35 Questions
Which nucleotide derivative serves as the universal currency of energy?
ATP
What is formed when a nucleoside is esterified to a phosphate group?
Nucleotide
What type of nitrogenous base is adenine?
Purine
What are the components of a nucleotide?
Purine base, pentose sugar, esterified phosphate groups
What is the difference between a nucleoside diphosphate and a nucleoside triphosphate?
Number of phosphate groups esterified
What is the role of NAD+ in cellular processes?
Component of co-enzymes
Which statement about DNA and RNA is correct?
Both DNA and RNA contain the same nitrogenous bases but differ in sugar composition
What is the function of cAMP and cGMP?
Metabolic regulation
What type of nucleic acid is concerned with the storage and transfer of genetic information?
DNA
What is formed when a base combines with a pentose sugar?
Nucleoside
What are the purine bases present in RNA and DNA?
Adenine and guanine
Which of the following best describes the function of transfer RNA (tRNA)?
It functions as an adapter, bringing a specific amino acid to the site of protein synthesis
What is the approximate size of transfer RNA (tRNA)?
75 nucleotides
How many tRNAs are found in humans, despite there being 20 amino acids?
32 tRNAs
What gives transfer RNA (tRNA) its clover leaf shape?
Intrastrand hydrogen bonds
Which sequence is present towards the 3’ end (acceptor arm) of transfer RNA (tRNA)?
CCA
What is the role of the last nucleotide, adenine, at the 3’ end of transfer RNA (tRNA)?
It binds covalently to a specific amino acid
What does the anticodon arm of transfer RNA (tRNA) have?
Triplet codon complementary to mRNA codon
What is the major difference between ribosomal RNAs (rRNAs) and transfer RNA (tRNA)?
rRNAs are involved in translation, while tRNAs are associated with ribosomes
What is the sugar component in DNA?
Deoxyribose
Where is RNA found?
In both nucleus and cytoplasm
Which of the following bases are found in RNA?
A, U, G and C
What is the nature of DNA?
Double stranded
Which of the following are purine bases in nucleic acids?
What is the main difference between nucleosides and nucleotides?
Nucleotides contain phosphate esters
How are deoxyribonucleosides denoted to avoid confusion?
They are denoted with the prefix 'd-'
What is the significance of 5'-phosphates in nucleotides?
They serve as energy currencies
Which position of ribose or deoxyribose can be phosphorylated to form nucleotides?
3'
What are nucleoside triphosphates, such as ATP, used for in biological processes?
Energy currencies and cofactors
How are cyclic nucleotides, such as cAMP and cGMP, formed?
By phosphodiester linkages between the 3' and 5' positions of the ribose group
What is the role of nucleotide triphosphates in biological processes?
They serve as energy currencies
What is the composition of RNA?
Ribose sugar, nitrogenous bases, and phosphate
What stabilizes mRNA and assists in its translation?
Poly(A) tail at the 3' end
What role does transfer RNA (tRNA) play in protein synthesis?
It assists in translating the genetic code from mRNA to protein
What holds together the structure of RNA?
Phosphodiester bonds between nucleotides
Study Notes
- The purine bases in nucleic acids are adenine and guanine, while pyrimidine bases are cytosine, thymine, and uracil
- Nucleosides are formed when bases attach to pentose sugar (ribose or deoxyribose) through a beta-N-glycosidic bond
- Deoxyribonucleosides are denoted with the prefix "d-" and have different carbon designations to avoid confusion
- Nucleotides are phosphate esters of nucleosides, and most biologically active ones are 5'-phosphates
- Nucleotides can be formed with either ribose or deoxyribose, which can be phosphorylated at the 3' or 5' positions
- Nucleoside triphosphates, such as ATP, are high-energy compounds used as cofactors and energy currencies
- Cyclic nucleotides, such as cAMP and cGMP, are formed by phosphodiester linkages between the 3' and 5' positions of the ribose group
- Nucleotides and nucleic acids absorb ultraviolet light, and nucleotide triphosphates play essential roles in various biological processes
- RNA is a single-stranded polymer of ribonucleotides, and messenger RNA (mRNA) carries genetic information from DNA for protein synthesis
- RNA is composed of ribose sugar, nitrogenous bases, and phosphate, and its structure is held together by hydrogen bonds between bases and by phosphodiester bonds between nucleotides.
- mRNA contains a poly(A) tail at its 3' end, which stabilizes the mRNA and helps in its translation
- Transfer RNA (tRNA) plays a role in translating the genetic code from mRNA to protein
- The structure of DNA, proposed by Watson and Crick, consists of two complementary strands coiled around the same axis and held together by hydrogen bonds between the bases.
- RNA comes in various forms, such as messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA), and each type plays distinct roles in the cell.
By Ahmed Safaa Telegram channel : https://t.me/mcqb2
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