BIOL 1000 Chapter Notes - Chapter 5&8: Lipid Bilayer, Signal Transduction, Semipermeable Membrane

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6 Apr 2019

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Chapter 5 cell membrane & chapter 8 (back of textbook) cell communication: It is asymmetric in that the phospholipids, proteins and other components that make up each side of the bilayer are different: the different phospholipids, proteins, etc. have different functions. Integral (within cell membrane) and peripheral (outside cell membrane) Important for transport, enzymatic activity, signal transduction, recognition, and attachment: carbohydrates, on the outside linked to lipids (glycolipids), or linked to proteins (glycoproteins) Fluid mosaic model: membranes must be fluid, but not too fluid, mosaic because of the variety of proteins, as well as lipids and carbohydrates. Fluid because the lipids and proteins can generally flow freely: fluidity is affected by, temperature. High temperature = high fluidity as molecules are high energy. Low temperature = low fluidity as molecules are low energy: the abundance of saturated and unsaturated fatty acids. High % of saturated fatty acids = low fluidity because of tight packing (no double bonds no kinks)

Related Questions

3. In an aqueous environment, the phospholipids of a membrane____.

a) are arranged in a single layer

b) are arranged in a bilayer with the polar heads of each layerlocated at the surface

c) are arranged in a bilayer with the fatty acid tails locatedat the surface

d) are arranged in a bilayer but the phospholipids have nospecific orientation

e) dissolve

4. which of the following molecules demonstrate dual solubilitycharacteristics

a) sterols only

b) proteins only

c) phospholipids only

d) sterols and phospholipids

e) sterols, phospholipids, and proteins

5. The "mosaic" part of the fluid mosaic model refers to themembrane ____.

a) proteins

b) phospholipids

c) cholesterol

d) functions

e) layers

9. Transport of a molecule across a cell membrane by facilitateddiffusion ____.

a) does not exhibit specificity for a particular type ofmolecule

b) requires the input of energy

c) depends on a concentration gradient

d) goes against the concentration gradient

e) allows non-polar uncharged molecules to diffuse across amembrane

13. A transport system in which transport of an ion in onedirection provides the energy for active transport in the oppositedirection is known as ____.

a) primary active transport

b) active diffusion

c) secondary active transport

d) cotransport

e) osmosis

14. Cells undergo exocytosis ____.

a) to pump protons down a concentration gradient

b) when replicating

c) to secrete protein and wastes from the cell

d) to ingest nutrients

e) as a means of cellular protection

15. What is the molecular basis of familialhypercholestremia?

a) HDL enters cells using a specific receptor on the cellsurface

b) LDL enters cells using a specific receptor on the cellsurface

c) HDL exits cells using a specific receptor on the cellsurface

d) LDL exits cells using a specific receptor on the cellsurface

e) receptor-mediated exocytosis

16. Carrier molecules are utilized for ____.

a) active transport only

b) passive transport only

c) both active and passive transport

d) osmosis

e) transport of all types of molecules

17. All of the following are functions of integral membraneproteins EXCEPT ____.

a) transport of polar molecules

b) reception of chemical signals form other cells

c) cell division

d) recognition of other cells as being "like"

e) cell-cell binding

olivecod348

Cholesterol is transported in the bloodstream in lipoproteinparticles. There are several classes of lipoprotein particles, butone of the most important classes is called Low-densitylipoproteins (LDL). LDL particles are composed of a single moleculeof a large protein called apolipoprotein, as well as thousands ofcholesterols molecules and phospholipids. Part of theapolipoprotein forms the surface of the particles and faces theaqueous phase, while other parts face the hydrophobic interior ofthe particle where they interact with cholesterol and thehydrophobic tails of the phospholipids. When cells need additionalcholesterol, they produce a receptor protein on the surface oftheir plasma membrane that binds to the apolipoprotein andinitiates the uptake of LDL particles into the cell via a processcalled endocytosis.

1. What is the likely reason that LDL particles are used totransport cholesterol in the blood stream?

a. Cholesterol in LDL particles easily inserts into lipidbilayers

b. Cholesterol id largely insoluble in aqueous solutions

c. Cholesterol is synthesized within LDL particles

d. LDL particles can form lipid rafts in the lipid bilayer

2. What is the most likely location of phospholipids in LDLparticles?

a. Bound to the hydrophilic domain of apolipoprotein

b. In the lipid bilayer that surrounds LDL particles

c. On the surface interacting with the aqueous environment aswell as interacting with the hydrophobic core of the particle

d. Within the hydrophobic core of the particle

3. What best describes the class of protein that apolipoproteinbelongs to?

a. Amphipathic proteins

b. Cell surface proteins

c. Membrane associated protein

d. Multipass membrane proteins

4. What kind of molecule on the surface of the cell would bemost likely to serve as a receptor for LDL particles?

a. a cholesterol binding protein

b. a glycolipid

c. a phospholipid

d. trans membrane protein

5. What conditions would be most likely to trigger increaseduptake of LDL particles by cells?

a. increased glycolipid synthesis

b. increased plasma membrane growth

c. increased protein secretion

d. increase protein synthesis

Are the following correct?

1. Which type of lipids do not make up a membrane?

a. Triglycerides <--

b. Glycerophospholipids

c. Sphingolipids

d. Chloesterol

2. A lipid bilayer becomes a membrane with the addition of _____.

a. Polar heads

b. Hydrophobic tails

c. Cholesterol

d. Proteins <--

3. A transporter protein has to have how many polar regions (minimum) on a hydropathy plot?

a. 3

b. 1-2 <--

c. 4

d. 0

4. Molecule X goes down its gradient molecule Y goes against its gradient using the same transporter. This is an example of ___ and ___ if they are both entering the cell.

a. Active, antiport <--

b. Active, symport

c. Facilitated, antiport

d. Facilitated, symport

5. Facilitated and active transport have all in common except _____.

a. Sigmoidal graphs

b. Ability to find Km

c. The use of ATP <--

d. Higher rates compared to diffusion

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BIOL 1000 Chapter Notes - Chapter 5&8: Lipid Bilayer, Signal Transduction, Semipermeable Membrane

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