Cell Biology Overview and Cell Theory
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Questions and Answers

What is the former name for cell biology?

Cytology

What is the term for the primary or essential substance containing a nucleus?

Protoplasm

What are the two basic plans of cellular organization?

  • Prokaryotes and Eukaryotes (correct)
  • Somatic cells and Gametes
  • Unicellular and Multicellular
  • Plant cells and Animal cells

Which of the following is NOT a characteristic of prokaryotes?

<p>Multiple linear chromosomes with histones (C)</p> Signup and view all the answers

Match the following cell structures with their primary function in the cell:

<p>Nucleus = Contains DNA and controls cellular activities Endoplasmic Reticulum = Modifies and packages proteins and lipids for export Mitochondria = Powerhouse of the cell, responsible for energy production Golgi Apparatus = Network of membranes involved in protein synthesis and lipid metabolism Lysosomes = Digests cellular waste and foreign material</p> Signup and view all the answers

Plant cells contain chloroplasts for photosynthesis.

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

Which of the following is NOT a component of the cell's outer membrane?

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

What is the main component of the plasma membrane and what is it composed of?

<p>The phospholipid bilayer. It is composed of two fatty acids, phosphoric acid, and glycerol.</p> Signup and view all the answers

Which type of transport requires energy?

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

Which of the following is NOT a type of passive transport?

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

What is the role of transmembrane proteins in facilitated diffusion?

<p>They act as carriers or create channels to help larger molecules pass through the membrane.</p> Signup and view all the answers

What type of transport is used to move large particles into the cell?

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

Pinocytosis is a type of endocytosis that involves the uptake of fluids.

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

Exocytosis is a process where materials are moved out of the cell.

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

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Flashcards

Cell Biology

The study of cells, their structure, function, interactions, division, and death.

Cell Theory

All living organisms are composed of cells, cells are the basic unit of structure and function in living organisms, and new cells arise from pre-existing cells.

Prokaryotes

Cells that lack a nucleus and other membrane-bound organelles, typically smaller and simpler than eukaryotes.

Eukaryotes

Cells that have a true nucleus enclosed within a membrane, as well as other membrane-bound organelles. These cells are typically larger and more complex than prokaryotes.

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Cell Membrane

A phospholipid bilayer that surrounds the cell, regulating the passage of molecules in and out.

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Cytoplasm

The fluid inside a cell, excluding the nucleus.

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Nucleus

The central organelle in eukaryotic cells that contains the genetic material (DNA).

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Endoplasmic Reticulum (ER)

A network of membranes within the cytoplasm of eukaryotic cells, involved in protein synthesis and lipid metabolism.

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Golgi Apparatus

A stack of flattened, membrane-bound sacs in eukaryotic cells that processes and packages proteins and lipids.

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Lysosomes

Small, spherical organelles in eukaryotic cells that contain enzymes for breaking down cellular waste and debris.

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Vacuoles

Large, fluid-filled sacs in eukaryotic cells that store water, nutrients, and waste products.

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Mitochondria

Organelles in eukaryotic cells that are responsible for the production of ATP (energy) through cellular respiration.

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Cytoskeleton

A network of protein filaments that provide structural support, facilitate movement, and transport materials within eukaryotic cells.

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Cell Wall

A rigid outer layer that provides structural support and protection for plant cells.

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Chloroplasts

Organelles in plant cells that are responsible for capturing light energy and converting it to chemical energy (photosynthesis).

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Passive Transport

The movement of molecules across a membrane from a region of high concentration to a region of low concentration, without requiring energy.

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Facilitated Diffusion

A type of passive transport that uses membrane proteins to facilitate the movement of molecules across a membrane.

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Active Transport

The movement of molecules across a membrane from a region of low concentration to a region of high concentration, requiring energy.

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Bulk Transport

The movement of large molecules, such as proteins and polysaccharides, into or out of a cell.

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Exocytosis

The process by which a cell releases materials from its interior to the exterior.

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Endocytosis

The process by which a cell takes in materials from its exterior.

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Pinocytosis

A type of endocytosis that involves the engulfment of fluids.

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Phagocytosis

A type of endocytosis that involves the engulfment of solid particles.

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Organelles

Specialized structures within eukaryotic cells that perform specific functions.

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Manufacturing in Cells

The process of manufacturing proteins, lipids, and other molecules within the cell, involving the nucleus, ribosomes, ER, and Golgi apparatus.

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Breakdown of Molecules

The process of breaking down molecules within the cell, such as waste products or internalized bacteria, involving lysosomes, vacuoles, and peroxisomes.

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Energy Processing

The process of generating energy for the cell, primarily through cellular respiration in mitochondria.

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Structural Support, Movement, and Communication

The maintenance of structural integrity, movement, and communication within the cell, involving the cytoskeleton and plasma membrane.

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Phospholipid Bilayer

The primary component of the cell membrane, composed of two layers of phospholipid molecules arranged with their hydrophilic heads facing the watery environment and their hydrophobic tails facing each other.

