Nat4/5Cell Biology

How much do I know?

DNA / Protein Synthesis

Traffic Lights:

Green = Fully understand

Orange = Understand most of it – needs further revision

Red = Do not understand – this is a priority

After Class Revision / After Home Revision
State that an individual’s DNA is unique
Describe the structure of a DNA molecule as a double helix made up of two strands of nucleotides.
Name the 4 bases – Cytosine, Guanine, Thyamine and Adenine.
Describe complementary base-pairing between the DNA bases.
State that base pairs are held together by weak hydrogen bonds. These hold both DNA strands together in the double helix.
State that the sequence of the 4 bases determines the genetic code.
State that DNA carries the genetic information for making proteins.
State that proteins are made up of amino acids.
State the order of amino acids is determined by the base sequence on the DNA.
State that mRNA (messenger RNA) is a type of molecule that can copy the DNA base sequence of a gene.
State that mRNA carries this copy of the DNA base sequence out of the nucleus into the cytoplasm where it becomes attached to a ribosome.
State that ribosomes are the site of protein synthesis.
State that amino acids joined together in a particular order to make an individual protein molecule.

Q1.DNA is present in which part of the cell?

  1. Cytoplasm
  2. Nucleus
  3. Cytoplasm and nucleus

Q2.What shape is a DNA molecule?

Q3.DNA is made up of which of the following?

  1. Nucleotides
  2. Amino acids
  3. Fatty acids

D.. Glucose molecules

Q4.Name the three components that make up a nucleotide.

Q5.Name the base that pairs with Thymine.

Q6.Name the base that pairs with Cytosine.

Q7.How many codons are present on the following molecule of DNA?

A A A A G A A T A A C A G A A G G A G T A G C A

Q8.What are the building blocks that make proteins?


How much do I know?

Enzymes

Traffic Lights:

Green = Fully understand

Orange = Understand most of it – needs further revision

Red = Do not understand – this is a priority

After Class Revision / After Home Revision
State that an enzyme is a biological catalyst that is made of protein.
Describe what is meant by a biological catalyst.
State that enzymes are not used up by a reaction.
State that enzymes are non living.
State that enzymes are specific. Explain
Describe what is meant by the optimum conditions for enzymes.
Describe what is meant by the working range of an enzyme.
Name the term given to the permanent change in the shape of an enzymes under extreme temperatures or pH.
State that enzymes and substrates fit together like a lock and key. Explain
State that enzymes have an active site
Describe what is meant by a breakdown reaction and a synthesis reaction
Give the word equations for 4 breakdown reactions
Give the word equations for 1 synthesis reaction.
Describe what is meant by immobilising enzymes.
State two benefits of immobilising enzymes
State the difference between biological and non biological detergents.
State two benefits of biological detergents.
Name the three sources of rennet

Question

You have already learned that temperature plays an important role on the activity of enzymes. The activity of an enzyme is also affected by the pH of its surroundings. Remember that ACIDS have a pH of 1–6, ALKALIS have a pH of 8-14 and substances with a pH of 7 are NEUTRAL.

Egg albumen (white of an egg) is protein which may be acted upon by pepsin. Albumen can be used in experiments to find out the effect of pH on the activity of the enzyme pepsin. In the experiment described here, glass tubes are filled with albumen and heated. Glass tubes, each with a solid rod of white albumen are produced.

The rods of albumen were placed in beakers of pepsin. Each beaker of pepsin had a different pH as shown in the diagram below:

The beakers were placed in an incubator a 37oC for 12 hours.

The rods of albumen were then removed and are shown below:

  1. From the results above, construct a table with the headings; pH, Initial Length, Final Length and Decrease in Length

(Handy Hints: Measure in mm, the albumen rods are shown life size and there was no digestion in albumen rod 6)

  1. At what pH is the activity of pepsin most active?
  1. Predict the length of the albumen tube at a pH of 1
  1. Do you think your prediction in question 3 was correct? What has actually happened at pH 1?
  1. Write down a definition of the term ‘WorkingRange’
  1. Use class resources to sketch the working range of some common enzymes.
  1. What is the working range of the enzyme catalase (and indicate this on your diagram)

1)Choose words from the list to complete the following sentences about enzymes

a)Enzymes ______or catalyse the chemical ______which occur in ______. They are ‘biological ______made of ______.

b)Enzymes are ______in that they only control one type of reaction.

c)Enzymes are ______by excess heat and are also sensitive to changes in pH. They conditions which an enzyme works best is described as it’s ______condition.

d)Enzymes are important because that ______where and when the cell’s reaction takes place.

2)The following results were obtained from an experiment in which a solution of the enzyme amylase was mixed with a starch suspension. Samples of the mixture were kept in water baths at different temperatures for 15 minutes. At the end of this time the samples were analysed to find out how much sugar had been produced in each. The results are given below.

Temp oC / 0 / 10 / 20 / 30 / 40 / 50 / 60 / 70 / 80
Units of Sugar / 12 / 36 / 65 / 90 / 90 / 60 / 30 / 4 / 2

b) Between what two temperatures is the optimum

temperature found?

c) How could the accuracy of the experiment be improved?

(2) Continued

d) Why is their no sugar formed at 80 oC?

e) State 2 other factors, besides temperature, would affect

the amount of sugar produced in the starch and amylase

mixture.

f) Can amylase break down any substances other than

starch? Explain your answer.