How was it discovered http edtedcom lessonsinsightsintocellmembranesviadishdetergentethanperlsteinwatch The Plasma Membrane What is the plasma membrane Flexible sturdy barrier of the cell ID: 794809
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Slide1
A&P: The Cell
Slide2The Plasma Membrane
How was it discovered?
http://
ed.ted.com
/lessons/insights-into-cell-membranes-via-dish-detergent-ethan-perlstein#watch
Slide3The Plasma Membrane
What is the plasma membrane?
Flexible, sturdy barrier of the cell.
Fluid mosaic model: proteins float freely in sea of lipids.
Lipid bilayer: phospholipids, cholesterol, glycolipids.
Phospholipids are amphipathic (have both polar and nonpolar parts
)
Fluidity depends on double bonds in lipids, and amount of cholesterol
Slide4The Plasma Membrane
What is it made of?
Integral proteins extend through membrane-
nost
are
transmembrane
(go all the way through)
Peripheral proteins are not firmly imbedded in
membrane
Many of these proteins are glycoproteins (have carbohydrate groups)
Slide5The Plasma Membrane
What do the membrane proteins do?
Ion channels: pores which selectively allow ions in or out
Transporters: selectively move a substance in or out
Receptors: cell recognition site (binds to ligand)
Enzymes: catalyze reaction
Linkers: anchor to proteins inside or outside cell, or to proteins of neighbor cell
Cell Identity Marker- allows cells to recognize each other, tells identity.
Slide6The Plasma Membrane
Permeability
Permeability: the ability of substances to pass through
The plasma membrane is selectively permeable.
Permeable to nonpolar, uncharged molecules such as O2, CO2, steroids.
Impermeable to ions and large, uncharged polar molecules such as glucose.
Slightly permeable to small uncharged polar molecules such as water.
Slide7The Plasma Membrane
Gradients
Concentration gradient: difference in concentration of a substance inside and outside the cell.
Substances will move from area of high concentration to low.
Electrical gradient: difference in electrical charge. The inner surface of the membrane is negatively charged, the outside is positive.
Positively charged substances will move toward negative area, and vice versa.
Slide8Homework
Read pages 60-65. Do page 65 #1-7
Article (Sleep deprivation) summary due Friday. Include in your summary a personal angle (personal story about sleep, how reading the article changed/may change your sleeping habits,
etc
)
Slide9The Plasma Membrane
https://
www.youtube.com
/
watch?v
=kfy92hdaAH0
Slide10The Plasma Membrane
Passive Transport
no energy or ATP needed.
Substances move with gradient.
Osmosis, dialysis, facilitated
difuusion
are examples.
Facilitated diffusion involves proteins
Slide11The Plasma Membrane
Active Transport
Material is moved through the membrane using a protein carrier using ATP.
Examples: uptake of iodine into the thyroid, sodium/potassium pump.
Slide12https://
www.youtube.com
/
watch?v
=P-imDC1txWw
Slide13The Plasma Membrane
Endocytosis
Endocytosis needs ATP, and brings materials in by forming vesicles around large particles.
A lysosome will join with the vesicle to break down the particles.
Phagocytosis is intake of solids.
Pinocytosis is intake of liquids.
Slide14https://www.youtube.com
/
watch?v
=-ZFnO5RY1cU
https://
www.youtube.com
/watch?v=hacbn_xcZdU
Slide15The Plasma Membrane
Receptor mediated endocytosis
Receptor mediated endocytosis- molecules bind to receptors, a vesicle forms as the membrane sinks in
A lysosome joins with the vesicle, enzyme break down the substance so it can be absorbed.
The receptor returns to membrane.
Slide16The Plasma Membrane
Exocytosis
Exocytosis releases materials from the cell.
Secretory cells release enzymes, hormones, mucus.
Nerve cells release neurotransmitters.
Slide17http://science.education.nih.gov
/supplements/nih2/addiction/activities/lesson2_neurotransmission.htm
Slide18The Plasma Membrane
Homework: Read pages 69-74, do page 74 #12 and #15
Slide19Slide20Organelles and human disorders
Tay
-Sachs Disease
Inherited condition
Absence of Hex A (a
lysosomal
enzyme)
Hex A breaks down a membrane glycolipid found abundantly in nerve cells.
Effects: seizures, muscle rigidity, blindness, dementia, death
Slide21http://vimeo.com/
62446736
Lily
Foundation
Mitochondrial
Disease
Slide22Organelles and human disorders
Mitochondrial Disease
Results from failures of the mitochondria.
Less energy is generated for the cell.
Cell injury or death occurs.
Organs and organ systems may fail.
Symptoms include loss of motor control, muscle weakness/pain, gastrointestinal disorders, poor growth, cardiac disease, liver disease, vision/hearing problems, developmental delays.
