Med238 Cytogenetics Chapter 3
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Questions and Answers

What is the primary function of DNA Polymerase I?

  • To unwind the DNA double helix
  • To add nucleotides in the 5’ - 3’ direction
  • To synthesize new DNA strands
  • To remove RNA primers and fill gaps with DNA (correct)

    • Which process converts RNA into amino acids?

  • Transcription
  • Translation (correct)
  • Transformation
  • Replication

    • What role does helicase play in DNA replication?

  • It adds nucleotides to the growing DNA strand
  • It synthesizes RNA molecules
  • It unwinds the double strand of DNA (correct)
  • It seals nicks in the DNA backbone

    • Which type of RNA carries genetic information needed for protein synthesis?

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

    What is the function of DNA ligase in DNA replication?

    <p>To seal nicks in the DNA</p> Signup and view all the answers

    Which statement about topoisomerase is true?

    <p>It relieves torsional strain during DNA replication</p> Signup and view all the answers

    Which component is responsible for maintaining the separation of DNA strands during replication?

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

    What is the direction of nucleotide addition by DNA Polymerase III during DNA replication?

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

    What is the primary role of RNA primase in DNA replication?

    <p>It synthesizes short RNA sequences to act as primers.</p> Signup and view all the answers

    During DNA replication, which direction is the leading strand synthesized?

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

    What are Okazaki fragments?

    <p>Segments of DNA synthesized on the lagging strand.</p> Signup and view all the answers

    Which enzyme is responsible for adding nucleotides to the growing DNA strand during replication?

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

    How is DNA read during transcription?

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

    What is the significance of nicks in the DNA strand?

    <p>They are gaps or breaks that can affect replication.</p> Signup and view all the answers

    What are codons and their function in mRNA?

    <p>They are groups of three nucleotides that code for amino acids.</p> Signup and view all the answers

    Which process describes the flow of genetic information from DNA to RNA?

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

    What is the main purpose of post-translational modification?

    <p>To give the protein its final functional form</p> Signup and view all the answers

    What does the term apoptosis refer to?

    <p>Programmed cell death</p> Signup and view all the answers

    Which statement correctly describes the process of translation?

    <p>It involves ribosomes synthesizing specific proteins from mRNA.</p> Signup and view all the answers

    What is an anticodon?

    <p>A three-nucleotide sequence on tRNA complementary to a codon on mRNA</p> Signup and view all the answers

    Who was the first scientist to discover cells and their structure?

    <p>Robert Hooke</p> Signup and view all the answers

    How many different tRNAs are typically found in each cell?

    <p>Approximately 20 or more</p> Signup and view all the answers

    What is the approximate number of human cells in the body?

    <p>30 trillion</p> Signup and view all the answers

    Which type of cell is most abundant in the human body?

    <p>Red blood cells</p> Signup and view all the answers

    What is the primary role of transfer RNA (tRNA) in protein synthesis?

    <p>Transports amino acids to ribosomes</p> Signup and view all the answers

    Which statement correctly describes the role of ribosomal RNA (rRNA)?

    <p>It is the most abundant type of RNA.</p> Signup and view all the answers

    What happens at the 3 prime end of transfer RNA (tRNA)?

    <p>Amino acid is attached.</p> Signup and view all the answers

    Which of the following best describes the process of transcription termination?

    <p>It is triggered when polymerase encounters a stop signal.</p> Signup and view all the answers

    During the base pairing process in RNA synthesis, which nucleotide aligns with adenine (A)?

    <p>Uracil (U)</p> Signup and view all the answers

    What is the result of the conversion of heterogeneous nuclear RNA (hnRNA) to mature messenger RNA (mRNA)?

    <p>Exons are joined together.</p> Signup and view all the answers

    What shape does transfer RNA (tRNA) typically take?

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

    What role does RNA polymerase play in the synthesis of hnRNA?

    <p>Links ribonucleotides to the growing strand.</p> Signup and view all the answers

    What is the primary composition of the glycocalyx?