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Study Notes

Cell Biology

  • Cell biology, formerly called cytology, is a branch of biology.
  • It studies cells, their physiological properties, structure, interactions with their environment, division, function, and death.
  • This study is conducted at both the microscopic and molecular levels.

Cell Theory

  • Proposed by Matthias Schleiden, Theodor Schwann, and Rudolf Virchow.
  • All living things are made up of cells.
  • Cells are the basic units of structure and function in an organism.
  • New cells are produced from existing cells.
  • Schleiden (1838): All plants are made of cells.
  • Schwann (1839): All animals are made of cells.
  • Virchow (1855): All cells come from pre-existing cells.

Cellular Organization

  • Early studies described cells as consisting of protoplasm (essential substance) containing a nucleus and surrounded by a membrane (cell/plasma membrane).
  • The protoplasm surrounding the nucleus is called cytoplasm, and the nucleus's protoplasm is called nucleoplasm.
  • Electron microscopy (EM) revealed two fundamental cell types:
    • Prokaryotes (before nucleus): simpler, without a nuclear envelope or compartmentalization.
    • Eukaryotes (true nucleus): more complex, with a nuclear envelope and organelles.

Prokaryotes vs. Eukaryotes

Feature Prokaryote Eukaryote
Size of cell Typically 0.2-2.0 µm in diameter Typically 10-100 µm in diameter
Nucleus No nuclear membrane or nucleolus True nucleus with nuclear membrane and nucleolus
Organelles Absent Present; examples include lysosomes, Golgi complex, endoplasmic reticulum, mitochondria, and chloroplasts
Flagella Consist of two protein building blocks Complex; consists of multiple microtubules
Glycocalyx Present as a capsule or slime layer Present in some cells that lack a cell wall
Cell Wall Usually present; chemically complex; examples include peptidoglycan in bacterial cell walls, or cellulose or chitin in plants Usually present; chemically complex in plants, some protists, fungi
Plasma Membrane No carbohydrates and generally lacks sterols Sterols and carbohydrates that can serve as receptors
Cytoplasm No cytoskeleton or cytoplasmic streaming Cytoskeleton; cytoplasmic streaming
Ribosomes Smaller size (70S) Larger size (80S); smaller size (70S) in organelles
Chromosome (DNA) Usually single circular chromosome; typically lacks histones Multiple linear chromosomes with histones
Cell Division Binary fission Involves mitosis
Sexual Recombination None; transfer of DNA only Involves meiosis

Cell Structure and Functions

  • Specific cellular structures and functions*:
Structure Function
Nucleus DNA synthesis, RNA synthesis, assembly of ribosomal subunits; contains chromosomes and nucleolus
Ribosomes Protein synthesis
Rough ER Synthesis of membrane lipids and proteins; packaging of proteins in vesicles for transport
Smooth ER Lipid synthesis; detoxification in liver cells; calcium ion storage; modification and transport of macromolecules
Golgi apparatus Modification and transport of macromolecules; formation of lysosomes and transport vesicles
Lysosomes Digestion of ingested food, bacteria, damaged organelles, macromolecules; recycling materials
Vacuoles Digestion; storage of chemicals; cell enlargement; water balance
Peroxisomes Metabolic processes, breakdown of H2O2
Mitochondria Conversion of chemical energy of food to chemical energy of ATP
Chloroplasts Conversion of light energy to chemical energy of sugars

  • Cell support, movement, and communication*:

  • Cytoskeleton: maintains cell shape, anchors organelles, aids in movement, and transmits signals

  • Extracellular matrix: binding of cells in tissues, surface protection, and regulation of cellular activities

  • Cell junctions: cell communication and tissue integrity

  • Cell walls: maintenance of cell shape for structure and protection, and interaction between cells

Cell (Plasma) Membrane

  • Composed of a mix of proteins and lipids.
  • Lipids include phospholipids and cholesterol, forming a phospholipid bilayer.
  • Proteins include integral (penetrate the bilayer) and peripheral (on surfaces) proteins.
  • Carbohydrates (oligosaccharides) are attached to proteins (glycoproteins) or lipids (glycolipids), acting as receptors and recognition molecules.

Transport Across Membranes

  • The cell membrane regulates material exchange.
  • Passive Transport: Movement down a concentration gradient; includes diffusion (small molecules like CO2 and H2O), and facilitated diffusion (large molecules via transmembrane proteins).
  • Active Transport: Movement against a concentration gradient; requires energy and transmembrane proteins.
  • Bulk Transport: Movement of large particles; includes endocytosis (into cell—pinocytosis for fluids, phagocytosis for solids) and exocytosis (out of cell).

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Description

This quiz covers the essential concepts of cell biology, including its definition and historical context. It delves into cell theory, which highlights the foundational principles regarding the structure and function of cells. Additionally, it explores cellular organization and the composition of cells.

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