Cell Biology: Nucleus and Chromatin
10 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

What is the primary characteristic of heterochromatin?

  • It is typically found in the nucleolus.
  • It consists of coiled chromatin with inactive genes. (correct)
  • It is associated with active gene expression.
  • It is always located at the cell membrane.
  • Which structure is primarily responsible for the formation of rRNA?

  • Nuclear sap
  • Chromatin islets
  • Peripheral chromatin
  • Nucleolus (correct)
  • Which of the following is NOT a function of the nucleus?

  • Carries genetic information
  • Manufactures proteins (correct)
  • Forms three types of RNA
  • Controls cell division
  • In the electron microscopy of the nucleolus, which area contains mature rRNA?

    <p>Pars granulosa</p> Signup and view all the answers

    What is the composition of the nuclear sap (nucleoplasm)?

    <p>Jelly-like substance with nucleoproteins, enzymes, and metabolites</p> Signup and view all the answers

    What is the typical number of nuclei in most cells?

    <p>Usually mononucleated</p> Signup and view all the answers

    What is the appearance of euchromatin in the nucleus?

    <p>Pale and extended</p> Signup and view all the answers

    Which component of the nucleus is responsible for the formation of nuclear pores?

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

    Which of the following statements about the nuclear envelope is true?

    <p>It is composed of an outer and an inner membrane</p> Signup and view all the answers

    Which shape is NOT associated with the nucleus?

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

    Study Notes

    Heterochromatin

    • Dark staining, inactive chromatin.
    • Tightly coiled with inactive genes.
    • Types:
      • Peripheral chromatin: Attached to the inner nuclear membrane.
      • Chromatin islets.
      • Nucleolus associated chromatin: Attached to the nucleolus.

    Nucleolus

    • Darkly basophilic mass within the nucleus when viewed under light microscopy.
    • Under electron microscopy, shows a dark area with:
      • Pars amorpha: Contains filaments of DNA.
      • Pars fibrosa: Newly formed rRNA.
      • Pars granulosa: Mature rRNA.
    • Also contains a light area called the nucleolar sap.
    • Functions in the formation of rRNA.

    Nuclear Sap (Nucleoplasm)

    • Jelly-like, amorphous substance.
    • Fills spaces between chromatin.
    • Composed of nucleoproteins, enzymes, and metabolites.
    • Provides a medium for the transport of RNA and nucleoproteins.

    Functions of the Nucleus

    • Controls all vital functions of the cell.
    • Controls cell division.
    • Carries genetic information (heredity).
    • Forms the three types of RNA.

    Nucleus under Light Microscopy (LM)

    • Stains basophilic due to the presence of DNA.
    • Appearance can be pale or vesicular (active) or dark (less active).
    • Usually, cells have one nucleus (mononucleated), but some can have two (binucleated) or many (multinucleated).
    • Shape can be rounded, oval, flat, bilobed, or lobulated.
    • Location can be central, eccentric, basal, or peripheral.

    Nucleus under Electron Microscopy (EM)

    • Nuclear Envelope:

      • Outer membrane: Ribosomes attached to it, continuous with the rough endoplasmic reticulum (rER).
      • Inner membrane: Attached to peripheral chromatin.
      • Perinuclear space: Located between the inner and outer membranes.
      • Nuclear pores: Where the inner and outer membranes fuse. Composed of octagonal rings formed of nucleoporins. Filaments extending into the cytoplasm and nucleus.
    • Nuclear Chromatin (DNA):

      • Euchromatin: Pale staining, active. Extended chromatin with active genes.

    Studying That Suits You

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

    Quiz Team

    Description

    Explore the intricate details of the nucleus, heterochromatin, and nucleolus through this quiz. Learn about the structural components and functions associated with the nucleus, including its role in controlling cell functions and genetic information. Perfect for students of cell biology and genetics.

    More Like This

    Nucleus Structure, Function, and Mitosis Quiz
    10 questions
    Nucleus Structure in Eukaryotic Cell
    16 questions
    Cell Biology: Nucleus and DNA Structure
    40 questions
    Use Quizgecko on...
    Browser
    Browser