BIOL 1000 Lecture Notes - Lecture 5: Aquaporin, Facilitated Diffusion, Exocytosis

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rubycrab690

2 Jul 2018

School

University of Manitoba

Department

Biological Sciences

Course

BIOL 1000

Professor

All

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Tuesday & Thursday , Feb 1 & 6, 2018

BIOL1000-THE WORKING OF THE CELL

5.1 MEMBRANES ARE FLUID MOSAICS OF LIPIDS AND PROTEINS WITH MANY

FUNCTIONS:

•The phospholipid bilayer and the membrane proteins form the fluid mosaic model of the cell

membrane where the fluid in the membrane helps the constituents to move around which is the

phospholipids and some proteins. Whereas, the mosaic ; the proteins dot surface like tiles in a

mosaic.

•The plasma membrane is semi-permeable which is it allows the flow of substances in and out

of the cell.

•There are many proteins which serve different functions such as: A)TRANSPORT PRO-

TEINS: they allow specific ions, molecules and materials to enter or exit the cell. B)EN-

ZYMES: some membrane proteins are enzymes, enzymes may be grouped to carry out se-

quential reactions. C)ATTACHMENT PROTEINS: attach to the extracellular matrix and cy-

toskeleton, help support the membrane and can coordinate external and internal changes.

D)RECEPTOR PROTEINS: signalling molecules bind to receptor proteins, they relay the

message by activating other molecules inside the cell. E)JUNCTION PROTEINS: form in-

tercellular junctions that attach adjacent cells. F)GLYCOPROTEINS: serve as ID tags, may

be recognized by membrane proteins of other cells.

5.2 PASSIVE TRANSPORT IS DIFFUSION ACROSS A MEMBRANE WITH NO ENERGY

INVESTMENT:

•Diffusion is the tendency of particles to spread out evenly in an available space.

•Diffusion across a cell membrane does not require energy, so its called passive transport.

5.3 OSMOSIS IS THE DIFFUSION OF WATER ACROSS A MEMBRANE:

•The diffusion of water across a selectively permeable membrane is called osmosis.

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Document Summary

Tuesday & thursday , feb 1 & 6, 2018. 5. 1 membranes are fluid mosaics of lipids and proteins with many. Functions: the phospholipid bilayer and the membrane proteins form the fluid mosaic model of the cell membrane where the fluid in the membrane helps the constituents to move around which is the phospholipids and some proteins. Teins: they allow specific ions, molecules and materials to enter or exit the cell. Zymes: some membrane proteins are enzymes, enzymes may be grouped to carry out se- quential reactions. C)attachment proteins: attach to the extracellular matrix and cy- toskeleton, help support the membrane and can coordinate external and internal changes. D)receptor proteins: signalling molecules bind to receptor proteins, they relay the message by activating other molecules inside the cell. E)junction proteins: form in- tercellular junctions that attach adjacent cells. F)glycoproteins: serve as id tags, may be recognized by membrane proteins of other cells.

Related Questions

Explain the cell theory; know the three basic tenets of the theory.

All cells have to carry out certain functions, what do all cells have in common?

Compare/contrast an Eukaryotic vs a Prokaryotic cell type.

Understand the concept of selective toxicity. What do all effective targets of an antimicrobial agent have in common? What are some characteristics of Prokaryotic cells that can be targeted?

Explain the unity and diversity of prokaryotic cells in terms of evolutionary theories.

Describe the three basic shapes (morphologies) of bacteria.

What are the functions of the plasma membrane, how does the structure of the plasma membrane aid in carrying out these functions?

Describe the fluid mosaic model of the plasma membrane. Draw out the plasma membrane, include the phospholipid bilayer (indicating polar/hydrophilic and nonpolar/hydrophobic components) and peripheral and integral proteins. Also indicate the intracellular (cytoplasmic) and extracellular regions.

What are the functions of the components of the plasma membrane? Phospholipids, proteins?

Transport. Compare/contrast the following mechanisms of transport in terms of the types of molecules transported, with or against the concentration gradient, if any Energy input is required, if a transport molecule is involved, and if Euk and or Prok use this mechanism.

