Cytoplasmic Organelles Figure 3.4 The Nucleus Figure 3.1b.
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Transcript of Cytoplasmic Organelles Figure 3.4 The Nucleus Figure 3.1b.
Cytoplasmic Organelles
Figure 3.4
The Nucleus
Figure 3.1b
Plasma Membrane
Figure 3.2
Plasma Membrane Specializations
• Membrane junctions– Tight junctions
• Impermeable junctions • Bind cells together into leakproof sheets
– Desmosomes • Anchoring junctions that prevent cells from being
pulled apart
– Gap junctions • Allow communication between cells
Plasma Membrane Specializations
Figure 3.3
Cytoplasmic Organelles
Figure 3.4
Rough Endoplasmic Reticulum
Figure 3.5, step 1
Ribosome
Protein
mRNA
Rough ER
As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern.
Rough Endoplasmic Reticulum
Figure 3.5, step 2
Ribosome
Protein
mRNA
Rough ER
As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern.
In the cistern, the protein foldsinto its functional shape. Shortsugar chains may be attachedto the protein (forming aglycoprotein).
Rough Endoplasmic Reticulum
Figure 3.5, step 3
Ribosome
Protein
Transportvesicle buds off
mRNA
Rough ER
As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern.
In the cistern, the protein foldsinto its functional shape. Shortsugar chains may be attachedto the protein (forming aglycoprotein).
The protein is packaged in atiny membranous sac called atransport vesicle.
Rough Endoplasmic Reticulum
Figure 3.5, step 4
Ribosome
Protein
Protein insidetransport vesicle
Transportvesicle buds off
mRNA
Rough ER
As the protein is synthesizedon the ribosome, it migratesinto the rough ER cistern.
In the cistern, the protein foldsinto its functional shape. Shortsugar chains may be attachedto the protein (forming aglycoprotein).
The protein is packaged in atiny membranous sac called atransport vesicle.
The transport vesicle buds fromthe rough ER and travels to theGolgi apparatus for furtherprocessing or goes directly tothe plasma membrane where itscontents are secreted.
Figure 3.6
Extracellular fluid
Plasma membrane
Golgi vesicle containingmembrane componentsfuses with the plasmamembrane
Golgi vesicle containingdigestive enzymesbecomes a lysosome
Proteins in cisterna
Lysosome fuses withingested substances
Membrane
Transportvesicle
Pathway 3
Pathway 2
Secretory vesicles Pathway 1
Golgiapparatus
Golgi vesicle containingproteins to be secretedbecomes a secretoryvesicle
Cisterna
Rough ER
Proteins
Secretion byexocytosis
Cytoplasmic Organelles
• Cytoskeleton– Network of protein structures that extend
throughout the cytoplasm– Provides the cell with an internal framework
Figure 3.7a
Figure 3.7b–d
Cytoplasmic Organelles• Cytoskeleton
– Three different types of elements
• Microfilaments (smallest)• Intermediate filaments• Microtubules (largest)
Cytoplasmic Organelles
• Centrioles– Rod-shaped bodies made of microtubules– Direct the formation of mitotic spindle during cell
division
Cellular Projections
• Not found in all cells• Used for movement
– Cilia move materials across the cell surface• Located in the respiratory system to move mucus
– Flagella propel the cell • The only flagellated cell in the human body is sperm
Cell Physiology: Membrane Transport
• Membrane transport—movement of substances into and out of the cell
• Two basic methods of transport– Passive transport
• No energy is required
– Active transport• Cell must provide metabolic energy (ATP)
Solutions and Transport
• Solution—homogeneous mixture of two or more components– Solvent—dissolving medium; typically water in the
body– Solutes—components in smaller quantities within
a solution• Intracellular fluid—nucleoplasm and cytosol• Interstitial fluid—fluid on the exterior of the
cell
Transport Terminology
Selective Permeability:• Passive Transport
– Diffusion– Osmosis
• Active Transport– Vesicular Transport– Exocytosis– Endocytosis
• Phagocytosis & Pinocytosis
Figure 3.11, step 1
Extracellular fluid
Cytoplasm
Binding of cytoplasmic Na+
to the pump proteinstimulates phosphorylationby ATP, which causes thepump protein to change itsshape.
