Cell Biology Quiz
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Questions and Answers

Microfilaments are primarily composed of myosin subunits.

False (B)

Cilia and flagella both have a 9+2 arrangement of microtubules.

True (A)

Ribosomes are composed of equal parts RNA and protein.

False (B)

Fixed ribosomes are responsible for synthesizing soluble proteins that remain in the cytoplasm.

<p>False (B)</p> Signup and view all the answers

The nucleus is responsible for the majority of cell functions.

<p>False (B)</p> Signup and view all the answers

Cytosol makes up approximately 70% of the cell volume.

<p>True (A)</p> Signup and view all the answers

The sedimentation coefficient of ribosomes is 70S.

<p>True (A)</p> Signup and view all the answers

Microvilli contain clusters of actin filaments that are not cross-linked to each other.

<p>False (B)</p> Signup and view all the answers

The cytoplasm's aqueous component is made up of 90% water and 10% macromolecules.

<p>False (B)</p> Signup and view all the answers

Cytogel is the liquid form of cytoplasm.

<p>False (B)</p> Signup and view all the answers

Centrioles are involved in the direct formation of the mitotic spindle in a 9+0 array.

<p>True (A)</p> Signup and view all the answers

ATP provides energy for the movement of microvilli.

<p>False (B)</p> Signup and view all the answers

Zone A of the cytoplasm contains the centrioles and centrosphere.

<p>True (A)</p> Signup and view all the answers

Zone B of the cytoplasm is primarily gelated.

<p>False (B)</p> Signup and view all the answers

Ectoplasm is the term used to describe the interior liquid of the cell.

<p>False (B)</p> Signup and view all the answers

The composition of cytosol includes RNA.

<p>True (A)</p> Signup and view all the answers

The inner membrane of the mitochondria contains enzymes for the Krebs cycle and cholesterol metabolism.

<p>False (B)</p> Signup and view all the answers

Under aerobic conditions, glycolysis and the citric acid cycle can produce 36 molecules of ATP per mole of glucose.

<p>True (A)</p> Signup and view all the answers

The rough endoplasmic reticulum is associated with protein synthesis and has ribosomes on its surface.

<p>True (A)</p> Signup and view all the answers

The smooth endoplasmic reticulum has ribosomes that are important for the synthesis of proteins.

<p>False (B)</p> Signup and view all the answers

During post-translational modification, the signal-recognition particle enhances the elongation of polypeptides.

<p>False (B)</p> Signup and view all the answers

Decarboxylation reactions in the citric acid cycle produce CO2 and H atoms, which are ultimately converted to water.

<p>True (A)</p> Signup and view all the answers

Cytochromes b, c, c1, a, and a3 are part of the electron transport system located in the outer membrane of the mitochondria.

<p>False (B)</p> Signup and view all the answers

Granular or rough endoplasmic reticulum is associated with storage and transport of lipids.

<p>False (B)</p> Signup and view all the answers

The rough endoplasmic reticulum participates in the contraction process in muscle cells.

<p>True (A)</p> Signup and view all the answers

Smooth endoplasmic reticulum is primarily found in muscle cells.

<p>False (B)</p> Signup and view all the answers

The Golgi apparatus is responsible for the detoxification of substances.

<p>False (B)</p> Signup and view all the answers

Lysosomes contain hydrolytic enzymes and are involved in the degradation of cellular components.

<p>True (A)</p> Signup and view all the answers

During interphase, chromatin adjacent to centromeres is associated with fibrous lamina.

<p>True (A)</p> Signup and view all the answers

Lysosomes maintain a low pH due to the presence of proton pumps in their membranes.

<p>False (B)</p> Signup and view all the answers

The Golgi apparatus modifies and concentrates proteins before transport.

<p>True (A)</p> Signup and view all the answers

Euchromatin is more electron-dense than heterochromatin.

<p>False (B)</p> Signup and view all the answers

Glycoconjugates are finished by adding remaining sugars in lysosomes.

<p>False (B)</p> Signup and view all the answers

Chromatin consists mainly of coiled strands of RNA bound to basic proteins.

<p>False (B)</p> Signup and view all the answers

Heterochromatin is associated with a more inactive metabolic state than euchromatin.

<p>False (B)</p> Signup and view all the answers

The nuclear envelope is usually continuous with the smooth endoplasmic reticulum.

<p>False (B)</p> Signup and view all the answers

Nuclear pores are approximately 70nm in size and are bridged by an electron-dense membrane.

<p>True (A)</p> Signup and view all the answers

The fibrous lamina is composed of three main proteins known as lamins.

<p>True (A)</p> Signup and view all the answers

The size of the nucleolus is directly unrelated to the synthetic activity of the cell.

<p>False (B)</p> Signup and view all the answers

Nucleoli may fuse to form a single nucleolus as the cell progresses through the cell cycle.