Slide23https://www.youtube.com/watch?v=F8-Xg8sO5AM&list=PLio7GaXoQ3Sg14ms4m2wKJNLtawJ-
diBO
The Triumphant Story of Sam
Berns
,
Progeria
Slide24Organelles and Human Disorders
Progeria
Caused by a mutation for a protein (
Lamin
A) which is the structural scaffolding that holds the nucleus together.
This change in the protein makes the nucleus unstable, and leads to premature aging.
Symptoms include growth failure, loss of body fat and hair, stiffness of joints, heart disease/stroke.
Life expectancy is 14 years.
Slide25https://www.youtube.com/watch?v=Twjg7v-
pTO4
Current TV presents ‘Dying Young’
Slide26Organelles and human disorders
Cystic Fibrosis
Defect in protein channels in the cell membrane leading from certain glands.
The channel transports
Cl
- into and out of cells, controlling the movement of water.
Water is needed to thin the mucus.
Thick mucus in the lungs, leading to infection.
Clogged pancreas, prevents digestive juices from reaching intestines.
Salty sweat.
Slide27Continue the Tonicity Experiment
Homework: Read pages 74-84. Complete worksheet (glue into notebook). Also make sure notebook is ready for check.
Slide28Tonicity Lab is complete.
Homework: Complete the lab write-up. It should include:
Introduction paragraph (you did this Friday)
Data tables
Conclusion paragraph
Also: read pages 85-87, do page 86 #20-22
Slide29The nucleus
The structure of the nucleus
Large and spherical
Most human cells have a single nucleus
Exceptions: mature blood cells have none, skeletal muscles have several.
Nuclear envelope is a double membrane to separate the nucleus from the cytoplasm
Slide30The nucleus
The structure of the nucleus
Nucleoli are clusters of protein, DNA, and RNA inside the nucleus. The control the creation of the ribosomes.
Nuclear pores are
transmembrane
proteins that control the movement of molecules in and out of the nucleus.
Slide31The nucleus
The function of the nucleus
Controls cellular structure and directs cellular function.
Genes contain instructions for the cell structure and function- located on chromosomes.
Chromosomes are made of chromatin- a complex of DNA, proteins, and RNA.
Slide32http://www.dnalc.org/resources/3d/12-transcription-
basic.html
Transcription basic video
Slide33The nucleus
Transcription and Translation
Transcription
DNA and RNA store information as sets of three nucleotides called codons.
RNA polymerase catalyzes transcription of DNA.
Three types of RNA are made from the DNA template:
Messenger RNA (mRNA)- directs the synthesis of a protein.
Ribosomal RNA (
rRNA
)- joins with ribosomal proteins to make ribosomes
Transfer RNA (
tRNA
)- involved in protein synthesis.
Slide34http://www.dnalc.org/resources/3d/15-translation-
basic.html\
Translation basic video
Slide35The nucleus
Transcription and Translation
Translation
Ribosomes and
tRNA
use the sequence of the mRNA to assemble amino acids into proteins.
Steps:
Initiator
tRNA
with anticodon UAC attaches to the start codon AUG on the mRNA.
Large and small ribosomal subunits attach.
The next
tRNA
attaches to the next codon.
The large RNA subunit catalyzes the formation of a bond between the two amino acids.
The first
tRNA
detaches, the ribosome shifts down the mRNA. Steps 3-6 repeat.
Synthesis ends at the stop codon, the protein is freed and the ribosome detaches.
Slide36https://www.youtube.com/watch?v=
eWVuCDQKB5k
https://www.youtube.com/watch?v=
cZEPQ3kkwHo
https://
www.youtube.com
/
watch?v=LelFL9CrqQs
Slide37Recombinant DNA
Recombinant DNA
Recombinants
Genetic Engineering
DNA combined from different sources
Organisms with recombinant DNA
The manipulation of genetic material and creation of recombinants.
Medical uses: human proteins produced in bacteria in large quantities, then harvested and purified for distribution to patients.
Examples:
human growth hormone, insulin, interferon, and erythropoietin
Slide38Recombinant DNA
Restriction enzymes
Molecular tool used to cut DNA- cuts the DNA at a specific point.
Examples: Eco RI, Bam HI
Some restriction enzymes create “sticky ends”
DNA can be inserted- like a puzzle piece.
DNA ligase ligates (“glues) the pieces together.
http://www.hhmi.org/biointeractive/genetic-
engineering
Slide39Recombinant DNA
How does the engineered DNA get into the bacteria?
Antibiotic sensitive bacteria are treated with CaCl2.
Engineered DNA (which has both the gene wanted and also a gene for antibiotic resistance) is added, taken in by bacteria
Bacteria are grown on media containing the appropriate antibiotic.
Only the bacteria with the engineered DNA will grow.