Gene Expression Overview
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Questions and Answers

What two nucleic acids are found in all living things?

DNA and RNA

What is the major group of biomolecules that DNA and RNA belong to?

Nucleic acids

What are the three component parts of a nucleotide?

A phosphate group, a pentose sugar, and a nitrogen-containing base

Name the four bases found in DNA.

<p>Adenine, guanine, cytosine, and thymine</p> Signup and view all the answers

What is the name of the bond that joins nucleotides together in a polynucleotide chain?

<p>A phosphodiester bond</p> Signup and view all the answers

What is the role of mRNA?

<p>mRNA carries genetic information from DNA to ribosomes.</p> Signup and view all the answers

Which of the following statements is TRUE about RNA compared to DNA?

<p>RNA is shorter than DNA, often containing only one gene.</p> Signup and view all the answers

A single point mutation in the genetic code can lead to significant medical conditions in humans.

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

What are the two main stages of gene expressions?

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

Where does transcription occur in a eukaryotic cell?

<p>In the nucleus</p> Signup and view all the answers

What is the enzyme that catalyses the synthesis of RNA from DNA during transcription?

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

What does 'pre-mRNA' refer to?

<p>The original RNA transcript produced during transcription before it undergoes further processing</p> Signup and view all the answers

Transcriptional control is a key mechanism in regulating gene expression.

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

What is the role of proteins called histones? Why are they important in the context of DNA?

<p>Histones are proteins that help package and organize DNA. They are crucial for efficiently storing and protecting the long DNA molecule within the nucleus of a cell.</p> Signup and view all the answers

Which of the following is NOT a component part of DNA?

<p>Fatty acid</p> Signup and view all the answers

What is the role of codons in the transfer of genetic information?

<p>Codons are three-base sequences that specify which amino acid should be added to a growing polypeptide chain during protein synthesis.</p> Signup and view all the answers

Which type of RNA carries information specifying the amino acid sequences from DNA to ribosomes?

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

Which of the following is true about the base pairing rules in DNA and RNA?

<p>Uracil substitutes for thymine in RNA.</p> Signup and view all the answers

RNA is double-stranded like DNA.

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

What is the process by which DNA is copied to make a complementary RNA molecule?

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

What is the process by which mRNA is used to generate a protein?

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

What is the name of the enzyme that catalyzes transcription?

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

What is an example of transcriptional regulation?

<p>The binding of a regulatory protein to DNA.</p> Signup and view all the answers

The sequence of nucleotides in DNA determines the sequence of amino acids in a protein.

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

Which of the following is NOT a common type of RNA?

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

What is the name of a three-base sequence in mRNA that codes for a specific amino acid?

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

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

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

What is the name of the structure in a eukaryotic cell that contains DNA?

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

Where does transcription take place in a eukaryotic cell?

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

A single point mutation can cause a change in the amino acid sequence of a protein.

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

What is the name of a mutation that changes a single nucleotide in a DNA sequence?

<p>Point mutation</p> Signup and view all the answers

What is the name of a mutation that changes a codon to code for a different amino acid?

<p>Missense mutation</p> Signup and view all the answers

What is a type of RNA that is found in ribosomes?

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

What is the name of the complex of DNA and proteins that make up chromosomes?

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

What is the name of the repeating unit of chromatin?

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

The nuclear envelope separates transcription from translation in prokaryotic cells.

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

Which of the following is NOT involved in pre-mRNA processing?

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

What is the name of a type of RNA that is involved in splicing?

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

Introns are non-coding regions of DNA that are removed during splicing.

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

What is the name of the process by which introns are removed from pre-mRNA?

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

What is the name of the process by which a 5' cap is added to pre-mRNA?

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

What is the name of the process by which a polyadenylation signal is added to pre-mRNA?

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

What is the name of the part of the DNA that is transcribed into RNA?

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

What is the name of the process by which the information in mRNA is used to synthesize a protein?

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

What is the name of the molecule that carries amino acids to the ribosomes?

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

The genetic code is universal, meaning that the same codons specify the same amino acids in all organisms.

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

What is the term for the end of a DNA molecule that has a free 3' hydroxyl group?

<p>3' end</p> Signup and view all the answers

What is the term for the end of a DNA molecule that has a free 5' phosphate group?

<p>5' end</p> Signup and view all the answers

What is the name of the bond that links nucleotides together in a DNA or RNA molecule?