<p>True (A)</p> Signup and view all the answers

The human genome contains 5 pairs of chromosomes that do not include nucleolar organizer.

<p>False (B)</p> Signup and view all the answers

The Pars fibrosa consists of primary transcripts of rRNA genes.

<p>True (A)</p> Signup and view all the answers

Active ribosomes are found in the nucleolus during protein synthesis.

<p>False (B)</p> Signup and view all the answers

Nucleoli are prominent in nerve and Sertoli cells due to their metabolic activity.

<p>True (A)</p> Signup and view all the answers

Lamellar bodies in cells contain proteins for immediate cellular functions.

<p>False (B)</p> Signup and view all the answers

Glycogen granules are visible as dark 15-30 nm wide granules in electron microscopy.

<p>True (A)</p> Signup and view all the answers

Negri bodies are a type of lipid droplet found in the cytoplasm.

<p>False (B)</p> Signup and view all the answers

The nucleolus is primarily composed of proteins and metabolites.

<p>False (B)</p> Signup and view all the answers

Flashcards

Cytoplasm

The gel-like substance that fills the space between the cell membrane and the nucleus, containing various organelles and molecules.

Cytoskeleton

A network of protein filaments that provides structural support, helps with cell movement, and facilitates transport within the cell.

Microfilaments

Thin protein filaments primarily composed of actin that play a role in cell shape, movement, and muscle contraction.

Intermediate filaments

Fibrous proteins that provide mechanical support, maintain cell shape, and help anchor organelles.

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Thick filaments

Thick protein filaments composed of myosin subunits, mainly found in muscle cells and involved in muscle contraction.

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Microtubules

Hollow tubes made of tubulin subunits that provide structural support, facilitate transport, and form components like cilia and flagella.

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Centrioles

Barrel-shaped structures composed of microtubules, involved in cell division by organizing microtubules to form the mitotic spindle.

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Ribosomes

Small, non-membranous organelles responsible for protein synthesis.

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Multicellularity

The state of being composed of multiple cells, forming a complex organism.

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Cell Specialization

Cells developing unique structures and functions to perform specific tasks in a multicellular organism.

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Cytosol

The fluid portion of the cytoplasm, primarily water with dissolved molecules, salts, and enzymes.

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Organelles

Specialized structures within the cytoplasm that perform specific functions for the cell, such as energy production or protein synthesis.

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Nucleus/Cytoplasmic Ratio

The ratio of the volume of the nucleus to the volume of the cytoplasm. It varies based on cell type and activity.

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Cytocentrum

A region in the cytoplasm that contains centrioles and centrosphere, often surrounded by Golgi apparatus. It's involved in cell division.

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Rough ER Function

It aids in protein synthesis and participates in muscle cell contraction as the sarcoplasmic reticulum.

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Smooth ER Duty

It's involved in detoxification of harmful substances by oxidation, conjugation, and methylation processes, especially in liver cells.

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Golgi Apparatus Function

It packages and ships proteins, renews the cell membrane, and modifies and concentrates products for release.

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What are Glycoconjugates?

Secretory products that have sugars added using glycosyltransferases, found in cartilage and mucus.

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Lysosomes Role

They are membrane-bound organelles containing hydrolytic enzymes responsible for breaking down cellular waste and debris.

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Lysosomes Characteristics

They are dense, membrane-bound bodies containing acid phosphatase and urate oxidase, and are numerous in cells with high turnover or phagocytosis.

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What is the Nucleus?

The control center of the cell, containing genetic material, the nucleolus, and the nuclear matrix, with an outer membrane.

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Nucleus Membrane Connection

The outer membrane of the nucleus is continuous with the rough endoplasmic reticulum, and the inner membrane connects with the fibrous lamina.

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Fibrous Lamina

A protein structure located on the inner membrane of the nuclear envelope, composed of three main proteins called lamins that form part of the nuclear matrix.

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Chromatin Association

During interphase, the chromatin adjacent to centromeres of chromosomes is associated with the Fibrous Lamina.

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Nuclear Pore

A channel through the nuclear envelope, about 70nm in diameter, bridged by a dense membrane.

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Chromatin Types

There are two main types of chromatin: Euchromatin and Heterochromatin.

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Heterochromatin

Electron-dense and appears as coarse granules in the electron microscope. It seems to represent the more inactive metabolic state.

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Euchromatin

Visible as an organized structure only in the electron microscope. It is more active in the synthesis of RNA.

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Nucleolus

A spherical structure within the nucleus, involved in the synthesis of ribosomes. Its size is directly related to the synthetic activity of the cell.

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Nucleolar Organizer DNA

Regions of DNA within the nucleolus that code for ribosomal RNA.

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Pars fibrosa

The densely packed, fibrous region of the nucleolus where primary transcripts of rRNA genes are found. Represents rRNA being transcribed from DNA.

