Cell structures

Hello to everyone who loves Biology. For the students who are new to Biology, you might want to start off with the most basic topic in Biology, which is the cells. This is the most easy topic that you will find eventually, comparing with the other topics.


Ok, lets move on to our most interesting topic for today.

A cell is a unit of life. It consists of a mass of living matter called protoplasm.

Protoplasm is the living essence of a cell. It includes the cell surface membrane, the nucleus and the cytoplasm, where numerous biochemical reactions take place.

Protoplasm exists in two forms:

•  Sol state (or liquid state)
•  Gel state (or semi-solid state)

Figure below shows a typical animal cell and plant cell as seen under a light microscope.

Animal cell

Plant cell

The following diagrams are cell structures as seen on the electric microscope, therefore they are much detailed but I emphasized you to know the most basic one, which is the previous diagrams. This is to let you know that in cells, there are lots of organelles that can be found.

Plant cell

Ok, lets read some facts about these two cells.

i)                    All cells (animal or plant) have cell membrane around the outside. Inside the cell membrane is a jelly substances called cytoplasm, in which are found many small structures called organelles. The most obvious of these is usually the nucleus.

The cell membrane is a very thin layer of protein and fat. It is very important to the cell as it controls what goes in and out of the cell. It is partially permeable that is it only allows some substances through but not others.

ii)                   All plants cells are surrounded by a cell wall made of cellulose. Animal cells never have cell walls. Cellulose forms fibres which criss-cross over one another to form a very strong covering to the cell. This helps to protect and support the cell. Unlike the cell membrane, cell wall is fully permeable.

iii)                 Cytoplasm is a clear jelly like structure found in both plant and animal cells. It is made up of about 70% water. It contains many dissolved substances especially proteins. Many metabolic reactions take place in the cytoplasm.

iv)                 Most cells contain vacuole which is a space in a cell surrounded by a membrane and containing a solution. Most plant cells have very large vacuole, containing a solution of sugars and other substances called cell sap.

Animal cells have much smaller vacuoles, which may contain food or water.

v)                  Chloroplasts can only be found in plant cells (most but not all). They contain a green pigment called chlorophyll. Chlorophyll absorbs sunlight, and the energy of sunlight is then used for making food for the plant by photosynthesis.

vi)                 Most cells have mitochondria, because it is here that the cell releases energy from food. The energy is needed to help the cell move and grow. Mitochondria are sometimes called the ‘powerhouses’ of the cell. The energy is released by combining food with oxygen, in a process called aerobic respiration. The more active the cell, the more mitochondria it has.

vii)               The nucleus is where the inherited information is stored which helps the cell to make the light sort of proteins. The information is kept on the chromosomes, which are inherited from the organism parents.

 Still can't imagine how these cells are being situated inside the body and plant? If not, let us watch two videos that are associated with these cells. Its really interesting!

Please don't forget to take some notes when you are watching the video.





Ok, so that's our topic for today and I hope that you like it :)


For additional notes, please click here





In case that your teacher want to do a presentation about this topic, please refer to this slide presentation taken from www.slideshare.com :) hope it helps.

Cellular Structures and Their Functions

View more presentations from cgales.