Cell Biology, Cell Structure and Function

CELL BIOLOGY

Tues fundamental for the biological sciences. All organisms consist of cells. Cells are the unit structure and unit functions in biological systems. Cell as a unit structure, as all systems were prepared by cell biology. While the cell as a functional unit, because all life events that show the characteristic of life going on inside the cell. The living cell is a miniature chemical industry, where thousands of reactions going on inside a room that is microscopic cells.


In the hierarchy of biological organization, this cell is a simple collection of materials that can live. In addition, there are various forms of life intangible as single-celled organisms. More complex organisms, including plants and animals, are multicellular; its body is a collaboration of various types of specialized cells that will not survive long if each stood alone. However, when the cell is organized into a higher level of organization, such as tissues and organs, cells can be separated as the basic unit of structure and function of organisms.

In plants and animals, many cells produce a chemical material which is then delivered for use on other baigan of these organisms. For example, enzymes and hormones are used for the metabolism of cells, tissues and organs. Chemical process known as cellular respiration will move the mobile economy by extracting the energy stored in sugar and other food reserves (catabolism). In contrast, cells use this energy to carry out various types of work, such as synthesis of macromolecules (anabolisme).

Since the discovery of return and recognition of the principles of Mendel, born in 1902 a new science called cytogenetics. Clearly it seems that cytogenetics is a hybrid science pengetaahuan cytology and genetics as the parent.

CELL STRUCTURE AND FUNCTION

Cell structure

The aim is to separate cells fraksionasil cell into parts, separate the major organelles so that their respective functions can be studied
Fractionation preceded by homogenization, in order to break the cell without being too damaging organelles. This activity makes the researchers to prepare specific components of cells in large numbers to study the composition and function.
The main part of the cell were: wall / cell membrane, cytoplasm, and nucleus of cells. But thanks to the discovery of electron microscopy, it has been identified in the cytoplasm of the cell organelles

Cell membrane

Type a variety of membrane is the basis for setting the cell. In general, biological membranes consist of a single phospholipid bilayer (double leyer) and other lipids. Various proteins trapped inside or attached to the surface of the lipid bilayer

With the membrane structure, the molecular organization of the membrane causes the selective permeability of cell membranes (Figure 4). Thus some of the basic functions of cell membranes are:
1. Passive transport is diffusion across a membrane
2. osmosis is the passive transport of water (solvent)
3. cell survival depends on the balance of absorption and release of water
4. Specific proteins facilitate passive transport of selected solutes
5. active transport is the pumping of solutes against gradiennya
6. some ion pumps generate voltage across the membrane
7. dalm kotranspor, mengkopel membrane protein transport of a substance dissolved with other solute
8. eksositosis and endocytosis transport large molecules

Cell organelles
The inner structure of cells and present in the cell cytoplasm called organelles, among them: endoplasmik reticulum, mitochondria, ribosomes, lysosomes, peroxisomes, Golgi apparatus, plastids, vacuoles, etc..

Reticulum Endoplasmik

It is known there are two kinds of endoplasmic reticulum (ER), namely RE-rough (rough RE) and RE-smooth (smooth RE) (Figure 5). Re-refined various cell types function in the metabolism of eg lipid synthesis, carbohydrate metabolism, and offers (detoksikasi) drugs and poisons. Re-refined essential for synthesis of lipids, including phospholipids and steroids. Among the steroid sex hormone that is in the male / male (testosterone), female / female (estrogen), and various steroid hormone produced by the adrenal glands (corticosteroids, aldosterone, cortisone, etc.). Cells that actually synthesize and secrete this hormone testosterone (testes) and estrogen (ovarian), for example, contains many fine RE, which is characteristic of structural and in accordance with the function of these cells.

