Cell Theory and Historical Perspectives

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Questions and Answers

What structural feature is characteristic of prokaryotic cells?

Presence of a true nucleus

Multiple organelles

Single chromosome in nucleoid (correct)

Absence of a cell membrane

Which factor does NOT affect cell shape?

Viscosity of the cytoplasm

Surface tension

Amount of genetic material (correct)

Elasticity of the membrane

What is the size range of prokaryotic cells as mentioned in the content?

10 to 100 μm

100 to 1000 μm

0.1 to 1 μm

1 to 10 μm (correct)

What is the ideal shape for an isolated cell to maximize surface area?

Spherical Signup and view all the answers

Which type of cell is considered the smallest in size?

Mycoplasma Signup and view all the answers

What distinguishes eukaryotic cells from prokaryotic cells regarding their nuclear structure?

Eukaryotic cells have a membrane-bound nucleus Signup and view all the answers

Which component is NOT typically found in eukaryotic cells?

Chloroplasts (in absence of photosynthesis) Signup and view all the answers

What is the primary function of the plasma membrane in eukaryotic cells?

Regulates the traffic of materials into and out of the cell Signup and view all the answers

What term did Robert Hooke use to describe the structures he observed in cork?

Cells Signup and view all the answers

How does the structure of eukaryotic ribosomes compare to prokaryotic ribosomes?

Eukaryotic ribosomes are larger than prokaryotic ribosomes Signup and view all the answers

Which scientist is known for perfecting the construction of the compound microscope?

Anton van Leeuwenhoek Signup and view all the answers

What did Rudolf Virchow conclude about cells in 1858?

Cells come only from pre-existing cells. Signup and view all the answers

What is the significance of the fluid-mosaic model of the plasma membrane?

It illustrates the dynamic arrangement of lipids and proteins Signup and view all the answers

Which structure is unique to eukaryotic cells and absent in prokaryotic cells?

Mitochondria Signup and view all the answers

The cell theory established by Schleiden and Schwann includes which of the following statements?

All organisms are composed of cells. Signup and view all the answers

What is the role of microvilli in eukaryotic cells?

To enhance surface area for absorption Signup and view all the answers

What substance did Felix Dujardin identify within cells?

Protoplasm Signup and view all the answers

Which of the following statements about eukaryotic and prokaryotic cells is true?

Only eukaryotic cells can form multicellular organisms Signup and view all the answers

Which advancement in microscopy was made by Max Knoll and Ernst Ruska?

Creation of the first transmission electron microscope Signup and view all the answers

James Watson and Francis Crick are primarily known for their discovery regarding what?

Structure of DNA Signup and view all the answers

What major concept is included in the cell theory concerning the capability of cells?

Cells are capable of self-modification. Signup and view all the answers

What is the primary function of the sap vacuole in plant cells?

To store resources and maintain turgor pressure Signup and view all the answers

Which statement correctly describes a contractile vacuole?

It expels excess water and waste from unicellular organisms Signup and view all the answers

What is the protoplasm?

The living material of the cell that exhibits properties and activities of life Signup and view all the answers

Which of the following accurately describes the cytoplasm?

It is the most active region of the cell, containing organelles and inclusions Signup and view all the answers

Which structure is responsible for protein synthesis?

Ribosome Signup and view all the answers

What is the role of protein channels in the cell membrane?

To allow the passage of molecules along a concentration gradient Signup and view all the answers

Which characteristic of protoplasm helps it change from sol to gel?

Its colloidal nature Signup and view all the answers

What is one of the physical properties of protoplasm?

Viscous and may vary in form Signup and view all the answers

What does the cell wall primarily do in plant cells?

Support and protect the cell Signup and view all the answers

Which of these structures is specifically involved in cellular reproduction?

Nucleus Signup and view all the answers

What is the primary function of the Rough Endoplasmic Reticulum?

Transport and protein synthesis Signup and view all the answers

What role do Lysosomes play in the cell?

Intracellular digestion Signup and view all the answers

Which structure is primarily associated with the process of photosynthesis?

Chloroplast Signup and view all the answers

What is the main function of the Golgi Apparatus?

Protein synthesis and secretion Signup and view all the answers

What is the composition of the Cytoskeleton?

Microtubules and microfilaments Signup and view all the answers

Which structure is specifically involved in the process of cellular respiration?

Mitochondrion Signup and view all the answers

What is the role of the Thylakoid in chloroplasts?

Light energy trapping Signup and view all the answers

What is true about Vacuoles and vesicles?

