Nucleic Acids: DNA and RNA + DNA replication Flashcards
(26 cards)
What are nucleic acids?
Biologocial molecules that store and transmit genetic infomation
What are the building blocks of nucleic acids?
Nucleotides
What are the three components of a nucleotide?
A nitrogenous base, a pentose sugar (deoxyribose in DNA, ribose in RNA), and a phosphate group
What is a phosphodiester bond?
The bond that links adjacent nucleotides in a nucleic acid chain, formed by a condensation reaction
What are the four nitrogenous bases found in DNA?
Adenine (A), Thymine (T), Guanine (G), and Cytosine (C)
What are the four nitrogenous bases found in RNA?
Adenine (A), Uracil (U), Guanine (G), and Cytosine (C)
What is the complementary base pairing rule in DNA?
A pairs with T, and G pairs with C, linked by hydrogen bonds.
How many hydrogen bonds are between A and T?
Two
How many hydrogen bonds are between G and C?
Three
What is the shape of DNA?
A double helix.
What is the function of DNA?
Stores genetic information and instructs the cell to make proteins
What is the function of RNA?
Involved in protein synthesis and gene regulation
What is the sugar found in DNA?
Deoxyribose
What is the sugar found in RNA?
Ribose
What is meant by semi-conservative DNA replication?
Each new DNA molecule consists of one original strand and one newly synthesized strand
What enzyme unzips the DNA double helix during replication?
DNA helicase.
What enzyme synthesizes new DNA strands during replication?
DNA polymerase.
What is the role of mRNA?
Carries the genetic code from DNA to ribosomes for protein synthesis
What is the role of tRNA?
Transports amino acids to ribosomes during protein synthesis
What is the role of rRNA?
Forms part of the ribosome structure, where proteins are synthesized.
Explain the process of DNA replication
DNA helicase unwinds the double helix.
Each strand serves as a template for the new strand.
Free nucleotides pair with their complementary bases on the template.
DNA polymerase synthesizes the new strand by adding nucleotides.
What is the Meselson-Stahl experiment?
An experiment that provided evidence for semi-conservative replication.
What is the difference between DNA and RNA structure?
DNA is double-stranded, while RNA is usually single-stranded;DNA contains deoxyribose, while RNA contains ribose;DNA contains thymine, while RNA contains uracil.
How did Meselson and Stahl distinguish between old and new DNA strands?
They used different isotopes of nitrogen (¹⁵N and ¹⁴N) to label the DNA (one heavier and one lighter)
