General Physiology: Cell Functions
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Questions and Answers

The basic living unit of the body is the tissue.

False (B)

The cell membrane is composed of proteins, lipids, and carbohydrates.

True (A)

The lipid layer of the cell membrane is impermeable to fat-soluble substances.

False (B)

Integral proteins provide structural integrity to the cell membrane.

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

The extracellular fluid is the fluid found inside the cell.

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

Channel proteins provide a route for diffusion of water-soluble substances like glucose and electrolytes.

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

The protein layers of the cell membrane are found only on one side of the lipid layer.

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

Receptor proteins serve as antigen sites for intermediate substances.

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

Glycocalyx is a thick and rigid covering over the cell membrane.

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

Carbohydrates make up 40% of the cell membrane composition.

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

Water-soluble materials can easily pass through the lipid layer of the cell membrane.

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

The cytoplasm contains a clear liquid portion called cytosol.

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

All organelles in the cytoplasm are bounded by a limiting membrane.

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

Some carbohydrate molecules form receptors for certain hormones.

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

Endoplasmic reticulum is made up of tubules and microsomal vesicles.

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

Carbohydrate molecules are positively charged and facilitate the movement of negatively charged substances.

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

The Golgi apparatus is present in all cells, including red blood cells.

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

The cis face of the Golgi apparatus is located near the cell membrane.

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

Lysosomes are filled with enzymes synthesized in the smooth endoplasmic reticulum.

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

Primary lysosomes are active lysosomes that can digest substances.

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

Lysosomes digest unwanted substances using enzymes like proteases and lipases.

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

Secondary lysosomes are formed by the fusion of primary lysosomes with phagosomes.

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

The Golgi apparatus functions like a post office by processing and packing substances.

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

All lysosomes have secretory functions.

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

Peroxisomes contain oxidative enzymes such as catalase and urate oxidase.

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

The mitochondrion is described as a cylindrical structure.

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

The centrosome consists of two structures called centrioles.

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

Secretory vesicles are formed solely in the mitochondrion.

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

Mitochondria are often referred to as the 'Power house of the cell'.

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

Peroxisomes participate in the formation of myelin and bile acids.

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

Cristae are folds found in the outer membrane of the mitochondrion.

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

Mitochondria are the only organelles that contain their own DNA.

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

Mitochondria are involved in apoptosis.

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

Ribosomes have a diameter of 25 nm.

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

Ribosomes are known as protein factories.

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

Free ribosomes synthesize enzymes and hormonal proteins.

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

Prokaryotic cells contain a nucleus.

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

The nucleus is covered by a double layered membrane.

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

Chromatin threads become chromosomes only after cell division.

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

Microtubules provide mechanical support to the cell.

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

The nucleolus contains RNA and some proteins similar to those found in ribosomes.

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

Necrosis is the programmed cell death controlled by genes.

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

Apoptosis is often referred to as 'cell suicide'.

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

In the context of cell death, necrosis is also referred to as 'cell suicide'.

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

The nucleus synthesizes RNA and sends genetic instructions to the cytoplasm.

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

Flashcards

Cell Membrane

A protective layer surrounding a cell, separating the inside (intracellular fluid) from the outside (extracellular fluid).

Extracellular Fluid (ECF)

The fluid outside a cell.

Intracellular Fluid (ICF)

The fluid inside a cell.

Semipermeable membrane

A membrane that allows some substances to pass through but not others.

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Lipid bilayer

Two layers of lipids forming the cell membrane.

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Phospholipids

A type of lipid found in the cell membrane.

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Integral Proteins

Proteins embedded within the cell membrane, providing structural support.

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Cell, basic unit

The fundamental living constituent of a body.

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Channel Proteins

Provide a pathway for water-soluble substances (glucose, electrolytes) to pass through the cell membrane.

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Carrier Proteins

Assist in the transport of substances across the cell membrane.

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Receptor Proteins

Bind to hormones and neurotransmitters, triggering cellular responses.

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Enzyme Proteins

Control chemical reactions within the cell membrane.

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Glycocalyx

A carbohydrate-rich layer over the cell membrane, acts as a protective coating.

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Cytosol

The liquid part of the cytoplasm.

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Organelles

Specialized structures within the cytoplasm, performing specific functions.

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Endoplasmic Reticulum

An organelle made of tubules and vesicles, involved in protein and lipid production.

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Nucleolus: What's its purpose?

The nucleolus is a structure within the nucleus responsible for creating ribosomes, the cellular machinery that builds proteins.

