BIOL 1000 Chapter Notes -Peripheral Membrane Protein, Lipid Bilayer, Fluid Mosaic Model

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ivorybeaver448

3 Jan 2014

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Cystic fibrosis occurs when the protein cftr has a mutation in genes, hampering its function. This transport protein carries negative chlorine ions out of cells (that are line the lungs and intestinal tract) towards the mucous. As a result, positive sodium ions follow then, water from the cells follow. If the lining is dry, then mucous can build up and prevent normal breathing. The mucous buildup can also give individuals bacterial infections. Plasma membrane is semi-permeable, allowing key components to enter cell and others to exit. 5. 1a- a membrane consists of proteins in a fluid of lipid molecules. Fluid mosaic model suggests the membranes consists of proteins within a mixture of lipid molecules. The proportions of lipids and proteins in a membrane depend on the type and main function of membrane. Eg mitochindrial membrane contains more protein because of electron transport. Internal and external side of membranes vary in function (membrane asymmetry)

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Part A

The ultimate problem with cholera that can lead to death is __________.

only water loss

fluid loss with electrolyte concentrations remaining normal

severe dehydration and electrolyte imbalance

only electrolyte loss

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Part B

The loss of chloride ions is occurring as a result of an continuously open __________, found in certain intestinal epithelial cells.

chloride channel protein

sodium pump

ATP dependent sodium/potassium pump

potassium pump

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Part C

The main purpose of the chloride channel proteins on the apical surface of the intestinal epithelial cells is to create an osmotic gradient that ultimately causes __________ to move through the intestinal epithelium and into the intestinal lumen to assist in the formation of mucus. These are the same chloride channel proteins, adversely affected in cystic fibrosis.

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Part D

The main physiologic mechanism used to control the opening of the chloride channel protein is through the use of __________.

G proteinâlinked receptors

potassium pump

enzyme-linked receptors

sodium pump

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Part E

The main factor that causes cholera is the overstimulation of __________ by the __________.

guanylate cyclase; the bacterium Vibrio cholerae

adenylate cyclase; the bacterium Vibrio cholerae

guanylate cyclase; cholera toxin

adenylate cyclase; cholera toxin

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Part F

The normal physiologic mechanism used by G proteinâlinked receptors is for a ligand to bind to the G proteinâlinked receptor; this in turn activates __________ located in the intracellular side of the plasma membrane, which eventually leads to the physiologic effector action.

diacylglycerol

inositol triphosphate

G protein

cyclic AMP

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Part G

Cholera toxin bypasses the normal sequential cascade of events involving G protein activation. The __________subunit of cholera toxin enters into the cell and directly activates __________. This leads to a non-physiologic (non-homeostatic) action of inappropriately maintaining the chloride channel proteins open. This causes excessive __________, sodium, and water to leave the intestinal epithelial cells.

A; G protein; chloride

B; G protein; chloride

B; inositol triphosphate; calcium

A; diacylglycerol; chloride

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Part H

A defect in the chloride channel protein, causing it to not open, will _________ the chloride, sodium, and water loss in cholera. However, it will also cause the individual to have __________ mucus.

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Part I

A drug that prevents the cholera toxin from attaching to the __________ in the intestinal epithelial cell could be a useful treatment.

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Part J

The best method to reduce the spread of cholera is to __________.

never travel to underdeveloped countries

provide properly treated water supplies

give everyone antibiotics

give everyone antacids

20. All living things must maintain a constantinternal environment to function properly through the process of__. (Points : 2)

metamorphosis
alkalosis
homeostasis
cryogenesis

Question 21.21. Glucose, fructose, sucrose,starch and glycogen are all examples of ___. (Points : 2)

proteins
carbohydrates
lipids
nucleic acids

Question 22.22. Some insects can "walk onwater" because __. (Points : 2)

water has a high surfacetension
water is adhesive
water istransparent
water expands when itfreezes

Question 23.23. To overcome an energy barrierbetween reactants and products in a chemical reaction, energy mustbe provided to get the reaction started. This energy is called ___energy. (Points : 2)

potential
reaction
initiation
activation

Question 24.24. Where in the cell doesglycolysis takes place? (Points : 2)

lysosomes
cytoplasm
mitochondria
nucleus

Question 25.25. Photosynthesis uses sunlightto convert water and carbon dioxide into __. (Points : 2)

carbon dioxide andwater
oxygen and sugars
proteins and sugars
carbon dioxide andoxygen

