Download Cells Are Classified by Internal Organization Cell Structure Reflects

Chapter 3
Structure and
Function of Cells
Suggested Lecture
Presentation
Robert J. Sullivan
Marist College
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Cells Are Classified by Internal Organization
 Eukaryotes have
 Plasma membrane
 Nucleus: information center
 Cytoplasm: fluid within membrane
 Organelles: structures with specialized
functions
 Prokaryotes have
 No nucleus
 No true organelles
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Cell Structure Reflects Cell Function
 Muscle cells
 Contain numerous organelles providing
energy needed for muscle contraction
 Nerve cells
 Long and thin to carry impulses over
distance
 Small size is efficient
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1
The Plasma Membrane
Extracellular environment
Receptor
protein
Channel protein
(always open)
Gated channel
protein (closed
position)
Cytoskeleton Phospholipid
filaments
Cytoplasm
Carbohydrate
groups
Lipid Transport Glycoprotein
bilayer protein
Cholesterol
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Figure 3.5
Structural Features of the Plasma Membrane
 Lipid bilayer
 Phospholipids: polar head and nonpolar tail
 Cholesterol: makes membrane a bit more
g
rigid
 Proteins: provide means of transportation
through membrane
 Carbohydrates: recognition patterns for cells
and organisms
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Diffusion: Passive Transport Through
Membrane
 Passive transport
 No energy
required
 Diffusion
 Movement from
area of high
concentration to
low
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Figure 3.6
2
Osmosis: Diffusion of Water
 Osmosis: net diffusion of water across a
semipermeable membrane
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Figure 3.7
Three Forms of Passive Transport
 Passive transport is powered by the
concentration gradient. In the cell it occurs
as
 Diffusion through lipid layer
 Diffusion
Diff i th
through
h protein
t i channels
h
l
 Facilitated transport
 Transport or carrier proteins in the
membrane assist in moving molecules
across the membrane, down the
concentration gradient, without expending
energy
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Active Transport
 Active transport
requires energy to
move substances
from an area of
l
lower
concentration
i
to an area of higher
concentration.
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Figure 3.9
3
Endocytosis and Exocytosis Move Materials
in Bulk
 Endocytosis moves material into cell
 Exocytosis moves material out of cell
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Figure 3.10a–b
Receptor Proteins in Active Transport
 Receptor proteins
 Span membrane
 Receptor sites
 Bind specific
molecules
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Figure 3.11
Active Transport: The Sodium–Potassium
Pump
 Sodium–potassium pump expels unwanted ions,
keeps needed ones, and maintains cell volume
 ATP is used to expel three sodium ions for every
two potassium ions brought into the cell
 IIncrease cellll volume
l
= iincrease water
t iin
cytoplasm by decreasing pumping and allowing
more sodium inside cell
 Decrease cell volume = less water in cytoplasm
by increasing pumping and expelling more
sodium ions
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4
Active Transport: The Sodium–Potassium
Pump
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Figure 3.12a
Active Transport: The Sodium–Potassium
Pump
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Figure 3.12b
Variations in Tonicity
 Isotonic
 Extracellular and intracellular ionic
concentration equal
 Hypotonic
yp
 Extracellular ionic concentration less than
intracellular
 Hypertonic
 Extracellular ionic concentration more than
intracellular
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5
Tonicity
Figure 3.13a
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Internal Structures of an Animal Cell
Cytosol
Semifluid gel material
inside the cell
Peroxisome
Destroys cellular toxic waste
Nucleus
Information
center for the
cell. Contains
DNA
Centrioles
Microtubular structures
involved in cell division
Cytoskeleton
Structural framework
of the cell
Smooth endoplasmic reticulum
Primary site of
macromolecule
synthesis other than
proteins
Rough endoplasmic reticulum
Primary site of protein
synthesis by ribosomes
Golgi apparatus
Refines, packages, and
ships macromolecular products
Secretory vesicle
Membrane-bound
shipping container
Ribosomes
Site of protein synthesis
Mitochondrion
Produces energy
for the cell
Plasma membrane
