Chp 8 - Nucleic Acids Flashcards
What are the two general types of nucleic acids, and their primary roles?
- DNA: Stores and transfers genetic information; passed during cell division.
- RNA: Involved in protein synthesis and enzymatic activities.
What are the components of a nucleotide?
- A sugar (pentose monosaccharide).
- One (or more) phosphate groups.
- A nitrogenous base.
List three main differences between DNA and RNA.
- DNA contains deoxyribose; RNA contains ribose.
- DNA uses thymine (T), RNA uses uracil (U).
- DNA is double-stranded, RNA is single-stranded.
What are the five nitrogen-containing bases, and which are exclusive to DNA or RNA?
Pyrimidines: Cytosine (C), Thymine (T, only in DNA), Uracil (U, only in RNA).
Purines: Adenine (A), Guanine (G).
How is a nucleoside formed?
A pentose sugar reacts with a nitrogenous base at the anomeric carbon through condensation.
What are the key functions of nucleotides?
- Building blocks of genetic material.
- Carriers of activated intermediates.
- Second messengers.
- Energy sources (ATP).
- Regulate metabolism.
What is the most precise modern definition of a gene?
A segment of genetic material that codes for one polypeptide or RNA product.
What is the sugar component in DNA and RNA called?
DNA: Deoxyribose
RNA: Ribose
What are the two types of nitrogenous bases?
Purines and Pyrimidines.
What are the structural differences between purines and pyrimidines?
Purines (A, G) have two rings; Pyrimidines (C, T, U) have one ring.
What type of bond joins nucleotides together in DNA and RNA?
Phosphodiester bond.
What is the function of a phosphodiester bond?
It links the 3’ carbon atom of one sugar molecule to the 5’ carbon atom of another.
What is the role of ATP as a nucleotide?
ATP acts as an energy source in metabolic processes.
Describe the structure of a DNA double helix.
Two strands of DNA form a double helix, with a sugar-phosphate backbone and nitrogenous bases paired inside.
What are the complementary base pairing rules in DNA?
A pairs with T (2 hydrogen bonds), and G pairs with C (3 hydrogen bonds).
How do base pairing rules differ in RNA?
A pairs with U (instead of T), and G pairs with C.
What are the differences between a nucleotide and a nucleoside?
A nucleotide includes a sugar, a phosphate group, and a nitrogenous base; a nucleoside lacks the phosphate group.
What is the role of mRNA in protein synthesis?
mRNA carries the genetic code from DNA to the ribosome for translation.
What is the role of tRNA in translation?
tRNA brings the correct amino acid to the ribosome during translation.
What is the function of rRNA?
rRNA forms the core of ribosomes and catalyzes protein synthesis.
What are plasmids and where are they found?
Plasmids are small, circular DNA molecules found in bacteria and some eukaryotes.
What is the primary structure of a nucleic acid?
The sequence of nucleotides in the polymer.
What are the two strands in DNA described as?
They are complementary and antiparallel.
What is the significance of the antiparallel arrangement in DNA?
It allows the formation of hydrogen bonds between complementary bases.
What are the key structural differences between DNA in eukaryotic cells and prokaryotic cells?
Eukaryotic DNA is linear and stored in the nucleus; prokaryotic DNA is circular and found in the cytoplasm.
What are the main features of the universal dogma?
Replication, Transcription, and Translation.
What are the major roles of RNA in a cell?
- Protein synthesis.
- Enzymatic functions.
- Structural components (e.g., rRNA).
How does DNA replication occur?
By unwinding the double helix and synthesizing new complementary strands.
What enzymes are essential for DNA replication?
DNA polymerase, helicase, primase, ligase.
What are Okazaki fragments, and where are they found?
Short fragments of DNA synthesized on the lagging strand during replication.
What produces sticky ends? What about blunt ends?
Cleavage sites off the center in the recognition sequence produce sticky ends. Cleavage sites in the center of the recognition sequence produce blunt ends.
