CellDivision Enzymes and Microorganisms

Question 1

Give a summary of what cell division is and state three reasons why it is important.

Answer 1

Cell division produces new body cells. This is important for three reasons;

1. Increasing the number of cells allows organisms to grow.
2. New cells are needed by organising to repair or replace damaged tissue.
3. Single-felled organisms, e.g. bacteria use cell division to reproduce

Question 2

Explain a diagram of cell division.

Answer 2

O- Parent cell
       |
      O- DNA replication
      / \
    O  O- 2 daughter cells 

The changes in the division of the nucleus is called mitosis.

Question 3

What is cell division controlled by?

Answer 3

Cell division is controlled by the nucleus.

Question 4

Where does the nucleus get the information from to control the cell division.

Answer 4

Theo’s information is stored on structures called called chromosomes that are found in the nucleus.

Question 5

What are chromosomes?

Answer 5

Chromosomes are long, thread like structures that are usually so thin that they cannot be seen easily even in powerful microscopes. The chromosomes in a human cell laid end to end in their thread like state would measure 2 meters!

Question 6

What must happen before cell division can take place?

Answer 6

The chromosomes have to be copied before cell division can take place. Theo’s ensures that the two new cells formed will each receive a complete set of information.

Question 7

What are chromatids?

Answer 7

In mitosis the original set of chromosomes are copied to produce two sets. Each copy is called a chromatid. The two chromatids are held together by a structure called a centromere.

Question 8

What happens to a chromosomes once that are copied?

Answer 8

Once copied the chromosomes shorten and thicken.
In their shortened and thickened form the two chromatids can be separated more into each of the two new cells produces( called daughter cells ).

Each daughter cell then contains the same number of chromosomes as the original cell. The daughter cells contain the same instructions as the original cell and can function normally.
If anything goes wrong in the process of mitosis information may be lost. A cell without important information would function abnormally or even not function at all.

Question 9

Explain the 5 stages of mitosis

Answer 9

1. Chromosomes become visible
2. Chromosomes replicate to form 2 identical chromatids, joined by a centromere.
3. Chromosomes line up along the equator of the cell and spindle givers attach onto the chromatids.
4. Spindle divers pull chromatids to opposite ends of the cell
5. Cytoplasm divides, new nuclear membrane forms and 2 identical cells are formed. Each cell contains the same number of chromosomes as the original cell.

Question 10

What is genetic engineering?

Answer 10

New ways have been developed to use cells to treat diseases or injury by making products that the body cannot make or by repacking faulty cells.

Genetic engineering is the transfer of genetic information from one organism to another.

Bacterial cells can be given human genes so that they make human proteins

When the bacterial cells divide, copies of the human genes will be passed on to the new cells. Bacterial cells divide very rapidly so large quantities of human proteins can be produced.

Question 11

Give examples of genetic engineering!

Answer 11

Examples;

Insulin a hormone that regulates the level of glucose in the blood. Some people with diabetes cannot make their own insulin.

Factor VII a protein that is needed to male blood clot. It can be given to people with haemophilia A as they cannot produce their own factor VII.

Human growth hormone which is needed for cell growth it can be used to treat children with growth disorders.

Question 12

What are stem cells Where are they found and what can they be used for?

Answer 12

Stem cells are cells found in animal bodies and are capable of carrying out cell division and developing into specialised types of cells.

Stem cells could potentially be give. to people to help replace parts of organs that have been damaged by injuries or diseases.

Question 13

What are the types of stem cells

Answer 13

There are two types of stem cells:

Adult stem cells- these are unspecialised cells that can develop into many types of cells

Embryonic stem cells- these are unspecialised cells that can develop into any type of cell,

Question 14

What are the properties of an Enzyme

Answer 14

Enzymes
Catalyst

Biological catalyst. Important- correcting functioning of cells as chemical reactions would happen too slowly at body temperature without them.

Made of proteins

Specific- only work on one substrate

Each enzyme only acts on one substance called substrate to produce a product.

