UIC BIOS 110 EXAM II

Diffusion

Spontaneous movement of molecules from areas of high concentration to areas of low concentration

How does diffusion occur?

Occurs via random kinetic movement

What are molecules which cannot diffuse across a membrane called

molecules which cannot diffuse across a membrane are called osmotically active solutes

What is osmosis

Osmosis is the movement of water across a membrane in response to different concentrations of osmotically active solutes

Biological membranes are ___________________ meaning:

Biological membranes are semi-permeable meaning that certain substances can pass through it but not others

How does the water move in osmosis

The water from the solution with the lowest concentration will move across the membrane to the solution of the highest concentration (lowest to highest)

What happens after the water moves across the membrane

This will concentrate the solution with the lowest concentration and dilute the solution with the highest concentration, bringing them closer to equilibrium

How do uniports work

Uniports only carry one type of molecule/ion across a membrane

How do symports work

Symports carry two molecules/ion across a membrane in the same direction

How do antiports work

Antiports carry two molecules/ions across a membrane in different directions

i.e. one molecule enters a cell while the other leaves the cell

What do Facilitated Diffusion, Ion Channels, and Active Transport have in common

Facilitated Diffusion, Ion Channels, and Active Transport all require transport protiens to carry molecules across a membrane

Which direction do facilitated diffusion and ion channels carry molecules and does it require energy?

Facilitated diffusion and ion channels only carry molecules down their concentration gradient

(does not require energy)

(only carries molecules)

Which direction does active transport carry molecules/ions and does it require energy?

Active transport carries molecules/ions across a membrane, either down or against their gradient

(requires an expenditure of energy [ATP])

(carrries molecules and ions)

What is the function of the Na+ /K+ pump

actively transports sodium ions (Na+) out of a cell and potassium ions (K+) into the cell, essentially maintaining the correct concentration gradients of these ions across the cell membrane

What can easily diffuse across a membrane (has the highest permeability)

small, non-polar molecules (O2, CO2, N2)

What has difficulty diffusing across a membrane

small, uncharged polar molecules (H2O, glycerol) and large non-polar molecules

What can not diffuse across a membrane (low permeability)

large, uncharged polar molecules (glucose, sucrose) and ions (K+, Na+, CI-)

Solution A has a glucose concentration of 100mM. Solution B has a fructose concentration of 75mM. Which way will water move?

B to A (lower concentration moves to higher concentration)

What is Co-Transport

Co-transort is a linked system, typically involving an active transport pump and a fascilitated diffusion symport/antiport

This is still considered to be an active transport system

Can be confusing because the facilitated transport symport appears to transport one molecule against its gradient. However, when you consider the gradient of BOTH substances, you can see there is a net gradient across the membrane and the two substances are, in fact, moving down their net gradient

Describe the many functions of membranes in cells

Form specialized compartments by selective permeability Unique environment

Creation of concentration gradients

pH and charge (electrical, ionic) differences create electrochemical potentials

Controls and regulates reaction sequences

Product of one enzyme is the substrate for the next enzyme Can "line up" the enzymes in the proper sequence

Cell-Cell recognition • Site for receptor molecule biding for cell signaling

Receptor binds ligand (such as a hormone)

Induces intracellular reactions

describe the structure and chemical properties of phospholipids

Structure: Are amphipathic - they have a polar head and a non-polar tail

Chemical properties: a glycerol molecule, two fatty acids, and a phosphate group that is modified by an alcohol

Are phospholipids soluble in water

Yes, phospholipids are soluble in water

List other molecules which are found in and on biological membranes

cholesterol, surface & integral proteins, glycolipids, glycoproteins

in extreme conditions (i.e. near boiling and near freezing), membrane cholesterol is ______

in extreme conditions (i.e. near boiling and near freezing), membrane cholesterol is high

What factors increase membrane permeability?

