Nutritional Biochemistry Genetics Quiz
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Questions and Answers

What percentage of genes in the human genome is the same between humans?

  • 98.7%
  • 99.9% (correct)
  • 97.5%
  • 90.0%

    • Which part of a nucleotide is replaced by hydrogen in DNA's sugar?

  • 3ʹ carbon
  • 1ʹ carbon
  • 5ʹ carbon
  • 2ʹ carbon (correct)

    • Which type of bond exists between adenine and thymine in DNA?

  • 1 hydrogen bond
  • 3 hydrogen bonds
  • 4 hydrogen bonds
  • 2 hydrogen bonds (correct)

    • What is the structure of DNA best described as?

    <p>Double helix</p> Signup and view all the answers

    What components form a nucleoside?

    <p>Sugar and base</p> Signup and view all the answers

    How many steps per turn does the helical structure of DNA have?

    <p>10.5 steps</p> Signup and view all the answers

    What type of molecules do polynucleotides form?

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

    Which nucleotide base pairs with guanine?

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

    What is the final step in the synthesis of the lagging strand during DNA replication?

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

    What type of bond forms between the 5ʹ phosphate of one nucleotide and the 3ʹ carbon of the next nucleotide?

    <p>3ʹ-5ʹ phosphodiester bond</p> Signup and view all the answers

    How is DNA organized for mitosis to ensure equal distribution into daughter cells?

    <p>As chromosomes</p> Signup and view all the answers

    What is the primary role of genes within a DNA molecule?

    <p>To direct the synthesis of proteins</p> Signup and view all the answers

    How do the strands of DNA run in relation to each other?

    <p>In opposite directions</p> Signup and view all the answers

    Which process involves transcribing genetic information into a messenger format?

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

    What structural unit does DNA first wrap around for compaction?

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

    What type of RNA carries the genetic message to the ribosome for protein synthesis?

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

    What do telomeres protect at the ends of chromosomes?

    <p>From degradation</p> Signup and view all the answers

    Which proteins are crucial for the initiation of transcription in mammalian cells?

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

    Which process is DNA replication a part of?

    <p>Cell cycle</p> Signup and view all the answers

    What replaces thymine in messenger RNA (mRNA)?

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

    What is formed when nucleosomes further condense?

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

    What primarily regulates gene expression in cells?

    <p>Hormones and growth factors</p> Signup and view all the answers

    What is the role of histones in relation to DNA?

    <p>To help compact DNA</p> Signup and view all the answers

    What defines a gene?

    <p>A discrete segment of DNA encoding an amino acid sequence</p> Signup and view all the answers

    What is the primary function of the TATA box in gene transcription?

    <p>To locate RNA polymerase at the initiation site</p> Signup and view all the answers

    What role do enhancers play in transcription?

    <p>They bind to transcription factors to enhance gene activation</p> Signup and view all the answers

    During transcription initiation, which nucleotides replace thymine in RNA?

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

    What is the direction of RNA strand growth during transcription?

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

    What happens when RNA polymerase reaches the transcription-termination sequence?

    <p>It dissociates from the DNA</p> Signup and view all the answers

    Which of the following statements is true regarding introns and exons?

    <p>Exons are protein-coding sequences, introns are non-coding</p> Signup and view all the answers

    Which molecules assist in the translation process by attaching amino acids to form proteins?

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

    Where are ribosomes primarily formed?

    <p>From proteins associated with ribosomal RNA (rRNA)</p> Signup and view all the answers

    What are the two subunits of a ribosome called?

    <p>Large and small subunits</p> Signup and view all the answers

    What structure does tRNA have?

    <p>Clover leaf structure</p> Signup and view all the answers

    Which site in the ribosome does the start tRNA bind to?

    <p>Either the A or P site</p> Signup and view all the answers

    What is the function of the anticodon in tRNA?

    <p>It binds to the complementary triplet code on mRNA</p> Signup and view all the answers

    What mediates the joining of amino acids to form a peptide bond?

    <p>Peptidyl transferase</p> Signup and view all the answers

    What signals the termination of protein synthesis?

    <p>Presence of a stop codon</p> Signup and view all the answers

    Where does the ribosome dissociate after protein synthesis is complete?

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

    Which cycle occurs within the mitochondria as part of energy production?

    <p>Tricarboxylic Acid Cycle (TCA)</p> Signup and view all the answers

    What can lead to the shunting of pyruvate to lactate in high metabolic demand tissues?

    <p>Cellular acidosis due to anaerobic ATP production</p> Signup and view all the answers

    What role do mitochondrial DNA mutations play in Parkinson's Disease?

