cell membrane structure and function
DESCRIPTION
Cell Membrane Structure and Function. Cystic Fibrosis. • most common autosomal recessive disease affecting Caucasian populations •incidence of 1 in 2000 births •Clinical features •pulmonary obstruction and infection •recurrent and persistent infections •exocrine pancreatic dysfunction - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/1.jpg)
Cell Membrane Structure and
Function
![Page 2: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/2.jpg)
Cystic Fibrosis
•most common autosomal recessive disease affecting Caucasian populations – •incidence of 1 in 2000 births
•Clinical features – •pulmonary obstruction and infection – •recurrent and persistent infections – •exocrine pancreatic dysfunction – •infertility, especially in males
![Page 3: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/3.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 4: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/4.jpg)
Diagnosis
• failure to thrive -child fails to gain weight despite a good appetite
• sweat test -chloride concentration greater than 60 meq/liter
• life expectancy now often >30 years
• this was the disease most people thought would be a good candidate for gene therapy
![Page 5: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/5.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 6: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/6.jpg)
Metabolic Basis of Disease• defect in a single gene on chromosome 7 that
encodes a cAMP-regulated chloride channel
• called Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)
• resides on the apical surface of epithelial cells lining the airways, intestines, vas deferens, sweat ducts, and pancreatic ducts
![Page 7: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/7.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 8: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/8.jpg)
Genetics and Epidemiology• autosomal recessive
• 4-5% of Americans have at least one CF allele
• >900 different mutations (.F508, ~70% of CF alleles)
• ~50% of the patients are homozygous for the .F508 mutation
![Page 9: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/9.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 10: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/10.jpg)
Consequences of Disease
• Loss of CFTR function
– fluid secretion is insufficient
– protein portions of the secretions become viscous
– results in obstruction in the ducts and eventual organ dysfunction
![Page 11: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/11.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 12: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/12.jpg)
Lung Disease• accounts for much of the morbidity and nearly all the
mortality from the disease
• bacterial infections become soon after birth, and remain difficult to stop
• Pseudomonas aeruginosais the main agent in patients 18 or older
• bacterial resistance to antibiotics results in mucoid coating of lungs, and subsequent decline in lung
![Page 13: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/13.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 14: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/14.jpg)
Cystic Fibrosis
![Page 15: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/15.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 16: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/16.jpg)
Membrane Functions
• Isolate the cell’s contents from the external environment
• Regulate traffic in and out of the cell
• Communicate with other cells
![Page 17: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/17.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 18: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/18.jpg)
II. Plasma membrane structure and functions
The phospholipid bilayer and isolation
1. Impermeable to water-soluble and polar molecules, ions
2. Permeable to small and nonpolar molecules
3. Lipids oriented with polar heads facing out
![Page 19: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/19.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 20: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/20.jpg)
tails(hydrophobic)
head(hydrophilic)
![Page 21: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/21.jpg)
hydrophobictails
hydrophilicheads
hydrophilicheads
extracellular fluid(watery environment)
cytoplasm(watery environment)
phospholipid
bilayer
![Page 22: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/22.jpg)
Membrane Structure and Function
• Membranes are “fluid mosaics” with proteins embedded in or attached to the membrane
• Proteins can move within the fluid lipid bilayer
![Page 23: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/23.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 24: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/24.jpg)
extracellular fluid (outside)
cytoplasm (inside)protein filaments
recognition protein receptor protein transport protein
binding sitephospholipid
bilayer
phospholipid cholesterolcarbohydrate
![Page 25: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/25.jpg)
![Page 26: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/26.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 27: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/27.jpg)
![Page 28: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/28.jpg)
Types of Membrane Proteins
1. Transport proteins
– regulate the movement of water-soluble molecules across the membrane
• Channel proteins
• Carrier proteins
![Page 29: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/29.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 30: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/30.jpg)
Types of Membrane Proteins
2. Receptor Proteins
• trigger cellular response when specific molecules bind to them
Nervous system
Endocrine system
![Page 31: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/31.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 32: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/32.jpg)
Types of Membrane Proteins
3. Recognition proteins
• act as ID tags and cell surface attachment sites
– the immune system
![Page 33: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/33.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 34: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/34.jpg)
![Page 35: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/35.jpg)
• Key Classes of Membrane Proteins •• A.Transport channels-Intergral
– 1. Membrane selects what substances will enter – 2. Take up molecules present in high concentration– 3 Part of protein extends through bilayer – 4. May be non polar helix beta-pleated sheets of non polar