Increase temperature

Increase amount of unsaturated bonds

Make fatty acid tails shorter

Reduce concentration of cholesterol

What factors decrease membrane permeability?

Decrease temperature

decrease amount of unsaturated bonds

Make fatty acid tails longer

Increase concentration of cholesterol

Describe the structure of most integral proteins

Typically consist of one to many alpha-helices

The parts of the alpha helix in the center of the membrane consist of hydrophobic amino acids

The parts of the alpha helix near the surface of the membrane consist of hydrophillic amino acids

What is photosynthesis? What does it produce?

Photosynthesis is an endergonic process which takes in CO2 from the atmosphere and H2O from the roots and uses sunlight energy to ultimately convert these into glucose (C6H12O6) and water

What are the two components of photosynthesis?

Light harvesting reactions and Calvin cycle

What is the function of light harvesting reactions?

Light-harvesting energizes electrons stolen from water and runs them through electron transport chains. This flow of electrons pumps H+ into the thylakoid space, which can later be used by ATP Synthase to produce ATP and reduces NADP+ to form NADPH. Both ATP and NADPH are used as energy and a source of reducing power for the Calvin Cycle.

What is the function of the Calvin cycle?

The Calvin Cycle uses ATP and NADPH generated in the light-harvesting reactions to reduce CO2 and form glucose (C6H12O6)

What is the ultimate energy source of photosynthesis

The sun

What organ and organelles performs photosynthesis

Leaves are the organ and chloroplasts are the organelle

What wavelenghts of light are absorbed by chloroplasts? What wavelenghts are reflected?

Violet/Blue and Orange/Red are the primary colors absorbed by chloroplasts. Green/Yellow are reflected

What is the ultimate source of electrons in photosynthesis?

The electrons energized by the sun are ultimately taken from H2O, forming H+, O2, and electrons

What processes of photosynthesis produces ATP?

Both cyclic and non-cyclic photophosphorylation produce ATP

What processes of photosynthesis consumes ATP?

the Calvin Cycle consumes ATP

What process of photosynthesis consumes CO2?

the Calvin Cycle consumes CO2

What process of photosynthesis produces O2?

non-cyclic photophosphorylation produces O2

What chemical serves as the raw material for all plant growth?

CO2 serves as the raw material for all plant growth

How is ATP generated in the light-harvesting reactions?

As electrons move through the electron transport chain, the interatction between Plastoquinone and the Cytochrome complex pump H+ from the stroma to the thylakoid space. This builds up an electrochemicial gradient that is used as an energy source by ATP synthase to generate ATP

What is the difference between cyclic and non-cyclic photophosphorylation? What does each produce? What molecules are involved in each?

Non-cyclic: Uses PS II and PS I. Produces ATP, NADPH, and O2 Cyclic: Uses PSI. Produces only ATP

what are photosynthetic pigments and what do they do

Photosynthetic pigments are molecules which can absorb visible light and eventually transfer that energy to a reaction center at the center of the antenna complex

what are Antenna complexes and what do they do

Antenna complex are groups of photosyntetic pigments which will ultimately funnel the light energy to reaction center which can use that light energy to increase the energy of a bound electron and reduce an electron acceptor (typically phaeophyton or ferredoxin)

interpret the photosynthetic absorption/action spectrum

The absorption spectrum indicates the wavelengths of light absorbed by each pigment (e.g. chlorophyll). The action spectrum indicates the overall rate of photosynthesis at each wavelength of light. In the graph below, the absorption spectrums of individual pigments are shown by the lighter-colored lines while the action spectrum is shown by the darker line.

True or false: All living plant cells contain functional mitochondria, but only some living plant cells contain functional chloroplasts.

True, All living plant cells contain functional mitochondria, but only some living plant cells contain functional chloroplasts.

