BIO 121 Lecture Notes - Lecture 9: Organelle, Cytosol, Fluid Mosaic Model

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lilacgoose335

15 Feb 2017

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Bio 121 - week 5 lecture 9 (cont. ) The two major plasma membranes molecules are phospholipids and proteins. Short carbohydrate chains may attach the phospholipids, forming ____and to the proteins, forming __________. ____________- may be interspersed among the phospholipids. Phospholipids contain a hydrophobic tail and a hydrophobic head (phosphate group) This arrangement leeps the hydrophobic tails out of contact with water and the hydrophilic heads in contact with water (the fluid inside or outside the cell) Peripheral proteins attach to either the outside or inside of the membrane, form the outside or inside of the cell. Integral proteins span across the entire membrane, from the outside to the inside of the cell. Plasma membranes are described as fluid mosaics: membranes are a mosaic of proteins embedded among phospholipids, membranes are fluid because the proteins and phospholipids drift laterally within the membrane. The nucleus is a eukaryotic cell"s control center . A double membrane surrounding the nucleus, lined with pores: dna.

Related Questions

1. The plasma membrane of liver cells contains a glucose uniportthat transports glucose by facilitated diffusion. When the[glucose] is higher inside the liver cell than the [glucose]outside the liver cell, the glucose uniport will

A. couple the transport of glucose out of the cell to thehydrolysis of ATP

B. couple the transport of glucose into the cell to thehydrolysis of ATP

C. switch to a closed conformation, allowing no transport ofglucose

D. transport glucose out of the cell by passive transport

E. transport glucose in of the cell by passive transport

2. Unlike the positive charged ion shown in the middle diagramof figure 11-4B, K+ is higher in concentration inside the cell. Howwill the membrane potential of a cell at rest (shown in both themiddle and right-hand diagrams of Figure 11-4B) affect theelectrochemical gradient for K+?

A. The membrane potential will increase the electrochemicalgradient

B. The membrane potential will decrease the electrochemicalgradient

C. The membrane potential will have no effect on theelectrochemical gradient

3. Which of the following proteins carries out activetransport?

A. gluclose symport

B. Bacteriorhodopsin

C. ABC transporter

D. NA K pump

E. All of the above

4. Aquaporin will not transport Na+ ions because

A. Two asparagine residues in the channel prevent the passage ofNa+ ions by binding the oxygen of each water molecule as it passesby

B. Na+ ions are repelled by the positive charges at the entranceto the channel

C. Na+ ions cannot make contact with the carbonyl (C=O) groupson all four sides of the channel

D. The passage of Na+ ions is energetically unfavorable becauseone side of the channel is hydrophobic in nature

5. The acetylcholine receptor is different from other channelproteins we have discussed, such as the K+ leak channel,because

A. The acetylcholine channel is composed of a single polypeptiderather than multiple subunits

B. The acetylcholine channel transports Na+ ions against theconcentration gradient for sodium

C. The acetylcholine channel has a much smaller diameter thanother channel proteins

D. The acetylcholine channel transports ions with theirassociated shell of water molecules

E. The acetylcholine channel is always open, and never switchesto a closed conformation

6. After opening briefly along the axon of a neuron,voltage-gated ion channels switch to an inactivated conformationthat slowly returns to the original closed conformation of theprotein. This slow change in conformation, requiring about amillisecond, is important because

A. all of the ions that were transported across the membranewhen the ion channels were open must be actively transported backto the other side of the membrane, restoring the originalconcentration gradient, before the ion channels can open again

B. ATP hydrolysis is necessary to drive this energeticallyunfavorable change in conformation

C. it prevents the action potential from reversing direction andtraveling back toward the cell body of the neuron

D. the channel protein must be dephosphorylated in order tocomplete the transport process and return to the originalnonphosphorylated conformation

limeelephant476

Question 1

Which of the following provides the best description of adifference between prokaryotic and eukaryotic cells?.l.14.3>

The cell membrane of prokaryotic cells contains proteins, whilethe cell membrane of eukaryotic cells contains only lipids andcarbohydrates.

The DNA in eukaryotic cells is enclosed in the nucleus, whilethe DNA in prokaryotic cells is not separated from the rest of thecellÃ¢â¬â¢s contents.

Eukaryotic cells have cell walls that consist mainly of sugars,while prokaryotic cells do not.

Prokaryotic cells contain chloroplasts and mitochondria, whileeukaryotic cells do not contain specialized organelles.

Question 2

Cellular respiration is a process involving the breakdown ofglucose molecules in order to generate energy for cellularactivities. Given the general reaction below, which of thefollowing best describes the products labeled x andy?

C₆H₁₂O₆ + O₂ Ã¢â â _x___+ __y___ + energy.l.18.8>

The products are CO (carbon monoxide) andH₂O₂ (hydrogen peroxide), which thendecompose into carbon dioxide (CO₂) and water(H₂O).

The products are H2O (water) and CO₂ (carbondioxide), which then undergo anaerobic respiration.

The products are CO₂ (carbon dioxide) andH₂O (water), which then become the reactants forphotosynthesis.

The products are O₂ (oxygen) and H₂O(water), which are then used for growth and to keep the organismhydrated.

Question 3

If a researcher added a quantity of phospholipid molecules to abeaker of water, what would be most likely to happen to theorientation of the phospholipid molecules?.l.14.2>

They would break apart, and the remaining lipid tails wouldfloat up and form a layer on the surface of the water.

Their lipid tails would align within a spherical double layerwith their phosphate heads in the water inside and outside thesphere.

They would form a single-layered sphere with the phosphate headspointing outward and the lipid tails pointing inward.

Their lipid tails would adhere to the glass of the beaker andtheir phosphate heads would float in the water.

