Medical Biology Lecture 8 : Cell Structures and Function
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Questions and Answers

What type of protein makes up microfilaments?

  • Dynein
  • Actin (correct)
  • Keratin
  • Tubulin

Which cellular appendages are composed of specialized microtubules and covered by a specialized extension of the cellular membrane?

  • Intermediate filaments
  • Microfilaments
  • Cilia and flagella (correct)
  • Centrioles

What is the main function of actin filaments?

  • Maintaining the shape of the cell
  • Forming spindle fibers during cell division
  • Projecting from certain cells and shortening or extending (correct)
  • Assisting in the movement of chromosomes

What is the name of the protein that makes up microtubules?

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

Which structure is composed of 9 microtubules arranged in a very particular pattern?

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

What is the function of microtubules in cell division?

<p>Forming spindle fibers to assist in the movement of chromosomes (B)</p> Signup and view all the answers

What is the core of the structure termed in cilia and flagella?

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

Which type of cells contain a special organelle called a centriole?

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

What is the name for the arrangement where nine doublets oriented about two additional microtubules form cilia and flagella?

<p>(9+2) arrangement (C)</p> Signup and view all the answers

What is attached to a cell at a structure termed the basal body in eukaryotic cilia and flagella?

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

What are eukaryotic cilia and flagella composed of?

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

What plays a very important role in organizing the microtubules that position the chromosomes in the correct location during cell division?

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

Which organelle has a relatively simple phospholipid bilayer and contains protein structures called porins?

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

What is the primary function of the inter-membrane space in the mitochondria?

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

Which organelle is responsible for modifying proteins received from the rough endoplasmic reticulum (RER)?

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

Which organelle is involved in autophagy and the storage of nutrients such as lipids, proteins, and carbohydrates?

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

In which organelle are membranous sacs filled with enzymes produced by the Golgi apparatus found?

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

What is the main function of peroxisomes?

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

Which cellular organelle packages and sorts proteins and other molecules before sending them to their final destination?

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

What is the role of the cytoskeleton in a cell?

<p>Cell structure and support (A)</p> Signup and view all the answers

What does the inner membrane of mitochondria contain that aids in the production of ATP?

<p>Cristae that increase the surface area for ATP synthesis (A)</p> Signup and view all the answers

What is the main function of lysosomes within a cell?

<p>Digestion of complex molecules and recycling within the cell (D)</p> Signup and view all the answers

What is the main function of the cytoplasm in a cell?

<p>To hold together the organelles and provide a medium for metabolic reactions (A)</p> Signup and view all the answers

What is the composition of the cytoplasm?

<p>Cytosol, vesicles, inclusions, and organelles excluding the nucleus (B)</p> Signup and view all the answers

In a eukaryotic cell, where is the cytoplasm located?

<p>Between the cell membrane and the nuclear envelope (D)</p> Signup and view all the answers

Which organelle is described as 'the powerhouse of the cell'?

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

What is the size range of mitochondria?

<p>0.5 - 10μm (A)</p> Signup and view all the answers

Which component of the cytoplasm provides a medium for metabolic reactions to occur?

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

What percentage of water does the cytoplasm consist of?

<p>Up to 90% (D)</p> Signup and view all the answers

What is the protoplasm composed of in a eukaryotic cell?

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

What does the mitochondrion generate most of for the cell?

<p>Adenosine triphosphate (ATP) (A)</p> Signup and view all the answers

Flashcards

What is cytoplasm?

The jelly-like substance found within a cell, excluding the nucleus.

What are the main components of cytoplasm?

Water makes up the majority (up to 90%) of cytoplasm, along with cytosol, vesicles, cytoskeleton, inclusions, and organelles.

Where is cytoplasm located within a cell?

The region between the cell membrane and the nuclear envelope.

What are the main functions of cytoplasm?

It holds organelles together, provides nutrients for the cell, and serves as the medium for many metabolic reactions.

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What is a mitochondrion?

A double membrane-bound organelle responsible for generating most of the cell's ATP, the energy currency.

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Describe the size and shape of a mitochondrion.

Mitochondria are typically round to oval-shaped and range in size from 0.5 to 10 micrometers.

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Describe the structure of a mitochondrion.

A mitochondrion has an outer membrane, an inner membrane, an intermembrane space, and a matrix. The inner membrane forms folds called cristae, increasing surface area.

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What is the main function of mitochondria?

Mitochondria are responsible for oxidative phosphorylation, an essential process for ATP production.

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What is the endoplasmic reticulum?

A network of interconnected membranous sacs and tubules involved in protein synthesis, lipid synthesis, and detoxification.

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What are the two types of endoplasmic reticulum?

The endoplasmic reticulum is categorized into two types: rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).

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What are the functions of the rough endoplasmic reticulum (RER)?

The rough endoplasmic reticulum (RER) is studded with ribosomes and involved in protein synthesis, calcium storage, and signaling.

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What are the functions of the smooth endoplasmic reticulum (SER)?

The smooth endoplasmic reticulum (SER) lacks ribosomes and plays roles in lipid and steroid synthesis, detoxification, and steroid hormone production.