                               Enzyme
          Substrate —————> Product

Question 15

What are the types of Enzymes

Answer 15

In cells the chemical reactions can be either degradation or synthesis reactions.

Substrate Enzyme Product remember S/D

Starch Amylase Maltose SAM Degradation

Hydrogen Catalase Oxygen+ HPCOW Degradation
Peroxide Water

Glucose Phosphorylase Starch G1PPS Synthesis
1 Phosphate

Question 16

How do enzymes work?

Answer 16

The way in which enzymes work is described as a lock and key system. The Enzyme is the key and the substrate is the lock.

The substrate has a complementary shape to the active site of the enzymes.

Question 17

Explain enzyme specificity!

Answer 17

An enzyme can only act on one type of substance( it’s substrate). The enzyme amylase, for example is only able to promote the breakdown of starch and no other substance.

Each enzyme is therefore said to be specific to its substrate. The shape of the substrate fits exactly onto a part of the enzyme surface known as the active site, in much the same way as a key fits exactly into a lock.

Question 18

Explain how enzymes and microorganisms are made in the cheese and yoghurt industry.

Answer 18

Fresh milk from a cow normally contains many bacteria. During the souring of the milk, the bacteria feed on the sugar in milk called lactose and break it down using enzymes into lactic acidosis.

  Lactose  ———————>  Lactic Acid 

The manufacture of cheese and yoghurt depend on the curdling of milk. Lactic acidosis is needed to make the milk curdle. It is produced during fermentation by special strains of Bacteria added to milk for this purpose.

Question 19

How is yoghurt made?

Answer 19

1. Milk is heated to 73 C for at least 30 seconds to make it virtually sterile.
2. Sterilised milk cooled 44 C.
3. Special yoghurt bacteria added to sterilised milk.
4. Milk kept at 44 C for 4 hours to allow bacteria to convent it to yoghurt by making lactic acid.
5. Yoghurt stored in cartons at 4 C to slow down further bacterial action.

Question 20

How is cheese manufactured?

Answer 20

There are several steps in the manufacturing of cheese;

The milk is pasteurised you kill most bacteria

Special bacteria is added to convert the milk sugar into lactic acid

Enzymes (rennet) are added to clot the proteins in milk.

This forms curds and whey

The milk clotting enzymes (rennet), which were used originally, always came from animals such as calves. Enzymes used in cheese 🧀 making can come from a variety of different sources:

rennet from calves

An enzyme similar to rennet but is made by a fungus

An enzyme which is produced by heat which have been genetically modified to produce rennet

Question 21

What is yeast?

Answer 21

Yeast is a single celled fungus. It uses glucose as a food source. Carbon dioxide and alcohol are waste products.

Question 22

What is yeast used in?

Answer 22

It is used in bread making to male dough rise due to CO2 bubbles released

It is used in the production of alcohol. As yeast grows it uses the sugar for energy and changes into alcohol.

Question 23

What does the word detergent mean and what does it therefore include?

Answer 23

The word detergent means: something which cleans. So it includes soaps, washing up liquid and washing powder.

Question 24

Describe biological washing powders, what do they contain?

Answer 24

Biological washing powders contain enzymes and are added to the washing powder because they improve the way in which it cleans.

In biological washing powders only about 1% is enzymes.

The enzymes mean that you can wash clothes with biological powders at a lower temperature than with non biological and this saves energy.

Question 25

Name other enzymes in industry and their uses.

Answer 25

Protease: used to predigest proteins the manufacture of baby foods

Lipase: used together with protease- in biological detergents to break down, digest the substances in stains into smaller, waters soluble substances

Carbohydrase: used to convert starch syrup, which is relatively cheap, into sugar syrup, which is more valuable- for example, as an ingredient in sports drinks.

Isomerase: used to convert glucose syrup into fructose syrup. Fructose is sweeter than glucose so it can be used in smaller amounts in slimming foods.