BIOL1020 Lecture Notes - Lecture 7: Exergonic Reaction, Nicotinamide, Light-Dependent Reactions

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blueclam798

20 May 2018

School

Department

Biology

Course

BIOL1020

Professor

Dr Paul Ebert

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L7 - Energy !

•Energy ﬂows from organism

•producers - capture light and convert it to chemical energy through photosynthesis

•Consumers - use the chemical energy from producers and use it by respiration

Cellular respiration

Equation for cellular respiration:

Delta G = -686 kcal/mol (-2870 kJ/mol)

Glucose + oxygen = carbon dioxide + water

•Most cells generate energy from glucose

•this is a very exergonic reaction and releases large amounts of energy

•Because it’s exergonic, the reaction is called spontaneous (even though the reaction

doesn't happen by itself).

•The reaction does have an activation barrier and there is energy that has to be put in to

start this reaction. However, the output energy will compensate for the initial energy put

in.

•Because this energy is so big, we cannot release this energy in one go. If this happened,

the cell would explode.

•There are a series of chemical reactions that break down the glucose to produce energy

(in the form of ATP) in small amounts.

•At each step electrons are moved between the reactants and products to enable

breaking of chemical bonds (REDOX reactions)

•In redox reactions, electrons (and protons, aka H+ atoms) are transferred from one

compound to another

•Electrons in the oxygen in glucose

is of higher energy and when it falls

into oxygen of carbon dioxide, it is

lower energy. This change in energy

is used for ATP.

•To make this an efﬁcient process cells have ‘invented’ an electron shuttle compound

– NAD (nicotinamide adenine dinucleotide)

•When NAD carries a proton, it is called NADH

• the whole purpose of the shuttle if for ﬂexibility.

Oxidation: loss of an electron !

Reduction: addition of an electron

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NAD(H)!

•NAD+ can transfer energy, 2 electrons and one proton around the cell

•The enzymatic transfer of 2 electrons and 1 proton (H+) from an organic molecule in

food to NAD+ reduces the NAD+ to NADH. This is because NAD+ has the capability to

accept 2 electrons and the two electrons come as a hydride ion (so the hydrogen proton

accompanies the 2 e).

•Using reduced NADH enables oxidized compounds to become more reduced

•NADH is used in the last phase of cellular respiration !

Nicotinamide: The top part is the “business end” which

accepts the proton.

There are a couple of ribose sugars, phosphate

group, adenine

Steps of cellular respiration

There are 2 major stages of respiration:

Step 1: Glycolysis

Step 2: pyruvate oxidation and critic acid cycle

Step 3: oxidative phosphorylation (also called electron transport chain)

Each step has 24 approx enzymatic reactions (dont memorise this).

Flavin adenine dinucleotide (FAD)!

•Another electron acceptor used in cellular respiration. !

•The reduced form of FAD is FADH2. !

•FAD is structurally and functionally similar to NAD. !

•FADH pics up 2 electrons and 2 protons whereas NADH picks up 2 electrons and 1 p!

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Stage I: Glycolysis: in cytosol !

Input

•1 molecule glucose

Output

•2 molecule pyruvate / one molecule glucose

•2 NADH

•2 ATP (actually generate 4 ATP, but consumes 2 so net is 2)

During this step we are basically moving phosphate groups. This is called substrate-level

phosphorylation.

Stage 2 A (pyruvate oxidation): mitochondrial matrix !

•breaking down pyruvate

Input:

•2 molecules pyruvate

•CoA enzyme

Output:

•Acetyl-CoA / pyruvate (total 2 ACoA per one glucose)

•carbon dioxide

•1 NADH / pyruvate (2 NADH molecule generated per molecule glucose)

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Document Summary

L7 - energy: energy ows from organism, producers - capture light and convert it to chemical energy through photosynthesis, consumers - use the chemical energy from producers and use it by respiration. However, the output energy will compensate for the initial energy put in: because this energy is so big, we cannot release this energy in one go. This change in energy is used for atp. Reduction: addition of an electron: to make this an ef cient process cells have invented" an electron shuttle compound. Nad (nicotinamide adenine dinucleotide: when nad carries a proton, it is called nadh, the whole purpose of the shuttle if for exibility. Nad(h: nad+ can transfer energy, 2 electrons and one proton around the cell, the enzymatic transfer of 2 electrons and 1 proton (h+) from an organic molecule in food to nad+ reduces the nad+ to nadh. Nicotinamide: the top part is the business end which accepts the proton.

