What are the three major types of a cell??

Question

What are the three major types of a cell??

Answer 1

animal, plant, bacterium

Answer 2

Slide 1  :  The Immune System  

Because the human body provides an ideal environment for many microbes, they try to pass your skin barrier and enter. Your immune system is a bodywide network of cells, tissues, and organs that has evolved to defend you against such "foreign" invasions.

The proper targets of your immune system are infectious organisms--bacteria such as these streptococci; fungi (this one happens to be Candida, the cause of yeast infections); parasites, including these worm-like microbes that cause malaria; and viruses such as this SARS virus.



Slide 2  :  Markers of Self  

At the heart of the immune response is the ability to distinguish between "self" and "non-self." Every cell in your body carries the same set of distinctive surface proteins that distinguish you as "self." Normally your immune cells do not attack your own body tissues, which all carry the same pattern of self-markers; rather, your immune system coexists peaceably with your other body cells in a state known as self-tolerance.

This set of unique markers on human cells is called the major histocompatibility complex (MHC). There are two classes: MHC Class I proteins, which are on all cells, and MHC Class II proteins, which are only on certain specialized cells.



Slide 3  :  Markers of Non-Self  

Any non-self substance capable of triggering an immune response is known as an antigen. An antigen can be a whole non-self cell, a bacterium, a virus, an MHC marker protein or even a portion of a protein from a foreign organism.

The distinctive markers on antigens that trigger an immune response are called epitopes. When tissues or cells from another individual enter your body carrying such antigenic non-self epitopes, your immune cells react. This explains why transplanted tissues may be rejected as foreign and why antibodies will bind to them.



Slide 4  :  Markers of Self: Major Histocompatibility Complex  

Your immune cells recognize major histocompatibility complex proteins(MHC) when they distinguish between self and non-self. An MHC protein serves as a recognizable scaffold that presents pieces (peptides) of a foreign protein (antigenic) to immune cells.

An empty "foreign" MHC scaffold itself can act as an antigen when donor organs or cells are introduced into a patient's body. These MHC self-marker scaffolds are also known as a patient's "tissue type" or as human leukocyte antigens (HLA) when a patient's white blood cells are being characterized.

For example, when the immune system of a patient receiving a kidney transplant detects a non-self "tissue type," the patient's body may rally its own immune cells to attack.

Every cell in your body is covered with these MHC self-marker proteins, and--except for identical twins--individuals carry different sets. MHC marker proteins are as distinct as blood types and come in two categories--MHC Class I: humans bear 6 markers out of 200 possible variations; and MHC Class II: humans display 8 out of about 230 possibilities.



Slide 5  :  Organs of the Immune System  

The organs of your immune system are positioned throughout your body.

They are called lymphoid organs because they are home to lymphocytes--the white blood cells that are key operatives of the immune system. Within these organs, the lymphocytes grow, develop, and are deployed.

Bone marrow, the soft tissue in the hollow center of bones, is the ultimate source of all blood cells, including the immune cells.

The thymus is an organ that lies behind the breastbone; lymphocytes known as T lymphocytes, or just T cells, mature there.

The spleen is a flattened organ at the upper left of the abdomen. Like the lymph nodes, the spleen contains specialized compartments where immune cells gather and confront antigens.

In addition to these organs, clumps of lymphoid tissue are found in many parts of the body, especially in the linings of the digestive tract and the airways and lungs--gateways to the body. These tissues include the tonsils, adenoids, and appendix.



Slide 6  :  Lymphatic System  

The organs of your immune system are connected with one another and with other organs of the body by a network of lymphatic vessels.

Lymphocytes can travel throughout the body using the blood vessels. The cells can also travel through a system of lymphatic vessels that closely parallels the body's veins and arteries. Cells and fluids are exchanged between blood and lymphatic vessels, enabling the lymphatic system to monitor the body for invading microbes. The lymphatic vessels carry lymph, a clear fluid that bathes the body's tissues.



Slide 7  :  Lymph Node  

Small, bean-shaped lymph nodes sit along the lymphatic vessels, with clusters in the neck, armpits, abdomen, and groin. Each lymph node contains specialized compartments where immune cells congregate and encounter antigens.

Immune cells and foreign particles enter the lymph nodes via incoming lymphatic vessels or the lymph nodes' tiny blood vessels. All lymphocytes exit lymph nodes through outgoing lymphatic vessels. Once in the bloodstream, they are transported to tissues throughout the body. They patrol everywhere for foreign antigens, then gradually drift back into the lymphatic system to begin the cycle all over again.



