Cell Biology: Organelles and Processes
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Questions and Answers

What is the primary function of the cytoplasm?

  • Store genetic information
  • Facilitate metabolic reactions (correct)
  • Synthesize DNA
  • Control cell division

Which component of the nucleus is responsible for the synthesis of ribosomal RNA?

  • Nuclear Envelope
  • Nucleolus (correct)
  • Centrosome
  • Chromatin

What are microtubules primarily composed of?

  • Collagen
  • Actin
  • Myosin
  • Tubulin (correct)

Which part of the cytoskeleton is involved in cell movement and shape?

<p>Microfilaments (C)</p> Signup and view all the answers

What structure is responsible for organizing microtubules during cell division?

<p>Centrosome (D)</p> Signup and view all the answers

Which structure propels cells, such as sperm, through fluid?

<p>Flagella (D)</p> Signup and view all the answers

What is the role of the nuclear envelope?

<p>Separate the nucleus from the cytoplasm (C)</p> Signup and view all the answers

During cell division, chromatin condenses to form what structure?

<p>Chromosomes (D)</p> Signup and view all the answers

What is the primary function of ribosomes?

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

Which process is responsible for removing waste materials from the cell?

<p>Lysosome activity (D)</p> Signup and view all the answers

In which stage of mitosis do sister chromatids separate and move to opposite poles of the cell?

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

How does mitochondrial dysfunction affect cellular respiration?

<p>It leads to decreased ATP production. (C)</p> Signup and view all the answers

Why might the patient in the mitochondrial dysfunction case experience elevated lactic acid levels?

<p>Increased reliance on anaerobic glycolysis (D)</p> Signup and view all the answers

What is the role of cell cycle checkpoints in preventing cancer?

<p>To correct DNA damage before division (A)</p> Signup and view all the answers

How might mutations in genes regulating the G1 phase contribute to tumor growth?

<p>By enabling uncontrolled cell division (C)</p> Signup and view all the answers

Which of the following best describes mitochondrial myopathy?

<p>Characterized by energy deficits in muscle cells (A)</p> Signup and view all the answers

What is the primary function of microvilli in intestinal cells?

<p>Increasing the surface area for absorption (B)</p> Signup and view all the answers

Where does the Krebs cycle occur within the cell?

<p>In the mitochondria (C)</p> Signup and view all the answers

Which organelle is responsible for modifying, sorting, and packaging proteins?

<p>Golgi complex (D)</p> Signup and view all the answers

Which of the following processes produces ATP in the mitochondria?

<p>Cellular respiration (C)</p> Signup and view all the answers

Which structure is involved in detoxification and lipid synthesis?

<p>Smooth endoplasmic reticulum (A)</p> Signup and view all the answers

Which type of RNA is responsible for carrying amino acids to the ribosome?

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

What is the role of lysosomes in the cell?

<p>Digesting waste materials and recycling (B)</p> Signup and view all the answers

What serves as the final electron acceptor in the electron transport chain?

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

Which process involves the synthesis of mRNA from a DNA template?

<p>Transcription (D)</p> Signup and view all the answers

What is removed during mRNA processing?

<p>Introns (D)</p> Signup and view all the answers

In which phase do sister chromatids separate?

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

What is the primary outcome of meiosis?

<p>Reduction of chromosome number by half (C)</p> Signup and view all the answers

What is the main role of ribosomes in protein synthesis?

<p>Decoding mRNA (C)</p> Signup and view all the answers

Which of the following phases occurs before mitosis?

<p>All of the above (D)</p> Signup and view all the answers

What is a characteristic feature of apoptosis?

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

What type of cell division results in four genetically diverse cells?

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

Flashcards

What is the cytoplasm?

The gel-like substance within a cell, excluding the nucleus. It contains the cytosol, organelles, and various molecules. It serves as the site for many metabolic reactions and provides a medium for the organelles to remain suspended.

What is the nucleus?

The control center of the cell, containing the cell's DNA. It is enclosed by a double membrane called the nuclear envelope, which contains nuclear pores allowing the exchange of materials between the nucleus and the cytoplasm.

What is the nuclear envelope?

A double lipid bilayer that encloses the nucleus, separating it from the cytoplasm. It contains nuclear pores allowing the exchange of materials between the nucleus and the cytoplasm.

What is the nucleolus?

A dense region within the nucleus where ribosomal RNA (rRNA) is synthesized and ribosome assembly begins.

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What is chromatin?

A complex of DNA and proteins that condenses to form chromosomes during cell division.

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What is the cytoskeleton?

