Name the three major assumptions made by the "Cell theory". (i) The lipid membrane is composed of lipid molecules. Explain the principle of membrane formation highlighting the role of the physical properties of the lipids. (ii) Comparing dimensions and length scales is often a first step in an analysis. Give an approximate value for the thickness of a lipid bilayer and the linear length of a helical turn of a DNA double helix.

Name the three major assumptions made by the "Cell theory". (i) The lipid membrane is composed of lipid molecules. Explain the principle of membrane formation highlighting the role of the physical properties of the lipids. (ii) Comparing dimensions and length scales is often a first step in an analysis. Give an approximate value for the thickness of a lipid bilayer and the linear length of a helical turn of a DNA double helix.

Biology 2e

2nd Edition

ISBN:9781947172517

Author:Matthew Douglas, Jung Choi, Mary Ann Clark

Publisher:Matthew Douglas, Jung Choi, Mary Ann Clark

Chapter3: Biological Macromolecules

Section: Chapter Questions

Problem 2VCQ: Figure 3.23 Which categories of amino acid would you expect to find on the surface of a soluble...

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Researchers have discovered a new membrane protein that has three transmembrane domain αhelixes that span the lipid bilayer.a. If the lipid bilayer is 30 Å thick, what is the smallest number of amino acid residues thatcan be in each α-helixes for them to be long enough to span the bilayer?
Transmembrane portrudes on both sides. Integral protein is in the width of the bilayer and may portrude on one or both sides of the bilayer. Is Transmembrane Protein semi-similar to Integral Proteins? How can we tell the difference of the two?
Biological membranes are critical components of cells that allow compartmentalisation of cellular contents. The diagram shows a biological membrane comprised of a lipid bilayer with a single polypeptide integrated into the membrane and spanning the membrane seven times. What types of amino acids are likely present in the parts of the polypeptide chain labelled 1-7 and in the parts of labelled A-G? What is the name of the effect that forces the polypeptide to arrange itself like this within the lipid bilayer? Give an example of a type of molecule that can move freely across the lipid bilayer and explain why it can do so based on its chemical properties.
Distinguish between transmembrane proteins, integral proteins, and peripheral proteins. 7. Integral proteins are often found spanning the membrane of a cell or organelle. These proteins serve as channels for specific molecules to travel through the membrane, either into or out of the cell. Indicate on the picture of the integral protein where you would most likely find amino acids with hydrophobic R-groups. Next, indicate on the picture of the integral protein where you would most likely find amino acids with hydrophilic R-groups. Explain your reasoning.
Using the the enzyme acid hydrolase in the lysosome: What is the final destination in which the protein will function? Which features will the protein receive during its manufacture? What is the primary structure (general)? Where is the primary structure made? Where are the secondary and tertiary structures made? Will the protein travel through any organelles during its manufacture? Which ones? What would be the overall result if some part of the manufacture process went wrong, such that the protein ended up as nonfunctional?
Proteins may be bound to the exoplasmic or cytosolic face of the plasma membrane by way of covalently attached lip- ids. What are the three types of lipid anchors responsible for tethering proteins to the plasma membrane bilayer? Which type is used by cell surface proteins that face the external medium? By glycosylated proteoglycans?
Can you list two different ways in which nucleotides can carry energy and draw a diagram of the cross-section of a typical plasma membrane?
The plasma membrane of E. coli is about 75% protein and 25% phospholipid by weight. How many molecules of membrane lipid are present for each molecule of membrane protein? Assume an average protein Mr of 50,000and an average phospholipid Mr of 750. What more would you need to know to estimate the fraction of the membrane surface that is covered by lipids?
Create a figure that includes a schematic of the topological map of AlaE. In your topological map, label; a. the cytoplasm, periplasm and membrane, b. the start and end of each predicted transmembrane helix with the residue letter and number found there, c. the N- and C-termini. The amino acid sequence is 149 in length: MFSPQSRLRHAVADTFAMVVYCSVVNMCIEVFLSGMSFEQSFYSRLVAIPVNILIAWPYGMYRDLFMRAARKVSPSGWIKNLADILAYVTFQSPVYVAILLVVGADWHQIMAAVSSNIVVSMLMGAVYGYFLDYCRRLFKVSRYQQVKA
To get an idea of the different sizes of various cellular components, do the following calculations: Assume that the cell, its nucleus, and a globular protein – for example, and enzyme – are spherical. In addition, assume the diameter of the protein is 5 nm (nanometers), the diameter of the cell is 100 μm (micrometers), and the diameter of the nucleus is 40 μm. You may have to review your metric conversions! If you draw the globular protein as a sphere with a diameter of 2 cm (approximately the diameter of a U.S. penny), what size would each of the following measurements of the cell be if drawn to the same scale (5 nm real length = 2 cm)? a. The radius of a microtubule, 15 nm b. The diameter of the nucleus c. The diameter of the cell d. The volume (V = 4/3 ∏r3) of the globular protein, in decimal form to the hundredths place. e. The volume of the nucleus f. The volume of the cell
In the "fluid " _______ cell membrane model, lipids are organized in a ________ arrangement, such that _______ portions of the lipids are exposed to either the interior or exterior of the cell, while the lipid portions are sandwiched in the middle of the membrane. As part of the cell membrane, a main function of peripheral proteins is to provide _________ , while a main function of proteins is to provide _________ . Other cell membrane molecules include a compound called __________, which functions to provide fluidity to rigid membranes and rigidity to fluid membranes; and surface carbohydrates, which function in the membrane not to provide energy, but instead to provide _________ _____ . Aminophospholipids (including PE and ) move to the inner leaflet of the membrane, by an enzyme known as the ._______ A main function of the cell membrane is to be very selective as to what is able to cross through, a condition known as a barrier.
Explain three differences between alpha helix and beta pleated sheets or smooth endoplasmic reticulum and rough endoplasmic reticulum Please write down the differences of only one of the selected choice