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

    Which of the following describes the plasma membrane?

    <p>It serves as a selective barrier.</p> Signup and view all the answers

    What role do membrane proteins play?

    <p>They facilitate transport and signaling functions.</p> Signup and view all the answers

    What characterizes the structure of a phospholipid?

    <p>It has two hydrophobic tails and one hydrophilic head.</p> Signup and view all the answers

    Where are ribosomes typically found?

    <p>Free-floating in the cytoplasm or attached to rough endoplasmic reticulum.</p> Signup and view all the answers

    What function does cholesterol serve in the plasma membrane?

    <p>It restricts movement and modulates fluidity.</p> Signup and view all the answers

    What is the primary role of ribosomes?

    <p>To synthesize proteins from amino acids.</p> Signup and view all the answers

    What is the main function of the endoplasmic reticulum?

    <p>To synthesize proteins and lipids.</p> Signup and view all the answers

    What characteristic of membrane proteins is crucial for function?

    <p>Their specific amino acid sequences.</p> Signup and view all the answers

    Which component is NOT part of the plasma membrane's structure?

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

    Study Notes

    Central Dogma

    • Systematic flow of genetic material from generation to generation; crucial for gene expression.
    • Francis Crick identified DNA as the genetic material.
    • Nucleotides, the building blocks of DNA, consist of a sugar, nitrogen base, and phosphate group.

    RNA Primase and DNA Replication

    • RNA primase synthesizes short RNA primers, initiating DNA replication.
    • Leading strand synthesized continuously; lagging strand formed in short Okazaki segments separated by nicks.

    DNA Polymerases

    • DNA Polymerase III forms phosphodiester linkages between nucleotides, elongating DNA strands in a 5' to 3' direction.
    • It has a 3' to 5' exonuclease activity, correcting mismatched nucleotides.
    • DNA Polymerase I removes RNA primers and replaces them with DNA.
    • DNA Ligase seals nicks in the DNA strand.

    Transcription

    • DNA serves as a template to produce RNA in the nucleus, resulting in mRNA.
    • mRNA contains codons that code for specific amino acids.
    • Transcription involves unwinding a DNA segment, aligning free nucleotides, and using RNA polymerase to create hnRNA, where Uracil (U) replaces Thymine (T).

    Post-Transcriptional Modifications

    • hnRNA is converted to mRNA, removing introns and splicing exons, which code for proteins.
    • Post-translational modifications give proteins a functional form.

    Apoptosis

    • Programmed cell death to regulate cell numbers, remove excess tissue, and eliminate damaged or potentially cancerous cells.

    Translation

    • The process of synthesizing proteins based on the mRNA codons.
    • tRNA carries specific amino acids, with each tRNA molecule possessing an anticodon complementary to mRNA codons.

    Cell Structures and Functions

    • Cells are the fundamental unit of life, with approximately 30 trillion human cells, including 80% red blood cells.
    • Glycocalyx, made up of carbohydrates, acts as a cell recognition and adhesion layer.

    Plasma Membrane

    • The plasma membrane is a selective barrier that regulates material passage.
    • Composed of phospholipids (amphipathic) with hydrophilic heads and hydrophobic tails.
    • Membrane proteins serve for recognition and signaling functions; cholesterol modulates membrane fluidity.

    Ribosomes

    • Ribosomes synthesize proteins by assembling polypeptides from amino acids based on mRNA sequences.
    • Can be free-floating or attached to the rough endoplasmic reticulum.

    Endoplasmic Reticulum

    • Rough Endoplasmic Reticulum consists of membranous tubules and sacs with attached ribosomes, responsible for synthesizing proteins and lipids.

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    Description

    This quiz covers Chapter 3 of the Med238 Cytogenetics course, focusing on the Central Dogma of molecular biology and the role of RNA primase in DNA replication. Test your knowledge of genetic material flow and the enzymes involved in replication processes.

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