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Apoptosis: How does it work?

Apoptosis is a programmed cell death process where the cell self-destructs in a controlled manner, essential for development and removing damaged cells.

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Necrosis: What causes it?

Necrosis is uncontrolled cell death caused by external factors like injury or toxins, leading to cell damage and inflammation.

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Nucleus: What is its main role?

The nucleus is the control center of the cell, housing the genetic material (DNA) and directing all cellular activities.

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Ribosome Synthesis: Where does it happen?

Ribosomes are assembled within the nucleolus, using RNA and proteins.

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Endoplasmic Reticulum (ER)

A network of interconnected membranes within the cell, linking organelles and the cell membrane.

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Golgi Apparatus

Processes and packages proteins and lipids, sorting and delivering them to their destinations inside or outside the cell.

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Lysosome

A cell organelle containing digestive enzymes, breaking down waste materials and cellular debris.

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Primary Lysosome

Newly formed lysosome containing inactive digestive enzymes, awaiting fusion with another structure.

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Secondary Lysosome

Active lysosome formed by the fusion of a primary lysosome with other vesicles (like phagosomes or endosomes).

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Rough Endoplasmic Reticulum

ER studded with ribosomes; responsible for protein synthesis and modification

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Smooth Endoplasmic Reticulum

ER without ribosomes; involved in lipid synthesis, detoxification, etc.

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Functions of Lysosomes

Digestion of waste, removal of excess secretory products, and secretory functions (secretory lysosomes).

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Apoptosis

Programmed cell death, a controlled process where cells self-destruct.

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Mitochondrial role in Apoptosis

Mitochondria play a crucial role in apoptosis by releasing signaling molecules that trigger the breakdown of the cell.

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Ribosomes: Structure

Small granular structures containing RNA and proteins, responsible for protein synthesis.

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Ribosomes: Function

Ribosomes are the sites of protein synthesis, translating genetic information from mRNA into proteins.

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Free Ribosomes

Ribosomes not attached to the endoplasmic reticulum, responsible for synthesizing proteins for use within the cytosol or other organelles.

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Cytoskeleton: Function

A network of protein fibers that provides structural support, shape, and stability to the cell, enabling cellular movement and response to stimuli.

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Nucleus: Presence

A spherical structure containing the cell's DNA, found in eukaryotic cells, enabling cell division and enzyme synthesis.

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Nucleus: Structure

The nucleus is surrounded by a double-layered membrane called the nuclear membrane, which encloses the nucleoplasm.

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Peroxisome

A small, membrane-bound organelle containing oxidative enzymes that break down harmful substances like hydrogen peroxide.

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Peroxisome functions

Peroxisomes perform various essential tasks, including detoxification of harmful substances, oxygen utilization, fatty acid breakdown, and synthesis of certain molecules.

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Centrosome

A region near the nucleus of a cell that contains paired cylindrical structures called centrioles.

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Centriole function

Centrioles play a critical role in cell division by organizing microtubules that move chromosomes to opposite ends of the cell.

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Secretory Vesicles

Small, membrane-bound sacs that store and transport substances produced by the cell to be released outside the cell.

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Mitochondrion

A bean-shaped organelle with a double membrane, responsible for producing energy (ATP) for the cell through cellular respiration.

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Mitochondrial cristae

Folds in the inner membrane of the mitochondria that increase surface area for enzyme activity, crucial for ATP production.

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Mitochondrial DNA

DNA found within the mitochondria, distinct from nuclear DNA, responsible for some of the organelle's functions.

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Study Notes

General Physiology (Cell)

  • Physiology is the study of the functions of living organisms and their parts.
  • General physiology focuses on the fundamental processes of living cells.

Introduction

  • Cell: The basic structural and functional unit of the living body.
  • Tissue: A group of cells with similar function.
  • Organs: Structures formed by two or more primary tissues.
  • Systems: A group of organs working together to perform a specific function.

Cell

  • The basic living unit of the body.
  • Composed of a cell body and a cell membrane (plasma membrane).
  • Important cell parts include the cell membrane, cytoplasm and cell nucleus.