A network of protein fibers that provides structural support for the cell, enables movement, and facilitates intracellular transport.

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What are microfilaments?

The thinnest components of the cytoskeleton, composed of actin. They are involved in cell movement, shape, and division.

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What are microtubules?

Hollow tubes made of tubulin that maintain cell shape, allow intracellular transport, and are crucial during cell division as they form the mitotic spindle.

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What are microvilli?

Finger-like extensions of the plasma membrane that increase surface area for absorption, especially in the intestines.

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What are ribosomes?

The sites of protein synthesis, where mRNA is translated into polypeptide chains. They can be found floating freely in the cytoplasm or attached to the endoplasmic reticulum.

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What is the endoplasmic reticulum?

A network of membranes involved in the synthesis and modification of proteins, lipids, and steroids. It comes in two forms: rough and smooth.

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What is rough ER?

Studded with ribosomes, it synthesizes and modifies proteins destined for secretion or other cellular compartments.

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What is smooth ER?

Lacks ribosomes, it is involved in lipid synthesis, detoxification, and calcium storage.

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What is the Golgi complex?

A complex of flattened sacs involved in modifying, sorting, and packaging proteins and lipids for transport.

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What are lysosomes?

Membrane-bound organelles containing digestive enzymes that break down waste materials, cellular debris, and foreign substances.

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What are mitochondria?

The powerhouses of the cell, where ATP is produced through cellular respiration.

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What is transcription?

The process by which DNA is copied into mRNA. This happens in the nucleus of the cell.

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What is translation?

The process by which mRNA is converted into a protein. This happens in the ribosomes of the cell.

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What is the S phase?

The phase of the cell cycle where DNA is replicated. This ensures that each daughter cell receives a full set of chromosomes.

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What is mitosis?

Cell division that produces two identical daughter cells. This is how our bodies grow and repair themselves.

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What is apoptosis?

The tightly regulated process by which cells commit suicide, playing a role in development and removing damaged cells.

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What is meiosis?

Cell division that produces four daughter cells with half the chromosomes of the original cell. This is how sex cells are created.

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What is uncontrolled cell proliferation?

Cell division that is out of control, leading to the formation of tumors and ultimately cancer.

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What is interphase?

The part of the cell cycle where the cell grows and prepares for division. This is also where the bulk of the cell's activity occurs.

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What is the primary function of ribosomes?

Ribosomes are cellular organelles responsible for the synthesis of proteins, using messenger RNA (mRNA) as a template.

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What is the role of lysosomes in cellular function?

Lysosomes are membrane-bound organelles containing digestive enzymes that break down waste materials, cellular debris, and foreign substances.

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When do sister chromatids separate during mitosis?

Anaphase is the stage of mitosis where the sister chromatids, which are identical copies of a chromosome, separate and move towards opposite poles of the cell.

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How does mitochondrial dysfunction affect cellular respiration?

Mitochondrial dysfunction can disrupt the process of cellular respiration, leading to a decrease in ATP production. This may result in muscle weakness, fatigue, and exercise intolerance.

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Why might a patient with mitochondrial dysfunction have elevated lactic acid levels?

Elevated lactic acid levels may occur in individuals with mitochondrial dysfunction due to a dependence on anaerobic glycolysis for energy production. Anaerobic glycolysis is less efficient than aerobic respiration and produces lactic acid as a byproduct.

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What is the role of cell cycle checkpoints in preventing cancer?

Cell cycle checkpoints, particularly the G1 checkpoint, play a critical role in preventing uncontrolled cell proliferation, which can lead to cancer.

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How might mutations in genes regulating the G1 phase contribute to tumor growth?

Mutations in genes regulating the G1 phase of the cell cycle can disrupt the normal regulation of cell division. This can lead to uncontrolled cell growth and the development of tumors.

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What is the role of tumor suppressor genes and oncogenes in cell cycle regulation?

Tumor suppressor genes and oncogenes play opposing roles in regulating cell cycle progression. Tumor suppressor genes inhibit cell growth, while oncogenes promote it. Mutations in these genes can disrupt the balance, leading to uncontrolled proliferation.

