nucleic acids Flashcards
(14 cards)
What are nucleic acids, and what is their function? (2 marks)
A:
Nucleic Acids: DNA and RNA are carriers of genetic information.
Function: Store, transmit, and express genetic instructions.
Composition: Made up of nucleotides.
What are the components of a nucleotide? (2 marks)
A:
Phosphate group.
Pentose sugar: Deoxyribose in DNA; ribose in RNA.
Nitrogenous base: Adenine (A), Thymine (T)/Uracil (U), Cytosine (C), Guanine (G).
How are nucleotides linked in a nucleic acid strand? (2 marks)
A:
Phosphodiester Bond: Links phosphate of one nucleotide to the sugar of another.
Directionality: Strands have a 5′ to 3′ orientation.
What is the structure of DNA, and how are its strands held together? (3 marks)
A:
Double Helix: Two antiparallel strands.
Hydrogen Bonding: Complementary base pairs:
A-T: 2 hydrogen bonds.
G-C: 3 hydrogen bonds.
Significance: Ensures stability and specificity in base pairing.
What are the key features of the genetic code? (2 marks)
A:
Universal: Same triplet codons code for the same amino acids across organisms.
Conservation: Ensures consistency in protein synthesis.
Compare DNA and RNA. (3 marks)
A:
DNA: Double-stranded, deoxyribose sugar, Thymine as a base.
RNA: Single-stranded, ribose sugar, Uracil replaces Thymine.
What is the importance of complementary base pairing in DNA? (2 marks)
A:
Ensures accurate replication and transcription.
Provides a template for creating complementary strands.
How is DNA efficient as an information storage molecule? (3 marks)
A:
Compact Storage: Packed in chromosomes.
Efficiency: Encodes vast information in sequences of bases.
Replication: Semi-conservative, preserving one original strand.
Why is the 5′ to 3′ orientation significant? (2 marks)
A:
Necessary for enzymes like DNA polymerase.
Dictates replication and transcription processes.
How is DNA structured and packed efficiently? (3 marks)
A:
Helix: DNA twists into a helical structure for stability.
Nucleosomes: DNA wraps around histone proteins, allowing efficient packing into chromatin.
What was the purpose and conclusion of the Hershey & Chase experiment? (3 marks)
A:
Purpose: Confirm DNA as genetic material.
Method: Traced radioactive isotopes in bacteriophages.
Conclusion: DNA, not protein, carries genetic information.
What are Chargaff’s rules, and why are they important? (2 marks)
A:
Rules:
%A = %T and %G = %C in DNA.
Importance: Provides the basis for complementary base pairing.
How was the tetranucleotide hypothesis disproved? (2 marks)
A:
Early hypothesis suggested repetitive sequences.
Disproved by evidence of sequence variability and Chargaff’s rules.
What are the applications of molecular visualization software? (2 marks)
A:
Models 3D structures of nucleic acids.
Enhances understanding of DNA-RNA interactions.
