Molecular Biology: DNA and Experiments
45 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Who discovered that DNA is the genetic material?

Hershey and Chase

What did Griffith discover about transformation in bacteria?

A substance from dead virulent bacterial cells transformed non-virulent cells into pathogenic cells.

What is the shape of the DNA molecule?

Double helix

Which of the following are the components of a nucleotide in DNA?

<p>Phosphate group, 5-carbon sugar, nitrogenous base</p> Signup and view all the answers

Which of the following are purines?

<p>Adenine and Guanine</p> Signup and view all the answers

Which nitrogenous bases pair together in DNA?

<p>Adenine with Thymine, Guanine with Cytosine</p> Signup and view all the answers

DNA replication is the process of copying one DNA molecule into two identical molecules.

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

Which model of DNA replication proposes that the two original strands stay together, and two new strands are formed?

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

Which model of DNA replication proposes that each new DNA molecule has one original strand and one newly synthesized strand?

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

Which model of DNA replication proposes that each new DNA molecule is a mix of old and new DNA strands?

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

What is the name of the specific site where DNA replication begins?

<p>Origin of replication</p> Signup and view all the answers

What enzyme unwinds the DNA helix during replication?

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

What proteins prevent the separated DNA strands from re-binding?

<p>Single-stranded binding proteins</p> Signup and view all the answers

What enzyme relieves the strain on the DNA molecule caused by unwinding?

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

What is the role of primase in DNA replication?

<p>Primase lays down RNA primers that are used by DNA polymerase as a starting point to build the new complementary strand.</p> Signup and view all the answers

What is the main enzyme responsible for copying DNA during replication?

<p>DNA polymerase III</p> Signup and view all the answers

The lagging strand is synthesized continuously towards the replication fork.

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

What are the short fragments of DNA synthesized on the lagging strand called?

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

DNA replication is terminated when the synthesis of the new DNA strands is complete.

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

What is the central dogma of molecular biology?

<p>Information flow from DNA to mRNA by transcription, and mRNA to protein by translation.</p> Signup and view all the answers

What is the process called where DNA is used as a template to synthesize RNA?

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

What is the process called where mRNA is used as a template to synthesize protein?

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

What is a codon?

<p>A triplet of nucleotides on mRNA that codes for a particular amino acid or stop signal.</p> Signup and view all the answers

What is a start codon? What is its sequence?

<p>A start codon signals the ribosome that translation should begin. The start codon is AUG.</p> Signup and view all the answers

What is a stop codon? What is its role in translation?

<p>A stop codon signals the end of translation to a ribosome.</p> Signup and view all the answers

The genetic code is redundant, meaning that more than one codon can code for the same amino acid.

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

The genetic code is continuous, meaning that it is read as a series of three-letter codons.

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

What are introns? What is their role in gene expression?

<p>Introns are non-coding sequences that are removed from the RNA molecule before protein synthesis.</p> Signup and view all the answers

What type of RNA carries the genetic information from DNA to ribosomes for protein synthesis?

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

What type of RNA forms the structural and functional core of ribosomes?

<p>Ribosomal RNA (rRNA)</p> Signup and view all the answers

What type of RNA delivers amino acids to the ribosome during protein synthesis?

<p>Transfer RNA (tRNA)</p> Signup and view all the answers

What is the name of the region in DNA that is recognized by RNA polymerase to initiate transcription?

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

What is the name of the sequence of A's and T's in the promoter region that is recognized by RNA polymerase in eukaryotes?

<p>TATA box</p> Signup and view all the answers

Which strand of DNA is transcribed into RNA?

<p>Template strand</p> Signup and view all the answers

In which direction does RNA polymerase move along the template strand to synthesize RNA?

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

What signals the termination of transcription?

<p>Specific nucleotide sequences in the DNA template</p> Signup and view all the answers

What component of translation carries the genetic information that determines the amino acid sequence of a protein?

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

What component of translation contains an anticodon that base pairs with a codon on mRNA and carries a corresponding amino acid?

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

What is the name of the complex composed of rRNA and proteins that is involved in protein synthesis?

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

What is the name of the three-nucleotide sequence on tRNA that is complementary to a codon on mRNA?

<p>Anticodon loop</p> Signup and view all the answers

What is the name of the region on tRNA where the amino acid is attached?

<p>Acceptor strand</p> Signup and view all the answers

What is the name of the binding site on the ribosome where the tRNA carrying the growing polypeptide chain is located?

<p>P site (peptide)</p> Signup and view all the answers

What is the name of the binding site on the ribosome where the tRNA carrying the next amino acid to be added to the polypeptide chain is located?

