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Essentials of Anatomy and PhysiologyEssentials of Anatomy and PhysiologyFifth editionFifth edition
Seeley, Stephens and TateSeeley, Stephens and Tate
Slide 2.1Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Chapter 3: Cell Structures and their Functions
Selective PermeabilitySelective Permeability
Slide 3.22Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Membrane permeability is ‘selective’
Some materials pass while others are excluded
Permeability includes movement into the cell and out of the cell
Cellular Physiology:Cellular Physiology:Membrane TransportMembrane Transport
Slide 3.20Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Membrane Transport – movement of substance into and out of the cell
Transport is by two basic methods Passive transport
No energy (ATP) is required
Active transport
The cell must provide ATP
Solutions and TransportSolutions and Transport
Slide 3.21Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Solution – homogeneous mixture of two or more components
Solvent – dissolving medium (fluid, usually water)
Solutes – components in smaller quantities within a solution (“dissolved particles”)
Solutions and TransportSolutions and Transport
Slide 3.21Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
In living systems:
Intracellular fluid – nucleoplasm and cytosol (cytoplasm)
Interstitial fluid – fluid on the exterior of the cell interstitial = “in spaces” or…
extracellular = “outside cells”
Passive Transport ProcessesPassive Transport Processes
Slide 3.23Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Diffusion Particles tend to distribute themselves
evenly within a solution Movement is
from high concentration to low concentration, or down a concentration gradient
Figure 3.8
Passive Transport ProcessesPassive Transport Processes
Slide 3.24aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Types of diffusion
Simple diffusion
Unassisted process
Solutes are lipid-soluble materials or small enough to pass through membrane pores
Passive Transport ProcessesPassive Transport Processes
Slide 3.24bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Types of diffusion, con’t.
Osmosis – simple diffusion of water
Highly polar water easily crosses
Movement of water depends on solute concentrations
“more concentrated” solutions attract water (“salt draws water”)
Passive Transport ProcessesPassive Transport Processes
Slide 3.24bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Types of diffusion, con’t.
Facilitated diffusion
Substances require a protein carrier for passive transport
Example: glucose movement into cells
Diffusion through the Plasma Diffusion through the Plasma MembraneMembrane
Slide 3.25Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.9
Passive Transport ProcessesPassive Transport Processes
Slide 3.26Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Filtration
Water and solutes are forced through a membrane by hydrostatic pressure
A pressure gradient must exist
Solute-containing fluid moves from a high pressure area to a lower pressure area
Active Transport ProcessesActive Transport Processes
Slide 3.27Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Moves substances that are unable to pass by diffusion because…
They may be too large
They may not be able to dissolve in the fat core of the membrane
They may have to move against a concentration gradient
Active Transport ProcessesActive Transport Processes
Slide 3.28aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Two types of active transport:
Solute pumping
Amino acids, some sugars and ions are transported
ATP moves substances against concentration gradients
Active Transport ProcessesActive Transport Processes
Slide 3.28bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.10
Active Transport ProcessesActive Transport Processes
Slide 3.29aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Bulk transport Exocytosis
Moves materials out of the cell
Material is carried in a membranous vesicle
Vesicle migrates to plasma membrane
Vesicle fuses with plasma membrane
Material is emptied to the outside
Active Transport ProcessesActive Transport Processes
Slide 3.29bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.11
Active Transport ProcessesActive Transport Processes
Slide 3.30aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Bulk transport
Endocytosis
Extracellular substances are engulfed by being enclosed in a membranous vesicle
Material is moved into the cell for “processing”
Active Transport ProcessesActive Transport Processes
Slide 3.30aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Types of endocytosis
Phagocytosis – cell eating
Pinocytosis – cell drinking
Active Transport ProcessesActive Transport Processes
Slide 3.30bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.12
Phagocytosis
Pinocytosis
Cell Life CycleCell Life Cycle
Slide 3.31Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cycle has two major periods
Interphase
Cell grows
Cell carries on metabolic processes
DNA replicates
Cell Life CycleCell Life Cycle
Slide 3.31Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cell Division
Cell replicates itself
Function is to produce more cells for growth and repair processes
Cell Life CycleCell Life Cycle
Slide 3.31Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Interphase
Longest phase
Averages 96% of cell life cycle
Cell “does” what it is specialized to do
Toward end, DNA replicates
Cell prepares for division
DNA ReplicationDNA Replication
Slide 3.32Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Genetic material duplicates
Occurs toward end of interphase
DNA uncoils, each strand serves as a template for a new strand
Requires enzymes and ATP
Figure 3.13
DNA ReplicationDNA Replication
Slide 3.32Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Utilizes stored nucleotides
From nucleolus
Enzymes are used to add complementary DNA nucleotides
A=T
C=G
Figure 3.13
DNA ReplicationDNA Replication
Slide 3.32Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Produces two identical strands of DNA
Half of each is from the “parent” strand
Half of each is “new” DNA
Called “semiconservative” replication
Figure 3.13
Events of Cell DivisionEvents of Cell Division
Slide 3.33Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Mitosis Division of the nuclear material
Results in the formation of two daughter nuclei Identical to parent nucleus
Identical to each other
Events of Cell DivisionEvents of Cell Division
Slide 3.33Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cytokinesis Division of the cytoplasm
Begins when mitosis is near completion
Results in the formation of two daughter cells
Stages of MitosisStages of Mitosis
Slide 3.34aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Interphase
No cell division occurs
The cell carries out normal metabolic activity and growth
Long, complex phase
Toward end, DNA replicates
Stages of Mitosis: InterphaseStages of Mitosis: Interphase
Slide 3.36aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.14; 1
Stages of MitosisStages of Mitosis
Slide 3.34aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Prophase
First part of cell division
Centrioles migrate to the poles
Nuclear membrane, nucleolus “disappear”
Chromosomes become visible
Stages of Mitosis: ProphaseStages of Mitosis: Prophase
Slide 3.36aCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.14; 1
Stages of MitosisStages of Mitosis
Slide 3.34bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Metaphase
Spindles attach to chromosomes
Chromosomes align around “equator” of the cell
Stages of Mitosis: MetaphaseStages of Mitosis: Metaphase
Slide 3.36bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.14; 2
Sister Chromatids
Stages of MitosisStages of Mitosis
Slide 3.35Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Anaphase
Daughter chromosomes are pulled toward the poles
By spindle fibers
The cell begins to elongate
Stages of Mitosis: AnaphaseStages of Mitosis: Anaphase
Slide 3.36bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.14; 2
Stages of MitosisStages of Mitosis
Slide 3.35Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Telophase
Daughter nuclei begin forming
A cleavage furrow (for cell division) begins to form
Stages of Mitosis: TelophaseStages of Mitosis: Telophase
Slide 3.36bCopyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 3.14; 2
Cell Life CycleCell Life Cycle
Slide 3.31Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Cytokinesis
Division of the cytoplasm and organelles
Functions to distribute material to new daughter cells
Each receives ~1/2 the “stuff”
Cell can now begin to grow and function