Slide 8  :  Cells of the Immune System  

Cells destined to become immune cells, like all blood cells, arise in your body's bone marrow from stem cells. Some develop into myeloid progenitor cells while others become lymphoid progenitor cells.

The myeloid progenitors develop into the cells that respond early and nonspecifically to infection. Neutrophils engulf bacteria upon contact and send out warning signals. Monocytes turn into macrophages in body tissues and gobble up foreign invaders. Granule-containing cells such as eosinophils attack parasites, while basophils release granules containing histamine and other allergy-related molecules.

Lymphoid precursors develop into the small white blood cells called lymphocytes. Lymphocytes respond later in infection. They mount a more specifically tailored attack after antigen-presenting cells such as dendritic cells (or macrophages) display their catch in the form of antigen fragments. The B cell turns into a plasma cell that produces and releases into the bloodstream thousands of specific antibodies. The T cells coordinate the entire immune response and eliminate the viruses hiding in infected cells.



Slide 9  :  B Cells  

B cells work chiefly by secreting soluble substances known as antibodies. They mill around a lymph node, waiting for a macrophage to bring an antigen or for an invader such as a bacteria to arrive. When an antigen-specific antibody on a B cell matches up with an antigen, a remarkable transformation occurs.

The antigen binds to the antibody receptor, the B cell engulfs it, and, after a special helper T cell joins the action, the B cell becomes a large plasma cell factory that produces identical copies of specific antibody molecules at an astonishing pace--up to 10 million copies an hour.



Slide 10  :  Antibody  

Each antibody is made up of two identical heavy chains and two identical light chains, shaped to form a Y.

The sections that make up the tips of the Y's arms vary greatly from one antibody to another; this is called the variable region. It is these unique contours in the antigen-binding site that allow the antibody to recognize a matching antigen, much as a lock matches a key.

The stem of the Y links the antibody to other participants in the immune defenses. This area is identical in all antibodies of the same class--for instance, all IgEs--and is called the constant region.



Slide 11  :  Immunoglobulins  

Antibodies belong to a family of large protein molecules known as immunoglobulins.

Scientists have identified nine chemically distinct classes of human immunoglobulins, four kinds of IgG and two kinds of IgA, plus IgM, IgE, and IgD.

Immunoglobulins G, D, and E are similar in appearance. IgG, the major immunoglobulin in the blood, is also able to enter tissue spaces; it works efficiently to coat microorganisms, speeding their destruction by other cells in the immune system. IgD is almost exclusively found inserted into the membrane of B cells, where it somehow regulates the cell's activation. IgE is normally present in only trace amounts, but it is responsible for the symptoms of allergy.

IgA--a doublet--guards the entrance to the body. It concentrates in body fluids such as tears, saliva, and secretions of the respiratory and gastrointestinal tracts.

IgM usually combines in star-shaped clusters. It tends to remain in the bloodstream, where it is very effective in killing bacteria.



Slide 12  :  Antibody Genes  

Scientists long wondered how all the genetic information needed to make millions of different antibodies could fit in a limited number of genes.

The answer is that antibody genes are spliced together from widely scattered bits of DNA located in two different chromosomes. Each antibody molecule is made up of two separate chains, a heavy chain and a light chain. The heavy chain is where the binding of antigens occurs, so much genetic variation is involved in its assembly. For example, to form a heavy chain, 1 of 400 possible variable gene segments (V) combines with 1 out of 15 diversity segments (D) and 1 out of 4 joining (J) segments. This makes 24,000 possible combinations for the DNA encoding the heavy chain alone. As this part of the gene assembles, it joins the variable coding segments with those for the constant-C segments of the heavy-chain molecule.



Slide 13  :  T Cells  

T cells contribute to your immune defenses in two major wa

Answer 3

Um, well I'll give what I know.  There are 3 major domains of life.  These are Bacteria, Archaebacteria, and Eukaryotes.  These really aren't 3 cell types, but the cell types arelocalized under this.  There are single celled prokaryotes (or anucleated cells), muticellular prokaryotes, single celled eukaryotes (nucleated cells), and multicellular eukaryotes.  You may be looking for a detailed explanation of 3 cell types within one of these divisions, but these are the 4 major types of organizsms that exist, and the domains to which they belong.

Answer 4

The only ones I know of are prokaryotes and eukaryotes.

Answer 5

eukaryotic and prokaryotic are the two main types. for the third you must be thinking of a sub-division of the first two.