<p>A site (aminoacyl)</p> Signup and view all the answers

What is the name of the binding site on the ribosome where the tRNA is released after it has delivered its amino acid to the polypeptide chain?

<p>E site (exit)</p> Signup and view all the answers

Explain the wobble hypothesis.

<p>The third nucleotide in the template strand is often less important than the first two. The third nucleotide is in the wobble position.</p> Signup and view all the answers

Study Notes

Griffith's Experiment

  • Griffith discovered a transforming substance from dead virulent bacterial cells that could transform non-virulent cells into pathogenic cells.

Hershey-Chase Experiment

  • Hershey and Chase, using bacteriophages, determined that the genetic material of the virus is DNA.

Watson and Crick's Model

  • Watson and Crick proposed the double helix model of DNA.
  • Key components include a sugar-phosphate backbone (the "handrails"), phosphate bridges, and hydrogen bonds between nitrogenous bases.

DNA Structure

  • DNA comprises a phosphate group, a 5-carbon sugar, and nitrogenous bases.
  • Two types of bases:
    • Purines (double ring): Adenine (A) and Guanine (G)
    • Pyrimidines (single ring): Thymine (T) and Cytosine (C)
    • Base pairing rules: A=T (2 hydrogen bonds), G=C (3 hydrogen bonds - requiring more energy to break)

DNA Replication

  • DNA replication is the process of creating two identical DNA molecules from one.
  • Occurs during interphase.
  • Three models of replication:
    • Conservative: One molecule with original strands, one with new strands.
    • Semi-conservative: Each strand serves as a template for a new strand, resulting in two hybrid molecules.
    • Dispersive: Each strand is a mix of old and new DNA, resulting in hybrid molecules.
  • The model accepted is Semi-conservative.

DNA Replication Phases

  • Initiation:
    • Begins at the origin of replication.
    • Helicase unwinds the DNA by breaking hydrogen bonds.
    • Single-strand binding proteins prevent the separated strands from re-joining.
    • Topoisomerase relieves the strain on the DNA caused by unwinding.
  • Elongation:
    • Primase creates RNA primers, which are used by DNA polymerase (the main copying enzyme) to start building new complementary strands.
    • DNA polymerase III adds nucleotides to create complementary strands.
    • Leading strand is built continuously towards the replication fork.
    • Lagging strand is built in short segments (Okazaki fragments) away from the replication fork.
  • Termination:
    • Occurs when replication of new strands is complete.

Central Dogma

  • Information flow: DNA (transcription) → mRNA (translation) → protein.

Gene Expression (Transcription and Translation)

  • Transcription: DNA sequence serves as a template for RNA synthesis in the nucleus.
    • Steps:
      • Initiation: RNA polymerase binds to the promoter region (before the gene), unwinding DNA.
      • Elongation: RNA polymerase moves along the template strand, synthesizing mRNA.
      • Termination: RNA polymerase reaches termination sequence, detaching from DNA.
  • Translation: mRNA sequence serves as a template for protein synthesis in the cytoplasm.
    • Components:
      • mRNA (messenger RNA): carries genetic code.
      • tRNA (transfer RNA): carries amino acids to the ribosome.
      • Ribosomes: site of protein synthesis.
    • Codons: three-nucleotide sequences on mRNA that code for amino acids or signals.
    • Start codon: AUG (methionine)
    • Stop codons: signal translation termination.
    • Redundancy: Multiple codons can code for the same amino acid.
    • Introns (non-coding) and exons (coding) are involved
  • Ribosomes have three sites (A, P, E) for tRNA binding.
  • Anticodons (on tRNA) are complementary to mRNA codons.

Transcription Stages:

  • Initiation: RNA polymerase binds to the promoter region.
  • Elongation: RNA polymerase synthesizes mRNA.
  • Termination: RNA polymerase reaches a termination signal.

Translation Components and Function

  • mRNA: carries genetic code
  • tRNA: carries amino acids; anticodon base pairs with codon.
  • Ribosomes: site of protein synthesis

Wobble Hypothesis

  • The 3rd base (wobble position) of the codon is less critical in determining the amino acid.

Central Dogma Summary

  • DNA carries genetic information
  • Replication copies the DNA
  • Transcription produces mRNA from DNA
  • Translation uses mRNA to synthesize proteins

Studying That Suits You

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

Quiz Team

Description

Explore key concepts in molecular biology through this quiz, which covers Griffith's Experiment, Hershey-Chase Experiment, and Watson and Crick's double helix model. Test your understanding of DNA structure, replication, and the significance of these groundbreaking experiments.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser