Your body is made up of billions of tiny cells, each performing a specific function to help you survive.

Beta cells, Skeletal muscle cells, ,Neurons, RBC and WBC are all specialised cells, with the soul purpose of keeping you alive an healthy

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How did you grow to the person you are today?

You started life out as a single cell, actually 2 separate cells, carrying half your DNA.

One sperm from your father and an egg from your mother.

As you grow in the womb, you go from a single cell, capable of sitting on the head on a pin, to a multi cellular organism, weighing up to 7.5 pounds.

Within the first week, you multiply into 100 cells. After 2 month your main organs have developed, and now the baby is called a fetus.

In adult hood, your body with contain over 10,000,000,000 cells.

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From these simple cells arise all your muscles, bones, neurons, lungs and organs.

Your body is made up of billions of tiny cells, each performing a specific function to help you survive.

As your cells, divide and specialise they group together, forming tissue.

We can categories tissue into:

• Connective (blood, cartilage, bone and lymph)
• Muscle (smooth, skeletal and cardiac)
• Nervous (nervous system)
• Epithelia (skin)

Once similar cells have banded together to from tissue, the tissues join to form organs.

Organs are specialised structures which perform a task, important for survival.

• Brain
• Heart
• Lungs
• Liver

Eventually all these organs come together, forming organ systems.

• Nervous system (brain and spinal cord)
• Circulatory system (heart and blood vessels)
• Digestive system (stomach, intestines and oesophagus).

Every single cell in your body has the exact same amount and type of DNA. Cells in your muscles and cells in your nervous system, contain the exact same DNA.

So why do they look so different?

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1. What is unique about a sperm and egg cell?

2. Where is DNA stored?

3. From smallest to largest, order the following

Atom

Tissue

Mitochondria

DNA

Cell

Digestive system

Heart

4. List 4 types of specialised cells and explain how their structure is related to their function

5. When you are first conceived, in that moment, how many cells are you, and how many chromosomes do you have?

6. After roughly two week, how many cells are you?

7. What is a stem cell?

8. Explain how plants grow taller, longer roots and thicker girth.

9. What are three organs of the body, and state which organ system they belong too

10. How can Meristems be used to create more plants

As you know, at birth, your cells have the potential to become any type of cell they need to be. As they mature, certain sections of DNA are locked off, making them specialised.

Cells which have the ability to become any type of cell are called Stem-cells.

In plants, meristem cells are unspecialised cells, capable of becoming any type of cell the plant needs.

If a plant gets its leaf cut off, meristem cells can specialise into leaf cells and re-grow.

Farmers cut off the shoots and leaves from a plant and, in the right conditions, they will grow a new root network. Forming a new plant.

Some animals in this world keep some of their stem cells. If you’ve ever grabbed a newt’s you’ll notice it comes off. However over time they’ll actually re-grow their tail.

The same for their arms and legs.

Human however, do not have this ability. Almost all the cells in our bodies are specialised. Meaning that, skin cells and only grow into skin cells.

Humans can re-grow finger tips, but cut too far down and it won’t grow back.