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Pars granulosa

The granular region of the nucleolus where maturing ribosomes are found. It is characterized by 15-20 nm granules.

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What is the relationship between the nucleolus and ribosomes?

The nucleolus is the site of rRNA synthesis and ribosome assembly. Ribosomal subunits are exported from the nucleus to the cytoplasm, where they mature and become functional.

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What are inclusion bodies?

Non-living, non-participating, poorly structured cell elements, usually found within the cytoplasm. They are often the result of metabolic activity or cellular processes.

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Examples of inclusion bodies

Inclusion bodies can include fat droplets, glycogen granules, pigments, crystals, viral capsids, and intracellular parasites. They can be either benign or pathogenic.

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What are the characteristics of inclusion bodies?

Inclusion bodies are non-motile, non-living structures. They are usually found in the cytoplasm, but may rarely be seen in the nucleus. They may represent stored food, byproducts of metabolism, or accumulated substances that cannot be broken down.

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What is the significance of inclusion bodies?

Inclusion bodies can provide clues about cellular activity and health. They can indicate the presence of metabolic disorders, infections, or other cellular stress.

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Mitochondrial Matrix

The inner space of mitochondria, containing enzymes for the Krebs cycle and fatty acid beta-oxidation, as well as rounded, dense granules rich in calcium and magnesium.

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Inner Mitochondrial Membrane

The inner membrane of mitochondria, housing cytochromes involved in electron transport, F1 ATPase for oxidative phosphorylation, and certain dehydrogenases.

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Acetyl-CoA in Mitochondria

Acetyl-CoA, generated outside the mitochondria, enters the organelle and combines with oxaloacetate to initiate the citric acid cycle.

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Citric Acid Cycle (Krebs Cycle)

A metabolic pathway within the mitochondrial matrix that involves a series of reactions to oxidize acetyl-CoA, releasing CO2 and generating electron carriers for energy production.

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Electron Transport Chain

A series of protein complexes embedded in the inner mitochondrial membrane that use electron carriers to generate a proton gradient, ultimately driving ATP synthesis.

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ATP Production in Mitochondria

The process of generating ATP from ADP and phosphate, utilizing the energy released during electron transport.

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Aerobic Respiration

The complete breakdown of glucose in the presence of oxygen, generating 36 ATP molecules per molecule of glucose by combining glycolysis, the citric acid cycle and electron transport.

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Rough Endoplasmic Reticulum (rER)

A network of interconnected membranes studded with ribosomes, involved in protein synthesis and the segregation of proteins destined for export or intracellular use.

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Smooth Endoplasmic Reticulum (sER)

A network of interconnected membranes that lacks ribosomes, involved in lipid synthesis and detoxification processes.

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Signal-Recognition Particle (SRP)

A protein complex that recognizes and binds to a signal sequence on a newly synthesized polypeptide, pausing translation until it docks with the endoplasmic reticulum.

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Docking Protein

A protein on the endoplasmic reticulum membrane that binds to the SRP-ribosome complex, initiating the delivery and translocation of the polypeptide into the lumen of the ER.

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Post-Translational Modification

Changes made to a polypeptide after its translation, including folding, glycosylation, and signal sequence cleavage, to ensure proper function.

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Polyribosomes

Groups of ribosomes attached to an mRNA molecule, translating the same mRNA to synthesize multiple copies of a protein.

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Protein Synthesis Begins on Polyribosomes

All protein synthesis starts on polyribosomes, which then associate with the endoplasmic reticulum to facilitate the segregation of proteins for export or intracellular use.

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Study Notes

Cell Cytoplasm & Nucleus

  • Objectives: Students will gain thorough knowledge of cell multicellularity, specialization, cytoplasm composition, cytoplasmic zones, membrane-bound organelles, non-membrane-bound organelles, the cell nucleus and its components, and applied/clinical anatomy.

Introduction

  • The hallmark of multicellular life is diverse cellular types working together for development, physiological responses, and reproduction of the whole organism.
  • Eukaryotic cells evolved from prokaryotic cells following multicellularity and specialization.

Cell

  • The cytoplasm carries out most cell functions, depending on the nucleus for guidance and renewal.
  • The nucleus-to-cytoplasm ratio commonly falls within a range of 1:3 to 1:5.

Cytoplasm (I)

  • Cytoplasm fills the cell as a homogeneous, clear, jelly-like material.
  • It's primarily cytosol (~70% of cell volume) and organelles (except the nucleus).
  • Cytosol is composed of water, salts, organic molecules, enzymes, and a significant amount of RNA.
  • Hyaloplasm is another name for the watery component of the cytoplasm.

