Cell Biology

Cell Structure

This week in National 4/5 Biology we have been learning about cell structure.

Many of these structures should be familiar to you. These include;

Cell wall, cell membrane, cytoplasm, nucleus, chloroplasts and vacuoles.

In addition we have learned to new structures in the cell; the mitochondria, ribosomes and endoplasmic reticulum.

Watch the following video to find out what each part of the cell does.

Label the main structures on the images provided – Cell Structure

Now try to match the structure to the function on the Card sort – unmatched. If you are catching up on work that you have missed glue this into your jotter.


On Wednesday the class produced an onion cell slide with a little iodine on the slide to stain the cells. Stains are often used to make the structures of the cell easier to see. Here is a summary of the steps involved in producing a microscope slide.

Onion Cell Slide Instructions

We also learned about the main parts of the microscope.  Here is the main image which was used in class;

Microscope Image

If you have any difficulties with this let me know.

Plant and Animal Cell Homework

In this homework you will need to take a red pen and correct the work of this pupil. If you lose the sheet that you have been given in class a spare can be downloaded here – Plant and Animal Cells homework

This homework is due to be handed in on Wednesday 20th June. If you have any difficulties and questions about the homework you can either ask me in class or post a comment on the blog. However, this MUST be done before the due date!

I look forward to some excellent homework being handed in.

Cells Folio Piece

This week we have started our first folio piece for National 4/5 Biology. We have been learning about people like Robert Hooke and Robert Remak who first discovered cells and cell division. We mainly used the BBC documentary on called The Cell to find out more about them. You can recap what you learned by following this link;

In your folio piece you need to announce that you have discovered one of the parts of the cell. You can choose yourself which part you have discovered. Then you need to explain the history of microscopes and cell discovery. This should include a little about

– Anton van Leewenhoek, Robert Hooke, Robert Brown and Robert Remak.

What did they discover and how did you improve on their work?

Bacterial and Fungal Cells

Also, this week each student has been working hard at learning the structure and function of all the parts of the cell. We added to this work today by learning about fungal and bacterial cells.

Try to remind yourself of what we did today by labelling the cells in the file below. Remember some labels are missing!

Bacterial and Fungal Cells

Cell Division

Cell division is important for growth, repair and replacement of lost cells.  Repairing damaged cells and repairing lost cells are particularly important in mature animals.  However, mature plants still use cell division for growth at the root and shoot tips.  The main difference between plant and animal cells is that plant cells also need to lay down a cell wall during cell division.

Remember, all cell division is controlled by the nucleus of the cell.

The two new daughter cells produced during cell division have the same chromosome complement as the mother cell. This is important since it gives the cells all the genetic information they need to function.

Follow the link below and see if you can correctly describe the stages of mitosis;

Mitosis Quick Check

The class also produced some lovely posters showing the main steps in mitosis. Here are some photos of their work;

You now have some homework to complete about cell division and mitosis.  If you lose the sheet you can download one from here;

Cell Division Homework

Here is a wee link which might help with your research;


You will not find all of the answers here but it may help a little. Hope you enjoy the research!

Just to finish off this topic on mitosis, here is a little mitosis song to brighten up your revision;

Remember, that you do not need to remember the names of all the different stages.

Transport across the Membrane

Diffusion is the movement of a substance from a region of high concentration to an area of low concentration. This is also known as substances moving down a concentration gradient.

It is a passive form of transport which does not require energy.

This is important so that plants get the raw material they need for photosynthesis;

In – carbon dioxide and water.

Out – Oxygen and Glucose

This is important so that animals get the raw materials they need for respiration;

In – Oxygen and Glucose.

Out – Carbon Dioxide and Water.

If the concentration of glucose inside and outside the cell is the same, diffusion will not take place.

I have attached here the powerpoint of the notes we have taken so far. If you have been off, use this to help you catch up.

Transport Across Membranes


Osmosis is the movement of water from an area of high concentration to an area of low concentration, across a selectively permeable membrane.  This is a passive process in which the water moves down a concentration gradient.

Here is a wee video to summarise.

Practical applications of osmosis include the generation of electricity;

Reverse Osmosis can be used to purify water;

The students are currently working on producing leaflets to advertise and sell one of these technologies.

DNA to Protein

We have now started learning more about DNA and how it was discovered. To begin with we watched a video called The Secret of Life. If you have missed class you can catch up below;

Then everybody did an excellent job of extracting DNA from raspberries, it was very pretty!

You can have a look through any notes you have missed using the link below;


By now you should understand the order of size from Organisms down to Base pairs. You should also be able to explain how DNA codes for a protein.

Try the questions below, leaving a comment and use your class notes to help!!

1. What do genes carry the instructions to produce?

2. Explain how DNA and genes code for proteins.

Good luck!!

Today we started to put together letters about inherited diseases. Below I have added the cards to help with completing the letters at home.

Inherited diseases case study

Genetic Engineering

This week we will be learning about genetic engineering as demonstrated by the spider goat.

Proteins and Enzymes

This week in Biology we reminded ourselves of what proteins were. In particular we learned about the 3 types of protein, fibrous, globular and conjugated. It is important that you all remember the 3 types of protein and are able to give an example of each type of protein.