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Study Notes

Organelles and Cellular Processes

  • Cells have essential organelles, crucial for function, replication, and response to the environment
  • Organelles include cytoplasm, nucleus, cytoskeleton, endoplasmic reticulum, Golgi complex, lysosomes, and mitochondria
  • These organelles facilitate key cellular processes: protein synthesis, DNA replication, and cell division

Cytoplasm

  • Cytoplasm is the gel-like substance, excluding the nucleus
  • Contains cytosol, organelles and various molecules
  • Site of metabolic reactions
  • Provides medium for organelle suspension

Nucleus

  • Nucleus is the cell's control center, housing the cell's DNA
  • Surrounded by a double membrane (nuclear envelope) with nuclear pores
  • Pores allow material exchange between nucleus and cytoplasm
  • Components include:
    • Nuclear Envelope: double lipid bilayer separating nucleus from cytoplasm
    • Nucleolus: dense region synthesizing ribosomal RNA (rRNA) and ribosome assembly
    • Chromatin: DNA and proteins that condense into chromosomes during cell division

Cytoskeleton

  • Provides structural support, enabling movement, and facilitating intracellular transport
  • Components include microfilaments (actin), involved in cell movement, shape, and division

Microtubules

  • Hollow tubes made of tubulin
  • Maintain cell shape, allow intracellular transport, and are crucial during cell division (mitotic spindle)

Centrosome

  • Organizes microtubules
  • Contains centrioles, key in organizing the mitotic spindle

Cilia and Flagella

  • Cilia: short, hair-like structures moving fluid or cells
  • Flagella: long, whip-like structures propelling cells

Microvilli

  • Finger-like extensions of plasma membrane
  • Increase surface area (absorption, particularly in intestinal cells)

Ribosomes and Endoplasmic Reticulum

  • Ribosomes: sites of protein synthesis (mRNA translation to polypeptides)
  • Found free in cytoplasm or attached to endoplasmic reticulum (ER)
  • Endoplasmic Reticulum (ER):
    • Rough ER: studded with ribosomes, modifies/synthesizes proteins for plasma membrane, lysosomes, or secretion
    • Smooth ER: lacks ribosomes, involved in lipid synthesis, detoxification, and calcium storage

Golgi Complex

  • Modifies, sorts, and packages proteins and lipids received from the ER
  • Transports them to different destinations within or outside the cell

Lysosomes and Mitochondria

  • Lysosomes: membrane-bound organelles
  • Contain digestive enzymes for waste material removal, cellular debris, foreign substances (cellular waste disposal and recycling)
  • Mitochondria: powerhouse of the cell
  • Produce ATP (adenosine triphosphate) through cellular respiration (glycolysis, Krebs cycle, electron transport chain)

Cellular Respiration

  • Glycolysis: first stage, breaks down glucose in cytoplasm, producing ATP and NADH
  • Krebs Cycle (citric acid cycle): occurs in mitochondria
  • Oxidizes acetyl-CoA, produces ATP, NADH, FADHâ‚‚, and releases COâ‚‚
  • Electron transport chain: inner mitochondrial membrane
  • Transfers electrons from NADH and FADHâ‚‚ to proteins, generating a proton gradient
  • Drives ATP synthesis, oxygen serves as final electron acceptor (forming water)

DNA, RNA, and Protein Synthesis

  • DNA (deoxyribonucleic acid): stores genetic information, guides protein synthesis and cell replication
  • RNA (ribonucleic acid): transmits genetic information from DNA to ribosomes for protein synthesis
  • mRNA (messenger RNA), tRNA (transfer RNA), rRNA (ribosomal RNA)
  • Protein Synthesis:
    • Transcription: mRNA synthesis from a DNA template in the nucleus.
    • mRNA processing: splicing, 5' cap, poly-A tail additions
    • Translation: ribosomes synthesize proteins by decoding mRNA

DNA Replication and Cell Division

  • DNA replication during S phase (cell cycle) ensures identical copies for daughter cells
  • Cell division:
    • Somatic cell division (mitosis): single cell to two identical daughter cells
      • Interphase: G1, S, G2 phases (cell growth, DNA synthesis, pre-division preparation)
      • Mitosis: prophase, metaphase, anaphase, telophase
    • Control of cell division regulated by checkpoints and signals
    • Necrosis (uncontrolled cell death from injury) and Apoptosis (programmede cell death)
    • Reproductive cell division (meiosis): half chromosome number in gametes (sperm/eggs)

Multiple Choice Questions (MCQs)

  • Mitochondria are responsible for ATP production
  • DNA replication occurs in the S phase

Clinical Cases

  • Mitochondrial dysfunction may lead to muscle weakness, fatigue, exercise intolerance, and elevated lactic acid levels

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Cell Organelles and Cellular Processes PDF

Description

Explore essential organelles within cells, including the cytoplasm and nucleus. Understand their functions in protein synthesis, DNA replication, and cell division. This quiz covers the key processes and components vital for cellular operations.

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