Cytoplasm (II)

  • Cytoplasm's watery component can vary between gel-like and liquid based on cell conditions and activity stages.
  • Cytogel is the gel-like state (viscid solid), and cytosol is the liquid state.
  • Typically, the cell's margins are more gel-like, while the interior is predominantly liquid.

Zones of Cytoplasm (I)

  • Zone A (Cytocentrum): Contains centrioles, centrosphere, potentially bounded by microtubules, and often surrounded by the Golgi apparatus.

Zones of Cytoplasm (II)

  • Zone B (Endoplasm): Most organelles are located here. Cytoplasmic streaming occurs, rapidly moving organelles.
  • Zone C (Ectoplasm): Gel-like. Capable of rapid sol-gel transformation; rich in microfilaments.

Cell Organelles

  • Cytoplasm includes cytosol and organelles (both membrane-bound and non-membrane-bound).

Non-membranous Organelles

  • Cytoskeleton:
    • Composed of microfilaments (actin), intermediate filaments, thick filaments (myosin), and microtubules (tubulin).
    • Provides support and facilitates movement of cell structures/materials.
  • Centrioles: Involved in direct formation of the mitotic spindle. Arranged in a 9+0 configuration from microtubules.
  • Ribosomes:
    • Composed of 60% RNA and 40% proteins.
    • Sedimentation coefficient of 70S. ~20 x 30 nm.
    • Can dissociate into large (50S) and small (30S) subunits.
    • Can be free or fixed, with fixed ribosomes often attached to rough ER. Free ribosomes build proteins for the cytoplasm & nucleus.
  • Cilia, Flagella, Stereocilia: All contain specialized arrangements of microtubules in a 9+2 array, and are involved in cell movement.
    • Microvilli: 1 µm long and 0.08 µm wide. Centrioles: 0.3 to 0.5 µm length, 0.15 µm wide; Cilia: 5 to 10 µm length, 0.2 µm wide; Flagella: 100 µm long; Stereocilia: longer than microvilli; not mobile

Mitochondria

  • 0.5-1 µm wide; up to 10 µm in length.
  • Accumulation in areas of high metabolic activity (e.g., cells with active transport).
  • Functions: Transform chemical energy from metabolites into usable energy for the cell;
  • Number: varies with cell's requirement; Mature RBCs lack mitochondria; rely on glycolysis for energy.
  • Composition: Primarily proteins, some lipids, DNA/RNA;
  • Membranes: Double membrane with inner layer folds (cristae) for increased surface area containing oxidative phosphorylation enzymes and e− transport systems. Cristae have increased density in high metabolic rate cells.
  • Matrix: Contains enzymes for Krebs Cycle and fatty acid β-oxidation and rounded e-dense granules rich in Ca and Mg.
  • Permeability: Outer membrane is relatively permeable; inner membrane is more selective.
  • Function: The major site of energy production for the cell that yields ATP from cellular respiration.

Smooth & Rough ER

  • Rough ER: Has ribosomes, associated with protein synthesis.
  • Smooth ER: Lacks ribosomes, associated with lipid synthesis, detoxification, and other metabolic functions in specific cells.

Golgi Apparatus

  • Concentrates, modifies, and packages secretory products for transport to the cell membrane or for intracellular use.
  • Completes formation of glycoconjugates (like the addition of sugars).

Lysosomes

  • Round, single-membrane-bound structures.
  • Contain hydrolytic enzymes to break down waste materials in the cell (e.g. digestion).
  • Involved in cellular digestion and recycling of material.

Nucleus

  • Shape: Variable (round, elongated).
  • Location: Variable, typically central.
  • Size: Variable, 5-10 µm.
  • Function: Contains genetic material (DNA) and controls cellular activities.
  • Components: Nuclear envelope, chromatin, nucleolus, nucleoplasm/nuclear matrix.
  • Nuclear envelope: Two parallel membranes separated by a perinuclear cisterna (40-70 nm).
  • Chromatin: Composed primarily of coiled DNA strands bound to basic proteins (histones). Euchromatin is more active than heterochromatin, where heterochromatin represents a more inactive metabolic state, while euchromatin is involved in RNA synthesis.
  • Nucleolus: Involved in ribosome synthesis; Size is related to synthetic activity of the cell.

Nuclear Matrix

  • Fills the space between chromatin and nucleoli.
  • Composed mainly of proteins, metabolites, ions, and fibrous lamina.

Cell Inclusions

  • Small non-living compartments; don't participate actively in cell metabolism.
  • Usually cytoplasmic and include various substances like fats, glycogen, pigments, and crystals.
  • May represent stored food or by-products, not vital for immediate life processes but can be built up in vacuoles.

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Cell Cytoplasm and Cell Nucleus ANA 215 PDF

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Test your knowledge on cell structures, their functions, and components with this quiz. Explore topics like ribosomes, microfilaments, and the cytoplasm’s properties. Perfect for students studying cell biology and related fields.

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