    <p>They damage mtDNA, affecting ATP production in dopaminergic neurons.</p> Signup and view all the answers

    What is the smallest unit of DNA?

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

    Which of the following best describes the structure of DNA?

    <p>A double helix formed by phosphodiester bonds between nucleotides.</p> Signup and view all the answers

    How do mitochondrial DNA and nuclear DNA differ?

    <p>Nuclear DNA is located in the nucleus while mitochondrial DNA is not.</p> Signup and view all the answers

    What type of bonds link nucleotides together in a DNA strand?

    <p>Covalent phosphodiester bonds</p> Signup and view all the answers

    What is a replication fork?

    <p>The point of separation for the two strands of DNA during replication.</p> Signup and view all the answers

    Which of the following statements about damaged nuclear DNA in cancer is true?

    <p>Point mutations in mtDNA have been observed in some cancers.</p> Signup and view all the answers

    Study Notes

    Nutritional Biochemistry - Introduction to Genetics

    Questions

    • Question 1: Proteins spanning the membrane with alpha helices contain amino acid side chains central to the complex
    • Question 2: Transport proteins moving solutes against a concentration gradient are carrier proteins, not channel proteins, because they bind to solutes and change shape to move them.
    • Question 3: Simple diffusion moves substances with their concentration gradient, while facilitated diffusion uses transport proteins.
    • Question 4: Active transport uses chemical or electrical energy.
    • Question 5: Na+ and K+ channels have similar structures but different orientations, allowing Na+ to enter the cell and K+ to exit.

    Learning Outcomes

    • Describe DNA structure and organization in the nucleus
    • Describe DNA replication
    • Outline the transcription and translation of a gene into a protein
    • Briefly outline the structure, control, and role of mtDNA, and associated diseases

    Genes and Genetics

    • Humans have 100 trillion cells, each nucleus containing 46 chromosomes (23 pairs).
    • Genes are DNA sections that code for protein synthesis.
    • Each chromosome pair receives one chromosome from each parent.

    The Genome

    • Every cell in an organism has the same genetic information.
    • The genome controls the biochemical activity in response to various stimuli.
    • The inherited traits are transmitted from generation to generation.
    • The human genome contains approximately 20,000-21,000 genes.
    • 99.9% of human genes are similar across individuals.

    The Structure of DNA

    • The genome is made up of DNA.
    • DNA is a long chain of nucleotides.
    • DNA is a double helix, analogous to a ladder.
    • DNA is 2nm wide and has 10.5 steps per turn (3.4 nm).

    DNA Methylation

    • DNA methylation involves adding a methyl group to DNA.
    • Demethylation is the removal of a methyl group.

    Nucleosides

    • Nucleosides consist of a sugar and a nitrogenous base.
    • The base is attached to the sugar via a bond.

    Nucleotide Structure

    • Nucleotides comprise three parts: a sugar, a base, and a phosphate group.
    • Nucleotides, connected by phosphodiester bonds, form the phosphate-sugar backbone.
    • Sugars are 5-carbon pentose sugars.

    Hydrogen Bonding Between Bases

    • DNA bases only bond with specific bases:
      • Adenine with Thymine
      • Guanine with Cytosine
    • Complementary base pairing is fundamental for DNA replication and translation.

    Polynucleotides

    • Nucleotides form polynucleotides, which are the fundamental structural units of DNA.
    • Phosphodiester bonds link nucleotides, creating the phosphate-sugar backbone.

    The DNA Double Helix

    • The deoxyribose chains and base-sugar bonding create a DNA double helix structure.
    • The DNA strands run antiparallel (3' and 5').
    • Directionality of the DNA strands is critical for DNA processes.

    Histones, Chromatin, and Chromosomes

    • DNA packaging for storage involves histones, forming nucleosomes.
    • Nucleosomes condense into chromatin fibers.
    • Chromatin fibers condense into chromosomes.

    Structure of Genes

    • A gene is a specific segment of DNA that encodes the amino acid sequence for a protein.
    • Genes are the fundamental units of inheritance.
    • Chromosomes have genes located in bands along their structure.

    Telomeres

    • Chromosomes have protective caps called telomeres.
    • Telomeres prevent degradation and fusion of chromosomes.

    The Cell Cycle

    • DNA replication is part of the cell cycle.
    • The cycle includes G1, S, and G2 phases, with G0 as a resting phase.
    • G1: Cytoplasm and organelles increase.
    • S: DNA is precisely duplicated.
    • G2: Cell and organelle growth.
    • M: Mitosis and cell division occur.

    Cell Cycle Checkpoints

    • Checkpoints ensure accuracy in replication and division.
    • 3 checkpoints:
      • G1 checkpoint.
      • S checkpoint.
      • M checkpoint.