Osmosis (explain the role of aquaporins)

Diffusion

Facilitated Diffusion

Active transport (proton motive force / ATP binding cassette system)

Group translocation

QUESTION 1

Which of the following statements about the bacterial cytoplasmic membrane is false?

	a.	It resists attachment of the bacterial chromosome to its inner surface.
	b.	It contains a protein complex that drives ATP synthesis.
	c.	It is asymmetric.
	d.	It consists of relatively equal amounts of phospholipids and proteins.

1 points

QUESTION 2

Which of the following statements regarding Mycobacteria is false?

	a.	The genome has relatively low Guanine (G) and Cytosine (C) content.
	b.	The cytoplasmic membrane is surrounded by a polymer (peptidoglycan) consisting of alternating N-Acetylglucosamine (NAG) and N-Acetylmuramic (NAM) acid units.
	c.	It infects approximately one-third of the global human population.
	d.	It has a Gram-positive cell wall with an additional waxy lipid layer of mycolic acid.

1 points

QUESTION 3

Which of the following outer membrane porins enables Mycobacteria to adapt to acidic and intracellular environments, and shows homology to outer membrane porin A?

	a.	OmpATb.
	b.	OmpA.
	c.	MspA.
	d.	Lipid A.

1 points

QUESTION 4

Based on your understanding of bacterial membranes, which of the following is not likely to be found in an E. coli outer membrane?

	a.	Membrane-anchored enzymes.
	b.	Mycolic acid.
	c.	Lipopolysaccharide.
	d.	Porin channels.

1 points

QUESTION 5

Based on the conclusions of this paper, which of the following statements would the author most likely disagree with?

	a.	Some archaeon do not contain all of the genes essential for life.
	b.	The membrane structures of prokaryotes show far greater diversity than those of eukaryotes.
	c.	As demonstrated in this definitive report, scientists have a great understanding of the majority of basic functions and evolution of bacterial membranes.
	d.	The outer membrane (and its associated components) of archaea, Gram-negative bacteria, and Gram-positive bacteria likely evolved independently of one another.

1 points

QUESTION 6

Which of the following is not true for Gram-negative, acid-fast, and archaeal membranes?

	a.	They modify their lipid content in response to environmental changes.
	b.	They have co-evolved the same outer membrane composition and structure.
	c.	They all have a cytoplasmic membrane.
	d.	Membrane transport proteins regulate nutrient uptake and waste removal.

1 points

QUESTION 7

Compared to Mycobacteria, Gram-negative bacterium contain:

	a.	More mycolic acid.
	b.	Pores of increased length.
	c.	Less peptidoglycan.
	d.	50-fold-lower numbers of porins.

1 points

QUESTION 8

Archaea are found to survive in strongly acidic lakes compared to bacteria and Eukaryotes. Which of the following supports this claim according to the study?

	a.	The presence of L-glycerol ether linked lipids in Archaea membranes.
	b.	The presence of D-glycerol ether linked lipids in Archaea membranes.
	c.	The presence of L-glycerol ester linked peptidoglycans in Archaea membranes.
	d.	The presence of L-glycerol ester linked lipids in Archaea membranes.

1 points

QUESTION 9

Based on your understanding of the symbiotic relationship between Nanoarchaeum equitans and Ignicoccus, which of the following below is not true?

	a.	The membrane lipids of N. equitans are synthesized by Ignoccocus.
	b.	In exchange for membrane lipids, N. equitans provide Ignicoccus with many essential cytoplasmic enzymes.
	c.	N. equitans lack enzymes capable of catalyzing lipid biosynthesis.
	d.	Intraperiplasmic vesicles produced by Ignicoccus allow for lipid transfer to N. equitans.

1 points

QUESTION 10

What is the role of hydrogen bonds in bacteria, as mentioned in the article?

	a.	They mediate transmembrane electron flow.
	b.	They mediate lipid biosynthesis.
	c.	They help to stabilize the cytoplasmic membrane.
	d.	They are responsible for the selective permeability of the cytoplasmic membrane.