The reaction: ADP + phosphate --> ATP is catalyzed by the enzyme ATP synthase in thylakoid membranes. This reaction is powered by:

A. Movement of electrons between photosystem II and photosystem I.

B. Oxidation of water

C. The electrochemical gradient of H+ generated by the electron transport chain

D. Oxidation of NADPH E. Absorption of photons by chloroplast pigment

C. The electrochemical gradient of H+ generated by the electron transport chain

During Cyclic Photophosphorylation:

A. ATP, NADPH, and O2 are not produced

B. ATP is produced; neither NADPH nor O2 are produced

C. NADPH and O2 are produced; ATP is not produced

D. ATP, NADPH, and O2 are all produced

B. ATP is produced; neither NADPH nor O2 are produced

During Non-Cyclic Photophosphorylation:

A. ATP, NADPH, and O2 are not produced

B. ATP is produced; neither NADPH nor O2 are produced

C. NADPH and O2 are produced; ATP is not produced

D. ATP, NADPH, and O2 are all produced

D. ATP, NADPH, and O2 are all produced

What is the function of the Calvin Cycle?

The Calvin Cycle takes CO2 (a form of highly-oxidized carbon) obtained from the atmosphere and uses the energy from ATP and NADPH, created in the light-harvesting reactions, to reduce this carbon and form sugars (usually in the form of glucose)

What does the Calvin cycle utilize? From were does it get these reactants and other molecules?

CO2 from the air, and ATP & NADPH from the light-harvesting reactions

What is photorespiration? Why does it occur? Is it bad for the plant?

Photorespiration is the reaction that occurs when O2 gas binds to the CO2 binding site in the active site of the enzyme Rubisco (making O2 a competitive inhibitor to CO2 in this reaction). Instead of forming two phosphoglycerates (PGAs), it forms one PGA and one phosphoglycolate. This reaction (RuBP + O2 >> PGA + phosphoglycolate) is photorespiration.

Phosphoglycolate is highly oxidized, and the cell must then spend a bunch of energy to convert the phosphoglycolate to more useful molecules. Correcting this problem creates a great energy drain on the cell, which is a tad ironic considering photosynthesis is an energy-generating process, but a 'mistake' ends up costing the plant a huge chunk (up to 40%) of its energy profits. So, yes, it is bad for the plant

What are C3 plants?

'suck it up and deal with it.' These are the C3 plants. They do absolutely nothing to reduce photorespiration, they just accept that many of their photosynthesis efforts will be wasted to deal with photorespiration. About 90% of all plants on Earth are C3 plants

What are C4 plants?

C4 plants isolate Rubisco from O2. 'C4 shuttle' - this utilized PEPCarboxylase to first fix CO2 to PEP to create a four-carbon molecule (hence, C4), and then transport this molecule to the bundle sheath. Once there, the CO2 is removed and Rubisco fixes it to RuBP and performs the Calvin Cycle

What are CAM plants?

Instead of isolating Rubisco in space, CAM plants isolate Rubisco in time. Mwahahahaha......At night, CAM plants turn off Rubisco and open their stomata, when it is cooler, bring in CO2, fix it to a 3-carbon molecule to form a 4-carbon molecule, and then wait. Since there is a limited amount of 3-carbon molecules in the chloroplast, they can only bring in a limited amount of CO2. Then, during the day, they turn Rubisco back on, release the CO2, and do the Calvin Cycle with what CO2 they have. Once this is used up, that's it. CAM plants aren't known for their growth rate

determine which environments will favor C3 and which will favor C4 plants

C4 works best in hotter, drier environments. C3 works best in moist and/or colder environments.

determine which environments increase and decrease photorespiration

Photorespiration is caused because O2 is a competitive inhibitor of CO2. So, environments with either MORE O2 or DECREASED CO2 will cause an INCREASE in photorespiration. Environment with either LESS O2 or INCREASED CO2 will cause a DECREASE in photorespiration.

The Rubisco in a C4 plant has _________ affinity for oxygen than the Rubisco in a C3 plant

A. more

B. less

C. the same

the same

In C4 plants, the first enzyme to fix carbon is PEP Carboxylase. PEP Carboxylase as _____ affinity for oxygen.