Types of Protein 2


We then moved on in our work to learn about catalysts and enzymes. You will find the notes attached below;

Enzymes and Catalyst

Enzyme Specificity

Hope this helps any of you who are away to catch up!!

This week we have been learning about the lock and key theory which models the way enzymes interact with their substrates. We have particularly been looking at breakdown and synthesis reactions. Some of the pupils have produced some fabulous models to show these reactions taking place;

In these models some pupils showed the breakdown of starch into maltose by amylase. The active site of the enzyme can be seen clearly, allowing for a binding site for the substrate.

Other pupils, showed the synthesis of starch from glucose-1-phosphate by phosphorylase.

In both cases, the substrate bind to the enzyme to form and enzyme-substrate complex. This then loosens or strengthens bonds in the substrate to form a product. Remember, the enzyme is the lock and the substrate is the key. Each enzyme can only act on one substrate. Each enzyme is specific to it’s substrate.

This week we have been learning about the different factors which affect how enzymes work. But before we move on to the factors affecting them, here is a nice little summary of how the lock and key mechanism works.


Temperature and Enzymes

All enzymes work best at 37°C, this is known as their optimum temperature.

Between 0°C and 40°C enzymes speed up the reaction until this reaches a maximum at 40°C.

After 40°C the enzyme’s activity decreases until it is denatured. This normally happens around 50°C.

When an enzyme is denatured the shape of the active site is altered so that the substrate can no longer bind to the enzyme.

pH and Enzymes

The pH number is a number which tells us if a substance is very acidic, very alkaline or neutral. Here is an example of the scale below.

Every enzyme has it’s own optimum pH that it will work best at. For example, amylase which is found in your mouth works best at pH 7, since your mouth is neutral. But other enzymes like pepsin work best at pH 1 because they are found in your stomach and your stomach is acidic.

If you have missed any of the notes this week, here they are;

Factors affecting Enzymes

Hope all of this helps!

Enzymes in Industry

Yesterday, we moved on from learning about the factors which affect enzymes to learning about some industries in which enzymes are essential.  An example of this is in detergents or washing up powders.

Biological detergents contain enzymes which are made by bacteria.

Non-biological detergents do not contain enzymes at all.

Therefore, we predicted that biological detergents would be more effective at stain removal and be more economical since they can be used at lower temperatures and save energy.

However, we discovered that modern day non-bio detergents are just as effective as the biological powders.

Questions to try;

1. Why would it be useful for some of the enzymes used in biological detergents to come from hot springs?

2. What are the advantages of using biological washing powders at mow temperatures?

3. Explain what would happen to the enzymes found in a biological detergent designed to be used at 40°C if they were used in a wash at


Microbes in Industry

This week we have been learning about how cheese and yoghurt are produced.

Cheese Making

The steps involved in the process are as follows;

1. Pasteurise the milk by heating it to 72°C.

2. Allow the milk to cool.

3. Add the bacteria of your choice.

4. Add rennet.

5. Separate the curds and whey allowing the curds to dry out by cutting it into blocks.

6. Add salt to the curds and let them dry out even more.

7. Put the curds into moulds and leave them to mature.

Now, try to add the reason for each step.  It is very important that you can describe why each step is carried out.

Yoghurt Making

Watch the video below to summarise the process of how yoghurt is made.



If you have missed aby of the notes so far, here is a little helping hand…


We have been learning about a wide variety of uses of microbes in the past week or so.

We started by investigating how yeast and bacteria can be used to make biofuels. Yeast can be used to make ethanol as shown below;

 Biofuel production

Make sure you can describe the steps shown in this diagram.  Once the ethanol has been produced it can be mixed with petrol to produce GASOHOL.

BIOGAS is produced when manure is broken down into methane gas by bacteria.  This methane can then be used to power cars and for cooking.

Wine Production

We then produced some wine carrying out the following steps;

•A sterilised container is used.

Grape juice, sugar and yeast is added.

Warm water is used to fill up the container.

Bubbles are seen in the container.

Why are each of these steps carried out?


Brewing is a process carried out by yeast cells.  The starch in the barley grains are too large for the yeast to use as a source of food.  Therefore, it is important for the yeast cells that the starch is broken down into maltose at the beginning of brewing.

This step is called malting.  Can you put the other steps of brewing in order?

Wort cooledHops added

Fermentation stopsMalting


Barley crushed


For those of you who were off or missed lessons last week here are the notes about respiration;


This is not the easiest of topics but I was really pleased with how everybody in the class tackled it head on and were determined to give it their best shot.

The carouselling task that we did on Friday without your books showed that you had a good grasp of the main concepts.  Remember to practice some Intermediate 2 exam questions to check your understanding.

This week in National 4/5 Biology we have been developing our problem solving skills by investigating the factors which might affect how well yeast makes dough rise.

Here is an example of their work;


It has been nice to see their confidence growing in writing up their experiments independently.  Keep up the good work!


4 comments on “Cell Biology

  1. Miss, I missed class on friday but i cant print out the page, should Ijust copy out the card sort?

  2. Your blog is great ,my daughter has just started biology and is working on proteins and enzymes so I will show her your blog as the info on her work sheet is sparce to say the least. Thanks Deborah

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