Human Anatomy and Physiology I Chapter 3 - Part 1 The Cell Instructor: Mary Holman
Dec 28, 2015
Levels of Organization
Subatomic particles
Atom
Molecule
Macromolecule
Organelle
Cell
Tissue
Organ
Organ system
Organism
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Fig 1.3
Cells
• Basic units of all living things• Differentiate into many different types• All cell types have some basic
characteristics in common
CytologyThe study of cellular structure
Fig. 3.2
(b) Epithelial cells protect underlying cells. (c) Muscle cells contract, pulling structures closer together.
(a) A nerve cell transmits impulses from one body part to another.
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Fig. 3.2
Fig. 3.3
Microtubules
Flagellum
Nuclear envelope
Basal body
Chromatin
Ribosomes
Cell membrane
Mitochondrion
Cilia
Microtubules
Microtubule
Golgiapparatus
Secretoryvesicles
Centrioles
Microvilli
Lysosomes
SmoothEndoplasmicreticulum
RoughEndoplasmicreticulum
Nucleolus
Nucleus
Phospholipid bilayer
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Pg 86
Fig. 3.3
Cell Membrane also called Plasma Membrane
• Outer surface of the cell
• Composed of phospholipid bi-layer
• Selectively permeable
• Protein molecules embedded in the membrane control entrance and exit of molecules
C
H H
HH
C
H
H
N
O
O
Fatty acid
Fatty acid
O
POCH
O–
Phosphate portion
(the unshaded portion may vary)
H
CH
C
H
H
O
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Fig. 2.15bA Phospholipid Molecule
Fig. 2.15c
Schematic representationof a phospholipid molecule
Water-insoluble(hydrophobic) “tail”
Water-soluble(hydrophilic) “head”
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Cell membrane
“Heads” ofphospholipid
“Tails” ofphospholipid
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Hydrophilic
Middle of membrane
Hydrophobic
Fig. 3.6b
cytoplasm
Fig. 3.7
Doublelayer ofphospholipidmolecules
Fibrous protein
Extracellular sideof membrane
Cytoplasmic sideof membrane
Carbohydrate
Hydrophobicfatty acid“tail”
Hydrophilicphosphate“head”
Cholesterolmolecules
Globularprotein
GlycolipidGlycoprotein
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Fig. 3.7
Nucleus
• Surrounded by a nuclear membrane which has pores to the cytoplasm
• Contains a nucleolus consisting primarily of ribonucleic acid (RNA)
• The nucleoplasm contains darkly staining chromatin
Fig. 3.19b
Nucleolus
Chromatin
Nuclearenvelope
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© Stephen L. Wolfe 7,500x
Fig. 3.19b
Cytoplasm
• Cellular material outside the nucleus but inside the cellular membrane
• Consists of a fluid portion called cytosol, a cytoskeleton, organelles, and inclusions
Microfilaments
• Slender fibers of the protein actin
• Bundles of microfilaments along with microtubules provide the framework of the cytoskeleton
• Connect to cellular components providing a matrix to the cytoplasm and lending strength
Microtubules
• Long slender hollow tubes made up of the protein tubulin
•Two to three times larger in diameter than microfilaments
• Provide the framework for movement of organelles within the cell
• Basic component of centrioles, cilia, and flagella
Fig. 3.18a
MitochondrionNucleus
Roughendoplasmicreticulum
Cell membrane
Microfilaments Ribosome Microtubules
Vesicle
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Fig. 3 18a
Microtubules
MicrofilamentsCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.© M. Schliwa/Visuals Unlimited
Fig. 3.17
35,000x
Kirschner MW, Suter MM, Weingarten MD, Littman DR: The role of in the assembly of microtubules in vitro. Annals NY Acad Sci, 253:90-106, 1975.
Weingarten MD, Suter MM, Littman DR, Kirschner MW: Properties of the depolymerization products of microtubules from mammalian brain. Biochemistry,
13:5529-5537, 1974.