amino acids – 5. Non polar portion held within interior of bilayer – 6. Polar ends protrude from both sides of membrane
• B. Enzymes – 1. Chemical reactions carried out on interior surface of membrane
• 2. Enzymes attached directly to membrane-carry out actions within the cell
• 3. Cell surface receptors-glycoproteins, glycolipids, oligosaccharides
– a. Membranes sensitive to chemical messages – b. Receptor proteins on surface act as antennae-
interpresurroundings– c. Receptors for extra cellular signals are also
single-pass anchors – d. Portion of receptor that sticks outward binds
with molecules – e. Binding induces changes in part of protein on
the inside
![Page 36: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/36.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 37: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/37.jpg)
• C. Glycoproteins-MH-ID tags -recognition
– a.self recognition-cells to other cells – b. Creates proteins/carb chains shaped for specific person
– c. self recognition– 2. Glycolipid-
» a. Tissue recognition» b. Lipid/carb chain» c. Specific for each tissue» d. Blood types
• D. Cell adhesion proteins – a. Cells use certain proteins to glue
themselves to one another – b. Some are detachable, others are permanent
• 4. Attachments to the cytoplasm-peripheral – a. Surface proteins may interact with other
cells – b. Often linked to cytoskeleton by proteins
![Page 38: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/38.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 39: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/39.jpg)
The Extracellular Matrix
• Structure: – Glycoproteins– Collagen– Glycolipids
• Functions:– Support, adhesion, movement– In Embryonic development - guides
movement of cells
![Page 40: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/40.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 41: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/41.jpg)
Intracellular Junctions
Tight junctions– Epithelial cells (surface): Seal cells together– Prevent molecules from ‘leaking’ through between
cells --> Keep integral proteins in place
• Adherins junctions:– Transmembrane proteins that span 2 cells– Hold cardiac cells together – May be responsible for contact inhibition
![Page 42: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/42.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 43: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/43.jpg)
More junctions• Gap Junctions: permit flow of substances b/w cells
flow of ions – allow all cells of heart to contract @ same time– allow muscles in uterus to contract simultaneously during
childbirth
• Desmosomes: patches that hold cells together– Breakdown of desmosomes may contribute to metastasis of
cancer
• Plasmodesmata:– Allow for continuous stream of cytoplasm b/w plant cells
![Page 44: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/44.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 45: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/45.jpg)
Transport across membranes
• Passive transport is a function of molecular size, lipid solubility, and size of the concentration gradient
1. Simple diffusion
![Page 46: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/46.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 47: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/47.jpg)
1 A drop of dye is placed in water.
2 Dye molecules diffuse into the water; water molecules diffuse into the dye.
drop of dye
pure water
3 Both dye molecules and water molecules are evenly dispersed.
![Page 48: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/48.jpg)
(a) simple diffusion
(extracellular fluid)
(cytoplasm)
![Page 49: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/49.jpg)
Transport across membranes
Passive transport…(cont.)
– 2. Osmosis• a. Isotonic • b. Hypertonic • c. Hypotonic
![Page 50: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/50.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 51: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/51.jpg)
free water molecule: can fit through pore
bound water moleculesclustered around sugar:cannot fit through pore
pore
sugar
H2O
bagbursts
selectively permeable membrane
water molecule
pure water
sugar molecule
(a)
selectively permeable membrane
(b)
![Page 52: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/52.jpg)
(a) isotonic solution (b) hypertonic solution (c) hypotonic solution10 micrometers
equal movement of waterinto and out of cells
net water movement out of cells
net water movement into cells
![Page 53: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/53.jpg)
Transport across membranes
Passive transport…(cont.)
– 3. Facilitated diffusion
![Page 54: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/54.jpg)
ions
(b) facilitated diffusion through a channel
channelprotein
proteins formingpermanenthydrophilic channel
![Page 55: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/55.jpg)
(extracellular fluid)
(cytoplasm)Carrier protein has binding site for molecule.
amino acids,sugars,
small proteins
(c) facilitated diffusion through a carrier
carrier protein
Molecule enters binding site.
Carrier protein changesshape, transporting moleculeacross membrane.
Carrier protein resumes original shape.
![Page 56: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/56.jpg)
![Page 57: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/57.jpg)
Transport across membranes
Energy-requiring transport
1. Active transport • Ion gradients and energy
production
2. Endocytosis
3. Exocytosis
![Page 58: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/58.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
![Page 59: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/59.jpg)
(extracellular fluid)
Transport protein binds ATP and Ca2+.
Transport protein uses energy from ATP to change shape and moveion across membrane.
Transport protein resumes original shape.
(cytoplasm)
transport protein
ATP binding
site
recognitionsite
ATP
Ca2+
![Page 60: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/60.jpg)
(extracellular fluid)
(cytoplasm)
food particle
particle enclosed in vesicle
phagocytosis
vesicle containing extracellular fluid
cell
pseudopod
pinocytosis
(a)
(b)
133
2
1 32
![Page 61: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/61.jpg)
(extracellular fluid)
(cytoplasm)
vesicle
plasma membrane
1
32
plasma membranesecretedmaterial
0.2 micrometer
![Page 62: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/62.jpg)
![Page 63: Cell Membrane Structure and Function](https://reader035.vdocument.in/reader035/viewer/2022062218/568160df550346895dd00fa9/html5/thumbnails/63.jpg)
• _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________