Cells • Revision Notes & Practice Quiz • Biology / Science

Key Takeaways

LEARNING OBJECTIVES

You need to know that plant and animal cells are eukaryotic cells, and that bacterial cells are prokaryotic cells.
Remember prokaryotic cells are much smaller than eukaryotic cells.
You need to know that most animal cells have nucleus, cytoplasm, cell membrane, mitochondria and ribosomes, and what roles they play in the functioning of the cell.
Remember that plant cells have the same parts as animal cells, but they also have a cell wall.
Know about the functions of permanent vacuole and chloroplasts.
Remember that bacteria cells have the following features: a cell wall, cell membrane and cytoplasm.
Know about DNA and plasmids, and know the function of each of these parts.

Please make sure you learn the above topics/points inside out to be fully prepared for your GCSE exam question relating to cells and cell biology.

Cell Biology Video

What are cells?

All living things are made of cells they're the building blocks of every organism on our planet. However, different organisms have different cell structures.

All living things in our planet are made up of cells.
Most cells are very small and you can only see them using a microscope.
Cells have different components and each component performs its own function within the cell.‍

Cells can be either prokaryotic or eukaryotic.

If we consider all cells in general, we can split them into two groups, eukaryotic cells, and prokaryotic cells.

Eukaryotic cells

Eukaryotic cells are complex and include animal, plant, fungi and protist cells. All of these organisms are known as eukaryotes.

Prokaryotic cells

Prokaryotic cells, on the other hand, are more simple, and a cell itself, is its own organism. For example, bacteria consist of a single prokaryotic cell, and so we class them as prokaryotes.

One of the things you need to know for your exams is the structure of both animal and plant cells, and you need to be able to compare the two.

What are the different types of cells?

Cells can be either prokaryotic or eukaryotic. Many students struggle with the pronunciation of these two words, so Prokaryotic is pronounced pro-kary-otik, and Eukaryotic is pronounced you-kary-otik. Once you say out loud a few times it becomes easy.

Eukaryotic cells are complex and include all animal and plant cells. Prokaryotic cells are smaller and simpler, e.g. bacteria.

Please remember that eukaryotes are organisms that are made up of eukaryotic cells. And a prokaryote is a prokaryotic cell, and it's a single -celled organism.

Eukaryotic and prokaryotic cells contain various cell parts which are called sub-cellular structures. As a student, you will be expected to know what these are called and their functions.

Learning About Cell Structures

‍Animal Cells

You will find that most animal cells will have the sub-cellular structures seen in the diagram below. Please make sure you know their names and functions.

Nucleus - The nucleus contains the genetic material that controls the activities of the cell.
Cytoplasm - is a gel-like substance where most of the chemical reactions happen. The cytoplasm contains enzymes that control these chemical reactions.
Cell membrane - is like the security guard or police, it holds the cell together and controls what goes in and out.
Mitochondria - the mitochondria is the place where most of the reactions for aerobic respiration take place. Respiration transfers energy that the cell needs to work.
Ribosomes - this is where proteins are made in the cell.

Plant Cells

Plant cells will have all the parts of the animal cells listed above (nucleus, cytoplasm, cell membrane, mitochondria and ribosome), plus they will have some extra parts, which are:

Cell wall - the cell wall is a rigid structure made of "cellulose". The cell wall supports and strengthens the cell. For example, the cells of seaweed and algae also have a rigid cell wall.
Permanent vacuole - contains cell sap, which is a weak solution of sugar and salts.
Chloroplasts - this is where the important process of photosynthesis occurs, which makes food for the plant. The chloroplasts contain a green substance called chlorophyll, which absorbs the light needed for photosynthesis to occur.

The diagram below shows a sub-cellular structure of a plant cell.

Bacteria Cells

Bacteria cells are prokaryotes or prokaryotic. A bacteria cell is more simple, and it has cytoplasm and a cell membrane surrounded by a cell wall. The cell doesn’t have a proper nucleus, but it has a single circular strand of DNA that floats freely in the cytoplasm. Some bacterial cells will also have one or more small rings of DNA called, which are called plasmids.