DNA Replication and Protein Synthesis
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Questions and Answers

What is the full name of DNA?

Deoxyribonucleic Acid

What is the function of the genetic code?

It's how cells store information to be passed on to the next generation.

What are the three subunits of a nucleotide?

A phosphate group, a 5-carbon sugar, and a nitrogen base.

Which of the following are purines?

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

What makes up the backbone of DNA?

<p>The sugars and phosphates.</p> Signup and view all the answers

The two strands of DNA are identical.

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

Each strand of DNA can serve as a pattern to put together the sequence of bases on the other half.

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

Why must a cell duplicate its DNA?

<p>So that each resulting cell has a complete copy of DNA.</p> Signup and view all the answers

What enzyme unzips and unwinds the two strands of DNA during replication?

<p>DNA helicase</p> Signup and view all the answers

What shape is formed where DNA separates during replication?

<p>A Y-shape, also called a replication fork.</p> Signup and view all the answers

What enzyme adds new nucleotides and bases to the exposed strands during DNA replication?

<p>DNA polymerases</p> Signup and view all the answers

DNA polymerases do not have a proofreading function.

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

What are the two components of each new DNA molecule after replication?

<p>One original strand and one new strand.</p> Signup and view all the answers

The process of turning genes into specific traits is called ______ expression.

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

What is the first step in gene expression?

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

Transcription creates an mRNA molecule that is identical to the DNA sequence.

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

What enzyme carries out transcription?

<p>RNA polymerase</p> Signup and view all the answers

What is the second step in gene expression?

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

What type of RNA carries genetic information from DNA to ribosomes?

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

What type of RNA reads the mRNA during translation and translates it into amino acids?

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

What type of RNA is found in ribosomes?

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

What is the difference between the sugar in DNA and RNA?

<p>DNA contains deoxyribose, while RNA contains ribose.</p> Signup and view all the answers

RNA is double-stranded.

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

DNA uses thymine as a nitrogenous base, while RNA uses uracil.

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

All base pairing rules apply to RNA, except adenine pairs with uracil instead of thymine.

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

What is the role of the promoter sequence in transcription?

<p>It's the starting point on DNA where RNA polymerase binds.</p> Signup and view all the answers

What does mRNA carry?

<p>Genetic information from DNA to the ribosomes where proteins are made.</p> Signup and view all the answers

What is a codon?

<p>A three-nucleotide sequence on a strand of mRNA.</p> Signup and view all the answers

What does each codon specify?

<p>An amino acid that is to be placed in the protein chain.</p> Signup and view all the answers

What is the process of using information in mRNA to assemble amino acids and make proteins called?

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

Besides the mRNA, what other types of RNA are involved in translation?

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

What is the final product of translation?

<p>A polypeptide, which is a chain of amino acids.</p> Signup and view all the answers

Translation occurs in a single step, involving only mRNA.

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

What binds with mRNA to start translation?

<p>A ribosome and a tRNA molecule carrying the amino acid methionine.</p> Signup and view all the answers

What happens when the ribosome encounters a stop codon during translation?

<p>The process ends, and the polypeptide is released from the ribosome.</p> Signup and view all the answers

Why does tRNA know which amino acid to bring to the ribosome?

<p>Because its anticodon is complementary to the mRNA codon.</p> Signup and view all the answers

Study Notes

DNA Replication and Protein Synthesis

  • DNA is deoxyribonucleic acid, the genetic code cells use to pass information to the next generation.
  • DNA is a macromolecule made of nucleotides.
  • Each nucleotide has three subunits: a phosphate group, a 5-carbon sugar, and a nitrogen base.
  • Four nitrogen bases exist: adenine, guanine, thymine, and cytosine.
  • Adenine and guanine are purines; thymine and cytosine are pyrimidines.
  • Nucleotides link to form DNA molecules. Sugars and phosphates form the DNA backbone.
  • DNA has a double helix structure.
  • The two strands of DNA are complementary, like puzzle pieces.
  • Each strand serves as a pattern for the other.
  • DNA replication occurs before cell division so each cell has a complete DNA copy.
  • DNA helicase unzips and unwinds DNA strands by breaking hydrogen bonds.
  • This creates a Y-shape called a replication fork.
  • DNA polymerases add new nucleotides and bases to exposed strands.
  • DNA polymerases proofread bases to ensure correct pairing.
  • Usually only one mutation happens per billion bases.
  • Two identical DNA molecules result, each with one original and one new strand.

DNA Replication - Example

  • Original DNA Strand: A-T-T-C-G-C-T-A-G-T-A
  • Complementary strand: T-A-A-G-C-G-A-T-C-A-T

RNA Introduction

  • Gene expression turns genes into specific traits, and is done by RNA.
  • Transcription copies part of the DNA sequence into RNA (ribonucleic acid).
  • RNA information is used to make a specific protein - this is called translation.

RNA Structure

  • RNA molecules are chains of nucleotides, single-stranded

RNA vs. DNA

  • RNA sugar is ribose; DNA sugar is deoxyribose.
  • RNA is single-stranded, DNA is double-stranded.
  • RNA has four nitrogen bases: adenine, guanine, cytosine, and uracil. Uracil replaces thymine.
  • All base-pairing rules apply: C=G, A=U

Types of RNA

  • Messenger RNA (mRNA) carries genetic information from DNA to ribosomes.
  • Transfer RNA (tRNA) reads mRNA during translation, producing amino acids.
  • Ribosomal RNA (rRNA) is RNA in ribosomes.

Transcription (RNA Synthesis)

  • RNA polymerase copies DNA into mRNA.
  • The RNA molecule is complementary to the DNA molecule, but not identical.
  • RNA polymerase binds to the promoter sequence (starting point on DNA) on DNA.
  • RNA polymerase unwinds and separates DNA.
  • Complementary RNA bases are added to DNA bases, making a single mRNA strand.
  • mRNA carries genetic information from DNA to ribosomes for protein production.

Transcription Practice

  • DNA: A-T-C-T-G-T-T-A
  • RNA: U-A-G-A-C-A-A-U

Nature of the Genetic Code

  • Genes ("directions") help make proteins; the DNA code is determined by arrangements of the four nitrogen bases.
  • Each three-nucleotide mRNA combination is a codon, or three-letter code word.

Codon Examples

  • C-U-G, A-C-U are both codons.
  • Codons specify amino acids to be added to the protein chain.

Translation

  • Translation uses mRNA information to put together amino acids and form proteins.
  • Occurs in steps, involves three types of RNA, and results in a polypeptide.

Translation Steps

  1. Ribosome, tRNA (with methionine), and mRNA bind together.
  2. A new tRNA arrives and binds to the next mRNA codon.
  3. The first tRNA detaches and leaves its amino acid.
  4. The process continues until a "stop" codon is reached.
  5. The amino acid chain is released, and the ribosome complex separates. A tRNA molecule has an anticodon that is complementary to an mRNA codon and carries the amino acids for the protein.

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DNA Replication and Protein Synthesis PDF

Description

Explore the intricate process of DNA replication and protein synthesis in this quiz. Understand how nucleotides form DNA and the role of enzymes such as DNA polymerases. Test your knowledge on the structure of DNA and the mechanisms that ensure accurate copying before cell division.

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