A Tour of the Cell
Overview
The Importance of Cells
• All organisms are made of cells
• The cell is the simplest collection of matter that can live
• Cell structure is correlated to cellular function
The Importance of Cells
• All organisms are made of cells
• The cell is the simplest collection of matter that can live
• Cell structure is correlated to cellular function
• Two types of cells make up every organism
– Prokaryotic
– Eukaryotic
Comparing Prokaryotic and Eukaryotic Cells
• All cells have several basic features in common
– They are bounded by a plasma membrane
– They contain a semifluid substance called the cytosol
– They contain chromosomes
– They all have ribosomes
• Prokaryotic cells
– Do not contain a nucleus
– Have their DNA located in a region called the nucleoid
– Prokaryotic
– Eukaryotic
Comparing Prokaryotic and Eukaryotic Cells
• All cells have several basic features in common
– They are bounded by a plasma membrane
– They contain a semifluid substance called the cytosol
– They contain chromosomes
– They all have ribosomes
• Prokaryotic cells
– Do not contain a nucleus
– Have their DNA located in a region called the nucleoid
• Eukaryotic cells
– Contain a true nucleus, bounded by a membranous nuclear envelope
– Are generally quite a bit bigger than prokaryotic cells
• The logistics of carrying out cellular metabolism sets limits on the size of cells
• A smaller cell has a higher surface to volume ratio, which facilitates the exchange of materials into and out of the cell
– Contain a true nucleus, bounded by a membranous nuclear envelope
– Are generally quite a bit bigger than prokaryotic cells
• The logistics of carrying out cellular metabolism sets limits on the size of cells
• A smaller cell has a higher surface to volume ratio, which facilitates the exchange of materials into and out of the cell
• The plasma membrane
– Functions as a selective barrier
– Allows sufficient passage of nutrients and waste
– Functions as a selective barrier
– Allows sufficient passage of nutrients and waste
A Panoramic View of the Eukaryotic Cell
Eukaryotic cells have extensive and elaborately arranged internal membranes, which form organelles
An animal cell
A plant cell
The Nucleus: Genetic Library of the Cell
• The nucleus contains most of the genes in the eukaryotic cell
• The nuclear envelope encloses the nucleus, separating its contents from the cytoplasm
• The nucleus contains most of the genes in the eukaryotic cell
• The nuclear envelope encloses the nucleus, separating its contents from the cytoplasm
Ribosomes: Protein Factories in the Cell
• Ribosomes are particles made of ribosomal RNA and protein and carry out protein synthesis
• Ribosomes are particles made of ribosomal RNA and protein and carry out protein synthesis
The endomembrane system regulates protein traffic and performs metabolic functions in the cell
• The endomembrane system includes many different structures
The Endoplasmic Reticulum: Biosynthetic Factory
• The endoplasmic reticulum (ER) accounts for more than half the total membrane in many eukaryotic cells
• The ER membrane is continuous with the nuclear envelope
• The endomembrane system includes many different structures
The Endoplasmic Reticulum: Biosynthetic Factory
• The endoplasmic reticulum (ER) accounts for more than half the total membrane in many eukaryotic cells
• The ER membrane is continuous with the nuclear envelope
• There are two distinct regions of ER
– Smooth ER, which lacks ribosomes
– Rough ER, which contains ribosomes
Functions of Smooth ER
• The smooth ER
– Synthesizes lipids
– Metabolizes carbohydrates
– Stores calcium
– Detoxifies poison
Functions of Rough ER
• The rough ER
– Has bound ribosomes
– Produces proteins and membranes, which are distributed by transport vesicles
The Golgi Apparatus: Shipping and Receiving Center
• The Golgi apparatus
– Receives many of the transport vesicles produced in the rough ER
– Consists of flattened membranous sacs called cisternae
• Functions of the Golgi apparatus include
– Modification of the products of the rough ER
– Manufacture of certain macromolecules
• Functions of the Golgi apparatus
– Smooth ER, which lacks ribosomes
– Rough ER, which contains ribosomes
Functions of Smooth ER
• The smooth ER
– Synthesizes lipids
– Metabolizes carbohydrates
– Stores calcium
– Detoxifies poison
Functions of Rough ER
• The rough ER
– Has bound ribosomes
– Produces proteins and membranes, which are distributed by transport vesicles
The Golgi Apparatus: Shipping and Receiving Center