Related Questions

1.When something appears blue, it is absorbing all colors except__________.

yellow

blue

red

green

orange

2.During heavy exercise, lactic acid can build up in ourmuscles. Why? How does this resemble the metabolism of bacteria andyeast?

lactic acid is results from insufficient oxygen during sugarmetabolism; it is fermentation

lactic acid accumulates when we are dehydrated; bacteria andyeast use the same pathway

lactic acid is built up from carbon dioxide; bacteria and yeaststore energy in this way

3.Why must a cell keep a similar concentration of dissolvedsubstances with the fluid surrounding them?

to avoid dilution of potential energy

to avoid osmotic imbalance and rapid gain or loss of water

to maintain the correct amount of dehydration and hydrolysis

4.What is entropy?

the amount of energy in a system

the amount of disorganization

the amount of organization

5.Burning a log is the reverse reaction found in photosynthesis.What products would be formed in burning a log?

carbon dioxide and water

glucose and oxygen

oxygen and carbon dioxide

oxygen and water

6.The main reason that cellular respiration needs to occur stepby step instead of a single, big reaction is

cells don't store enough oxygen

too much energy would be released for the cell to harness

cells don't have many mitochondria.

cells produce the enzymes needed for cellular respiration veryslowly

7.Enzymes are catalysts because they operate to:

raise activation energy

lower activation energy

supply activation energy

supply the reactants

8.When ATP powers a reaction it becomes ADP. The ADP

can reform ATP by an exergonic reaction

is a waste product for lysosomal breakdown

can reform ATP by an endergonic reaction

can reform ATP by an oxidation reaction

can reform ATP by an equilibrium reaction

9.The energy source that drives photosynthesis is

water

glucose

carbon dioxide

oxygen

sunlight

10. What is the process by which enzymes regulate their ownactivity?

osmosis

self-propulsion

feedback inhibition

11.Coupled reactions are reactions in which a

endergonic reaction drives a spontaneous reaction

exergonic reaction drives a spontaneous reaction

endergonic reaction drives an exergonic reaction

exergonic reaction drives an endergonic reaction

12.How is water used in photosynthesis?

as a substrate for ATP synthase

as an electron donor

to combine with ADP forming ATP

as an electron acceptor

13.Why are the âDark Reactionsâ of photosynthesis referred to asâDarkâ?

they do not require light

they can only occur at night

they generate excess sugar and the leaves turn brown

14.What is the difference between potential and kineticenergy?

potential is stored, kinetic is being used

potential is being used, kinetic is ready to be used

potential is negative, kinetic is positive

15.The products of cellular respiration are

carbon dioxide, water, and ATP

glucose, water, and ATP

glucose, carbon dioxide, and ATP

oxygen, ATP, and water

carbon dioxide, glucose, and water

16.All of the following are correct about energy except:

The biological world gets its energy from the sun.

Chemical bonds store potential energy.

A boulder perched on a hill has kinetic energy.

Energy is defined as the ability to do work.

All forms of energy can be converted to heat.

17.What is needed for the end product of glycolysis, pyruvate,to enter the citric acid cycle?

More glucose for energy

ATP

Oxygen

Carbon dioxide

18.The enzyme that forms a transmembrane channel in mitochondriaand phosphorylates ADP

a carrier protein

ATP synthase

acetyl CoA

19.Fermentation is most common in

plants

microorganisms

animals

20.During adsorption of sunlight by photosystems, H+ ions aregenerated. Where do they come from? What are they used for?

from the breakdown of sugar; they help form water

water; they help form sugar

from carbon dioxide; they help dissolve NaCl

21.Glycolysis

does not use oxygen

uses oxygen

uses carbon dioxide

22.Photosynthesis is

not dependent on chlorophyll

a process that produces glucose and oxygen

a process that produces water and carbon dioxide

23.Breakdown of glucose generates many ATP molecules, each ofwhich can be used independently. Why is ATP ideally suited to powerbiological reactions?

ATP has many hydrogen bonds

ATP has enough energy to power one biological reaction

ATP readily dissolves in water

24.Objects that are not actively moving but have the capacity todo so are said to possess:

kinetic energy

entropy

potential energy

living energy

25.The first stage of cellular respiration, called ___________,takes place in the cytoplasm of the cell and needs no oxygen.

photorespiration

citric acid cycle

glycolysis

oxidation

26.Diffusion

requires energy

utilizes proteins to move molecules across a membrane

moves molecules against a concentration gradient

does not require energy

cannot occur without a membrane present

27.What is the name of the molecule on which an enzymeworks?

substrate

monomer

polymer

28.ATP contains

phenylalanine

two phosphate groups

three nitrate groups

three phosphate groups

29.How does chlorophyll function in photosynthesis?

by absorbing carbon dioxide

by absorbing the sun's energy

by absorbing water

30.Objects that are moving are said to possess:

living energy

potential energy

entropy

kinetic energy

31.The respiration pathway that evolved first is probably

glycolysis

aerobic respiration

citric acid cycle

32.The energy source for the process of photosynthesis is

oxygen

sunlight

carbon dioxide

chlorophyll

glucose

33.Burning wood generates heat and light. What type of reactionis this?

exergonic

kinetic energy

endergonic

potential energy

equilibrium

34.What is meant by a âcoupled reactionâ in terms of energy?

many poymers are built simultaneously

energy released by one reactions powers another reaction

some reactions occur in the same organelle

35.The First Law of Thermodynamics states:

energy is constantly being created by entropy events

energy can be changed from one form to another, but cannot becreated or destroyed

energy can be used and then destroyed because of entropy'sactions on it

energy can be destroyed while it is producing entropy

36.How do we dispose of the carbon derived from the glucose thatis metabolized during respiration?