Cell Membrane

  • A protective sheath that surrounds the cell body.
  • Separates intracellular fluid (ICF) from extracellular fluid (ECF).
  • Semipermeable, allowing the exchange of certain substances between ECF and ICF.
  • Composed of proteins (55%), lipids (40%), and carbohydrates (5%).
  • Contains a lipid bilayer structure(phospholipids and cholesterol).
  • Semipermeable, allowing the exchange of fat-soluble substances (oxygen, carbon dioxide, alcohol), but not water-soluble substances (glucose, urea, electrolytes).
  • Contains various protein types (globular, alpha-helix, channel, integral, peripheral proteins).
  • Proteins in the membrane form glycoproteins, allowing tight cell fixation.
  • Carbohydrates form a thin layer called glycocalyx (pericellular matrix).
  • Glycoproteins & glycolipids act as cell receptors for hormones.
  • Negatively charged carbohydrates prevent negatively charged substances from entering/exiting.

Cytoplasm

  • The fluid inside the cell.
  • Contains cytosol (clear liquid) and various substances (proteins, carbohydrates, lipids, electrolytes).
  • Also contains organelles (with and without membranes).

Organelles in Cytoplasm

  • With Limiting membrane: Endoplasmic Reticulum, Golgi Apparatus, Lysosomes, Peroxisomes, Centrosome & Centriole, Secretory Vesicles, Mitochondrion.
  • Without Limiting membrane: Ribosomes, Cytoskeleton.

Endoplasmic Reticulum

  • Interconnected network of tubules and vesicles.
  • Acts as a link between organelles and cell membrane.
  • Two types: rough (studded with ribosomes) and smooth (no ribosomes).

Golgi Apparatus

  • Located near the nucleus.
  • Consists of both cis face (near endoplasmic reticulum) and trans face (near the cell membrane).
  • Functions like a post office — processing, packaging, and delivering substances (proteins and lipids) to different parts of the cell or outside the cell.
  • Also functions as a cell's shipping department - sorting and labeling materials.

Lysosomes

  • Small globular structures filled with enzymes (hydrolytic enzymes like proteases, lipases, amylases, and nucleases).
  • Digest and remove unwanted substances.
  • Involved in removing excess secretory products.
  • Responsible for secretory functions in immune cells.
  •  Two types: Primary (inactive) and secondary (active).

Peroxisomes

  • Pinched off from endoplasmic reticulum.
  • Contain oxidative enzymes (catalase, urate oxidase, D-amino acid oxidase).
  • Important for detoxification and breaking down excess fatty acids and other substances
  • Crucial for gluconeogenesis (synthesis of glucose)
  • Involved in the formation of myelin and bile.
  • Sometimes known as micro bodies.

Centrosome & Centriole

  • Located near the nucleus.
  • Composed of two centrioles.
  • Important for chromosome movement during cell division.

Secretory Vesicles

  • Globular structures.
  • Formed in the endoplasmic reticulum and processed in the Golgi apparatus.
  • Release secretory substances into the cytoplasm when needed.
  • These substances can be processed, sorted, packaged, and transported elsewhere.

Mitochondrion

  • Rod-shaped structure with a double membrane.
  • Inner membrane has folds called cristae.
  • Site of ATP production (energy production through oxidative phosphorylation).
  • Contains its own DNA.

Ribosomes

  • Small granular structures (15 nm).
  • Located on rough endoplasmic reticulum or free in the cytoplasm.
  • Made up of proteins (35%) and RNA (65%).
  • Sites for protein synthesis.

Cytoskeleton

  • Complex network of protein fibers.
  • Gives the cell shape, support, and stability.
  • Plays a role in cell movements and responses to external stimuli.
  • Composed of microtubules, microfilaments, and intermediate filaments.

Cell Nucleus

  • Spherical structure near the cell center.
  • Eukaryotic cells contain a nucleus; prokaryotic cells do not.
  • Enclosed by a double-layered membrane (nuclear envelope), containing pores.
  • Contains nucleoplasm, chromatin, nucleolus.
  • The chromatin threads become rod-shaped chromosomes during cell division.
  • Contains the RNA and proteins.
  • Site for genetic control and synthesis of RNA.
  • Involved in cell division and protein synthesis.

Cell Death

  • Two main types: Apoptosis and Necrosis
  • Apoptosis: Programmed cell death under genetic control. This is a normal process, helpful for development. It's often called cell suicide because genes of the cell are involved.
  • Necrosis: Uncontrolled and unprogrammed cell death due to external or internal damage such as injury, toxins, and infection. It's often called cell murder because the cell is killed externally. Uncontrolled death. Chemical substances from dead cells cause damage to neighboring tissues.

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Explore the fundamentals of cell physiology, including the structure and functions of cells, tissues, organs, and systems. This quiz covers essential concepts of living cells, their components, and the role of the cell membrane. Test your understanding of the basics of physiology.

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