Nucleic Acids And Nucleotides Essay Questions And Answers

Nucleic Acids And Nucleotides

Question 1. DNA&RNA
Answer:

DNA:

• It is deoxyribonucleic acid
• It was discovered in 1869 by Johann Friedrich Miescher
• It contains
  • Bases- adenine, guanine, cytosine & thymine
  • Sugars- D-deoxyribose
  • It is composed of monomeric units namely deoxy adenylate, deoxy guanylate, deoxycytidylate & deoxy thymidylate
  • It has a right-handed double helix structure
  • The transition between different helical forms of DNA plays a significant role in regulating gene expression

Read And Learn More: BDS Previous Examination Question And Answers

RNA:

• It is ribonucleic acid
• It contains

1. Bases- adenine, guanine, cytosine & uracil
2. Sugars- D-ribose

• It is usually a single-stranded polynucleotide

Types:

1. Messenger RNA-5-10%
2. Transfer RNA- 10-20%
3. Ribosomal RNA- 50-80%

• RNA is synthesized from DNA
• They are involved in the process of protein biosynthesis

Question 2. Structure & functions of tRNA
Answer:

Structure:

• It contains 71-80 nucleotides
• It resembles a cloverleaf
• It contains four arms

Functions:

• Carries amino acids from the cytosol to ribosomes

Question 3. Ribonucleic acid
Answer:

• It is ribonucleic acid.
• It contains
  1. Bases- adenine, guanine, cytosine & uracil
  2. Sugars- D-ribose
• It is usually a single-stranded polynucleotide
• RNA is synthesized from DNA
• They are involved in the process of protein biosynthesis

Types:

Question 4. Structure & functions of DNA
Answer:

Structure:

• It is a right-handed double helix
• The width of a double helix is 20 Armstrong
• Each turn of the helix is 34 Armstrong
• Helix consists of two polydeoxyribonucleotide chains twisted around each other on a common axis
• The two strands are anti-parallel
• Each strand has a hydrophilic deoxyribose phosphate on the outside while the hydrophobic bases are inside
• The two strands are held together by hydrogen bonds
• Hydrogen bonds are formed between a purine & pyrimidine only
• The two dinucleotide chains are not identical but complementary to each other
• Genetic information resides on the template strand or sense strand
• Opposite strand is antisense strand

Functions:

• DNA is the chemical basis of hereditary
• It may be regarded as the reserve bank of genetic information
• It is exclusively responsible for maintaining the identity of different species of organisms
• Every aspect of cellular function is under the control of DNA
• It is organized into genes which are THE fundamental units of genetic information
• These genes control protein synthesis through the mediation of RNA

Question 5. Nucleotides and their Functions
Answer:

• Nucleotides are composed of a nitrogenous base, a pentose sugar, and a phosphate
• They are monomeric units in the nucleic acid

Functions:

• They are building blocks in DNA & RNA str culture
• They are structural components of several coenzymes of the vitamin B complex
• They serve as carriers of high-energy intermediates in the biosynthesis of carbohydrates, proteins, and lipids
• They are involved in the energy reactions of the cell
• They control several metabolic reactions by their action as allosteric regulators
• Cyclic AMP and cyclic GMP are the second messengers in hormonal function

Question 6. Types of RNA
Answer:

Types of RNA:

Question 7. Watson and Crick’s model of DNA structure
Answer:

Double Helical Structure of DNA:

• Proposed by James Watson and Francis Crick in 1953

Features:

• It is a right-handed double helix
• Consists of two polydeoxyribonucleotide chains twisted around each other
• The bases present are adenine
• (A), Guanine(G), Cylosine(C) and Thymine(T)
• Two strands are antiparallel, one running from 5′ to 3′ and the other vice versa Width is 20 A°
• Each turn of helix is 34 A° with 10 pairs of nucleotides
  Two strands are held together by hydrogen bonds
• The A-T pair has 2 hydrogen bonds, G-C pair has 3 hydrogen bonds
  Content of adenine equals thymine and guanine equals cytosine – Char gaff’s rule

Question 8. What are nucleosides & nucleotides? Give examples of each
Answer:

Nucleotide:

• They are composed of a nitrogenous base, a pentose sugar & a phosphate
• They are monomeric units in the nucleic acid

Nucleoside:

• Nucleoside is a nucleotide without esterified phosphate groups
• Examples

Question 9. Name different types of RNA & their functions
Answer:

Question 10. Structures & functions of mRNA
Answer:

Structure:

• mRNA is capped at the 5′- terminal end by 7-methylguanosine triphosphate
• This helps to prevent the hydrolysis of mRNA by 5′-exonucleases
• The 3-terminal end of mRNA contains a polymer of adenylate residues known as polypeptide A tail
• This provides stability to mRNA
• mRNA contains certain modified bases such as 6-methyl adenylate in the internal structure

Functions:

• Carries genetic code from DNA to ribosomes

Question 11. Base pairing & its importance for the function & structure of DNA
Answer:

• Base pairing in DNA structure occurs between purine & pyrimidine
• If two purines face each other, they would not fit into allowable spaces
• Two pyrimidines would be too far for hydrogen bonds
  Thus, base pairing in DNA structure occurs only between purines & pyrimidines
• It occurs between
  1. Adenine and thymine or uracil
     • Two hydrogen bonds occur between them
  2. Guanine and cytosine
     • Three hydrogen bonds occur between them

Question 12. Describe the features of genetic code (or) Characteristics of genetic code
Answer:

1. Universality

• The same codons are used to code for the same amino acids in all the living organisms

2. Specificity

• A particular codon always codes for the same amino acids

3. Non-overlapping

• Genetic code is read from a fixed point as a continuous base sequence

4. Degenerate

• Most of amino acids have more than one codon
• This is because there are 61 codons for 20 amino acids

Question 13. Differences between DNA &. RNA.
Answer:

Question 14. Gout
Answer:

• Gout is a metabolic disorder associated with the overproduction of uric acid
• Due to excess uric acid, forms crystals of sodium really
• This gets deposited in the soft tissues, particularly in joints resulting in inflammation of joints and painful gouty arthritis

Types:

1. Primary gout

• It is an inborn error of metabolism due to the overproduction of uric acid

2. Secondary gout

• Occurs due to various diseases like various cancers, psoriasis, and increased tissue breakdown.

Treatment:

• Allopurinol is a drug of choice
• It is oxidized to alloxanthine by xanthine oxidase
• Alloxanthine is an inhibitor of xanthine oxidase
• Thus allopurinol acts by suicide inhibition mechanism