BIOL 102 Chapter Notes - Chapter 4: Proteome, Electron Microscope, Cytoskeleton

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6 Nov 2014

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Chapter 4: the principles and structure of cellular organization: explain the three important parameters in microscopy: resolution, contrast, and magnification. Magnification: ratio between size of an image of a specimen and its actual size. Resolution: ability to observe (resolve) two nearby objects. Contrast: ability of an image to stand out from its surroundings (can be enhanced using dyes: describe the major differences between light and electron microscopes. Creating and maintaining cell structure require: matter, energy, organization, and information. Proteome: proteins that are made in a particular time and under specific conditions (environment, the proteome is controlled by the genome. Plasma membrane: interior region contains hydrophobic hydrocarbon tails of fatty acids: explain what limits the size of prokaryotic cells, size of the cell is controlled by metabolic requirements, dna must be available to produce the enzymes and proteins needed for proper functioning, surface area to volume ratio.

Related Questions

What electron or light microscopy technique would you use toobserve the following?

a) the fine detail of the outer surface of hair cells in theinner ear.

b) the interior and exterior of surfaces of the plasma membraneto support the Fluid-Mosaic Model of membrane structure.

c) very thin cross sections made in Epon in order to visualizethe fine structure of cellular organelles and cell architecture inthe cell interior.

d) particulate matter (like large multisubunit enzyme complexesor viruses) so as to exhibit the subunit structure. Negativestaining.

e) specifically localize a molecule like tubulin in a cell usinga light microscope.

f) the highly organized structure at the molecular level of thespindle of a dividing cell using the lightmicroscope.

g) technique using lasers to optically section large specimens;the images may be computer-enhanced.

h) living cells without killing them by adding stain.

i) a three-dimensional view (almost bas-relief view)of chromosomes in a dividing cell.

j) living cells with high resolution and with extraordinarycontrast at extremely low light levels to keep the cells aliveduring the observation.

k) viewing poorly stained specimens by focusing light on thespecimen alone; the specimen stands out brightly against a darkerbackground

ceruleanfox955

Scenario 2:
You are trying to resolve the 3-dimensional organization of some sub-cellular organelle or protein distributed throughout the cytosol of a cell. The objects are typically organized spatially with sizes of ~0.5Î¼m diameters or separation. In this situation the sample can be fixed (i.e. no constraint on image time), but it may be advantageous to image live samples as well (i.e. some constraint on image time), so the ability to image each type of sample needs to be considered. Issues to consider include limits of 3-dimensional spatial resolution and ways to overcome this, including within live moving cells such as time and photodamage effects.

The scenario above describes commonly encountered problems in applying fluorescence microscopy to study biological samples. I would like you to discuss ways of overcoming the problems at hand.

The problems that needs to be overcome:

-What is the cause of the fundamental limitation(s) present in the problem when using a conventional fluorescence microscope system (wide field microscope or regular confocal microscope)? What are the tradeoffs (e.g. photobleaching, acquisition speed, spatial resolution, signal, noise and background, or other factors) that provide practical limitations?

-What type of optical imaging approach, technology or strategy could overcome these problems?

-What light source, optical detector, fluorophore and other key instrumentation/reagents will be needed and why? (you may want to provide specs for specific products where relevant).
-How will this strategy work and how will it generate new information about the object/process being studied: e.g. will fluorescence intensity be measured, or fluorescence lifetime, or scattering, some other property?

-What other limitations could there be in the approach planned? Can these also be minimized and how?

champagnesea-lion818

__________ 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 102 Chapter Notes - Chapter 4: Proteome, Electron Microscope, Cytoskeleton

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