ADP
Na+
Na+
Na+ P
ATP
Figure 3.11, step 2
Extracellular fluid
Cytoplasm
Binding of cytoplasmic Na+
to the pump proteinstimulates phosphorylationby ATP, which causes thepump protein to change itsshape.
The shape change expelsNa+ to the outside.Extracellular K+ binds,causing release of thephosphate group.
ADP
Na+
Na+
Na+
Na+
Na+
Na+
K+
K+
P
PP
ATP
Figure 3.11, step 3
Extracellular fluid
Cytoplasm
Loss of phosphate restoresthe original conformation ofthe pump protein. K+ isreleased to the cytoplasm andNa+ sites are ready to bind Na+
again; the cycle repeats.
Binding of cytoplasmic Na+
to the pump proteinstimulates phosphorylationby ATP, which causes thepump protein to change itsshape.
The shape change expelsNa+ to the outside.Extracellular K+ binds,causing release of thephosphate group.
ADP
Na+
Na+
Na+
Na+
Na+
Na+
K+
K+
K+
K+
P
PP
ATP
Active Transport Processes: Exocytosis
Figure 3.12b
Active Transport Processes: Endocytosis
Figure 3.13a, step 1
CytoplasmExtracellularfluid
Extracellularfluid
Plasmamembrane
Plasmamembrane
Ingestedsubstance
Pit
(a)
Active Transport Processes: Endocytosis
Figure 3.13a, step 2
CytoplasmExtracellularfluid
Extracellularfluid
Plasmamembrane
Detachmentof vesicle
Vesicle containingingested material
Plasmamembrane
Ingestedsubstance
Pit
(a)
Active Transport Processes: Endocytosis
Figure 3.13a, step 3
CytoplasmExtracellularfluid
Extracellularfluid
Plasmamembrane
Detachmentof vesicle
Vesicle containingingested material
Vesicle
Vesicle fusingwith lysosomefor digestion
Lysosome
Plasmamembrane
Ingestedsubstance
Pit
(a)
Active Transport Processes: Endocytosis
Figure 3.13a, step 4
CytoplasmExtracellularfluid
Extracellularfluid
Plasmamembrane
Detachmentof vesicle
Vesicle containingingested material
Vesicle
Vesicle fusingwith lysosomefor digestion
Release ofcontents tocytoplasm
Lysosome
Plasmamembrane
Ingestedsubstance
Pit
(a)
Active Transport Processes: Endocytosis
Figure 3.13a, step 5
CytoplasmExtracellularfluid
Extracellularfluid
Plasmamembrane
Detachmentof vesicle
Vesicle containingingested material
Vesicle
Vesicle fusingwith lysosomefor digestion
Release ofcontents tocytoplasm
Lysosome
Transport to plasmamembrane andexocytosis ofvesicle contents
Plasmamembrane
Ingestedsubstance
Pit
(a)
Active Transport Processes: Endocytosis
Figure 3.13a, step 6
Recycling of membraneand receptors (if present)to plasma membrane
CytoplasmExtracellularfluid
Extracellularfluid
Plasmamembrane
Detachmentof vesicle
Vesicle containingingested material
Vesicle
Vesicle fusingwith lysosomefor digestion
Release ofcontents tocytoplasm
Lysosome
Transport to plasmamembrane andexocytosis ofvesicle contents
Plasmamembrane
Ingestedsubstance
Pit
(a)
Active Transport Processes: Endocytosis
Figure 3.13b–c
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
Mitosis (divisionof nucleus)
GeneticallyIdentical“daughtercells”
S(DNA synthesis)
G1
G2 Cytokinesis(division of cytoplasm)
INTERPHASE (cell growth and chromosome duplication)
MITOTIC PHASE (M)
MITOSIS
Copyright © 2009 Pearson Education, Inc.
