Scientists believe that the first known cells originated on Earth around 3.8 billion years ago! These were prokaryotes – single celled organisms without a nucleus. There are 200 different types of cells in the human body, and around 3 to 5 pounds of bacteria!! Every day approximately 50 to 70 billion cells in your body will die. These are mainly skin cells and red blood cells, and it is important that this happens. Cell death clears away old and broken cells and replaces them with new ones. This is called apoptosis, the cells are actually programmed to die. For example, it can eliminate cells which could turn cancerous. It also contributes towards development in the womb. Apoptosis removed cells between your fingers and toes to shape them!
Your cells are also communicating with each other all the time, telling our heart cells to beat, forming memories, controlling levels of sugar and water in our bodies and much more. They release neurotransmitters and hormones, and pass on electrical impulses. Some even touch directly. Without this communication we would not function properly, and can develop many different diseases and disorders.
If you are in Year 7 or above, you need to be able to recognise the difference between bacterial cells, animal cells and plant cells. You should also be able to label and explain the functions of the organelles. For GCSE students it also explains the difference between prokaryotic and eukaryotic cells.
To help you understand, check out Part 1 of our “How to work with Cell Biology” guide. This describes the structure of an animal cell, a plant cell, and a bacterial cell. It also included some GCSE questions for you to practice, and answers to check your understanding.
Click on the picture below to see the guide.
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