A. great

B. little

C. no

no

Rice is a C3 plant while sugar cane is a C4 plant. You grow both plants in a growth chamber under ambient conditions (20% O2, 400 ppm CO2) and measure the rates of photorespiration in both. You then reduce the atmospheric CO2 concentrations to 300 ppm. What changes in photorespiration would you see in both plants?

Rice would show a great increase in the rate of photorespiration, sugar cane would show little to no change

Where is most of the Rubisco in a C4 plant?

In the bundle sheath cells

You sample plants in the below areas. Which are would show the greatest proportion of the plant communities to be C4 plants?

A. Washington rain forest (cool, moist)

B. Norther Canada (cold, dry)

C. Central Illinois (warm, seasonally dry)

D. Oklahoma City, Oklahoma (hot, dry)

E. Okefenokee Swamp, Florida (hot, moist)

D. Oklahoma City, Oklahoma (hot, dry)

When do CAM plants perform the Calvin Cycle?

A. During the day only

B. During the night only

C. Both during the day and the night

During the day only

Perforins are chemicals which punch holes in biological membranes, but do not affect the associated proteins. You inject perforins inside of a chloropast, and they punch large holes in the thylalkoid membranes, but do not affect the molecules in the electron transport chain. What effects would exposure to perforins have on the chloroplast's ability to synthesize ATP and NADPH?

A. The chloroplast would still be able to produce both ATP and NADPH

B. The chloroplast would be able to produce ATP but not NADPH

C. The chloroplast would be able to produce NADPH but not ATP

D. The chloroplast would not be able to produce ATP and NADPH

C. The chloroplast would be able to produce NADPH but not ATP

True or false: All living plant cells can get all the energy they need from photosynthesis. Therefore, they do not require O2 for aerobic respiration to produce energy

False

Plants use the glucose produced by photosynthesis for:

A. Cellular Respiration

B. Storage (starch)

C. Growth (cellulose)

D. B & C

E. A, B, & C

E. A, B, & C (cellular respiration, storage (starch), growth)

When do plants perform the Calvin Cycle?

During the day, when the light-harvesting reactions are occurring

Structurally, how does the Rubisco in a C3 plant differ from the Rubisco in a C4 plant?

There is no difference between the Rubisco in a C3 and c4 plant

Where would you find the greatest concentration of C4 plants?

A. The tropical rain forests (hot, wet)

B. The Illinois prairies (warm, sometimes wet, sometimes dry)

C. The grasslands in west Nebraska & Kansas (hot, dry)

D. The temperate rainforests of Oregon (sometimes warm, sometimes cold, always wet)

E. Northern Canada (cold, dry)

C. The grasslands in west Nebraska & Kansas (hot, dry)

What happens during photorespiration?

A. Oxygen reacts with glucose, breaking it down and consuming energy

B. Oxygen reacts with glucose, breaking it down and producing energy

C. Rubisco attaches an oxygen molecule to RuBP, oxidizing it

D. Rubisco attaches an oxygen molecule to RuBP, reducing it

E. None of the above

C. Rubisco attaches an oxygen molecule to RuBP, oxidizing it

Normal atmospheric conditions are 20% O2, 400 ppm CO2 (0.0400%). C3 plants grown under which of the following conditions will show the least amount of photorespiration?

A. 30% O2, 600 ppm CO2

B. 30% O2, 400 ppm CO2

C. 20% O2, 600 ppm CO2

D. 10% O2, 400 ppm CO2

E. 10% O2, 600 ppm CO2

E. 10% O2, 600 ppm CO2

You grow wheat (a C3 plant) and corn (a C4 plant) in a greenhouse and measure the photorespiration rate each. You then double the CO2 concentration while keeping all other environmental conditions the same. You then measure the photorespiration rate in the corn and the wheat. What will be your results?

