View source for Eukaryotes

Living organisms can be sorted into two groups; these&nbsp;are the&nbsp;[[Prokaryotes]] and the&nbsp;eukaryotes. Eukaryotes are organisms that contain cells with a membrane-bound nucleus as well as membrane-bound [[Organelles]]. Examples of eukaryotes include all [[Animal|animals]], [[Plant|plants]], [[Fungi|fungi]] and protists. Eukaryotes may variably be multicellular or unicellular. Conversley,&nbsp;[[Prokaryotes]]&nbsp;contain no nucleus, no membrane bound organelles and the majority are known to be unicellular, very rarely are they multicellular. Examples of prokayotes are, [[Bacteria|bacteria]] and [[Cyanobacteria|cyanobacteria]]. 

== Cell Structure  ==

=== Plasma Membrane:  ===

[[Plasma membrane|Plasma membrane]] separates the cell from the surrounding environment and controls the passage of the molecules in and out of the cell. This membrane is composed mainly of phospholipids. The plasma membrane is known as phospholipid bilayer because the phosphate group and the lipid molecules have different properties in water. The phosphate group is hydrophilic but lipids are hydrophobic; as water is found inside and outside the cell, phosphate molecules lies on the surface of the phospholipid bilayer while the [[Lipid|lipid molecules]] form the internal part of the phospholipid bilayer of the membrane. 

Most of the organelles inside the cell are surrounded with membrane which segregates its activity from the surrounding environment. 

=== Cytoplasm:  ===

Cytoplasm is composed of the cytosol and the organelles. The cytosol is gel-like substance. All the organelles are suspended in the cytosol. 

==== [[Endoplasmic Reticulum|Endoplasmic Reticulum]]: ====

There are two types of [[Endoplasmic reticulum|endoplasmic reticulum]]; [[Rough endoplasmic reticulum|rough]] and [[Smooth endoplasmic reticulum|smooth]]. [[Rough endoplasmic reticulum|Rough endoplasmic reticulum]], so called due to&nbsp;the [[Ribosomes|ribosomes]] found on its surface,&nbsp;synthesises [[Proteins|proteins]], and&nbsp;[[Smooth endoplasmic reticulum|smooth endoplasmic reticulum]]&nbsp;synthesizes [[Lipid|lipids]] and [[Carbohydrate|steroids]] and metabolizes [[Carbohydrate|carbohydrates]] and [[Steroids|steroids]]. The general structure is a network of sac-like structures called [[Cisternae|cisternae]], held together by the [[Cytoskeleton|cytoskeleton]]. 

==== Golgi Apparatus:  ====

The [[Golgi apparatus|Golgi&nbsp;apparatus]] gathers simple molecules and combines them to make molecules that are more complex which then get packaged them in [[Vesicles|vesicles]], and either stores them for later use or sends them out of the cell. It is builds [[Lysosome|lysosomes]]. The structure of the [[Golgi apparatus|Golgi apparatus]] can be described as a series of flattened sacs. 

==== Mitochondria: ====

[[Mitochondria|Mitochondria]] are vital organelles that provide energy for the cell to carry out all its functions, for example division. [[Mitochondria|Mitochondria]] have double membranes, with the outer membrane fairly smooth, and the inner membrane folded in to cristae, which&nbsp;greatly increases the surface area. It is on these cristae that sugar is combined with [[Oxygen|oxygen]] to produce [[ATP|ATP]] - the primary energy source for the [[Cell|cell]]. 

==== Nucleus:  ====

The [[Nucleus|nucleus]] controls all functions of the cell and contains genetic information in the form of [[DNA|DNA]], and its associated [[Proteins|protein]], [[Histones|histone]], which forms [[Chromosome|chromosomes]]. The [[Nucleus|nucleus]] is bounded by a double membrane, called&nbsp;the [[Nuclear envelope|nuclear envelope]].&nbsp;Within the double membrane nuclear envelope are passages which large molceules can pass through called [[Nuclear pores|nuclear pores]]. Each&nbsp;Nucleus contains one or more nucleolus; the site of ribosome synthesis.&nbsp; 

==== Cell Wall:  ====

[[Cell wall|Cell wall]] are present in [[Fungi|fungi]] and [[Plant cells|plant cells]], and exist around the outside of the [[Plasma membrane|plasma membrane]]. In [[Fungi|fungi]] [[Peptidoglycan|peptidoglycan]] forms the [[Cell wall|cell wall]] and in [[Plant|plants]], the strongest component of the cell wall is a [[Carbohydrate|carbohydrate]] called cellulose.&nbsp;Cells walls provide structural support and have no affect on the passage of [[Molecule|molecules]] and [[Ion|ions]] into and out of the [[Cell|cell]].<br> 

== Reproduction  ==

The cell cycle of eukaryotic cells has two major phases: the [[Interphase|interphase]] and cell division. During the interphase, the [[Cell|cell]] takes in nutrients, grows, and duplicates its [[Chromosome|chromosomes]]. During the cell division phase, the nucleus divides in a process called [[Mitosis|mitosis]] and then the divided [[Nucleus|nuclei]] are established in separate cells in a process called [[Cytokinesis|cytokinesis]]. Each [[Daughter cell|daughter cell]] produced will be genetically&nbsp;identical to that of the [[Parent cell|parent cell]].