– Mitosis progresses through a series of stages– Prophase– Prometaphase– Metaphase– Anaphase– Telophase
– Cytokinesis often overlaps telophase
8.6 Cell division is a continuum of dynamic changes
Copyright © 2009 Pearson Education, Inc.
– A mitotic spindle is required to divide the chromosomes
– The mitotic spindle is composed of microtubules– It is produced by centrosomes, structures in the cytoplasm
that– Organize microtubule arrangement – Contain a pair of centrioles in animal cells
– The role of centrioles in cell division is unclear
8.6 Cell division is a continuum of dynamic changes
Copyright © 2009 Pearson Education, Inc.
Video: Animal Mitosis
Video: Sea Urchin (time lapse)
Centrosomes(with centriole pairs) Kinetochore
Early mitoticspindle
Chromatin
INTERPHASE PROMETAPHASEPROPHASE
Centrosome Fragmentsof nuclearenvelope
Plasmamembrane
Chromosome, consistingof two sister chromatids
Nuclearenvelope
Spindlemicrotubules
Nucleolus
Centromere
Metaphaseplate
Nucleolusforming
METAPHASE TELOPHASE AND CYTOKINESISANAPHASE
Cleavagefurrow
Daughterchromosomes
NuclearenvelopeformingSpindle
INTERPHASE
PROPHASE
PROMETAPHASE
METAPHASE
ANAPHASE
TELOPHASE AND CYTOKINESIS
– Metaphase– How many chromosomes are present in one human cell?– How many chromatids are present in one human cell?
8.6 Cell division is a continuum of dynamic changes
Copyright © 2009 Pearson Education, Inc.
– Applying Your KnowledgeHuman cells have 46 chromosomes. By the end of interphase
– How many chromosomes are present in one cell?– How many chromatids are present in one cell?
8.6 Cell division is a continuum of dynamic changes
Copyright © 2009 Pearson Education, Inc.
– Applying Your KnowledgeBy the end of anaphase
– How many chromosomes are present in one human cell?– How many chromatids are present in one human cell?
8.6 Cell division is a continuum of dynamic changes
Copyright © 2009 Pearson Education, Inc.
– Telophase– Applying Your Knowledge
By the end of telophase – How many chromosomes are present in one nucleus within the
human cell?– Are the nuclei identical or different?
8.6 Cell division is a continuum of dynamic changes
Copyright © 2009 Pearson Education, Inc.
– Cytokinesis– Applying Your Knowledge
By the end of cytokinesis – How many chromosomes are present in one human cell?– How many chromatids are present in one human cell?
8.6 Cell division is a continuum of dynamic changes
Copyright © 2009 Pearson Education, Inc.