by breathing out

via our urine

it is broken down in lysosomes

37.Both plant and animal cells have mitochondria because theyboth

carry on respiration

carry on photosynthesis.

require water

38.What is Activation Energy?

the energy needed to initiate a reaction

the energy that transports water into cells

potential energy

39.If you put a plant in a chamber and shine a light on it

oxygen will decrease and carbon dioxide will increase

oxygen will increase and carbon dioxide will decrease

oxygen and carbon dioxide will increase

oxygen and carbon dioxide will decrease

40.What are the inputs and the output molecules for the overallphotosynthetic process?

input sugar and oxygen; output carbon dioxide and water

input oxygen and water; output sugar and carbon dioxide

input carbon dioxide and water;output sugar and oxygen

41.What kind of reaction is photosynthesis?

endergonic

kinetic energy

exergonic

potential energy

equilibrium

42.In the process of glycolysis, glucose is cleaved into a pairof three-carbon molecules called

lactate

pyruvate

acetyl CoA

ATP

alcohol

43.Entropy is

order

disorder

complexity

Both order and disorder are correct

Both complexity and disorder are correct

44.Glycolysis takes place in the _____________ and the citricacid cycle and electron transport chain take place in the___________.

cytoplasm; endoplasmic reticulum

mitochondria, chloroplast

mitochondria; cytoplasm

cytoplasm; mitochondria

45.The organelle that carries out photosynthesis in plants isthe

mitochondria

chloroplast

ribosome

chlorophylllysosome

46.The energy to power the Calvin cycle comes from

cellular respiration

oxygen

the light reactions of photosynthesis

47.Which of the following can be broken down into intermediateproducts that enter cellular respiration?

Proteins

Lipids

Carbohydrates

All of these.

48.When cellular product levels get too high, the responsibleenzyme is inhibited. This is an example of

promotion

denaturation

equilibrium

a coenzyme

feedback inhibition

49.How is respiration the opposite of photosynthesis?

respiration breaks sugar down to carbon dioxide; photosynthesisbuilds sugar from carbon dioxide

respiration builds sugar from carbon dioxide; photosynthesisbreaks sugar down to carbon dioxide

respiration requires energy input; photosynthesis gives offexcess energy

50.The molecule that absorbs sunlight for photosynthesis is

oxygen

carbon dioxide

chlorophyll

glucose

sunlight

amaranthbear841

The complete set of reactions carried out by an organism is called:

a. anabolism

b. catabolism

c. metabolism

Value: 2

The breakdown of starch is broken down to glucose is an example of:

a. anabolism

b. catabolism

c. metabolism

Value: 3

For the following statement, determine which description best describes the process: DNA is synthesized from free nucleotides.

a. anabolism

b. catabolism

c. metabolism

Value: 4

Fill in the blank: Catabolic reactions result in the synthesis of molecules of .............via cellular respiration. This is then used to power anabolic reactions.

Value: 5

The energy in organic molecules is released in a series of steps because:

a. it is not possible to release it in a single step.

b. more total energy is released in multiple steps than would be released in a single step

c. less total energy is released in multiple steps than would be released in a single step.

d. more energy can be harvested for cellular use in multiple steps than from a single step.

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

photosynthesis

1-The light reaction of photosynthesis does not include

a. chemiosmosis

b. oxygen liberation

c. glucose synthesis

d. electron transport

Value: 2

Photosynthesis takes place in the membranes of small sacs called

a. thylakoids

b. photosystems

c. stroma

d. photons

Value: 3

During what stage of photosynthesis is O2 produced?

a. the light-dependent reactions involving photosystems I and II

b. carbon fixation

c. the Krebs cycle

d. O2 is not produced during photosynthesis

Value: 4

The pigment molecules responsible for photosynthesis are located in the

a. mitochondria

b. cytoplasm of the cell

c. stroma of the chloroplast

d. thylakoid membrane of the chloroplast

Value: 5

During what stage of photosynthesis are ATP and NADPH converted to ADP + Pi and NADP+?

a. the light-dependent reactions

b. the light-independent reactions

c. both of the above

d. none of the above

Value: 6

What energy-rich organic compound is produced as a result of the Calvin cycle?

a. ATP

b. NADPH

c. glucose

d. H2O

Value: 7

During photosynthesis, photons raise electrons to higher energy levels. These excited electrons belong to what compound?

a. water

b. ATP

c. chlorophyll

d. electron transport chain

Value: 8

Which of the following statements accurately describes the relationship between photosynthesis and cellular respiration?

a. photosynthesis occurs only in autotrophs; cellular respiration occurs only in heterotrophs

b. photosynthesis uses solar energy to convert inorganics to energy-rich organics; respiration breaks down energy-rich organics to synthesize ATP

c. photosynthesis involves the oxidation of glucose; respiration involves the reduction of CO2

d. the primary function of photosynthesis is to use solar energy to synthesize ATP; the primary function of cellular respiration is to break down ATP and release energy

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.

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BIOL1020 Lecture Notes - Lecture 7: Exergonic Reaction, Nicotinamide, Light-Dependent Reactions

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