A. Both the corn and the wheat will show great reduction in their photorespiration rates

B. Only the corn will show a great reduction in its photorespiration rate

C. Only the wheat will show a great reduction in its photorespiration rate

D. Neither the corn nor the wheat will show great reduction in their photorespiration rates

C. Only the wheat will show a great reduction in its photorespiration rate

You grow wheat (a C3 plant) and corn (a C4 plant) in a greenhouse and measure the photosynthetic rate in each. You then double the CO2 concentration while keeping all other environmental conditions the same. You then measure the photosynthetic rate in the corn and the wheat. What will be your results?

A. Both the corn and the wheat will show great increase in their photosynthetic rates

B. Only the corn will show a great increase in its photosynthetic rate

C. Only the wheat will show a great increase in its photosynthetic rate

D. Neither the corn nor the wheat will show great increase in their photosynthetic rates

C. Only the wheat will show a great increase in its photosynthetic rate

Describe the interrelationship between the chemical reactions of photosynthesis and cellular respiration

Photosynthesis: 6 CO2 + 6 H2 O º C6H12O6 + 6 O2

Cellular Respiration: C6H12O6 + 6 O2 º 6 CO2 + 6 H2 O

They're opposites

What is the function of Cellular Respiration?

Cellular respiration uses oxygen to break down energy molecules (usually sugar) to form carbon dioxide and water. This is an exergonic reaction sequence, and the energy given off through this controlled release of energy is used to regenerate ATP from ADP and Pi

What are the steps of cellular respiration? Where do they occur in a eukaryotic cell?

Four Steps:

(1) Glycolysis, occurs in the cytoplasm

(2) Oxidation of Pyruvate, occurs in the mitochondria

(3) Citric Acid Cycle, occurs in the mitochondria

(4) Oxidative Phosphorylation, occurs in the mitochondria

Why do we eat? What are the two primary goals of eating?

We eat to obtain energy from the breakdown of molecules with high-energy bonds (sugars and lipids) and to obtain raw materials, usually amino acids, to synthesis proteins

What is the primary function of glycolysis? What does it produce?

Glycolysis breaks down a glucose molecule to form two pyruvates, 2 ATPs, and 2 NADH

What organisms can perform glycolysis?

occurs in the cytoplasm of ALL cells (bacteria, archaeans, and eukaryotes)

What is substrate-level phosphorylation? In what stages of cellular respiration does it occur?

Substrate-level phosphorylation is one of two main ways to regenerate ATP from ADP + Pi. In substrate-level phosphorylation, an enzyme takes a phosphate group from a phosphorylated molecule and transfers it to ADP to make ATP. It occurs in glycolysis and the citric acid cycle.

What is the function of the Oxidation of Pyruvate? What does it produce?

Oxidation of pyruvate takes the pyruvate produced in glycolysis and further breaks it down. Starting with the 2 pyruvates, it produces 2 Acetyl CoA, 2 CO2 , and 2 NADH

What is the function of the Citric Acid Cycle (aka the Krebs Cycle?) What does it produce?

The citric acid cycle takes the 2 acetyl CoA produced in the oxidation of pyruvate and completely breaks them down. It produces 4 CO2 , 6 NADH, 2 FADH2 , and 2 ATP.

How much of the initial glucose molecule remains after the Citric Acid Cycle is complete?

After the citric acid cycle, all six carbons have been oxidize to CO2 (two in oxidation of pyruvate, four in the citric acid cycle)

What is Oxidative Phosphorylation? What does it produce?

Oxidative phosphorylaton takes the NADH and FADH2 produced in the previous three stages, frees up the high-energy electrons from these molecules, runs them through an electron transport chain, with the final electron acceptor being O2 . This pumps H+ from the matrix to the intermembrane space. ATPsynthase will then use this H+ reservoir as an energy source to regenerate ATP from ADP + Pi.

When is oxygen used in cellular respiration?

