluid or secretions across the cell surface. Flagella propel sperm the cell surface. Flagella propel sperm through body fluid.through body fluid.

• Mitochondria generate most ATP for Mitochondria generate most ATP for the cell.the cell.

• The smooth endoplasmic reticulum is The smooth endoplasmic reticulum is the primary site of the primary site of lipid synthesislipid synthesis. The . The rough endoplasmic reticulum is the rough endoplasmic reticulum is the primary site of primary site of protein synthesisprotein synthesis..

• The Golgi apparatus packages protein The Golgi apparatus packages protein into vesicles. Secretory vesicles into vesicles. Secretory vesicles secrete their contain into the secrete their contain into the extracellular fluid.extracellular fluid.

Lysosomes and peroxisomes are storage vesicles that contain digestive enzyme.

The nucleus contains DNA, the genetic material that ultimately controls all cell processes, in the form of chromatin. The nuclear envelope has nuclear pore complexes that allow controlled chemical communication between the nucleus and cytosol. Nucleoli are nuclear areas that control the synthesis of RNA for ribosomes.

►TISSUE REMODELINGTISSUE REMODELING►Cell death occurs by necrosis, which Cell death occurs by necrosis, which

adversely affects neighboring cells, adversely affects neighboring cells, and by apoptosis, programmed cell and by apoptosis, programmed cell death that does not disturb the tissue.death that does not disturb the tissue.

►Most mature cells can reproduce Most mature cells can reproduce themselves. Nerve, muscle, and blood themselves. Nerve, muscle, and blood cells must be replaced by cells that cells must be replaced by cells that develop from unspecialized stem cells.develop from unspecialized stem cells.

►Organs are formed by groups of Organs are formed by groups of tissues that carry out related tissues that carry out related functions. The organs of the body functions. The organs of the body contain the four types of tissues in contain the four types of tissues in various ratios.various ratios.

2. CELLULAR 2. CELLULAR METABOLISMMETABOLISM• ENERGY IN BIOLOGICAL SYSTEMSENERGY IN BIOLOGICAL SYSTEMS

• Energy is the capacity to the work. Energy is the capacity to the work. Chemical work enables cells and Chemical work enables cells and organisms to grow, reproduce and carry organisms to grow, reproduce and carry out normal activities. Transport work out normal activities. Transport work enable cells to move molecules to create enable cells to move molecules to create concentration gradients. Mechanical work concentration gradients. Mechanical work is used for movement.is used for movement.

• Kinetic energy is the energy of motion. Kinetic energy is the energy of motion. Potential energy is stored energy.Potential energy is stored energy.

• ENZYMES• Enzymes are biological catalysts that speed up the

rate of chemical reactions without themselves being changed. Enzymes bind to reactant molecules, bringing them together into the best position for reacting with each other. In reaction catalyzed by enzymes, the reactants are called substrates.

• The part of the enzyme that binds to the substrates is called the binding site. The induced-fit model of enzyme-substrate interaction says that the binding site has and intermediate shape that can change to fir either the substrate or the produce molecules.

Specificity is the ability of an enzyme to catalyze a certain reaction or a group of closely related reactions.Some enzymes are produced as inactive precursors and must be activated. This may require the presence of a cofactor. Organic cofactors are called coenzymes.Enzyme activity is altered by temperature, pH, and modulator molecules. A modulator change the ability of the enzyme to (1) bind the substrate or (2) alter activation energy of the reaction.

When an enzyme is saturated with substrate, it When an enzyme is saturated with substrate, it works at its maximum possible rate.works at its maximum possible rate.

Reversible reactions go to a state of equilibrium, Reversible reactions go to a state of equilibrium, where the rate of the reaction in the forward where the rate of the reaction in the forward direction is exactly equal to the rate of the reverse direction is exactly equal to the rate of the reverse reaction. Reversible reactions obey the low of reaction. Reversible reactions obey the low of mass action : when a reaction is at equilibrium, the mass action : when a reaction is at equilibrium, the ratio of substrates to products is always the same. ratio of substrates to products is always the same. If the concentration of a substrate or product If the concentration of a substrate or product changes, the equilibrium will be disturbed.changes, the equilibrium will be disturbed.

Most reactions can be classified as oxidation-Most reactions can be classified as oxidation-reduction, hydrolysis-dehydration, addition-reduction, hydrolysis-dehydration, addition-subtraction-exchange or ligation reactions.subtraction-exchange or ligation reactions.

