Cells and MRS GREN revision

The 7 signs of life

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.

Animal and plant cells

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

nucleus

cytoplasm

cell membrane

7A What is a cell?

The Cell - a living factory!

Role Check

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 Do all cells look the same?

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.

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

7A Specialised rugby players

Whose cell is it anyway?

Plant cellsTherefore, 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.

Cytoplasm

Cell Membrane

NucleusStarch Grains

Cell Wall

Vacuole (contains cell sap)

Chloroplast (contains

chlorophyll)

Animal, plant or both?

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.

Cell shapes

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.

Bring it to life!

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

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.

• Cell Membrane• Nucleus• Cell Wall• Vacuole• Water

• Glucose• Starch• Chloroplast• Light• Waste Material

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.

Cell-play

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…

Animal

From Cell to Organism

Plant

Animal and Plant Cells

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.

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.

How is the body organised?

Examples of Tissues

Animal Tissues Plant Tissues

Muscle

Bone

Liver

Skin

Lung

Mesophyll

Phloem

Xylem

Can you think of any more types of tissue?

How is the body organised?

Together, they are known as an….

ORGAN

Different tissues link together to carry out a certain job.

TISSUECELL

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

Organ 1

Organ 2

Organ 3

Organ 4

To become..An organ system

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...

Cell Pupil

Tissue Registration groups

Organ Subject Classes

Organ system Year

Organism School

How is the body organised?

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.

Grow quicklyThis is how it is possible for the body to ...Repair cuts and replace dead cells quickly.Produce an enormous number of reproductive

cells.

Where do cells come from?

Cell Division

Activity – animal cell

Activity – plant cell