Oxygen is the final electron acceptor in the electron transport chain. O2 + 2 H+ + 4 e- º H2 O

How is the electron transport chains (ETCs) used in oxidative phosphorylation similar to those used in the light-harvesting reactions? How are they different?

The two ETCs run high-energy electrons through the chain, which pumps H+ from one side of a membrane to another. This sereves as an energy reservoir which can be released through ATP synthase to generate ATP.

In photosyntheis, the electrons are energized by absorbing solar energy. In oxidative phosphorylation, the electrons are still high-energy because they were taken from sugars.

What is chemiosmosis?

Chemiosmosis is the term used to describe the movement of ions from one side of a membrane to another through an carrier protein. In this case, it is used to describe the movement H+ from one side of a membrane to another through ATPsynthase to generate ATP.

How does the enzyme phosphofructokinase regulate glycolysis, and therefore all of cellular respiration?

Phosphofructokinase is regulated through feedback inhibition.

What is beta-oxidation? How is this used in the digestion of fats?

In beta-oxidation, the fatty acid chains are broken down into two-carbon units, converted to acetyl-CoA, and entered into the citric acid cycle. This is how you get energy from fats.

Fats have more energy per gram than sugars. For example one glucose molecule has a molecular weight of about 180 g/mol and produces 36 ATP. The same mass of fatty acids produces 72 ATP, which is double the amount.

What is function of fermentation?

to regenerate NAD+ by oxidizing NADH

Compare and contrast alcohol fermentation and lactic acid fermentation

In alcohol fermentation , the pyruvate is reduced to form ethanol and CO2 . In lactic acid fermentation, the pyruvate is reduced to form lactic acid. Alcohol fermentation famously occurs in yeast, lactic acid fermentation occurs in humans (animals)

In a human, when does lactic acid fermentation occur? Can your cells survive by just performing glycolysis and lactic acid fermentation?

In humans, lactic acid fermentation typically occurs when the muscles are anoxic (low on oxygen). This typically occurs during extreme exertion. It is a last resort to get some ATP from glucose, but your muscles cannot survive on this. They will soon cramp and stop functioning.

are. bu lovckedd in

yes

What is the final electron acceptor in the mitochondrial electron transport chain?

A. ATP

B. NADH

C. CO2

D. O2

E. H2O

D. O2

How much of an ATP reserve does your body have at any given moment?

A. Seven seconds

B. Seven minutes

C. Seven hours

D. Seven days

B. Seven minutes

What is the biological function of fermentation?

A. To produce either ethanol or lactic acid, both of which are useful to the cell B. To oxidize pyruvate, a deadly poison to the cell

C. To breakdown pyruvate and produce a few more ATPs

D. To oxidize NADH to form NAD+

E. None of the above

D. To oxidize NADH to form NAD+

What causes the bubbles in bread when it is baked??

A. The CO2 produced from oxidation of pyruvate

B. The CO2 produced from the citric acid cycle

C. The CO2 produced from fermentation

D. A & B

C. The CO2 produced from fermentation

You have a mixture of water and ethanol. You wish to concentrate the ethanol by distillation. The boiling point of ethanol is 78ºC and the boiling point of water is 100ºC. To what temperature should you set your heating plate to best distill the ethanol?

A. 70ºC

B. 85ºC

C. 100ºC

D. 120ºC

B. 85ºC

Which of the below changes will decrease the rate of glycolysis?

I. Increase the affinity of the phosphofructokinase active site to ATP

II. Increase the affinity of the phosphofructokinase allosteric site to ATP

III. Decrease the affinity of the phosphofructokinase active site to ATP

IV. Decrease the affinity of the phosphofructokinase allosteric site to ATP

A. I only

B. II only

C. III only

D. II & III

E. I & IV

D. II & III

When the Citric Acid Cycle is complete, where is most of the energy from the initial glucose molecule?

A. ATP

B. CO2

C. H2 O

D. O2

E. NADH

E. NADH