CELL MEMBRANESThe cell membrane is a barrier between the intracellular and extracellular fluid.The cell membrane regulated exchange and communication between the cell and its environment. It also provides structural support to the cell.The fluid mosaic model of membranes says that membranes are phospholipid bilayers with proteins inserted into the bilayer. Carbohydrates attach to the extracellular surface.

Membrane-spanning and other integral Membrane-spanning and other integral proteins are tightly bound to the proteins are tightly bound to the phospholipid bilayer. Associated proteins phospholipid bilayer. Associated proteins attach less tightly to either side of the attach less tightly to either side of the membrane.membrane.

Structural proteins maintain cell shape and Structural proteins maintain cell shape and form cell junctions that hold tissues form cell junctions that hold tissues together.together.

Membrane-associated enzymes catalyze Membrane-associated enzymes catalyze chemical reactions and help transfer signals chemical reactions and help transfer signals across the membrane.across the membrane.

Receptor proteins on the cell membrane are Receptor proteins on the cell membrane are part of the body’s chemical signaling part of the body’s chemical signaling system. A molecule that binds to a receptor system. A molecule that binds to a receptor is called its ligand.is called its ligand.

BODY FLUID COMPARTMENTS

Most cells of the body are surrounded by extracellular fluid (ECF), which can be subdivided into interstitial fluid bathing the cells and plasma, the fluid portion of the blood.

MOVEMENT ACROSS MEMBRANESThe cell membrane is a barrier that restricts free exchange between the cell and the interstitial fluid. The movement of a substance across the membrane depends on the permeability of the membrane to the substance.Lipid-soluble substances can diffuse through the phospholipid bilayer. Less lipid-soluble molecules require the assistance of a membrane protein to cross the membrane.Passive transport does not require the input of energy.

Diffusion is the passive movement of Diffusion is the passive movement of molecules from an area of higher molecules from an area of higher concentration to an area of lower concentration to an area of lower concentration. Diffusion stops when the concentration. Diffusion stops when the system reaches equilibrium, although system reaches equilibrium, although molecular movement continues.molecular movement continues.

Diffusion rate depends on the magnitude of Diffusion rate depends on the magnitude of the concentration gradient. Diffusion is the concentration gradient. Diffusion is slow over long distances, is directly related slow over long distances, is directly related to temperature and is inversely related to to temperature and is inversely related to molecular size.molecular size.

Simple diffusion is diffusion across the Simple diffusion is diffusion across the phospholipid bilayer of a membrane. phospholipid bilayer of a membrane. The rate of simple diffusion is directly The rate of simple diffusion is directly proportional to the surface are of the proportional to the surface are of the membrane, inversely proportional to membrane, inversely proportional to the thickness of the membrane, and the thickness of the membrane, and depends on the lipid solubility of the depends on the lipid solubility of the molecule that is diffusing.molecule that is diffusing.

Mediated transport is movement of Mediated transport is movement of molecules with the aid of a carrier molecules with the aid of a carrier protein. Passive mediated transport is protein. Passive mediated transport is called facilitated diffusion.called facilitated diffusion.

INTEGRETED MEMBRANE INTEGRETED MEMBRANE PROCESSES : PROCESSES :

INSULIN SECRETIONINSULIN SECRETION We have recently that the use of We have recently that the use of

electrical signals to initiate a cellular electrical signals to initiate a cellular response is not limited to the response is not limited to the excitable tissues of nerve and muscle. excitable tissues of nerve and muscle. The beta cell of the pancreas releases The beta cell of the pancreas releases insulin response to a change in insulin response to a change in membrane potential.membrane potential.

References :References :

• 1. library.thinkquest.org/c004535 / 1. library.thinkquest.org/c004535 / basic_cell_function.html.basic_cell_function.html.

• 2.2. www.sci.sdsu.duwww.sci.sdsu.du / classes / / classes / chemistry / chemistry / chem 4671 / mardahl / chem 4671 / mardahl / basiccell//.html.basiccell//.html.

• 3. Kuliah Prof dr Ieva3. Kuliah Prof dr Ieva

• 4.Kuliah Prof dr Subowo4.Kuliah Prof dr Subowo

TERIMA KASIHTERIMA KASIH