Explain each of the following terms in relation to DNA - Leaving Cert Biology - Question 8 - 2005
Question 8
Explain each of the following terms in relation to DNA.
(i) Replication
(ii) Transcription
As part of your practical activities you extracted DNA from a plant tis... show full transcript
Worked Solution & Example Answer:Explain each of the following terms in relation to DNA - Leaving Cert Biology - Question 8 - 2005
Step 1
Replication
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Replication is the process by which DNA makes a copy of itself. This occurs during cell division, ensuring that each new cell receives an identical set of DNA. The replication process involves unwinding the double helix structure, synthesizing a new complementary strand for each of the original strands, ensuring accuracy through base pairing.
Step 2
Transcription
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Transcription is the synthesis of RNA from a DNA template. In this process, a specific section of DNA is unwound and one strand is used as a template to build a single-stranded RNA molecule, known as messenger RNA (mRNA). This mRNA carries the genetic information needed for protein synthesis.
Step 3
What plant did you use?
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The plant used for DNA extraction can be any suitable specimen, such as a banana, onion, or spinach.
Step 4
It is usual to chop the tissue and place it in a blender. Suggest a reason for this.
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Chopping the tissue and placing it in a blender helps to break down the cell walls and release the cytoplasm, allowing for better access to the DNA contained within the cells.
Step 5
For how long should the blender be allowed to run?
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The blender should be allowed to run for a few seconds only, typically around 6 seconds, to prevent excessive blending that could damage the DNA.
Step 6
Washing-up liquid is normally used in this experiment. What is its function?
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Washing-up liquid functions to break down cell membrane components, including lipids and proteins. This action helps to release the DNA from the cells.
Step 7
Sodium chloride (salt) is also used. Explain why.
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Sodium chloride helps to separate the DNA from proteins and cellular debris by providing a conducive ionic environment, which stabilizes the DNA structure during the extraction process.
Step 8
What is a protease enzyme?
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A protease enzyme is a type of enzyme that breaks down proteins into smaller peptides or amino acids by cleaving the peptide bonds.
Step 9
Why is a protease enzyme used in this experiment?
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A protease enzyme is used to break down proteins associated with the DNA, such as histones, thereby allowing the DNA to be more easily separated during the extraction process.
Step 10
The final separation of the DNA involves the use of alcohol (ethanol). Under what condition is the alcohol used?
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The alcohol is used when it is ice cold, which helps precipitate the DNA out of the solution, making it visible as white strands.
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