Question 26.26. The _____ of photosynthesisare the _____ of cellular respiration. (Points : 2)

electrons, protons
pigments, products
products, reactants
elements, atoms

Question 27.27. The energy currency of thecell is __. (Points : 2)

glucose
ATP
starch
glycogen

Question 28.28. When blood glucose levelsdecrease (as between meals), what reserves are tapped first?(Points : 2)

glycogen
fats
steroids
amino acids

Question 29.29. When glucose is used as anenergy source, the largest amount of ATP is produced by the ____portion of the entire respiratory process. (Points : 2)

glycolytic
Kreb's cycle
acetyl-CoAformation
electron transportchain

Question 30.30. Pyruvic acid can be regardedas the end product of ____. (Points : 2)

glycolysis
fermentation
the Kreb cycle
the electron transportchain

Question 31.31. How can one increase the rateof a chemical reaction? (Points : 2)

Increase the activationenergy.
Cool the reactants.
Decrease the pH.
Add an enzyme(catalyst).

Question 32.32. A prokaryote has ___. (Points: 2)

membrane-boundorganelles
nucleus
mitochondria
a cell membrane

Question 33.33. Unlike animal cells, plantcells have __. (Points : 2)

cell membranes
cell walls
chromosomes
mitochondria

Question 34.34. Which of the followingrequires energy to move molecules across the cell membrane? (Points: 2)

diffusion
osmosis
active transport
passive transport

Question 35.35. The ___ is the site of proteinsynthesis. (Points : 2)

nucleus
ribosome
mitochondrion
cytoskeleton

Question 36.36. Diffusion of water through asemipermeable membrane is called __. (Points : 2)

osmosis
diffusion
active transport
passive transport

Question 37.37. Which component of a cellmembrane is likely to function as a transporter? (Points : 2)

cholesterol
lipids
proteins
carbohydrates

Question 38.38. If potato slice is placed indistilled water, the cells would most likely __. (Points : 2)

lose water and becomelimp
neither take up water orlose water
take up water andswell
transport water into thecell by active transport.

Question 39.39. The chloroplast functions in___. (Points : 2)

protein synthesis
lipid storage
DNA replication
photosynthesis

Question 40.40. The fluid mosaic modelpresents the modern view of ___. (Points : 2)

the cell membranestructure
chromosome movementduring mitosis
protein synthesis
ATP production

Question 41.41. During which stage of mitosisdo nucleoli reappear and the nuclear membrane reforms? (Points :2)

prophase
metaphase
anaphase
telophase

Question 42.42. During which stage of mitosisdo chromatids separate to form two sets of daughter chromosomes?(Points : 2)

prophase
metaphase
anaphase
telophase

Question 43.43. Which of the following is thelongest stage of mitosis? (Points : 2)

prophase
metaphase
anaphase
telophase

Question 44.44. When during the cell cycle isDNA replicated? (Points : 2)

metaphase
Synthesis phase (S)
G1
cytokinesis

Question 45.45. A cell with 10 chromosomesundergoes mitosis and cell division. How many daughter cells areproduced and what number of chromosomes do they have? (Points :2)

4 daughter cells, 20chromosomes each
4 daughter cells, 5chromosomes each
2 daughter cells, 10chromosomes each
2 daughter cells, 5chromosomes each

Question 46.46. Maize (corn) has a haploidnumber of 10. How many chromosomes are in a zygote of maize?(Points : 2)

5
10
20
Not enough informationprovided

Question 47.47. Crossing over is one of themost important events in meiosis because __. (Points : 2)

homologous chromosomesare separated into different daughter cells
the number of chromosomesallotted to each daughter cell must be halved
sister chromatids must beseparated into different daughter cells
it produces new arrays ofalleles on chromosomes and contributes to genetic diversity

Question 48.48. While viewing stained onionroot tip cells you notice that distinct chromosomes cannot beobserved in most of the cells. This is because most of the cells___. (Points : 2)

were killed whilepreparing the slide
are in Interphase
are in metaphase
are undergoingMeiosis

Question 49.49. Each offspring cell producedby binary fission contains __. (Points : 2)

half the chromosomes ofthe original cell
twice as many chromosomesas the original cell
an independent assortmentof the original cell's chromosomes
an identical copy of theoriginal cell's chromosome.

Question 50.50. A DNA strand has the sequenceA-C-A-G-C-C-G-T-A. What would be its complementary strand? (Points: 2)

G-T-G-A-T-T-A-C-G
A-C-A-G-C-C-G-T-A
T-G-T-C-G-G-C-A-T
U-G-U-C-G-G-C-A-U

erinmoose680

Class 6: Viruses (and Cells, continued)

Making connections: viruses and microbes Match the cell biology concept (on page 1) with an important application of that concept (on page 2). Then answer the follow-up questions at the bottom of page 2.

