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Describe the location, structure and functions of the DNA molecule and the process whereby copies of this molecule are made - NSC Life Sciences - Question 4 - 2016 - Paper 2
Question 4
Describe the location, structure and functions of the DNA molecule and the process whereby copies of this molecule are made. NOTE: NO marks will be awarded for answ... show full transcript
Worked Solution & Example Answer:Describe the location, structure and functions of the DNA molecule and the process whereby copies of this molecule are made - NSC Life Sciences - Question 4 - 2016 - Paper 2
Step 1
Location, structure and functions of the DNA molecule
Answer
DNA is a nucleic acid located primarily in the nucleus of eukaryotic cells, though it can also be found in chromosomes and genes. It has a double-stranded structure featuring a helical configuration.
The basic building blocks of DNA are nucleotides, which consist of three main components:
- Nitrogenous bases: The four nitrogenous bases present in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G). The base pairs are structured such that adenine pairs with thymine and cytosine pairs with guanine, linked by hydrogen bonds.
- Phosphate group: This forms the backbone of the DNA structure along with sugar.
- Deoxyribose sugar: This sugar constitutes part of each nucleotide, forming the structure of the DNA strand.
Sections of DNA carry hereditary information that encodes the instructions necessary for protein synthesis. This information is vital for the functioning and reproduction of organisms.
Step 2
the process whereby copies of this molecule are made
Answer
The process of DNA replication involves several steps:
- Unwinding the DNA helix: The double helix structure of the DNA unwinds, facilitated by enzymes such as helicase.
- Strand separation: The hydrogen bonds between the nitrogenous bases are broken, causing the two strands to separate.
- Template formation: Each original strand serves as a template for the formation of a new strand.
- Nucleotide pairing: Free nucleotides in the nucleus attach to their complementary nitrogenous bases on the original template strands (A to T and C to G).
- New strand synthesis: As pairs of nucleotides align, DNA polymerase catalyzes the binding to form a new strand. This results in two identical DNA molecules, each composed of one original and one new strand.