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Give a brief account of how you would produce a DNA profile - Leaving Cert Biology - Question 12 - 2017
Question 12
Give a brief account of how you would produce a DNA profile. (i) In the context of natural selection, explain how numbers in a population remain relatively constant... show full transcript
Worked Solution & Example Answer:Give a brief account of how you would produce a DNA profile - Leaving Cert Biology - Question 12 - 2017
Step 1
How you would produce a DNA profile
Answer
To produce a DNA profile, one must first extract DNA from a sample, such as blood or saliva. This DNA is then cut into fragments using restriction enzymes, which act as molecular scissors. These fragments are separated by size through a technique called electrophoresis. During electrophoresis, the DNA fragments are placed in a gel and an electric current is applied, causing the smaller fragments to move faster than the larger ones. Finally, the resulting pattern of DNA fragments is visualized for analysis.
Step 2
In the context of natural selection, explain how numbers in a population remain relatively constant despite the production of many offspring.
Answer
In stable populations, natural selection plays a crucial role in maintaining population numbers. Limited resources lead to competition among individuals, where only the best adapted will survive and reproduce. Factors such as predation, diseases, and environmental changes contribute to death rates. These death rates help balance the reproduction rates, ensuring that population numbers do not exponentially increase despite the production of many offspring.
Step 3
How son of haemophiliac father not haemophilic
Answer
The inheritance of haemophilia, a recessive and sex-linked condition, helps explain why the son of a haemophiliac father is not haemophilic. The mother, carrying the genotype XNXn, could provide either the dominant (normal) X or the recessive (haemophiliac) X chromosome. The father, with genotype XnY, can only contribute the Y chromosome to the son. Thus, the son (XY) could inherit the normal X from the mother (XN), resulting in him not having the condition despite his father's haemophilia.
Step 4
Step 5
Describe fully the roles played in protein synthesis by the three different types of RNA.
Answer
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Messenger RNA (mRNA): It carries the genetic information from DNA to ribosomes, where proteins are synthesized.
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Ribosomal RNA (rRNA): This type forms the core of ribosome structure, facilitating the assembly of amino acids into proteins.
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Transfer RNA (tRNA): It is responsible for transferring specific amino acids to the ribosome as dictated by the sequence of codons on the mRNA, thus playing a crucial role in translating genetic code into amino acid sequences.
Step 6
Once a protein has been synthesised, a final step is required for it to become fully functional. What is this step?
Answer
The final step for a protein to become fully functional is folding. Proper folding is essential as it determines the protein's three-dimensional structure and functionality.