<p>Phosphodiester bond</p> Signup and view all the answers

DNA polymerase is the enzyme that catalyzes transcription.

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

The central dogma of molecular biology states that information flows from DNA to RNA to protein.

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

Study Notes

Gene Expression Overview

  • Gene expression is the process of using DNA information to create proteins.
  • This process involves DNA as the starting material and protein as the end product.

Learning Outcomes

  • Understand the components of DNA
  • Understand the significance of codons in transmitting genetic information.
  • Identify mRNA, tRNA, and rRNA and their functions.
  • Understand the mechanism of transcription.
  • Understand the role of specific base sequences in transcription control.
  • Understand the mechanism of translation.

DNA and RNA Biomolecules

  • DNA and RNA belong to the group of nucleic acids.
  • Nucleic acids are built from nucleotides.
  • Nucleotides consist of a phosphate group, a pentose sugar (deoxyribose in DNA, ribose in RNA) and a nitrogenous base.

Nucleic Acids are Polynucleotides

  • Nucleic acids are polymers of nucleotides.
  • DNA has a double helix structure.
  • DNA base pairing rules are A-T and C-G.
  • RNA is typically single-stranded.
  • RNA contains uracil instead of thymine found in DNA.

DNA Structure

  • DNA is a polynucleotide.
  • The nucleotides are linked by phosphodiester bonds.
  • The sugar-phosphate backbone forms the outside of the double helix.
  • The nitrogenous bases are paired in the center.

RNA Compared to DNA

  • RNA is single-stranded, not double-stranded like DNA.
  • RNA is usually shorter than DNA, carrying a single gene's worth of information compared to DNA's carrying many genes.
  • RNA uses ribose sugar instead of deoxyribose.
  • RNA contains uracil (U) instead of thymine (T).
  • RNA cannot form stable double helices.

Types of RNA

  • mRNA (messenger RNA): carries genetic information from DNA to ribosomes for protein synthesis.
  • rRNA (ribosomal RNA): plays a structural and catalytic role in ribosomes.
  • tRNA (transfer RNA): carries amino acids to the ribosome for protein synthesis.
  • tRNA has an anticodon that base pairs with the codon on the mRNA.

Gene Expression Stages

  • Gene expression is divided into two main stages: transcription and translation.
  • Transcription occurs in the nucleus, converting DNA into mRNA.
  • Translation occurs in the cytoplasm, using mRNA to synthesize proteins on ribosomes.

Transcription and Translation

  • Cells use a cellular command chain (DNA → RNA → protein).
  • Transcription is the synthesis of RNA using DNA as a template, producing mRNA.
  • Translation is the synthesis of a polypeptide (protein) under the direction of mRNA, happening on ribosomes.

Chromatin

  • Chromatin, the material chromosomes are made of, is about 30% DNA, 60% histones, and 10% RNA.
  • Chromosomes condense during mitosis, becoming visible as X-shapes.

Transcription in Eukaryotes

  • In eukaryotic cells, the nuclear envelope separates transcription (in the nucleus) from translation (in the cytoplasm).
  • Extensive RNA processing occurs within the nucleus before mRNA leaves.

Transcription: Synthesis of RNA from DNA

  • Transcription is the synthesis of RNA from DNA, using a DNA template.
  • mRNA functions as a template for the production of proteins from amino acids.
  • RNA polymerase is the enzyme that catalyzes transcription.
  • The enzyme binds to DNA, opens the DNA strands, and inserts new RNA nucleotides.
  • Uracil substitutes for thymine in RNA during base-pairing (A-U, G-C).

Transcriptional Control

  • Gene expression is regulated at the transcription stage.
  • This regulation can be achieved by controlling the rate of RNA polymerase binding to DNA and by various mechanisms including initiation, elongation, and termination of transcription.
  • Specific base sequences can control transcription.

Single Point Mutations

  • Single point mutations in a gene can cause significant medical conditions.
  • Example: Sickle cell anaemia caused by a point mutation in the beta-haemoglobin gene, changing a GAG codon to GUG, resulting in an incorrect amino acid (valine instead of glutamic acid) being incorporated into the protein.

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Gene Expression AECC Handout PDF

Description

This quiz provides a comprehensive overview of gene expression, detailing the processes of transcription and translation. Participants will explore the roles of DNA and RNA, along with understanding nucleotides and codons. Test your knowledge on the mechanisms behind gene expression and the significance of these biomolecules.

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