DNA and RNA Structure Quiz

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary role of hydrogen bonds in DNA structure?

To provide energy for DNA replication

To facilitate the formation of phosphodiester bonds

To hold the two polynucleotide strands together (correct)

To protect the genetic sequence from mutation

How does the hydrogen bonding between bases contribute to DNA stability?

By forming covalent bonds which cannot be broken

By allowing random base pairing without specificity

By providing structural support without breaking easily (correct)

By allowing strands to separate easily without replication

What is meant by semi-conservative replication of DNA?

Only the leading strand is replicated while the lagging strand is left untouched

Each daughter DNA molecule contains two newly synthesized strands

Each daughter DNA molecule contains one old strand and one new strand (correct)

Both strands of DNA are completely degraded during replication

Which enzyme is responsible for breaking hydrogen bonds during DNA replication?

DNA helicase Signup and view all the answers

Why is the genetic code considered universal?

The same triplet codes for the same amino acid across all living organisms Signup and view all the answers

What characteristic of the genetic code allows for the presence of multiple codons for the same amino acid?

Degeneracy Signup and view all the answers

What is the main function of the sugar-phosphate backbone in DNA?

To provide stability and structural support Signup and view all the answers

Which factor primarily prevents spontaneous mutation in DNA?

The specificity of hydrogen bonds between complementary bases Signup and view all the answers

What role does DNA ligase play in the replication process?

Catalyzes the formation of phosphodiester bonds Signup and view all the answers

What does the term 'triplet code' refer to in genetics?

A sequence of three bases coding for one amino acid Signup and view all the answers

What three components make up a nucleotide?

Phosphate group, pentose sugar, and nitrogen base Signup and view all the answers

What is the primary function of ATP in cells?

To act as a universal energy currency Signup and view all the answers

How are polynucleotide chains formed?

Through condensation reactions and phosphodiester bonds Signup and view all the answers

Which bases are found in RNA but not in DNA?

Uracil and adenine Signup and view all the answers

What type of bond holds the two strands of DNA together?

Hydrogen bonds Signup and view all the answers

What is a characteristic of DNA strands?

They are anti-parallel Signup and view all the answers

Which of the following is not a use of ATP?

Photosynthesis Signup and view all the answers

What sugar is present in DNA nucleotides?

Deoxyribose Signup and view all the answers

Which nucleotides form adenosine triphosphate (ATP)?

Ribose, adenine, and three phosphate groups Signup and view all the answers

What type of reaction is involved in forming a mononucleotide from its components?

Condensation reaction Signup and view all the answers

Study Notes

Structure of DNA and RNA

Nucleic acids consist of polynucleotides formed by linking nucleotides via phosphodiester bonds.
Nucleotides are composed of a phosphate group, a pentose sugar (deoxyribose in DNA, ribose in RNA), and a nitrogenous base.
Formation of a mononucleotide involves a condensation reaction resulting in the elimination of two water molecules.

Nitrogenous Bases

DNA contains five nitrogenous bases: adenine (A), thymine (T), guanine (G), and cytosine (C).
RNA replaces thymine with uracil (U), comprising adenine (A), uracil (U), guanine (G), and cytosine (C).
Adenosine triphosphate (ATP) is a phosphorylated mononucleotide made from ribose, adenine, and can have one to three phosphate groups (AMP, ADP, ATP).

ATP Significance

ATP is termed the universal energy currency for cells.
It is small and water-soluble, facilitating easy diffusion between cell organelles.
Acts as an immediate energy donor, easily hydrolyzed to ADP to release energy.

Uses of ATP

Vital for cell division, muscle contraction, and maintenance of body temperature.
Plays a role in anabolic reactions, such as protein synthesis and nerve impulse transmission.

Formation of Polynucleotide

Occurs during interphase through condensation reactions creating phosphodiester bonds.
Links the phosphate of one nucleotide to the 3' carbon of the sugar in another nucleotide, creating a sugar-phosphate backbone.

Structure of DNA Molecule

Comprises two polynucleotide strands of deoxyribose, phosphate, and nitrogenous bases.
Strands run in opposite directions (antiparallel).
Hydrogen bonds between nitrogenous bases connect the strands, adhering to complementary base pairing (A=T, G≡C).

Importance of Hydrogen Bonding in DNA

Hydrogen bonds hold the two polynucleotide strands together and contribute to the DNA's 3D structure.
Provide stability, allowing for easier separation during replication and transcription.
Specificity in base pairing reduces replication errors, ensuring faithful genetic replication.

Structural Features Contributing to DNA Stability

Complementary base pairing and numerous hydrogen bonds enhance structural integrity.
The sugar-phosphate backbone is reinforced with phosphodiester bonds.
The double helix configuration protects bases from chemical attacks.

Importance of DNA Stability

Prevents spontaneous changes in sequences, minimizing mutation risk and ensuring functional proteins.
Ensures the preservation of genetic information across generations, maintaining integrity in daughter cells.
Keeps DNA size manageable for storage within the nucleus.

Semi-Conservative Replication of DNA

Semi-conservative replication generates two identical DNA molecules, each containing one original and one new strand.
Occurs during the S phase of the cell cycle, using each old strand as a template for new complementary strand synthesis.

Steps of DNA Replication

The double helix unwinds, and hydrogen bonds between complementary bases break, facilitated by the enzyme DNA helicase.
Free activated nucleotides align along the separated strands, pairing with complementary bases (A=T, C≡G).
DNA polymerase adds new nucleotides sequentially, while DNA ligase forms phosphodiester bonds between adjacent nucleotides.

Sense and Anti-sense Strands

Sense strand encodes for protein manufacture, while anti-sense strand stabilizes the DNA and serves as a template for mRNA synthesis.
A triplet of bases (codon) in the template strand codes for one amino acid, forming the genetic code.

Genetic Code Characteristics

Each triplet of bases specifies one amino acid, resulting in 64 possible codons from four bases.
The genetic code is universal across living organisms, suggesting a common ancestry.
Degenerate nature allows multiple codons to code for the same amino acid, totaling 61 codons usable for amino acids and three stop codons.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the structure of DNA and RNA in this quiz. Explore the basics of nucleic acids, nucleotides, and how their components come together to form these essential biomolecules. Perfect for biology students learning about molecular biology.