Question 4

While looking at a cell under a microscope, a scientist is ableto see a biological molecule. This molecule is a nucleic acid witha ladder structure and contains the nitrogenous bases adenine,thymine, cytosine, and guanine. Based on this information, whatconclusion can the scientist draw regarding this nucleicacid?.l.18.1>

The nucleic acid is RNA and would be found in the cellÃ¢â¬â¢snucleus.

The nucleic acid is RNA and would be found in the cytoplasm.

The nucleic acid is DNA and would be found in the cytoplasm.

The nucleic acid is DNA and would be found in the cellÃ¢â¬â¢snucleus.

Question 5

Which of the following is needed for cellular respiration tooccur?.l.18.8>

Sodium

Oxygen

Water

Nitrogen

Question 6

What would be the most likely effect if the side chain of an aminoacid group was unable to vary its structure?.l.18.4>

The organism would not be able to make and store starches.

The organism would not be able to process glucose moleculeseffectively.

The organism would not be able to regulate the creation ofspecialized cells.

The organism would not be able to make more than one type ofprotein.

Question 7

During photosynthesis, unused oxygen atoms form oxygen gas(O₂) which is released as a waste product. How did theseoxygen atoms originally enter the plant?.l.18.7>

They were part of the ATP molecules gathered by thechloroplasts.

They were part of the sugar molecules(C₆H₁₂O₆) the plant brought in forfood.

They were part of the carbon dioxide (CO₂) moleculesthat entered through the leaves.

They were part of the water molecules (H₂O) pulled inthrough the roots.

Question 8

Which of the following organelles houses DNA in eukaryoticcells?.l.14.3>

Endoplasmic reticulum

Golgi apparatus

Nucleus

Mitochondrium

Question 9

M. J. Schleiden shifted the scientific community's attention tocellular processes with his.l.14.1>

attention to disproving spontaneous generation

publication of ideas on cell generation

theories on the division of cells

claim that cells were the basic unit of all plant matter

Question 10

While the average human is able to hold his or her breath forapproximately one minute, a whale can dive for over 30 minuteswithout returning to the surface. Which of the following correctlydescribes this difference?.l.18.10>

Whales need less energy than humans.

Whales gather energy from their environment better thanhumans.

Whales are able to tolerate the products of cellular respirationbetter than humans.

Whales have a slower cellular respiration metabolism rate thanhumans.

Question 11

What can you conclude about the advantage of the cell membranehaving hydrophobic ends in the phospholipid bilayer?.l.18.3>

The cell requires the ability to digest and eliminateenzymes.

The cell requires a barrier between itself and itsenvironment.

The cell requires a means to store starches and glucose.

The cell requires a structure for eliminating waste.

Question 12

What would be the most likely outcome if the ribosomes of a cellwere damaged and stopped functioning?.l.14.3>

The cell would lose structure and shape.

Cell growth and repair would slow or stop.

Cell waste would no longer be processed.

The cell would produce more mitochondria.

ivoryjackal958

BIO 111: DNA Extraction: Strawberry

DNA Spooling

Background: Thelong, thick fibers of DNA store the information for the functioningof the chemistry of life. DNA is present in every cell of plantsand animals. The DNA found in strawberry cells can be extractedusing common, everyday materials. We will use an extraction buffercontaining salt, to break up protein chains that bind around thenucleic acids, and dish soap to dissolve the lipid (fat) part ofthe strawberry cell wall and nuclear membrane. This extractionbuffer will help provide us access to the DNA inside the cells.

Pre-labquestions:

What do you think the DNA will look like?

Where is DNA found?

Materials:

Heavy duty ziplocbag 10 mL DNA extraction buffer (soapy, salty water)

1strawberry glass rod, inoculating loop, or Popsicle stick

Cheeseclothfunnel 20 ml ethanol

50mL vial / test tube

Procedure:

1. Place one strawberry in aZiploc bag.

2. Smash/grind up thestrawberry using your fist and fingers for 2 minutes. Carefulnot to break the bag!!

3. Add the provided 10mL ofextraction buffer (salt and soap solution) to the bag.

4. Kneed/mush the strawberryin the bag again for 1 minute.

5. Assemble your filtrationapparatus as shown to the right.

6. Pour the strawberryslurry into the filtration apparatus and let it drip directly intoyour test tube.

7. Slowly pour cold ethanolinto the tube. OBSERVE

8. Dip the loop or glass rodinto the tube where the strawberry extract and ethanol layers comeinto contact with each other. OBSERVE

Conclusions and Analysis

It is important that you understand the steps in the extractionprocedure and why each step was necessary. Each step in theprocedure aided in isolating the DNA from other cellular materials.Match the procedure with its function:

PROCEDURE	FUNCTION
A. Filter strawberry slurry through cheesecloth	___ To precipitate DNA from solution
B. Mush strawberry with salty/soapy solution	___ Separate components of the cell
C. Initial smashing and grinding of strawberry	___ Break open the cells
D. Addition of ethanol to filtered extract	___ Break up proteins and dissolvecell membranes

2. What didthe DNA look like? Relate what you know about the chemicalstructure of DNA to what you observed today.

Explain what happened in the final step when you added ethanolto your strawberry extract.

(Hint: DNA is soluble in water, but not in ethanol)

A person cannot see a single cotton thread 100 feet away, but ifyou wound thousands of threads together into a rope, it would bevisible much further away. Is this statement analogous to our DNAextraction? Explain.

Why is it important for scientists to be able to remove DNA froman organism? List two reasons.

Is there DNA in your food? How do you know?

amberhornet175

BIO 121 Lecture Notes - Lecture 9: Organelle, Cytosol, Fluid Mosaic Model

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