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WK5 Cell Bio

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winniesmith's version from 2017-01-03 21:41

Section 1

Question Answer
What do phospholipids form in aqueous solutionsSpontaneously form bilayers, a stable barrier between two aqueous compartments.
How many types of phosopholipids do mammalian membranes have 5 major
What else do plasma membranes containglycolipids and cholesterol
In lipid bilayers how can molecules movefree to rotate and move laterally
What is membrane fluidity determined bytemperature and lipid composition (such as unsaturated fatty acids where the =bond results in kinks, increasing fluidity).
How does cholesterol influence membrane fluidity Ring structure, Interactions between the hydrocarbon rings and fatty acid tails makes the membrane more rigid. Cholesterol also reduces interaction between fatty acids, maintaining membrane fluidity at lower temperatures
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Section 2

Question Answer
When was the fluid mosaic model structure proposed By Singer and Nicolson in 1972.
Describe the fluid mosaic model Integral membrane proteins inserted into a phospholipid bilayer, with nonpolar regions in the lipid bilayer and polar regions exposed to the aqueous environment.
What are integral membrane proteinsembedded directly in the lipid bilayer.
What are peripheral membrane proteinsassociated with the membrane indirectly, generally by interactions with integral membrane proteins.
What are transmembrane proteins span the lipid bilayer, with portions exposed on both sides.
Structure of membrane-spanning proteins usually α-helical regions of 20 to 25 nonpolar amino acids. Or some proteins have a β-barrel, formed by folding of β sheets into a barrel-like structure. (In some bacteria, chloroplasts, and mitochondria).
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Section 3

Question Answer
Selective permeability allows what a cell to control its internal composition.
What can and cant diffuse through a bilayerSmall, nonpolar molecules can diffuse across the lipid bilayer: CO2, O2, H2O. Ions and larger uncharged molecules, such as glucose, cannot diffuse across.
What are channel proteins open pores across the membrane. They can be selectively opened and closed in response to extracellular signals
What are carrier proteins proteins that selectively bind and transport small molecules, such as glucose. They bind to specific molecules and then undergo conformational changes that open channels through which the molecule can pass.
What happens in passive transportmolecule movement across the membrane is determined by concentration and electrochemical gradients.
What happens in active transport molecules can be transported against a concentration gradient if coupled to ATP hydrolysis as a source of energy.
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Section 4

Question Answer
What is the systemic analysis of cell genomes calledgenomics
What is systems biology approacheeks to understand the integrated activities of cells at a global level.
What is a proteomeall of the proteins expressed in a given cell.
What does proteomics aim to do to identify all proteins expressed in a cell, where they are expressed, and their interactions
How many genes are expressed in any given cellapprox 10,000
How many different proteins are theredue to splicing and modification, estimated approx 100,000
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Section 5

Question Answer
What is 2D gel electrophoresis arge-scale separation of cell proteins.
In 2D gel electrophoresis how are proteins separated on charge and then size. This technique is biased toward the most abundant proteins.
Proteins can be excised from gels and identified by whatmass spectrometry
How does a mass spectrometer(ms) work? Step 1A protease cleaves the protein into small peptides.
How does a ms work? Step 2These are ionized and analyzed in a mass spectrometer, which determines the mass-to-charge ratio of each peptide. The mass spectrum is compared to a data base of known spectra.
How does a ms work? Step 3A “shot-gun” approach eliminates the gel electrophoresis.
How does a ms work? Step 4Cell proteins are digested with protease and the whole mixture sequenced by tandem mass spectrometry.
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Section 6

Question Answer
In proteomics how are proteins isolated by subcelluar fractionation
How do proteins function by interacting with other proteins in protein complexes and networks
How can protein complexes be analysedisolated from cells under gentle conditions so that protein complexes are not disrupted (then mass spectrometry). Screen for interactions in vitro. Genetic screens that detect interactions between pairs of proteins introduced into yeast cells (yeast two-hybrid method).
What have screen identified thousands of protein-protein interactions, which can be presented as maps that depict a network of interacting proteins within a cell.
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