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
Stages of Mitosis
• Metaphase– Chromosomes are aligned in the center of the cell
on the metaphase plate
Stages of Mitosis• Anaphase
– Chromosomes are pulled apart and toward the opposite ends of the cell
– Cell begins to elongate
Stages of Mitosis
• Telophase– Chromosomes uncoil to become chromatin– Nuclear envelope reforms around chromatin – Spindles break down and disappear
Stages of Mitosis
• Cytokinesis– Begins during late anaphase and completes during
telophase– A cleavage furrow forms to pinch the cells into
two parts
Stages of Mitosis
Figure 3.15, step 1
Centrioles
Plasmamembrane
Interphase
Nucleolus
Nuclearenvelope
Chromatin
Stages of Mitosis
Figure 3.15, step 2
Centrioles
Plasmamembrane
Interphase Early prophase
Nucleolus
Nuclearenvelope
Chromatin
Centrioles
Formingmitoticspindle
Centromere
Chromosome,consisting of twosister chromatids
Stages of Mitosis
Figure 3.15, step 3
Centrioles
Plasmamembrane
Interphase Early prophase Late prophase
Nucleolus
Nuclearenvelope
Spindlepole
Chromatin
Centrioles
Formingmitoticspindle
Centromere
Chromosome,consisting of twosister chromatids
Fragments ofnuclear envelope
CentromereSpindlemicrotubules
Stages of Mitosis
Figure 3.15, step 4
Metaphase
Sisterchromatids
Spindle Metaphaseplate
Stages of Mitosis
Figure 3.15, step 5
Metaphase Anaphase
Daughterchromosomes
Sisterchromatids
Spindle Metaphaseplate
Stages of Mitosis
Figure 3.15, step 6
Metaphase Anaphase Telophase and cytokinesis
Daughterchromosomes
Sisterchromatids
Nuclearenvelopeforming
Nucleolusforming
Spindle Metaphaseplate
Cleavagefurrow
PowerPoint® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College
Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings
4
Skin and Body Membranes
Integumentary System
• Skin (cutaneous membrane)• Skin derivatives
– Sweat glands– Oil glands– Hair– Nails
Skin Functions
Table 4.1 (1 of 2)
Skin Functions
Table 4.1 (2 of 2)
Skin Structure
• Epidermis—outer layer– Stratified squamous epithelium– Often keratinized (hardened by keratin)
• Dermis– Dense connective tissue
Skin Structure
Figure 4.3
Skin Structure
• Subcutaneous tissue (hypodermis) is deep to dermis– Not part of the skin– Anchors skin to underlying organs– Composed mostly of adipose tissue
Layers of the Epidermis
• Stratum basale (stratum germinativum)– Deepest layer of epidermis– Lies next to dermis– Cells undergoing mitosis– Daughter cells are pushed upward to become the
more superficial layers• Stratum spinosum• Stratum granulosum
Layers of the Epidermis
• Stratum lucidum– Formed from dead cells of the deeper strata– Occurs only in thick, hairless skin of the palms of
hands and soles of feet• Stratum corneum
– Outermost layer of epidermis– Shingle-like dead cells are filled with keratin
(protective protein prevents water loss from skin)
Layers of the Epidermis
• Summary of layers from deepest to most superficial– Stratum basale– Stratum spinosum– Stratum granulosum– Stratum lucidum (thick, hairless skin only)– Stratum corneum
Melanin
• Pigment (melanin) produced by melanocytes• Melanocytes are mostly in the stratum basale• Color is yellow to brown to black• Amount of melanin produced depends upon
genetics and exposure to sunlight
Dermis
• Two layers– Papillary layer (upper dermal region)
• Projections called dermal papillae – Some contain capillary loops– Other house pain receptors and touch receptors
– Reticular layer (deepest skin layer)• Blood vessels• Sweat and oil glands• Deep pressure receptors
Dermis
• Overall dermis structure– Collagen and elastic fibers located throughout the
dermis• Collagen fibers give skin its toughness• Elastic fibers give skin elasticity
– Blood vessels play a role in body temperature regulation
Skin Structure
Figure 4.4
Normal Skin Color Determinants
• Melanin– Yellow, brown, or black pigments
• Carotene– Orange-yellow pigment from some vegetables
• Hemoglobin– Red coloring from blood cells in dermal capillaries– Oxygen content determines the extent of red
coloring
Skin Appendages
• Cutaneous glands are all exocrine glands– Sebaceous glands– Sweat glands
• Hair• Hair follicles• Nails
