Bio的問題(英文回答)

先說說對不起,小弟的英文不好,有不好之地方,請大家原諒
Nucleus:Do you mean the cell's nucleus?If yes,all right ,here it is:
In cell biology, the nucleus (pl. nuclei; from Latin nucleus or nuculeus, "little nut" or kernel) is a membrane-enclosed organelle found in all eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these chromosomes are the cell's nuclear genome. The function of the nucleus is to maintain the integrity of these genes and to control the activities of the cell by regulating gene expression.

The main structures making up the nucleus are the nuclear envelope, a double membrane that encloses the entire organelle and separates its contents from the cellular cytoplasm, and the nuclear lamina, a meshwork within the nucleus that adds mechanical support, much like the cytoskeleton supports the cell as a whole. Because the nuclear membrane is impermeable to most molecules, nuclear pores are required to allow movement of molecules across the envelope. These pores cross both of the membranes, providing a channel that allows free movement of small molecules and ions. The movement of larger molecules such as proteins is carefully controlled, and requires active transport regulated by carrier proteins. Nuclear transport is crucial to cell function, as movement through the pores is required for both gene expression and chromosomal maintenance.



,Cell membrane and Cytoplasm..i am going to give their answer to you in a minate later!

2008-10-15 16:54:42 補充：
cytoplasm:
The cytoplasm is the contents of a cell that is enclosed within the plasma membrane.
The cytosol is a complex mixture of cytoskeleton filaments, dissolved molecules, and water that fills much of the volume of a cell. The cytosol is a gel, with a network of fibers dispersed through water.

2008-10-15 16:55:13 補充：
cytoplasm2:
The part of the cytoplasm that is not held within organelles is called the cytosol. The cytosol is a complex mixture of cytoskeleton filaments, dissolved molecules, and water that fills much of the volume of a cell. The cytosol is a gel, with a network of fibers dispersed through water.

2008-10-15 16:57:11 補充：
cell membrane:
The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer") is a selectively permeable lipid bilayer found in all cells..

2008-10-15 16:57:28 補充：
cell membrane2:
The plasma membrane also serves as the attachment point for both the intracellular cytoskeleton and, if present, the extracellular cell wall.

2008-10-15 16:59:53 補充：
picture:
http://upload.wikimedia.org/wikipedia/commons/3/3a/Cell_membrane_detailed_diagram_4.svg

Nucleus
-control the activitier of cell
-contain chromosomes
-made up of DNA
-inheritance(遺傳)

Cell wall
-made up of cellulose
-free permeable
-hard--->protect and support the cell
-large spaces between the cellulose fibres----->allow laege particles to penetrate(free permeable)

Cell membrane
-consist of protein snd lipid
-control the movement of material in or out of the cell
-control cell membrane is selectively permeable

Cytoplasm
-clear,jelly like
-consist of an aquesous solution of many substances(protein)
-provide a medium for chemical reactions to take place
-contain a lot of organelles and granules

Chloroplasts
-absorb sunlight for photosyntheis

Mitochondria
-respiration takes place---->release energy
-also called"power house"

Vacuole
-also called"cell sap"
-large at the centre
-contains a solution of sugars,protein and minerals
-provides support when it is fully filled with water

Non-living granules
-contain crystals of insoluble waste
-starch granules

This all are found in plant cells,there are 8

Nucleus:
-Nucleus controls all cellular activities
-Contains chromosomes which carry gentic informations

Cell Wall:
-Supports and gives shape to cells

Cell membrane:
-Encloses the cytoplasm
-To control the movement of materials into and out of cells

Cytoplasm:
-Provide a place for chemical reactions to take place inside the cell
-Contains organelles



All of them can be found in plant cells!