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What is the Golgi body?

A stack of slightly curved sacs called cisternae, responsible for packaging and sorting proteins and other molecules.

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What are the main functions of the Golgi body?

The Golgi body modifies proteins, transports lipids, and creates lysosomes.

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What types of molecules are processed by the Golgi body?

The Golgi body processes various molecules, including glycoproteins, lipids, and glucosaminoglycans.

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What are ribosomes?

Complex biological machines responsible for protein synthesis, the process of building proteins.

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Describe the structure of a ribosome.

A ribosome consists of two major components: a small ribosomal subunit and a large ribosomal subunit, each containing RNA molecules and proteins.

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What is a vacuole?

A membrane-bound organelle that stores water, nutrients, and waste products, and plays a role in separating metabolic processes.

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How do vacuoles contribute to waste removal?

Vacuoles can help remove waste products through a process called autophagy, where cell components are broken down and recycled.

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What are lysosomes?

Membranous sacs filled with digestive enzymes, responsible for breaking down complex molecules, recycling them for other uses, and removing harmful substances.

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What can happen if lysosomes lack certain enzymes?

Diseases like Tay-Sachs disease can occur when specific enzymes are missing from lysosomes, leading to an accumulation of certain substances.

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What are peroxisomes?

Small, membrane-enclosed organelles containing oxidative enzymes for various metabolic reactions, including detoxification.

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Where are peroxisomes particularly important?

Peroxisomes are particularly important in organs like the liver and kidneys, where they help detoxify various substances.

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What is the cytoskeleton?

A network of fibers that extends throughout the cytoplasm, providing structural support for the cell and acting as tracks for organelle movement.

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What are the main types of fibers in the cytoskeleton?

The cytoskeleton is categorized into three main types: microfilaments, intermediate filaments, and microtubules, each with distinct structures and functions.

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What are microfilaments and what are their functions?

Microfilaments, composed of actin protein, are involved in cell movement, muscle contraction, and cytokinesis.

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What are intermediate filaments and what are their functions?

Intermediate filaments, made of various proteins, provide structural support and help anchor organelles.

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What are microtubules and what are their functions?

Microtubules, composed of tubulin protein, act as tracks for motor proteins, help move organelles, and form the structure for cilia and flagella.

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Study Notes

  • College of Medicine Lecturer: Zahraa Ch. Hameed
  • Lecture: Medical Biology/ Lecture: 4, 5
  • Topic: Cell Structures and Function, specifically cytoplasm and organelles
  • Learning Objectives:
    • Students will learn the composition of the cell
    • Define the cell cytoplasm
    • Explain the types of cell organelles
    • Explain the Cytoskeleton of the cell
  • The Cytoplasm*
  • Jelly-like substance in the cell
  • Composition: up to 90% water, cytosol, vesicles, cytoskeleton, inclusions, and organelles excluding the nucleus
  • Located between the cell membrane and the nuclear envelope
  • Primary functions: holds organelles together, nourishes the cell, and provides a medium for metabolic reactions
  • Cellular Organelles*
  • Mitochondrion*
  • Double membrane-bound organelle
  • Generates most of the cell's supply of ATP
  • Sizes: 0.5 -10μm
  • Shape: round to oval
  • Structure: outer membrane, inner membrane, inter-membrane space, and matrix
  • Inner membrane has cristae for increased surface area
  • Cytoplasmic organelle for oxidative phosphorylation
  • Endoplasmic Reticulum*
  • Series of interconnected membranous sacs and tubules
  • Synthesizes and modifies proteins, lipids, and carbohydrates
  • Double membranes: rough ER (RER) and smooth ER (SER)
  • RER: performs protein synthesis, calcium storage, and signaling
  • SER: synthesizes and metabolizes lipids and steroids, detoxifies compounds, and creates steroid hormones
  • Golgi Body*
  • Stacks of slightly curved sacs (cisternae)
  • Packages and sorts proteins and other molecules
  • Modifies proteins, transports lipids, and creates lysosomes
  • Types of molecules processed: glycoproteins, lipids, and glucosaminoglycans
  • Ribosomes*
  • Complex biological machines for protein synthesis
  • Consists of two major components: small ribosomal subunit and large ribosomal subunit
  • Each subunit is composed of one or more ribosomal RNA molecules and a variety of ribosomal proteins
  • Vacuole*
  • Membrane-bound organelle
  • Stores water, nutrients, and waste products
  • Separates metabolic processes within the cell
  • Waste removal: autophagy
  • Lysosomes*
  • Membranous sacs filled with digestive enzymes
  • Digest complex molecules, recycle them for other uses, and remove harmful foreign substances
  • Diseases caused by missing enzymes: Tay-Sachs disease
  • Peroxisomes*
  • Small, membrane-enclosed cellular organelles
  • Contains oxidative enzymes for various metabolic reactions
  • Detoxifying organs: liver and kidneys
  • Cytoskeleton*
  • Network of fibers throughout the cell's cytoplasm
  • Maintains cell shape and acts as tracks for organelle movement
  • Divided into three categories: microfilaments, intermediate filaments, and microtubules.

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