DNA is made of units called nucleotides - Leaving Cert Biology - Question b - 2008
Question b
DNA is made of units called nucleotides. Draw a labelled diagram of a nucleotide to show its three constituent parts.
Which of the labelled parts in your diagram in ... show full transcript
Worked Solution & Example Answer:DNA is made of units called nucleotides - Leaving Cert Biology - Question b - 2008
Step 1
Draw a labelled diagram of a nucleotide
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Answer
To represent a nucleotide, draw a structure that includes three main components:
Phosphate group
Sugar molecule (either deoxyribose for DNA or ribose for RNA)
Nitrogenous base (adenine, guanine, cytosine, or thymine for DNA; adenine, guanine, cytosine, or uracil for RNA)
Label each part accurately, indicating which part is the phosphate, sugar, and base.
Step 2
Which of the labelled parts in your diagram in (i) may vary from nucleotide to nucleotide?
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Answer
The nitrogenous base varies from nucleotide to nucleotide. Depending on the nucleotide type, it could be adenine (A), thymine (T), cytosine (C), or guanine (G) in DNA, and adenine (A), uracil (U), cytosine (C), or guanine (G) in RNA.
Step 3
Briefly describe the nature of the genetic code.
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The genetic code is comprised of sequences of three bases, known as codons or triplets, on the DNA strand. Each codon corresponds to a specific amino acid that helps in protein synthesis. Thus, the sequence of bases directly dictates the structure and function of proteins in an organism.
Step 4
What is meant by non-coding DNA?
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Non-coding DNA refers to segments of DNA that do not code for proteins or do not have a direct role in coding for RNA. This DNA may have regulatory functions, structural roles, or may simply be remnants of evolutionary history.
Step 5
Give one structural difference between DNA and RNA.
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One structural difference between DNA and RNA is that DNA contains the base thymine whereas RNA contains uracil. Additionally, DNA is usually double-stranded and forms a double helix, while RNA is typically single-stranded.
Step 6
Name a cell organelle, apart from the nucleus, in which DNA is found.
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DNA is found in the mitochondrion or chloroplast.
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