    DNA Replication

    • Copying DNA to generate identical copies for daughter cells during cell division.
    • Replication occurs by unwinding the DNA double helix and synthesizing complementary strands on each parent strand.

    Replication Fork

    • The region where the DNA unwinds is known as the replication fork.
    • Replication takes place in the 5' to 3' direction.

    Leading/Lagging Strands

    • Leading strand: synthesised in a continuous manner following the replication fork.
    • Lagging strand: synthesised discontinuously in segments called Okazaki fragments.

    DNA Replication - Lagging Strand

    • RNA primer initiates synthesis steps.
    • DNA polymerase replaces RNA primer with DNA.
    • Okazaki fragments are joined together.

    Mitochondria DNA (mtDNA)

    • Mitochondria produce energy (ATP) via oxidative phosphorylation.
    • mtDNA is a small, circular, double stranded
    • mtDNA controls some mitochondrial functions.
    • mtDNA is only found in animal cells, maternally inherited.

    mtDNA Replication

    • The replication method of mtDNA is controversial.
    • Two theories exist for mtDNA lagging strand timing.

    mtDNA Transcription & Replication - Differences

    • mtDNA lacks introns and non-coding sequences.
    • Termination codons are post-transcriptionally created.

    Mitochondrial Disease

    • Mitochondrial dysfunction is linked to aging and degenerative diseases.
    • mtDNA is susceptible to damage from free radicals.
    • Certain disorders are caused by mutations in mtDNA.

    Energy Failure Through Damage

    • Cells lacking sufficient aerobic ATP production may resort to anaerobic respiration (using lactate).
    • Reduced ATP generation often results in cellular acidosis.
    • This is often observed in tissues with high metabolic demands, such as the CNS, heart, and skeletal muscle.

    Mitochondrial DNA Mutations

    • Parkinson's disease (PD) is one disorder in which mtDNA mutations have been identified.
    • mtDNA mutations may result from reactive oxygen species (ROS), affecting ATP production in dopaminergic neurons.
    • Cancer may be related to mtDNA mutations, but the relationship isn't fully understood yet.

    From Genes to Proteins

    • DNA carries the instructions to make proteins.
    • Transcription and translation are critical steps.
    • Proteins perform numerous cellular functions.

    Transcription

    • DNA acts as a template, creating an mRNA message.
    • The process is called transcription.
    • mRNA carries the information to the ribosomes.

    Initiation of Transcription – TFs

    • General transcription factors bind to the promoter region of DNA to initiate transcription correctly.
    • Transcription factors control the rate of transcription.
    • Hormones and messengers bind to, and activate, transcription factors.

    Initiation of Transcription – Other Regions

    • Enhancers and the TATA box further fine-tune transcription initiation efficiency.
    • The TATA box helps in locating RNA polymerase correctly.

    Chain Initiation

    • RNA polymerase begins attaching nucleotides to create an RNA molecule.
    • This process begins at the transcription start site.

    Chain Elongation

    • RNA polymerase synthesizes RNA in the 5' to 3' direction, according to the DNA template.

    Chain Termination

    • Special DNA sequences cause RNA polymerase to detach from the DNA molecule.

    Post-transcriptional Modification

    • Introns are removed from the initial RNA transcript, keeping only the exons coding for proteins.
    • mRNA splicing removes non-coding sequences.

    Translation

    • Amino acids are linked according to the mRNA codon sequence.
    • Ribosomes and transfer RNA (tRNA) facilitate amino acid attachment.

    Ribosomes

    • The site of protein synthesis.
    • Ribosomes are large RNA-protein complexes (rRNA + protein).
    • Ribosomes have 2 subunits, A and P sites, for amino acid binding and peptide bond formation.

    Transfer RNA (tRNA)

    • tRNA molecules carry amino acids to the ribosomes, based on the mRNA instructions.
    • tRNA contains an anticodon sequence.
    • Anticodon sequences are complementary to mRNA codons.

    The Triplet Code

    • Three bases (a codon) specify each amino acid.
    • The genetic code describes how codons relate to amino acids.

    Elongation of Peptide Chain

    • Subsequent amino acids are joined based on mRNA codons to extend the growing polypeptide chain.

    Termination of Translation

    • Termination of protein synthesis occurs after reaching specific stop codons.
    • Ribosomal subunits separate, releasing the polypeptide chain.

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    Description

    Test your knowledge on the essential concepts of genetics as they relate to nutritional biochemistry. This quiz covers topics including protein transport, DNA structure, and the mechanisms of diffusion and active transport. Challenge yourself with questions that will deepen your understanding of how genetic processes influence biochemistry.

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