Appendages of the Skin
• Sebaceous glands– Produce oil
• Lubricant for skin• Prevents brittle hair• Kills bacteria
– Most have ducts that empty into hair follicles; others open directly onto skin surface
– Glands are activated at puberty
Appendages of the Skin
Figure 4.6a
Appendages of the Skin
• Sweat glands– Produce sweat – Widely distributed in skin– Two types
• Eccrine– Open via duct to pore on skin surface
• Apocrine– Ducts empty into hair follicles
Appendages of the Skin
Figure 4.6b
Sweat and Its Function
• Composition– Mostly water– Salts and vitamin C– Some metabolic waste– Fatty acids and proteins (apocrine only)
• Function– Helps dissipate excess heat– Excretes waste products– Acidic nature inhibits bacteria growth
• Odor is from associated bacteria
Appendages of the Skin
• Hair– Produced by hair follicle– Consists of hard keratinized epithelial cells– Melanocytes provide pigment for hair color
Appendages of the Skin
Figure 4.7c
Appendages of the Skin• Hair anatomy
– Central medulla– Cortex surrounds
medulla– Cuticle on outside of
cortex• Most heavily
keratinized
Figure 4.7b
Appendages of the Skin
• Associated hair structures – Hair follicle
• Dermal and epidermal sheath surround hair root
– Arrector pili muscle • Smooth muscle• Pulls hairs upright when cold or frightened
– Sebaceous gland– Sweat gland
Appendages of the Skin
Figure 4.7a
Appendages of the Skin
Figure 4.8
Appendages of the Skin
• Nails– Scale-like modifications of the epidermis
• Heavily keratinized
– Stratum basale extends beneath the nail bed• Responsible for growth
– Lack of pigment makes them colorless
Appendages of the Skin
• Nail structures– Free edge– Body is the visible attached portion– Root of nail embedded in skin– Cuticle is the proximal nail fold that projects onto
the nail body
Appendages of the Skin
Figure 4.9
Skin Homeostatic Imbalances
• Infections– Athlete’s foot (tinea pedis)
• Caused by fungal infection
– Boils and carbuncles• Caused by bacterial infection
– Cold sores• Caused by virus
Skin Homeostatic Imbalances
• Infections and allergies– Contact dermatitis
• Exposures cause allergic reaction
– Impetigo• Caused by bacterial infection
– Psoriasis• Cause is unknown• Triggered by trauma, infection, stress
Skin Homeostatic Imbalances
Figure 4.10
Skin Homeostatic Imbalances
• Burns– Tissue damage and cell death caused by heat,
electricity, UV radiation, or chemicals– Associated dangers
• Dehydration• Electrolyte imbalance• Circulatory shock
Rule of Nines
• Way to determine the extent of burns• Body is divided into 11 areas for quick
estimation• Each area represents about 9% of total body
surface area
Rule of Nines
Figure 4.11a
Severity of Burns
• First-degree burns– Only epidermis is damaged– Skin is red and swollen
• Second-degree burns– Epidermis and upper dermis are damaged– Skin is red with blisters
• Third-degree burns– Destroys entire skin layer– Burn is gray-white or black
Severity of Burns
Figure 4.11b
Critical Burns
• Burns are considered critical if– Over 25% of body has second-degree burns– Over 10% of the body has third-degree burns– There are third-degree burns of the face, hands, or
feet
Skin Cancer
• Cancer—abnormal cell mass• Classified two ways
– Benign• Does not spread (encapsulated)
– Malignant• Metastasized (moves) to other parts of the body
• Skin cancer is the most common type of cancer
Skin Cancer Types• Basal cell carcinoma
– Least malignant– Most common type– Arises from stratum basale
Skin Cancer Types
Figure 4.12a
Skin Cancer Types
• Squamous cell carcinoma– Metastasizes to lymph nodes if not removed– Early removal allows a good chance of cure– Believed to be sun-induced– Arises from stratum spinosum
Skin Cancer Types
Figure 4.12b
Skin Cancer Types
• Malignant melanoma– Most deadly of skin cancers– Cancer of melanocytes– Metastasizes rapidly to lymph and blood vessels– Detection uses ABCD rule
Skin Cancer Types
Figure 4.12c
ABCD Rule
• A = Asymmetry– Two sides of pigmented mole do not match
• B = Border irregularity– Borders of mole are not smooth
• C = Color– Different colors in pigmented area
• D = Diameter– Spot is larger then 6 mm in diameter