Eukaryotic Cells
- Created by: rebecca53211
- Created on: 20-08-17 19:18
Eukaryotic Cells
Eukaryotic cells can be divided into two main types -
Animal and plant cells
Contents
The structure of eukaryotic cells, restricted to the structure and function of:
- cell-surface membrane
- nucleus (containing chromosomes, consisting of protein-bound, linear DNA, and one or more nucleoli)
- mitochondria
- Golgi apparatus and Golgi vesicles
- lysosomes (a type of Golgi vesicle that releases lysozymes)
- ribosomes
- rough endoplasmic reticulum and smooth endoplasmic reticulum
- cell wall (in plants, algae and fungi)
- cell vacuole (in plants).
- chloroplasts (in plants and algae)
In complex multicellular organisms, eukaryotic cells become specialised for specific functions. Specialised cells are organised into tissues, tissues into organs and organs into systems.
Cell Surface Membrane
The cell surface membrane regulates the movement of substances in and out of the cell.
The membrane consists of a phospholipid bilayer, the bilayer also contains proteins and glycolipids that allow for the selective transport of substances across the membrane.
Below is pictured the fluid mosaic model of a cell surface membrane.
Nucleus
Is the control centre of the cell. It contains chromosomes, linear DNA and one or more nucleoli.
The nucleus acts as storage for DNA, which is linear in Eukaryotes.
The nucleolus is a small body in the nucleus of a cell that contains protein and RNA and is the site for the synthesis of ribosomal RNA and for the formation of ribosomal subunits.
Mitochondria
Mitochondria are the energy producing centres of the cell. They convert oxygen and nutirients into ATP. These organelles allow organisms to respire aerobically.
Mitochondria have their own circular DNA (like those of prokaryotes). Mitochondria are similar to plant chloroplasts in that both organelles are able to produce energy and metabolites that are required by the host cell.
Golgi Body
The Golgi apparatus gathers simple molecules and combines them to make molecules that are more complex. It then takes those big molecules, packages them in vesicles, and either stores them for later use or sends them out of the cell. Proteins arrive in vesicles from the ER and in the Golgi apparatus they are folded in to their correct configurations and if required have lipids, carbohydrates or other complex molecules added to them.
Lysosomes
The digestion system of the cell - they contain digestive enzymes and break down things as required by the cell. They are created by the Golgi apparatus and are a type of specialised vesicle.
Ribosomes
Ribsomes are protein synetheising units. They are found in both eukaryotes and prokaryotes. Ribsomes can be found attached to the ER or floating freely in the cytoplasm.
They are made of two subunits which are called 60-S and 40-S in eukaryotes. Prokaryotes have slightly smaller ribsomes of the 50-S/30-S variety.
Endoplasmic Reticulum
The ER works as a manufacturing and packaging centre of the cell. It works in conjunction with the Golgi apparatus and ribosomes. The ER is split into two types the smooth and rough.
sER is a storage organelle and are part of the lipid and steroid manufacturing process in cells.
rER is called 'rough' because of the ribsomes attached to the organelle's membrane. The rER performs an important function in the synthesis and packaging of proteins.
Cell Wall
Cell walls are not found in animal cells, but they are present in plant cells. They are made of cellulose and help to keep structure of the cell.
Cellulose is a structural polymer
Fungi and insects have a cell wall, however this is made of chitin, a different type of structural carbohydrate.
Cell Vacuole
Is a storage bubble, it can be found in plant or animal cells but is generally much larger in plants.
The vacuole is generally used to store nutrients but can even be used for the storage of waste products. Plants use vacuoles to store water in, most of a plant's cell volume depends on the amount of water stored in the vacuoles. The vacuole provides structural support to the plant cell (in addition to that already provided by the cell wall).
Chloroplasts
Chloroplasts are present in plants and algae. Chloroplasts contain chlorophyll which give plants their green colour. They harness energy from sunlight, using it to convert carbon dioxide and water in to sugar and waste oxygen.
Rescources
For more in depth information on cell organelles see:
http://www.biology4kids.com/files/cell_main.html
Also this silly song may help you to remember cell structure:
https://www.youtube.com/watch?v=rABKB5aS2Zg
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