Biology
Home > Biology > Options > Biotechnology > Biotechnology: 4. Cell chemistry
9.6 Option – Biotechnology: 4. Cell
chemistry
| Syllabus reference (October 2002 version) | ||
|---|---|---|
4. Cell chemistry is utilised
in biotechnology
|
Students learn to:
|
Students: |
Extract from Biology Stage 6 Syllabus (Amended October 2002). © Board of Studies, NSW.
Prior learning: Stage 4-5 Syllabus,
5.8.2(a, b, c and d).
H.S.C. module 9.3 (subsection 3).
Background information: Deoxyribose nucleic acid (DNA) provides the blueprint for life. It does this by forming proteins, many of which are enzymes.
Enzymes are biological catalysts that increase the rate of
chemical reactions. Enzymes have a specific shape that fits
into other molecules forming an intermediate molecule. This
separates forming the new product and releasing the unchanged
enzyme that can once again take part in a reaction. Enzymes are
affected by pH, temperature and substrate concentration.
Enzymes have a range of optimum conditions within which they
work most effectively. If the conditions are outside of the
optimum for a particular enzyme then the enzyme may become
denatured and will no longer work.
outline, simply, the steps in the synthesis of protein in the cell, including:
- the difference between DNA and RNA
- the production of messenger RNA
- the role of transfer RNA
- the formation of the polypeptide chain(s)
- the formation of the protein from polypeptide chains
- The differences between DNA and RNA can be summarised in a table.
DNA RNA doubled stranded molecule of nucleotides in the shape of a spiral helix single stranded molecule of nucleotides contains a deoxyribose sugar contains a ribose sugar contains the nitrogen base thymine contains the nitrogen base uracil one type two types, messenger and transfer
For a diagram of the structure of DNA,
click here 
Molecular Station
For the structure of RNA click here Molecular Biology Notebook Online
- The first process in the synthesis of protein from DNA is transcription. The DNA molecule in the nucleus partly unzips and the code of nitrogen bases on the DNA is transferred to messenger RNA (mRNA). This is done by adenine bonding to uracil and guanine bonding to cytosine. Any non-coding sequences are removed at this point and the mRNA travels through the nuclear membrane to the cytoplasm.
- The second process is translation. Transfer RNA (tRNA) picks up amino acids in the cytoplasm and brings them to the mRNA that is attached to a ribosome. The first and second amino acids brought to the ribosome attach together, forming a peptide bond. The amino acids that link together will be determined by the order of bases on the mRNA. This linking continues down the code on the mRNA until a stop code is reached and then the chain of amino acids is released by the ribosome. This chain of amino acids is a polypeptide chain.
- The last process is the forming of a protein and this happens by the long polypeptide chain folding in particular shapes. The way they fold largely depends on the order of the amino acids. They fold several times to give their final structure.
plan and perform a first-hand investigation to test the conditions that influence the rate of enzyme activity
- To be able to plan your investigation you will need to decide which enzyme to use. The enzyme catalase breaks hydrogen peroxide into water and oxygen. The following experiment is a fairly simple one that shows the effect of pH on the action of an enzyme. Whether you do this investigation or another one you will need to decide which variables will be kept constant. In this investigation the variables that are kept constant are the test tubes, the amount and concentration of hydrogen peroxide solution and the size of the piece of liver put into each test tube. Other environmental conditions such as temperature, the amount of light and humidity are also kept constant. Therefore the only variable that is changed is the pH. Any differences between the test tubes could be accounted for by the differences in pH if all other variable are kept constant.
The effect of pH on catalase
Aim : To examine the rate of reaction of the
enzyme catalase at different pH levels.
Method: Fill six identical test tubes with
20mL of 10% hydrogen peroxide solution. The pH of each test
tube is then adjusted by adding drops of sulfuric acid or
sodium hydroxide solution. A pH meter is used to monitor the
pH so that there is a range from pH 1 to pH 11. To supply the
enzyme catalase, equal pieces of liver is placed into each
test tube. The rate of reaction is then measured by the
height of oxygen bubbles produced.
Results: Catalase was most effective at a pH
of 7. At pH 1 and pH 11 the reaction came to a stop.
Conclusion: The enzyme catalase is most
effective at pH 7 and then the rate of reaction decreases as
the pH increase or decreases from that point.
- This investigation involved the use of some caustic chemicals such as sulfuric acid and sodium hydroxide. Safe work practices must be maintained. This would include protective equipment such as rubber gloves and safety goggles should be worn. Covered shoes should also be worn to protect against spillage.
- Perform your investigation keeping the issues listed above in mind.
|