MCB 3020 Lecture Notes - Lecture 5: Bacterial Cell Structure, Gram-Negative Bacteria, Periplasm

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rubyprairie-dog409

20 Feb 2017

School

University of Florida

Department

Microbiology and Cell Science

Course

MCB 3020

Professor

ashgari

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Document Summary

Enclosed membranes and membrane bound organelles- unique to eukaryotes. Prokaryotes do not have dna enclosed membrane- nucleoid holds dna in eukaryotes. Ribosome and cell wall of bacteria are antibiotic targets because they have different composition from eukaryotic cells. Glycocalyx- compound covering exterior of cell; not for all cells. Gram positive and gram negative- if bacteria has no cell wall cannot be differentiated as gram positive or negative. Envelope- includes cell wall and cell membrane in gram positive: cell wall is peptidoglycan- layers of polysaccharides reinforced by short peptides. N-acetylmuramic acid (nam: nam and nag are polysaccharides reinforced by peptide ridges (about 25 layers cover gram positive bacteria, techoic acid attached to cell wall structure- unique to g+ Has cell wall, membrane and peptidoglycan, but only about 5 layers of peptidoglycan. Gram neg have additional layer called outer membrane that covers cell wall. Periplasmic space- compartment between outer membrane and cell membrane.

Related Questions

26.The best microscopy technique for observing different subcellular structures on the surface of bacteria is

(A) SEM (B) TEM

(E) fluorescence microscopy

27.Which type of microscopy exploits differences in the refractive index of the specimen, where light is retarded by one-quarter of a wavelength when it passes through a bacterial cell?

(A) SEM (B) TEM

(E) fluorescence microscopy

28.Which type of microscopy should be used to examine bacterial cells that have been Gram stained?

(A) TEM (B) fluorescence microscopy

(E) bright-field microscopy

29.Which of the following is most abundant in a prokaryotic cell (in dry weight)?

(A) RNA (B) DNA

(E) Lipid

30.Which of the following techniques uses the Svedberg unit (S)?

(A) electron microscopy (B) ultracentrifugation

(E) sonication

31.Which of the following is NOT a function performed by the cell membrane or its components?

(A) production of proteins (B) detection of environmental signals

(E) B and D

32.Which of the following statement is true?

(A) Lipopolysaccharides (LPS) are found in the cell wall of Gram-negative bacteria.

(B) Lipopolysaccharides (LPS) are found in the cell wall of Gram-positive bacteria.

(D) Teichoic acids are found in the cell wall of Gram-positive bacteria.

(E) Cholesterol is found in the cell wall of Gram-negative bacteria.

33.Which of the following is found in Archaeabut not in Bacteria?

(A) Hopanoids (B) Terpenoids

(E) Peptidoglycan

34.The glycan chain of archaeal cell wall is made of __________ and __________, while the glycan chain of bacterial cell wall is made of __________ and __________.

(A) peptidoglycan and murein, pseudopeptidoglycan and murein

(B) N-acetylglucosamine and N-acetyltalosaminuronic acid,

N-acetylmuramic acid and N-acetyltalosaminuronic acid

N-acetylglucosamine and N-acetylmuramic acid

(D) N-acetylglucosamine and N-acetylmuramic acid,

N-acetylglucosamine and N-acetyltalosaminuronic acid

(E) N-acetylmuramic acid and N-acetyltalosaminuronic acid,

N-acetylglucosamine and N-acetyltalosaminuronic acid

35.The sacculus of bacteria is composed primarily of

(A) phospholipids (B) peptidoglycans

(E) nucleic acids

36.Lysozyme attacks the following linkage in the bacterial cell wall:

(A) Î²(1,4)-glycosidic bonds

(B) Î²(1,3)-glycosidic bonds

(D) Peptide cross-links between glycan chains

(E) Peptide bonds between L-alanine and D-glutamic acid

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.

37.The major function of the cell wall is

(A) to facilitate cell divison (B) to serve as a diffusion barrier

(E) to serve as an anchor for proteins

38.Penicillin and vancomycin prevent cross-bridge formation between

(A) diaminopimelic acid and D-glutamic acid (B) L-alanine and D-alanine

(E) D-glutamic acid and D-alanine

39.An outer membrane is found in

(A) all cells (B) all prokaryotes

(E) all Gram-positive bacteria

40.The complex of DNA polymerase with its accessory components is called

(A) nucleoid (B) nucleus

(E) setpum

41.Which of the following is the bacterial homolog of tubulin?

(A) FtsZ (B) MreB

(E) MinD

42.Which of the following is an actin homolog that helps maintain cell shape?

(A) FtsZ (B) MreB

(E) MinD

43.Which of the following is least involved in photosynthesis?

(A) phycobilisomes (B) thylakoids

(E) stalks

44.Capsule is composed of

(A) nucleic acids (B) lipoproteins

(E) murein

45.Pili and fimbriae are composed of

(A) nucleic acids (B) lipopolysaccharides

(E) amino acids

46.Which of the following subcellular structures is involved in adherence?

(A) gas vesicles (B) storage granules

(E) phycobilisomes

47.As temperatures drop, membrane fluidity decreases. Which of the following changes to phospholipids will help maintain correct bacterial membrane fluidity under cold temperatures?

(A) Formation of lipid monolayer.

(B) An increase in the length of the fatty acid tails.

(D) An increase in saturated fatty acids.

(E) A switch from ester linkages between fatty acids and glycerol to ether linkages.

48.Which of the following statements regarding chemotaxis is true?

(A) Attractants cause counterclockwise rotation of the flagella that makes the cells tumble

(B) Attractants cause clockwise rotation of the flagella that makes the cells run

(D) Attractants cause clockwise rotation of the flagella that makes the cells tumble

(E) None of the above is true.

49.With 5 g of NaCl available, how much water is needed to make a solution at a concentration of 10 mg/mL?

(A) 0.5 mL (B) 5 mL

(E) 5 L

50.How much of 1 M glucose stock solution is needed to make a 500-mL solution containing 25 mM glucose?

(A) 12.5 Î¼L (B) 125 Î¼L

(E) 1.25 L

MCB 3020 Lecture Notes - Lecture 5: Bacterial Cell Structure, Gram-Negative Bacteria, Periplasm

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