Part (a) deals with DNA structure and replication - Leaving Cert Biology - Question 10 - 2010
Question 10
Part (a) deals with DNA structure and replication.
a) (i) Name the base in DNA that pairs with cytosine.
(ii) What are the two main events in the replication of DNA... show full transcript
Worked Solution & Example Answer:Part (a) deals with DNA structure and replication - Leaving Cert Biology - Question 10 - 2010
Step 1
a) (i) Name the base in DNA that pairs with cytosine.
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Answer
The base in DNA that pairs with cytosine is guanine.
Step 2
a) (ii) What are the two main events in the replication of DNA?
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The two main events in the replication of DNA are:
Separation of the DNA strands: The double helix structure unwinds and the strands separate, allowing each strand to be copied.
Synthesis of new strands: New nucleotides are added to each of the separated strands, resulting in two identical DNA molecules.
Step 3
b) (i) Explain the terms transcription and translation.
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Transcription is the process of synthesizing messenger RNA (mRNA) from a DNA template. Translation is the process by which a protein is synthesized from the mRNA code at the ribosome.
Step 4
b) (ii) In which structures in the cell does translation occur?
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Translation occurs in the ribosomes of the cell.
Step 5
b) (iii) How many bases in sequence make up a codon in mRNA?
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A codon in mRNA is made up of three bases.
Step 6
b) (iv) Each mRNA codon specifies one of three possible outcomes during protein synthesis. Name these three possible outcomes.
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The three possible outcomes each mRNA codon can specify during protein synthesis are:
Start: Initiates the synthesis of the protein.
Adding an amino acid: Each codon specifies an amino acid that gets added to the growing polypeptide chain.
Stop: Signals the termination of the protein synthesis.
Step 7
b) (v) What does the letter 't' stand for in tRNA?
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The letter 't' in tRNA stands for transfer, indicating its role in transporting specific amino acids to the ribosome during protein synthesis.
Step 8
b) (vi) During translation the end of a tRNA molecule attaches to an mRNA codon. What is usually attached to the other end of the tRNA molecule?
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At the other end of the tRNA molecule, an amino acid is usually attached.
Step 9
c) (i) Distinguish between Haploid and diploid.
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Haploid: A nucleus having one set of chromosomes (or one copy of each chromosome).
Diploid: A nucleus having two sets of chromosomes (or two copies of each chromosome).
Step 10
c) (ii) Distinguish between Homozygous and heterozygous.
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Homozygous: Refers to having two identical alleles for a particular gene.
Heterozygous: Refers to having two different alleles for a particular gene.
Step 11
c) (iii) Distinguish between Genotype and phenotype.
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Genotype: The genetic make-up or genes (alleles) present in an organism.
Phenotype: The observable expression of the genotype, influenced by the genotype and environment.
Step 12
c) (iv) Distinguish between Segregation and independent assortment.
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Segregation: Refers to the process whereby only one allele from each pair enters a gamete during gamete formation.
Independent assortment: Refers to the process where either member of a pair of alleles can combine (or assort) with either member of another pair during gamete formation.
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