Liver cells is one fine example of the role of RE in the metabolism of carbohydrates. Liver cells store carbohydrates in the form of glycogen, a polysaccharide. Glycogen hydrolysis causes the release of glucose from the liver cells, which are important in regulating blood sugar levels. Enzyme RE subtle help offered drugs and poisons (detoksikasi function), particularly in the liver. Offering of poison involves the addition of hydroxyl groups into the drug, which causes the drug more soluble and more easily removed from the body. Barbiturates phenobarbital and other sedatives are examples of drugs that are metabolized Obata this way by

RE subtle in liver cells.
Many types of specialized cells secrete a protein produced by ribosomes, which is attached to the RE rude. For example, certain cells in the pancreas to secrete the protein insulin, a hormone into the blood circulation. Most of the proteins skretoris form of glycoproteins, proteins covalently bound to the carbohydrate. In addition to making proteins skretoris, RE roughly a membrane factory that grows in place of adding proteins and phospholipids. Because of polypeptide that would be membrane proteins grow from ribosomes, the polypeptide is inserted into the membrane RE and held there by the hydrophobic proteins. RE coarse also create their own membrane phospholipids.

Golgi apparatus

After leaving the RE, many transport vesicles move to the Golgi apparatus. Organelle is considered a center of manufacturing, warehousing, sorting, and delivery of products from the cell. Here, the product RE modified, and saved, then sent to another destination. Thus, the Golgi apparatus is found in many cells that are specialized for secretion

Lysosomes

Merpakan membrane bound bags of hydrolytic enzymes used by cells to digest macromolecules (Fig. 6). There lysosomes enzymes that can hydrolyze proteins, polysaccharides, fats and nucleic acids. Enzi mini works very well in acidic pH, about pH 5. Lysosome membrane maintain a low pH in this by pumping hydrogen ions from the cytosol into the lumen of lysosomes. If the lysosomes rupture or leak its contents, aktvitas cytosol enzyme is reduced in a neutral environment.

Various hereditary disorder called lysosome storage diseases (lysosomal storage diseases) affect the metabolism of lysosomes. People with this deficiency one active hydrolytic enzymes that are normally present in lysosomes. Pompe disease, liver damaged by the accumulation of glycogen due to deficiency of enzymes that hydrolyze functioning liver glycogen (polysaccharides). In Tay-Sachs disease, lipid digestive enzymes are missing or inactive, and brain damaged because of the accumulation of lipids in the cell. Maybe one day with biotechnology to improve directly with the insert DNA (genes) for the missing enzyme.

Cytogenetics

Chromosome when viewed with electron microscope appears composed of thick fibers can range between 100-500 Angstrom. For purposes of analysis of chromosomes, then the specific cells can diguanakannya, eg T lymphocytes, which must first be cultured.

T lymphocyte cell culture

1. Approximately 2.5 cc of venous blood, cultured with TC 199 medium for 72 hours
2. Add PHA (phytohemaglutinin) as an antigen nonspecific T lymphocytes so that mitosis
3. Add veal serum to enhance / stimulate mitosis
4. Before harvest, add substance to stop colchisin remain in metaphase of mitosis
5. Add hipotonus KCl solution, thus damaging the cells and chromosomes didnding biases are removed from the cell.
6. Kmbil samples and used as drops in on an object-glass, fixation with ethanol, and color with Giemsa.
7. Chromosomes are ready to be used for analysis / karyotiping

Karyotiping (Charyotiping)

Is a group activity based on the shape and length of chromosome chromosome
Fundamental usefulness of chromosome analysis is to detect the amount and structure.

Detecting the Number of Chromosome Abnormalities

1. Turner Syndrome (45X0)
2. Klinerfilter Syndrome (47XXY)

Abnormalities of chromosome structure

1. Deletion
2. Insertion
3. Duplication
4. Inversion
5. Translocation

Sex chromatin

An activity in cytogenetics menentuan sex
1. Barr Body
Preparations for the inside of the cheek scrapings, place the object-glass, fixation with methanol and color with carbol fuchsin. Barr body positive result ()
2. Drum Stick
Smear preparations, put on the object-glass, and color fixation with phosphate buffered Giemsa
3. F-Body
Smear preparations, put on the object-glass, and color fixation with buffer quinacrine, view with fluorescence microscope. The result, F-body is male.