Eukaryotic Cells

?

Eukaryotic Cells

Eukaryotic cells can be divided into two main types -

Animal and plant cells

Eukaryotic Cell (http://images.tutorvista.com/cms/images/101/eukaryotic-cell.jpg)

1 of 13

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.

2 of 13

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.

Structure of plasma membrane (http://science-tuition.co.uk/wp-content/uploads/2013/11/plasma_membrane_labeled.jpg)

3 of 13

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.

(http://1789a7.medialib.edu.glogster.com/EiqwKZzBQiWLhjSWZZYH/media/a9/a92118acc28b21b0999b970c95e03947d837784e/cell-nucleus-diagram.jpg)

4 of 13

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.

Mitochondria Structural Features

5 of 13

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.

Process of Golgi forming vesicles (http://www.biology4kids.com/files/art/cell_golgi1.png)

6 of 13

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.

Digestion by lysosomes (http://www.biology4kids.com/files/art/cell_lysosome2.png)

7 of 13

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.

Ribosome subunits (http://www.biology4kids.com/files/art/cell_ribosome2.png)

8 of 13

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.

Rough Endoplasmic Reticulum and protein synthesis (http://www.biology4kids.com/files/art/cell_er3.jpg)

9 of 13

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 wall structure showing membrane and cell wall in a plant. (http://www.biology4kids.com/files/art/cell_wall1.png)

10 of 13

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).

Vacuoles help plants maintain structure (http://www.biology4kids.com/files/art/cell_vacuole1.jpg)

11 of 13

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. 

Cross-section of chloroplast with labels. Membranes, Stromal Lamellae, Thylakoid, Stroma, Sugars. (http://www.biology4kids.com/files/art/cell_chloroplast1.png)

12 of 13

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

13 of 13

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Cellular processes and structure resources »