• The Golgi apparatus
– Receives many of the transport vesicles produced in the rough ER
– Consists of flattened membranous sacs called cisternae
• Functions of the Golgi apparatus include
– Modification of the products of the rough ER
– Manufacture of certain macromolecules
• Functions of the Golgi apparatus
Lysosomes: Digestive Compartments
• A lysosome is a membranous sac of hydrolytic enzymes that can digest all kinds of macromolecules
• Lysosomes carry out intracellular digestion by Phagocytosis
• A lysosome is a membranous sac of hydrolytic enzymes that can digest all kinds of macromolecules
• Lysosomes carry out intracellular digestion by Phagocytosis
Autophagy
The Endomembrane System:
• The endomembrane system is a complex and dynamic player in the cell’s compartmental organization
• Relationships among organelles of the endomembrane system
• The endomembrane system is a complex and dynamic player in the cell’s compartmental organization
• Relationships among organelles of the endomembrane system
• Mitochondria change energy from one form to another
• Mitochondria are the sites of cellular respiration
Mitochondria: Chemical Energy Conversion
• Mitochondria are found in nearly all eukaryotic cells
• Mitochondria are enclosed by two membranes
– A smooth outer membrane
– An inner membrane folded into cristae
• Mitochondria are the sites of cellular respiration
Mitochondria: Chemical Energy Conversion
• Mitochondria are found in nearly all eukaryotic cells
• Mitochondria are enclosed by two membranes
– A smooth outer membrane
– An inner membrane folded into cristae
Peroxisomes: Oxidation
• Peroxisomes produce hydrogen peroxide and convert it to water
• Peroxisomes produce hydrogen peroxide and convert it to water
• The cytoskeleton is a network of fibers that organizes structures and activities in the cell
• The cytoskeleton is a network of fibers extending throughout the cytoplasm
• The cytoskeleton is a network of fibers extending throughout the cytoplasm
Roles of the Cytoskeleton: Support, Motility, and Regulation
• The cytoskeleton
– Gives mechanical support to the cell
– Is involved in cell motility, which utilizes motor proteins
• The cytoskeleton
– Gives mechanical support to the cell
– Is involved in cell motility, which utilizes motor proteins
Components of cytoskeleton
• There are three main types of fibers that make up the cytoskeleton
• There are three main types of fibers that make up the cytoskeleton
Microtubules
• Microtubules
– Shape the cell
– Guide movement of organelles
– Help separate the chromosome copies in dividing cells
Centrosomes and Centrioles
• The centrosome
– Is considered to be a “microtubule-organizing center”
– Contains a pair of centrioles
• Microtubules
– Shape the cell
– Guide movement of organelles
– Help separate the chromosome copies in dividing cells
Centrosomes and Centrioles
• The centrosome
– Is considered to be a “microtubule-organizing center”
– Contains a pair of centrioles
Cilia and Flagella
• Cilia and flagella
– Contain specialized arrangements of microtubules
– Are locomotor appendages of some cells
• Flagella beating pattern
• Cilia and flagella
– Contain specialized arrangements of microtubules
– Are locomotor appendages of some cells
• Flagella beating pattern
• Ciliary motion
• Cilia and flagella share a common ultrastructure
• The protein dynein is responsible for the bending movement of cilia and flagella
Microfilaments (Actin Filaments)
• Microfilaments are built from molecules of the protein actin and can be found in microvilli
• Microfilaments are built from molecules of the protein actin and can be found in microvilli
• Microfilaments that function in cellular motility contain the protein myosin in addition to actin
• Amoeboid movement involves the contraction of actin and myosin filaments
• Cytoplasmic streaming is another form of locomotion created by microfilaments
Intermediate Filaments
• Intermediate filaments
– Support cell shape
– Fix organelles in place
The Extracellular Matrix (ECM) of Animal Cells
• Animal cells
– Lack cell walls
– Are covered by an elaborate matrix, the ECM
• The ECM is made up of glycoproteins and other macromolecules
• Intermediate filaments
– Support cell shape
– Fix organelles in place
The Extracellular Matrix (ECM) of Animal Cells
• Animal cells
– Lack cell walls
– Are covered by an elaborate matrix, the ECM
• The ECM is made up of glycoproteins and other macromolecules
Cell Transport
Download HERE
the_cell_2.ppt | |
File Size: | 3351 kb |
File Type: | ppt |