Controls movement of
materials into and out of cell
Lysosome
Digests damaged organelles
and cellular debris
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Figure 3.14
Structure and Function of the Nucleus
 Functions
 Contains the genetic information of the cell
 Controls the cell
 Structural features
 Double-layered nuclear membrane
 Nuclear pores
 Chromosomes/chromatin
 Nucleolus
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6
Structure and Function of the Nucleus
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Figure 3.15
Endoplasmic Reticulum (ER) and Ribosomes
 Ribosomes
 Used in protein assembly
 Free and membrane bound
 Endoplasmic reticulum (ER)
 Packages the proteins
 Smooth ER: no ribosomes, lipid synthesis
 Rough ER: has ribosomes, protein
manufacture
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Endoplasmic Reticulum (ER) and Ribosomes
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Figure 3.16
7
Golgi Apparatus
 Receives substances from ER, refines and
packages them
Smooth ER
Golgi apparatus
Vesicle
Lysosome
Secretory vesicle
Plasma
membrane
Figure 3.17 (1 of 2)
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Vesicles Ship and Store Cellular Products
Harmless
waste
Alcohol
 Vesicles
 Ship and store
cellular products
 Secretory
membranemembrane
bound spheres
 Examples:
secretory,
endocytic,
peroxisomes,
lysosomes
Peroxisome
Golgi
apparatus
Cell toxic
waste
Lysosome
Residual
body
Bacterium
Plasma membrane
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Figure 3.18
Mitochondria: Provide Energy to the Cell
 Double
membrane
 Inner
membrane
contains
enzymes that
break down
foods
 Liberated
energy is used
to create ATP
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Figure 3.19a
8
Energy Storage
 Fat
 Triglycerides
 Long-term energy storage in animals
 Glycogen
 Carbohydrate storage
 Short-term energy storage in animals
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Cytoskeleton Supports the Cell
 Microtubules
 Microfilaments
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Figure 3.20
Cell Structures for Support and Movement:
Cilia, Flagella, Centrioles
 Cilia and flagella
 Used in
movement
 9 + 2 microtubule
arrangement
 Centrioles
 Used in cell
division
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Figure 3.20
9
Cells Use and Transform Matter and Energy:
Two Basic Metabolic Pathways
 Anabolism
 Requires enzymes
 Making/assembling large molecules
 May require energy (ATP)
 Used in building up cell components
 Used in storing energy
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Cells Use and Transform Matter and Energy:
Two Basic Metabolic Pathways
 Catabolism
 Requires enzymes
 Breakdown of molecules
 May release energy
 Used in breaking down nutrients and
recycling cell components
 Used to access energy storage
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Cellular Respiration: Cells Use Glucose and
Oxygen to Supply ATP
 Glucose provides
energy for the cell
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Figure 3.23
10
Stages of Cellular Respiration
 Glycolysis: in cytoplasm
 Splits glucose
 Produces two ATP and two pyruvate molecules
 Citric acid cycle: in mitochondria
 Also called the Krebs cycle
 Extracts high-energy electrons
 Produces two ATP and carbon dioxide
 Electron transport system: in mitochondria
 Energy from electrons is used to produce ATP
 Produces water and carbon dioxide
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Cellular Respiration: An Overview
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Figure 3.24
Glycolysis
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Figure 3.25
11
The Preparatory Step
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Figure 3.26
The Citric Acid Cycle
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Figure 3.27
Steps in the Electron Transport System
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Figure 3.28
12
Cellular Respiration: A Recap
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Figure 3.29a
Fats and Proteins:
Additional Energy Sources
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Figure 3.30
Fats and Proteins:
Additional Energy Sources
 Fats
 Triglycerides have twice the energy of
carbohydrates
 Proteins
 Same energy as carbohydrates
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13
Anaerobic Pathways:
Energy Extraction Without Oxygen
Glucose
(Glycolysis)
(2) ATP
Lactic acid
buildup
Pyruvate
Mitochondrial
metabolism
blocked without
oxygen
Mitochondrion
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Figure 3.31
14