2.1 The diagram below represents two processes that occur during protein synthesis - NSC Life Sciences - Question 2 - 2021 - Paper 2
Question 2
2.1 The diagram below represents two processes that occur during protein synthesis.
(a) Where in the cell does EACH of the following processes occur?
(i) X
(ii... show full transcript
Worked Solution & Example Answer:2.1 The diagram below represents two processes that occur during protein synthesis - NSC Life Sciences - Question 2 - 2021 - Paper 2
Step 1
Where does process X occur?
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Answer
Process X occurs in the nucleus, where DNA is transcribed into mRNA.
Step 2
Where does process Y occur?
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Answer
Process Y takes place in the ribosome, where mRNA is translated into protein.
Step 3
State ONE difference between the types of nitrogenous bases.
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DNA contains thymine (T) while RNA contains uracil (U) instead of thymine.
Step 4
Name and describe process X.
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Process X is called transcription. During transcription, the DNA molecule unwinds and the double-stranded DNA separates to form a single strand of mRNA. This mRNA is synthesized using free RNA nucleotides that pair with complementary DNA bases, enabling the genetic information to be copied for protein synthesis.
Step 5
Describe how non-disjunction may lead to Down syndrome.
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Non-disjunction is the failure of chromosomes to separate properly during cell division. When this occurs, it can result in gametes with an abnormal number of chromosomes. If such a gamete unites with a normal gamete during fertilization, the resulting zygote will have an extra copy of chromosome 21, leading to Down syndrome, also known as Trisomy 21.
Step 6
What are somatic cells?
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Somatic cells are all cells in the body except for gametes (sex cells). They are diploid, containing two sets of chromosomes.
Step 7
Name the specific type of chromosomes numbered 1 to 22.
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The specific type of chromosomes numbered 1 to 22 are called autosomes.
Step 8
State the origin of each chromosome in a homologous pair during zygote formation.
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One chromosome of each homologous pair comes from the mother (maternal origin) and the other comes from the father (paternal origin).
Step 9
List THREE characteristics that chromosomes in a homologous pair have in common.
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Size/Length
Position of genes/alleles
Genes coding for the same characteristic
Step 10
Explain ONE observable reason why the two individuals are not identical twins.
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The two individuals are not identical twins because they may have different combinations of alleles due to the genetic variations that occur during the formation of gametes and fertilization.