Cell Biology concepts
1. Bacteria that cannot construct new cell wall material become fragile and break down.
2. During influenza infection, the viral enzyme neuraminidase is required to release new viruses from the host cell in which they were made. Once released, the new viruses can infect many additional cells.
3. Thermus aquaticus is a bacterium found in hot springs and can live at temperatures up to ~80Â°C (175Â°F). It has adapted so that its enzymes are most functional at the elevated temperatures, compared with many organismsâ enzymes that function best ~37Â°C (98Â°F).
4. Until the isolation and investigation of retroviruses, scientists thought that RNA could be copied from DNA, but DNA could not be copied from RNA. Research on this class of viruses led to an update to this âCentral Dogmaâ of biology.
5. Some bacteria have adapted, so that the enzymes involved in making cell wall materials have a slightly different shape and can no longer be bound by certain drugs.
6. Rhizobia are bacteria that colonize the roots of certain plants (legumes, including beans and peas). The host plant benefits from the prokaryotesâ ability to âfixâ nitrogen, converting N2 from the atmosphere into a form that is usable by the plant.
7. Many species of bacteria contain the enzyme cellulase. More than 10 billion such bacteria and other symbiotic microbes may be found in a single milliliter of material from inside the digestive system of ruminant mammals.
8. Fungi, including those that cause athleteâs foot, use ergosterol to maintain healthy membranes. Animal cells do not make ergosterol, they use a similar lipid â cholesterol.
9. During retrovirus infection, a DNA copy is made of the virusâs RNA genome. A cut is made in the host cellâs DNA and the DNA copy of the viral genome is pasted into the host chromosome by a viral enzyme called integrase.
10. Prokaryotic cells contain smaller ribosomes (â70Sâ ribosomes) than eukaryotic cells (â80Sâ ribosomes). Both types of ribosomes synthesize proteins, but the macromolecules they use to do it are somewhat different.

2
Applications
_______ Oseltamivir, also called Tamiflu, binds and inhibits the viral protein neuraminidase.
_______ Clotrimazole is a drug that is used to treat certain infections. It interferes with synthesis of ergosterol, a lipid involved in phospholipid membranes.
_______ Penicillin is a drug that interferes with synthesis of peptidoglycans (these are biological molecules that are part protein and part carbohydrate) that are present in certain cell walls.
_______ HIV is often treated with several drugs that inhibit different parts of the viral replicative cycle. Raltegravir is an example of a drug that interferes with the integration of viral genes into the host cellâs chromosome.
_______ Cows, like other vertebrates, lack the ability to breakdown cellulose. Yet they are able to live on a diet of grass and other vegetation high in cellulose.
_______ Enzymes isolated from extremophiles have been very useful in laboratory research. For example, Taq polymerase facilitates PCR, a revolutionary technique for production of DNAs of particular sequences, which requires cycling reactions through high temperatures.
_______ Plants and animals require nitrogen to make biological macromolecules, however theyâre unable to convert atmospheric nitrogen (N2) into a biologically useful form.
_______ Azithromycin is a drug that binds to 70S ribosomes and blocks synthesis of any new proteins.
_______ Methicillin-Resistant Staphylococcus aureus (MRSA) can cause life-threatening infections of the skin and bloodstream. One of the reasons MRSA infections are so serious is that they are resistant to treatment by many antibiotics, including methicillin and penicillin.
_______ The enzyme reverse transcriptase, isolated from retroviruses, is an important tool in molecular biology research. Scientists interested in learning what genes are turned on in particular cells use it to make DNA copies of RNAs they are studying (The DNA copies are useful because they are more stable).

When you have completed the matching activity, answer these follow-up questions:
â¢ What types of infections can be treated with the following drugs?
o Penicillin
o Clotrimazole
o Azithromycin
o Tamiflu
o Raltegravir
â¢ Why are these drugs (above) safe for you to take? That is, why donât they kill your cells?
â¢ Cancer cells are your own human cells that have become deregulated so that they divide and pile up in an uncontrolled way. Many chemotherapy drugs treat cancer by interfering with cell division and other cell processes.
o Why are there so many more side effects for individuals undergoing chemotherapy than for individuals taking antibiotics?

BIOL 1000 Chapter Notes -Peripheral Membrane Protein, Lipid Bilayer, Fluid Mosaic Model

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