BIOL 1202 Lecture Notes - Lecture 27: Hans Christian Gram, Gram Staining, Magnetotaxis

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4 Sep 2018

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The organisms that make up the two prokaryotic domains (bacteria and archaea) were the first organisms to arise on earth (about 3. 5 billion years ago). Most prokaryotes range in size from 0. 2-5. 0 micrometers in diameter (see fig 27. 2). The thickness of a dime is about 1 millimeter (1000 micrometers). The two domains appear similar in many respects however they are different in some very basic ways: one main distinction between the bacteria and the archaea is the type of a semi- rigid permeable cell wall. This bacterial cell wall is composed of peptidoglycan: peptidoglycan is a type of polymer in bacterial cell walls consisting of modified sugar cross-linked by short polypeptides. While only about 5000 prokaryotic species have been described, there may be as many as 100-1000 times that number. The cell wall of a bacterium gives characteristic shapes (see fig. 27. 2: bacilli, cocci, spirilla, these are some shapes, but there are many variations of these basic shapes.

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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.

1. Deep sea thermal vents are characterized by extremepressures, very high water temp (exceeding 100 celsius) and veryhigh concentrations of minerals. What type of prokaryotic organismsare most likely to be found there and why?

Archaea; tetraethers are morethermally stable.

Archaea; the partial membranessurrounding the DNA provide more protection.

Bacteria; the peptidoglycans in thecell walls keep them from overheating.

Bacteria; they use the energy from the minerals to power theirchloroplasts.

2. Farmers often practice crop rotation to help enrichagricultural fields. Why are beans and other legumes often used inthe rotations?

Legumes remove toxins from thesoil.

Less carbon dioxide.

Bacteria in legume root nodules arenitrifiers.

Legumes enrich the soil by formingheterocysts.

Beans fix nitrogen.

3. The fungus Penicillium produces a compound thatblocks peptidoglycan assembly. Why is a fungus trying to killbacteria?

The compound produced by the fungusis used for nitrogen fixation, the antibacterial properties areaccidental.

The fungal compound is produced inresponse to a bacterial invasion of the fungal hyphae.

Fungi and bacteria are bothdecomposers and compete for resources.

Fungi eat bacteria.

4. If Chlamydia is often asymptomatic, why is it necessary totreat it?

Pelvic inflammatory disease is apotential complication and can render women sterile.

Tertiary chlamydia causesneurological problems.

Chlamydia infection is a major riskfactor for cervical cancer.

Vertical transmission of chlamydia causes birth defects.

5. A mutant strain and the wild-type have different growthrequirements, they are given below.

Wild-type growth factors: A,B,C,D
Mutant growth factors: A,B,C,D,E

Select all the true statements concerning this situation.

It is possible to formulate a mediathat will allow the mutant to grow but not the wild-type.

A minimal medium will allow themutant to grow.

The mutant is auxotrophic.

Replica plating would be used toidentify the mutant.

An early stop codon may have occurred in the mutant.

6. Cell X has 45% adenine in it's genome and a thickpeptidoglycan cell wall. It is most likely a(n)

cyanobacteria

fungal endospore

low CG Bacteria

thermophilic archaean

actinobacteria

7. Are transformation and transduction the same process?

No; only transformation passes ongenes for pathogenicity.

Yes; they both involve theacquisition of viral genes.

Yes; both processes transferspecific gene products to a specific bacterium.

No; although both involve gene transfer the sources of thegenetic material differ.

8. In terrestrial environments, nitrogen fixation only occurs insoils. Why is this the case?

	Free oxygen acts and atranscription inhibitor of nif genes.
	The enzymatic activity of thenitrogenase complex is inhibited by oxygen.
	UV-radiation denatures thenitogenase enzyme complex.
	nif genes are sensitive tolight.

raspberrylouse321

__________ are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location.

Lysosomes

Endosomes

Peroxisomes

Nucleosomes

Biologists cannot possibly study all living species. Instead, they try to understand cell behavior by studying a select subset of them. Which of the following characteristics are useful in an organism chosen for use as a model in laboratory studies?

rapid rate of reproduction

all of the above

ability to grow under controlled conditions

amenability to genetic manipulation

By definition, prokaryotic cells do not possess __________.

ribosomes.

a nucleus.

membrane bilayers.

replication machinery.

Cell biologists employ targeted fluorescent dyes or modified fluorescent proteins in both standard fluorescence microscopy and confocal microscopy to observe specific details in the cell. Even though fluorescence permits better visualization, the resolving power is essentially the same as that of a standard light microscope because the resolving power of a microscope is limited by the __________ of light.

intensity

absorption

wavelength

filtering

Choose the phrase that best completes this sentence: Microtubules ____________ and are required to pull duplicated chromosomes to opposite poles of dividing cells.

generate contractile forces

can rapidly reorganize

are found in especially large numbers in muscle cells

are intermediate in thickness

Despite the differences between eukaryotic and prokaryotic cells, prokaryotes have proteins that are distantly related to eukaryotic actin filaments and microtubules. What is likely to be the most ancient function of the cytoskeleton?

cell division

cell motility

vesicle transport

membrane support

DNA and RNA are different types of nucleic acid polymer. Which of the following is true of DNA but not true of RNA?

It contains thymine.

It has 5'-to-3' directionality.

It is single-stranded.

It contains uracil.

Double covalent bonds are both shorter and stronger than single covalent bonds, but they also limit the geometry of the molecule because they ____________________.

prevent additional bonds from being formed with the bonded atoms.

limit the rotation of the bonded atoms.

create a new arrangement of electron shells.

change the reactivity of the bonded atoms.

Drosophila melanogaster is a/an __________. This type of animal is the most abundant of all animal species, making it an appropriate choice as an experimental model.

mammal

amphibian

bird

insect

10.

If the isotope 32S has 16 protons and 16 neutrons, how many protons, neutrons, and electrons will the isotope 35S have, respectively?

16, 19, 17

16, 19, 15

16, 19, 16

16, 20, 15

11.

Living systems are incredibly diverse in size, shape, environment, and behavior. It is estimated that there are between 10 million and 100 million different species. Despite this wide variety of organisms, it remains difficult to define what it means to say something is alive. Which of the following can be described as the smallest living unit?

cell

organelle

protein

DNA

12.

Macromolecules in the cell can often interact transiently as a result of noncovalent interactions. These weak interactions also produce stable, highly specific interactions between molecules. Which of the factors below is the most significant in determining whether the interaction will be transient or stable?

the concentration of each molecule

the size of each molecule

surface complementarity between molecules

the rate of synthesis

13.

Many of the mechanisms that cells use for maintenance and reproduction were first studied at the molecular level in bacteria. Which bacterial species had a central role in advancing the field of molecular biology?

E. coli

S. pombe

C. elegans

D. melanogaster

14.

Many types of cells have stores of lipids in their cytoplasm, usually seen as fat droplets. What is the lipid most commonly found in these droplets?

cholesterol

isoprene

triacylglycerol

palmitic acid

15.

Mitochondria contain their own genome, are able to duplicate, and actually divide on a different time line from the rest of the cell. Nevertheless, mitochondria cannot function for long when isolated from the cell because they are __________________.

anaerobes.

viruses.

parasites.

endosymbionts.

16.

Mitochondria perform cellular respiration, a process that uses oxygen, generates carbon dioxide, and produces chemical energy for the cell. Which answer below indicates a correct pairing of material âburnedâ and the form of energy produced during cellular respiration?

17.

Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei. Which one of these molecules contains polar bonds?

BIOL 1202 Lecture Notes - Lecture 27: Hans Christian Gram, Gram Staining, Magnetotaxis

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