Cells and MRS GREN revision

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# Cells and MRS GREN revision - PowerPoint PPT Presentation

Cells and MRS GREN revision. The 7 signs of life. Animal and plant cells. Here is a picture of a plant cell and an animal cell. Cells are the smallest units of life. Some cells can exist on their own, whilst others are found in groups.

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### Cells and MRS GREN revision

Animal and plant cells

Here is a picture of a plant cell and an animal cell.

Cells are the smallest units of life.

Some cells can exist on their own, whilst others are found in groups.

Humans are a collection of many billions of cells, all working together.

7A What is a cell?

nucleus

cytoplasm

cell membrane

While some cells do look different, all cells have three basic features.

7A Do all cells look the same?

Most cells have three basic parts.

nucleus

cytoplasm

cell membrane

But cells can be different shapes and sizes and also have different functions. This is because they are…

specialised

The shape of a cell is related to its function.

Where do you see this idea in sport?

CLUE: World Cup!

7A Specialised rugby players

Why are the players in a rugby union team different shapes and sizes?

Rugby players are different shapes and sizes because they do different jobs for the team.

Like rugby players, cells are different shapes and sizes because they perform different jobs.

Plant cells

Cell Membrane

Vacuole (contains cell sap)

Chloroplast (contains chlorophyll)

Cytoplasm

Nucleus

Cell Wall

Starch Grains

Therefore, if plants and animals are different shapes, they must be made of different shaped cells. Let’s have a look at the shape of a basic plant cell.

Apart from the shape, the cell looks very similar to an animal cell.

However, here is how the plant cell differs from the animal cell.

Cell shapes

Now that we know what the basic structure of a plant and animal cell is, we can begin looking at the bigger picture.

Cells are not flat…..

…they are usually three-dimensional

The 3D shape of the cell will be determined by its location in the body and the job it does.

Bring it to life!

You can make your own 3D cell using the following equipment.

• Plastic bag
• Cellulose paste
• Cardboard box

You will need to find some small objects to suspend in the cellulose paste. These will represent the internal structures of the cell.

Try to make a model of both the plant and animal cell. Then label these and display them.

Cell-play

• Cell Membrane
• Nucleus
• Cell Wall
• Vacuole
• Water
• Glucose
• Starch
• Chloroplast
• Light
• Waste Material

A great way to visualize how a cell functions, is to become one!

You can get people to stand in a circle, holding hands to represent a cell membrane.

Then, get other people to be the nucleus and so on. If you are feeling adventurous, you can even dress up to represent the job of that part of the cell.

Make sure you have a cell membrane and a nucleus as a minimum. Then you can choose from the list and role-play cell activity.

From Cell to Organism

Plant

Animal

As we know, all life is built of cells. The way we look is the result of the types of cell we are made of and the way those cells are organised.

For example, if we look at the cells of the plant and animal, it is no surprise that plants and animals look different…

How is the body organised?

To help us understand this, think of how a school is organised.

A school needs to be very organised. Every pupil in the school needs to know where they should be and what they are doing. However...

Not all pupils study the same subjects.

Not all pupils can work together efficiently.

There is not room for all the pupils to be in the same place.

How is the body organised?

Therefore, a school uses the following system.

One pupil

Registration groups

Subject classes

A year group

A school

How is the body organised?

This hierarchy of organisation is also found in living organisms.

Each specific cell

Is grouped with cells similar in structure and function.

We call this a tissue.

Examples of Tissues

Animal Tissues

Plant Tissues

Muscle

Bone

Liver

Skin

Lung

Mesophyll

Phloem

Xylem

Can you think of any more types of tissue?

Organ 1

Organ 3

Organ 4

Organ 2

How is the body organised?

Next, different organs are linked together by tubes/ vessels…..

An organ system

To become..

Cell

Pupil

Tissue

Registration groups

Organ

Subject Classes

Organ system

Year

Organism

School

How is the body organised?

The body is then made up of different organ systems working together to carry out all the functions of a living organism.

In summary...

Where do cells come from?

Q. Can you think of a problem if one cell splits to produce two cells?

A. The two new cells would be smaller than the original cell.

Therefore, a cell needs to make new copies of the material inside itself as well as the membrane and nucleus.

Just before a cell divides, it will appear to grow slightly as it reproduces everything inside itself.

The nucleus must also divide into two equal halves.

This only occurs once the nucleus has doubled from its original size.

Where do cells come from?

Cell division occurs extremely quickly and can happen over and over again.

Produce an enormous number of reproductive cells.

Grow quickly

Repair cuts and replace dead cells quickly.

This is how it is possible for the body to ...