They store substances. Signup and view all the answers

Study Notes

Historical Background of Cell Theory

Robert Hooke (1665) observed cells in cork and coined the term "cells" due to their resemblance to monastery rooms.
Anton van Leeuwenhoek (1674) improved microscopes and discovered protozoa and red blood cells, calling microscopic life "animalcules."
Robert Brown (1831) identified the nucleus and described cytoplasmic streaming, known as Brownian movement.
Felix Dujardin (1835) demonstrated that cells contain protoplasm, a thick fluid.
Matthias Schleiden (1838) announced that plants are made of cells, initiating the plant cell theory.
Theodore Schwann (1839) proposed that animals are also composed of cells, contributing to the animal cell theory.
Rudolf Virchow (1858) stated that all cells arise from pre-existing cells, solidifying cell theory principles.
Max Knoll and Ernst Ruska (1932) developed the first transmission electron microscope.
James Watson and Francis Crick (1953) elucidated DNA structure, marking a pivotal moment in molecular biology.

Cell Theory

All organisms consist of cells; cells are the fundamental structural and functional units.
Cells have self-modifying capabilities and originate only from existing cells.

Types of Cells

Prokaryotic Cells

Lack a true nucleus, typical of bacteria; size ranges from 1 to 10 μm.
Contain cell wall, plasma membrane, ribosomes, thylakoids, enzymes, and a nucleoid with a single chromosome.

Eukaryotic Cells

Possess a true nucleus; characteristic of protists, fungi, plants, and animals.
Comprise plasma membrane, cytoplasm, and a distinct nucleus; organelles are compartmentalized.

Cell Size & Shape

Mycoplasma is the smallest known cell at 0.0001 mm; giraffe nerve cells can reach 3.0 m in length.
Human cells vary, with red blood cells measuring 0.00076 mm and liver cells being larger.
Common cell measurement unit is the micrometer (μm), equal to 1 x 10^-6 meters.
Smaller cells have a higher surface area-to-volume ratio, impacting efficiency.
Cell shape influences function; for example, elongated muscle cells allow contraction, while concave blood cells facilitate oxygen distribution.

Plasma Membrane

Composed of a phospholipid bilayer with proteins in a fluid-mosaic model.
Functions to provide structural support, protection, and regulate material traffic between the cell interior and environment.

Modification of the Plasma Membrane

Microvilli increase surface area for absorption.
Glycocalyx acts as a carbohydrate-protein or carbohydrate-lipid complex for cell interactions.
Plant cells have a thick cell wall for added support and rigidity.

Water Movement Pathways

Apoplast Pathway: Water moves through spaces between cells and cell walls.
Symplast Pathway: Water circulates from cytoplasm to cytoplasm through plasmodesmata.

Vacuoles in Cells

Sap Vacuole in plants stores resources and maintains turgor pressure.
Contractile Vacuole in protists expels excess water and waste products.
Food Vacuole in protozoans facilitates digestion of consumed materials.

Protoplasm

The living material of the cell that showcases life's properties and activities.

Physical Properties of Protoplasm

Colloidal and heterogeneous solution; resistant to gravity due to small particle size.
Exhibits viscosity and can transition between sol and gel states.
Characterized by transparency and various configurations (reticular, granular, etc.).

Cytoplasm

Multi-functional cell content external to the nucleus; contains proteins, carbohydrates, and lipids.
The site of numerous biochemical reactions involving organelles and cellular inclusions.

Cell Structures and Functions

Cell Wall: Composed of cellulose; provides support and protection (plant cells only).
Plasma Membrane: Phospholipid bilayer for molecular transit in and out of the cell.
Nucleus: Contains genetic material for reproduction and protein synthesis regulation.
Nucleolus: Area for ribosome production.
Ribosome: Protein synthesis units made of protein and RNA.

Membrane Proteins and Organelles

Protein Channels: Facilitate the movement of molecules across the membrane.
Carrier Proteins: Transport substances across membranes in both directions.
Endoplasmic Reticulum (ER): Site for protein and lipid synthesis, distinguished into rough (with ribosomes) and smooth (without ribosomes).
Golgi Apparatus: Processes and packages proteins for secretion.
Lysosomes: Intracellular digestion via digestive enzymes.
Mitochondria: Cellular respiration powerhouse with inner membrane cristae.
Chloroplasts: Site of photosynthesis in plant cells, containing thylakoids and grana for light reactions.

Structural Components

Cilia and Flagella: Microtubule arrangements for cell movement.
Cytoskeleton: Composed of microtubules and microfilaments; provides cell shape and facilitates movement.

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Description

Explore the foundational aspects of cell theory and its historical background, featuring key figures like Robert Hooke and Anton van Leeuwenhoek. Understand how their discoveries have shaped our understanding of cells and microscopy. This quiz will cover significant milestones in cellular biology and the evolution of scientific thought regarding microscopic life.