Nucleic Acids Overview

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Questions and Answers

What is the primary function of DNA?

To synthesize proteins directly

To provide energy for cellular functions

To hold genetic information (correct)

To transport amino acids to ribosomes

Which nucleotide component is unique to RNA?

Phosphate group

Deoxyribose

Ribose (correct)

Thymine

What type of bond joins nucleotides in a polynucleotide chain?

Phosphodiester bonds (correct)

Covalent bonds

Ionic bonds

Hydrogen bonds

Which process is catalyzed by ATP hydrolase?

Hydrolysis of ATP Signup and view all the answers

What is the role of inorganic phosphate in cellular functions?

It can phosphorylate other compounds Signup and view all the answers

What feature distinguishes the DNA double helix structure?

Consists of two polynucleotides joined by hydrogen bonds Signup and view all the answers

What outcome results from semi-conservative replication of DNA?

Formation of identical daughter cells Signup and view all the answers

Which of the following correctly describes ATP?

A nucleotide derivative with three phosphate groups Signup and view all the answers

What role does DNA helicase play in DNA replication?

It separates the two strands of DNA by breaking hydrogen bonds. Signup and view all the answers

Which of the following correctly describes a codon?

A sequence of three bases that codes for a specific amino acid. Signup and view all the answers

What is the significance of the genetic code being non-overlapping?

Each triplet of bases is read in isolation, reducing confusion in coding. Signup and view all the answers

Which enzyme is responsible for forming phosphodiester bonds during DNA replication?

DNA polymerase Signup and view all the answers

What are introns in the context of a gene's structure?

The non-coding regions of the DNA molecule. Signup and view all the answers

What does it mean when we say that the genetic code is degenerate?

More than one triplet can specify the same amino acid. Signup and view all the answers

How do mutations in the DNA base sequence potentially affect proteins?

They change the sequence of amino acids in a polypeptide chain. Signup and view all the answers

What is the process of joining adjacent nucleotides during DNA replication called?

Condensation reaction Signup and view all the answers

What is the primary function of start and stop codons in protein synthesis?

They initiate and terminate the process of protein synthesis. Signup and view all the answers

During transcription, which strand of DNA serves as the template for mRNA synthesis?

The antisense strand. Signup and view all the answers

What happens to the tRNA molecules after they facilitate the formation of peptide bonds?

They detach themselves from the amino acids. Signup and view all the answers

Which of the following best describes the role of RNA polymerase during transcription?

It catalyzes the formation of phosphodiester bonds. Signup and view all the answers

What is formed at the end of the translation process?

A polypeptide chain. Signup and view all the answers

What is the role of free nucleotides during transcription?

They bind to the DNA template. Signup and view all the answers

What term describes the sequence of amino acids produced during protein synthesis?

Polypeptide chain. Signup and view all the answers

How does tRNA recognize the correct amino acid to transport during translation?

By its binding site at one end. Signup and view all the answers

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.
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.
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.
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.
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.