Organelles
Small structures within cells with specialized functions
The number and type of organelles within a specific cell are related to the specific structure and function of that cell
Ribosomes
• Site of protein synthesis
• Non-membranous
• Scattered throughout the cytoplasm and attached to endoplasmic reticulum (ER)
• Composed of two sub-units
• Subunits are manufactured
separately in the nucleolus
ER membrane
Ribosomes
(a)
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Fig. 3.9a
Ribosomes on the Endoplasmic Reticulum
Endoplasmic Reticulum (ER)• Most extensive structure within the cytoplasm
• Composed of broad, flattened, interconnected sacs and tubules
• Interior spaces called cisternae
• Provides pathway for intracellular transport of molecules
• Called Rough ER (RER) when covered with ribosomes
ER Membranes
Ribosomes
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Endoplasmic ReticulumFig. 3.9
Smooth ER
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Fig. 3.9c
Golgi Apparatus• Connected to Rough ER (RER)
• Composed of stacks of flattened
membranous sacs called cisternae
• Modifies, packages, and distributes
proteins and lipids made on rough and
smooth ER
• Receives and transports molecules via
vesicles
Fig. 3.10b
Golgiapparatus
Nucleus
Cytosol
Transportvesicle
Secretion
Cell membrane
Nuclearenvelope
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RoughEndoplasmicreticulum
Fig. 3.10b Golgi Apparatus
Nucleus
Fig. 3.10a
Golgiapparatus
RoughEndoplasmicreticulum
Transportvesicle
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© Gordon Leedale/Biophoto Associates
48,500x
Golgi ApparatusFig.3.10a
Vesicles
• Small membranous sacs that vary in size and contents
• Form by pinching off of small pieces of membrane that surround a tiny amount of liquid or solid
• Method of distributing molecules within a cell and/or into and out of cell
Fig. 3.11
Carbohydrates
Cell membrane
Mitochondrion
Lysosome Nuclear poreNuclear envelope
mRNAMilkprotein
Lipids areSynthesizedin the smoothEndoplasmicreticulum (ER).
Most proteins are synthesizedOn ribosomes associated withMembranes of the rough ER,Using amino acids in the cytosol.
Sugars are synthesized in thesmooth ER and Golgi apparatusand may be attached to proteinsor secreted in vesicles.
Proteins are secreted fromvesicles that bud off of theGolgi apparatus.
Fat droplets pick up a layer oflipid from the cell membraneas they exit the cell.
2
3
4
5
6
7
Milk protein genes aretranscribed into mRNA.
1
mRNA exits throughNuclear pores.
Milk Proteinin Golgivesicle
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Fig 3.11 pg 93
Mitochondrion
• Rod-shaped bodies with double- layered walls
• Inner layer has many infoldings called cristae
• Major site of energy (ATP) production
• Have their own DNA and ribosomes which are inherited solely from the mother
Fig. 3.12a
Cristae
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© Bill Longcore/Photo Researchers, Inc.
Mitochondrion
28,000x
Fig.3.12
Lysosomes
• Membrane-enclosed vesicles of varying shape
• Contain a variety of enzymes
• Clean up the cell by destroying debris, unnecessary molecules, aging organelles and foreign particles
• Can play a role in facilitating cell death
Peroxisomes
• Similar to lysosomes in structure but usually smaller
• Contain enzymes for breaking down various often toxic substances
peroxidases and catalase
•Most abundant in liver and kidney cells which are active in detoxification
Centrosome
• Located near the nucleus
• Consists of 2 non-membranous
cylinders - centrioles, at right angles to each other
• Made up of microtubules
• Distribute chromosomes during cell division by forming spindle fibers
Fig. 3.14b Centriole(cross-section)
Centriole(longitudinal section)
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Centrioles
Pg 96
Fig. 3.14a
(a)
Centriole(cross-section)
Centriole(longitudinal section)
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a: © Don W. Fawcett/Visuals Unlimited
120,000x
Fig. 3.14a Centrioles
Cilia and Flagella• Hair-like appendages on some cells
• Function in providing movement
• Both originate from centrioles and are made up of microtubules
• Cilia are usually <20 um long
• Flagella can be thousands of um in length
• The only human cell with a flagellum is the sperm cell
Fig. 3.15a
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Epithelial cell lining the Respiratory Tract
Cilia 5,400x
Fig. 3.15a
Fig. 3.16
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© Colin Anderson/Brand X/CORBIS 1,400x
Fig. 3.16
Fig. 3.3
Microtubules
Flagellum
Nuclear envelope
Basal body
Chromatin
Ribosomes
Cell membrane
Mitochondrion
Cilia
Microtubules
Microtubule
Golgiapparatus
Secretoryvesicles
Centrioles
Microvilli
Lysosomes
SmoothEndoplasmicreticulum
RoughEndoplasmicreticulum
Nucleolus
Nucleus
Phospholipid bilayer
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Pg 78
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Microvilli
Cell membrane
Mitochondrion
Golgi apparatus
Nucleolus
Nucleus
(a)
Lumen Microvilli
(b)
Roughendoplasmicreticulum
Cytoplasm ofepithelial cell
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Intestinal Epithelial Cell
Chap 17 pg 678