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Questions and Answers
What is the primary function of DNA?
Which nucleotide component is unique to RNA?
What type of bond joins nucleotides in a polynucleotide chain?
Which process is catalyzed by ATP hydrolase?
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What is the role of inorganic phosphate in cellular functions?
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What feature distinguishes the DNA double helix structure?
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What outcome results from semi-conservative replication of DNA?
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Which of the following correctly describes ATP?
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What role does DNA helicase play in DNA replication?
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Which of the following correctly describes a codon?
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What is the significance of the genetic code being non-overlapping?
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Which enzyme is responsible for forming phosphodiester bonds during DNA replication?
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What are introns in the context of a gene's structure?
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What does it mean when we say that the genetic code is degenerate?
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How do mutations in the DNA base sequence potentially affect proteins?
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What is the process of joining adjacent nucleotides during DNA replication called?
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What is the primary function of start and stop codons in protein synthesis?
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During transcription, which strand of DNA serves as the template for mRNA synthesis?
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What happens to the tRNA molecules after they facilitate the formation of peptide bonds?
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Which of the following best describes the role of RNA polymerase during transcription?
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What is formed at the end of the translation process?
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What is the role of free nucleotides during transcription?
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What term describes the sequence of amino acids produced during protein synthesis?
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How does tRNA recognize the correct amino acid to transport during translation?
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Study Notes
Nucleic Acids
- Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are polymers of nucleotides.
- Nucleotides consist of:
- Pentose (5-carbon sugar)
- Nitrogen-containing organic base
- Phosphate group
DNA
- Components: deoxyribose, phosphate group, and one of the organic bases adenine, cytosine, guanine, or thymine.
- Structure: double helix composed of two polynucleotides joined by hydrogen bonds between complementary bases.
RNA
- Components: ribose, phosphate group, and one of the organic bases adenine, cytosine, guanine, or uracil.
- Structure: relatively short single polynucleotide chain.
ATP
- A nucleotide derivative consisting of ribose, adenine, and three phosphate groups.
- Energy is released when ATP is hydrolyzed to form ADP and a phosphate molecule.
- This process is catalyzed by ATP hydrolase.
- The inorganic phosphate can be used to phosphorylate other compounds, making them more reactive.
- Condensation of ADP and inorganic phosphate catalyzed by ATP synthase produces ATP during photosynthesis and respiration.
DNA Replication
- The semi-conservative replication of DNA ensures genetic continuity between generations of cells.
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Steps:
- The double helix unwinds, and the hydrogen bonds between the complementary bases break using DNA helicase, separating the two strands of DNA.
- Both strands serve as templates for new DNA strands, with complementary base pairing between template strands and free nucleotides.
- Adjacent nucleotides are joined by phosphodiester bonds formed through condensation reactions, using DNA polymerase.
Genetic Code
- The order of bases on DNA is called the genetic code, consisting of triplets of bases.
- Each triplet codes for a particular amino acid and is known as a codon.
- Amino acids are joined together by peptide bonds, forming a polypeptide chain.
- A gene is a sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chain.
- Non-coding sections of DNA are called introns, while coding regions are called exons.
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Features:
- Non-overlapping: each triplet is read only once, and triplets don't share bases.
- Degenerate: more than one triplet codes for the same amino acid, reducing the phenotypic effect of mutations.
- Mutations can alter the amino acid sequence and the protein, potentially leading to various effects.
Protein Synthesis
- Two stages: transcription and translation
Transcription
- Occurs in the nucleus, involving DNA and mRNA.
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Steps:
- The hydrogen bonds between complementary bases break, and the DNA uncoils, separating the two strands.
- One DNA strand serves as a template for RNA polymerase to make the mRNA molecule (the antisense strand).
- Free nucleotides line up by complementary base pairing, and adjacent nucleotides are joined by phosphodiester bonds by RNA polymerase, forming a single-stranded molecule of mRNA.
- mRNA moves out of the nucleus through a pore and attaches to a ribosome in the cytoplasm, the site of translation.
Translation
- Involves mRNA, tRNA, and ribosomes.
- During translation, amino acids are assembled together to form a polypeptide chain/protein.
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Steps:
- mRNA attaches to a ribosome, and transfer RNA (tRNA) collects amino acids from the cytoplasm and carries them to the ribosome.
- tRNA is a single-stranded molecule with a binding site at one end, allowing it to carry only one type of amino acid, and a triplet of bases at the other end.
- tRNA attaches to mRNA via complementary base pairing, with two molecules attaching to mRNA at a time.
- The amino acids attached to two tRNA molecules join by a peptide bond, and then tRNA molecules detach themselves from the amino acids, leaving them behind.
- This process repeats until a stop codon is reached on mRNA, ending protein synthesis.
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Description
This quiz covers the essential components and structures of nucleic acids, including DNA and RNA. It also examines ATP, its role in energy release, and the hydrolysis process. Test your knowledge on these fundamental biological molecules.
