Molecular Biology: Structure and Functions of DNA and RNA
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Questions and Answers

What is the function of the enzyme DNA helicase in DNA replication?

unwinds the DNA strands

What is the primary difference between DNA and RNA in terms of their functions?

DNA stores genetic information, RNA transfers genetic information

What is the role of the RNA primer in DNA replication?

provides a starting point for DNA synthesis

What is the name of the process by which DNA is replicated, resulting in two new molecules each composed of an old and new strand?

<p>Semiconservative Pattern</p> Signup and view all the answers

What is the function of the ligase enzyme during DNA replication?

<p>binds Okazaki fragments</p> Signup and view all the answers

What is the name of the process by which genetic information is transferred from DNA to RNA?

<p>Transcription</p> Signup and view all the answers

What is the role of the ribosome in protein synthesis?

<p>translates mRNA into protein</p> Signup and view all the answers

What is the name of the three types of RNA involved in protein synthesis?

<p>mRNA, tRNA, rRNA</p> Signup and view all the answers

What is the nucleotide base that pairs with adenine in DNA?

<p>thymine</p> Signup and view all the answers

During transcription, which RNA is synthesized in the 5' to 3' direction?

<p>messenger RNA (mRNA)</p> Signup and view all the answers

What is the first step in gene expression?

<p>transcription</p> Signup and view all the answers

During DNA replication, what is the role of the leading strand?

<p>continuous synthesis in the 5' to 3' direction</p> Signup and view all the answers

What is the enzyme responsible for joining Okazaki fragments during DNA replication?

<p>ligase</p> Signup and view all the answers

What is the term for the process by which DNA is replicated in a semi-conservative manner?

<p>semi-conservative replication</p> Signup and view all the answers

What is the role of helicase in DNA replication?

<p>unwinding the DNA double helix</p> Signup and view all the answers

What is the name of the experiment that demonstrated that DNA is the genetic material?

<p>Griffith experiment</p> Signup and view all the answers

What is the role of helicase in DNA replication?

<p>Unwinding the double helix at the replication fork</p> Signup and view all the answers

What is the function of RNA primer in DNA replication?

<p>Act as a starting point for DNA polymerase</p> Signup and view all the answers

What is the role of ligase in DNA replication?

<p>Joining up okazaki fragments</p> Signup and view all the answers

Which sugar is found in RNA but not in DNA?

<p>Ribose</p> Signup and view all the answers

What is the function of DNA polymerase in DNA replication?

<p>Building up nucleotides complementary to the parental DNA</p> Signup and view all the answers

Which type of organism has a genome composed of RNA?

<p>Viruses</p> Signup and view all the answers

What is the result of DNA replication in the first generation after transfer to a medium with light nitrogen?

<p>Half hybrid, half heavy</p> Signup and view all the answers

What is the role of DNA polymerase I in DNA replication?

<p>Act as a starting point for DNA synthesis on the lagging strand</p> Signup and view all the answers

Study Notes

Structure of Ribonucleotides

  • A ribonucleotide is formed of sugar (ribose), one phosphate, and nitrogenous bases (adenine, uracil, cytosine, guanine)
  • DNA and RNA molecules have slightly different functions

Functions of DNA and RNA

  • DNA molecules store genetic information of a cell, used to carry out cell functions
  • RNA is used to transfer genetic information from the nucleus
  • There are 3 types of RNA: mRNA, tRNA, rRNA

Gene

  • A gene is a fragment of DNA (sequence of nucleotides) transcribed into mRNA codons and then translated into protein

DNA Replication

  • The enzyme DNA helicase unwinds the 2 strands of DNA
  • DNA polymerase forms new DNA strands by complementary base pairing
  • We get 2 new molecules, each made of an old strand and new strand, following the Semiconservative Pattern
  • The DNA replication fork includes an RNA primer, which is labeled at the top

From Gene to Protein

  • DNA transcription and translation: DNA -> mRNA -> Amino acids -> Protein
  • In Eukaryotes, transcription occurs in the nucleus, and translation occurs in the cytoplasm
  • During transcription, the enzyme RNA polymerase unwinds DNA and forms mRNA strand by complementary base pairing
  • mRNA undergoes processing (removal of introns) before exiting the nucleus

DNA Replication Enzymes

  • DNA polymerase builds up nucleotides complementary to the parental DNA
  • Helicase unwinds the double helix at the replication fork
  • Ligase joins up Okazaki fragments

DNA Replication Experiment

  • Scientists grew bacteria in a medium containing heavy nitrogen (15N) as the only source of nitrogen
  • After many generations, all bacteria DNA contained heavy nitrogen
  • Bacteria were then moved to a medium with only light nitrogen (14N)
  • Analysis of DNA from subsequent generations showed hybrid DNA with both heavy and light nitrogen

RNA and DNA

  • RNA contains the sugar ribose, while DNA contains the sugar deoxyribose
  • Uracil is found in RNA, but not in DNA
  • Thymine is found in DNA, but not in RNA

DNA Replication and Transcription in Prokaryotes and Eukaryotes

  • In prokaryotes, DNA replication and transcription occur simultaneously
  • In eukaryotes, transcription occurs in the nucleus, and translation occurs in the cytoplasm

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Description

Learn about the structure of ribonucleotides, functions of DNA and RNA, and the role of genes in molecular biology.

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