BIOLOGY 253 Lecture Notes - Lecture 13: Membrane Fluidity, Membrane Lipids, Alpha Helix

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13 Jan 2017

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Saturated (max amount of hydrogens to a carbon) or unsaturated (less than maximum) Membrane lipids are amphipathic (hydrophilic and hydrophobic end) Cholesterol: membrane steroid that plays important role in membrane fluidity, :cool temp: maintains fluidity by preventing tight packing. Unsaturated fatty acid: fluid, fish (live in cold conditions) Larger u(cid:374)(cid:272)harged polar (cid:373)ole(cid:272)ules: e(cid:448)e(cid:374) harder, (cid:271)asi(cid:272)ally (cid:272)a(cid:374)"t get through. 3 principles of permeability: directly proportional to lipid solubility. Small molecules move through more easily than large molecules: prevented by electrical charge. Solute movements: concentration gradient, active transport, passive transport (protein is used, no energy required) Water moves from high concentration to low concentration. Mo(cid:448)e(cid:373)e(cid:374)t of protei(cid:374)s: pu(cid:373)ps (cid:894)o(cid:374)ly pu(cid:373)p (cid:449)hat it"s supposed to(cid:895), (cid:272)arriers (cid:894)(cid:374)eed to (cid:271)i(cid:374)d to (cid:272)argo a(cid:374)d transport across membrane, faster than a pump), channels (fast rate, passive transport because its moving down gradient) Limit to the speed of transport across the membrane. Example: tuberculosis infected pump, pumps out the antibiotic.

Related Questions

Which compartments are involved in vesicular transport? How are transport vesicles formed and targeted appropriately? What proteins are involved and what are their roles? What kinds of modifications are added to proteins in the ER? What determines whether a protein stays in the ER or moves on? Be sure to understand how vesicles fuse with their target membranes, and the consequences of fusion for the vesicleâs cargo as well as the proteins and lipids that are in the membrane. Know the structure of the Golgi apparatus and its role in intracellular trafficking. Understand the secretory process, endocytosis, exocytosis, function of the endosomes, and function of the lysosomes. Understand why endocytosis happens and how it can be regulated to take up specific molecules.

QUESTION 30

The function of centrosome is:

	1.	Microtubule initiation and organization in animal cells
	2.	Organization of thin filaments
	3.	Depolymerization of microtubules
	4.	Organization of intermediate filaments

2.5 points

QUESTION 31

The destinations of proteins synthesized on "free" ribomsomes include:

	1.	Endoplasmic reticulum
	2.	Nucleus
	3.	Mitochondria
	4.	Lysosomes

2.5 points

QUESTION 32

Microtubules can be assembled and disassembled quickly in response to the cellular changes is because:

	1.	Cells synthesize tubulin proteins very fast.
	2.	Cells can turn other cytoskeletal filaments into microtubules
	3.	Microtubules have an instable plus end and microtubules are probably organized by weak non-covalent interactions
	4.	The motor proteins of microtubules can organize the microtubules in response to the cellular changes

2.5 points

QUESTION 33

Both signal recognition particle and a translocon in rough endoplasmic reticulum membrane can recognize and bind to the signal sequence of a secretory protein, so they play the exact same role during protein co-translational translocation.

True

False

2.5 points

QUESTION 34

Rough endoplasmic reticulum is so named is because:

	1.	It has many proteins associated with its surface.
	2.	It has ribosomes associated with its cytosolic surface.
	3.	It is associated with nuclear membrane.
	4.	It has vesicles budding off its surface.

2.5 points

QUESTION 35

The membrane vesicles that transport materials between membrane compartments have a protein coat. The protein coat has similar functions in different vesicles. These functions include:

	1.	Help the enclosed material fold correctly.
	2.	Help degrade the protein in the vesicles
	3.	Maintain the internal pH of the vesicles
	4.	Function as mechanical device to form a vesicle and select the components to be carried by a vesicle.

2.5 points

QUESTION 36

Lysosomes are important for:

	1.	Receptor-mediated endocytosis.
	2.	Breaking down foreign particles brought into the cells by endosomes
	3.	Regulating the process of organelle turnover.
	4.	Protein trafficking between membrane compartments

2.5 points

QUESTION 37

Which of the following is correct about membrane biosynthesis?

	1.	Membranes are synthesized in Golgi Complex.
	2.	Membranes arise from preexisting endoplasmic reticulum membranes.
	3.	Membranes are synthesized on ribosomes.
	4.	Membranes of all organelles have the same composition of proteins and lipids, since they all originate from endoplasmic reticulum.

2.5 points

QUESTION 38

During skeletal muscle contractions, the shortening of the muscle fibers is because of:

		The shortening of the thin and thick myofilaments.
		The shortening of the cytoskeletal filaments.
		The kinesin proteins moving over microtubules.
		The actin and myosin filaments sliding over each other.

2.5 points

QUESTION 39

The assembly and disassembly of microtubules is regulated by rate of growth and shrinkage of the plus end.

True

False

2.5 points

QUESTION 40

The functions of Golgi complex include:

	1.	O-linked oligosaccharides and most of a cellâs complex polysaccharides are assembled in Golgi complex
	2.	Cis Golgi complex sorts proteins
	3.	Trans Golgi complex segregates proteins in different types of vesicles for dilevery.
	4.	N-linked oligosaccharides are further processed in Golgi complex

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BIOLOGY 253 Lecture Notes - Lecture 13: Membrane Fluidity, Membrane Lipids, Alpha Helix

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