Transcript cell transport and mitosis notes

PowerPoint® Lecture Slide Presentation
by Patty Bostwick-Taylor,
Florence-Darlington Technical College
Cells and
Tissues
3
PART B
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
Cell Physiology: Membrane Transport
 Membrane transport—movement of substances
into and out of the cell
 Two methods of transport
 Passive transport
 No energy is required, uses kinetic energy
( bouncing particles)
 Active transport
 Cell must provide metabolic energy (ATP)
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Selective Permeability
 The plasma membrane allows some materials to
pass while excluding others
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Passive Transport Processes
 Diffusion
 Movement
from high
concentration
to low
concentration,
Till particles equally distributed
Figure 3.9
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Passive Transport Processes
 Types of diffusion
 Simple diffusion: gases
 Small enough particles to pass through
membrane pores
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Passive Transport Processes
 Types of diffusion (continued)
 Osmosis—simple diffusion of water
 Isotonic Solution: no movement of water,
Cell at Equilibrium: homeostasis
 Hypertonic Solution: solution outside of cell high
in solute, low in water. Water flow out of cell,
Cell Shrinks: Plasmolysis, ex dehydration
 Hypotonic Solution: solution outside of cell low in
solute( pure water) Water flows in to reach balance,
Too much- Cell Burst: Cytolysis ex: cut in bath
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Passive Transport Processes
 Facilitated diffusion
 Substances require a protein carrier for
passive transport
 Transports large substances
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Passive Transport Processes
Figure 3.10b–c
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Passive Transport Processes
 Filtration
 Water and solutes are forced through a
membrane by fluid, or hydrostatic pressure
 A pressure gradient must exist
 Solute-containing fluid is pushed from a
high-pressure area to a lower pressure area
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Active Transport Processes
 Substances may be too large
 Substances may not be able to dissolve in the
fat core of the membrane
 Substances may have to move against a
concentration gradient
 ATP is used for transport
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Active Transport Processes
 Two common forms of active transport
 Solute pumping
 Vesicular transport:
 Exocytosis
 Endocytosis
 Phagocytosis
 Pinocytosis
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Active Transport Processes
 Active transport (solute pumping)
 Amino acids, some sugars, and ions are
transported by protein carriers called solute
pumps
 ATP energizes protein carriers
 In most cases, substances are moved against
concentration gradients
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Active Transport Processes
 Vesicular transport
 Exocytosis
 Moves materials out of the cell
 Material is carried in a membranous
vesicle
 Material is emptied to the outside
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Active Transport Processes: Exocytosis
Figure 3.12b
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Active Transport Processes
 Vesicular transport (continued)
 Endocytosis
 Extracellular substances are engulfed by
being enclosed in a membranous vescicle
 Types of endocytosis
 Phagocytosis—“cell eating”
 Pinocytosis—“cell drinking”
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Cell Life Cycle
 Cells have two major periods
 Interphase
 Cell grows
 Cell carries on metabolic processes
 Cell division
 Cell replicates itself
 Function is to produce more cells for
growth and repair processes
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DNA Replication
 Genetic material is duplicated and readies a cell
for division into two cells
 Occurs toward the end of interphase
 DNA uncoils and each side serves as a template
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Events of Cell Division
 Mitosis—division of the nucleus
 Results in the formation of two daughter
nuclei
 Cytokinesis—division of the cytoplasm
 Begins when mitosis is near completion
 Results in the formation of two daughter cells
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Stages of Mitosis
 Prophase
 First part of cell division
 Centrioles migrate to the poles to direct
assembly of mitotic spindle fibers
 DNA appears as double-stranded
chromosomes
 Nuclear envelope breaks down and
disappears
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Stages of Mitosis
 Metaphase
 Chromosomes are aligned in the center of the
cell on the metaphase plate
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Stages of Mitosis
 Anaphase
 Chromosomes are pulled apart and toward the
opposite ends of the cell
 Cell begins to elongate
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Stages of Mitosis
 Telophase
 Chromosomes uncoil to become chromatin
 Nuclear envelope reforms around chromatin
 Spindles break down and disappear
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Stages of Mitosis
 Cytokinesis
 Begins during late anaphase and completes
during telophase
 A cleavage furrow forms to pinch the cells into
two parts
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Stages of Mitosis
Centrioles
Plasma
membrane
Centrioles
Chromatin Forming
mitotic
spindle
Nuclear
envelope
Nucleolus
Early prophase
Interphase
Spindle
Chromosome,
consisting of two
sister chromatids
Centromere
Spindle
microtubules
Fragments of
nuclear envelope
Centromere
Spindle
pole
Late prophase
Nucleolus
forming
Metaphase
plate
Cleavage
furrow
Sister
chromatids
Metaphase
Daughter
chromosomes
Anaphase
Nuclear
envelope
forming
Telophase and cytokinesis
Figure 3.15
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Stages of Mitosis
Spindle
Metaphase
plate
Sister
chromatids
Metaphase
Figure 3.15, step 4
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