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Intro to Molecular and Cellular Biology > Molec and Cell 2 > Flashcards

Molec and Cell 2 Flashcards

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1
Q

Competitive inhibition

A

An inhibitor molecule is similar enough to a substrate that it can bind to an active site to prevent substrates from bonding

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2
Q

Noncompetitive inhibition

A

An inhibitor molecule binds to an enzyme in a location other than it’s active site

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3
Q

Allosteric site

A

A site that allows molecules to either activate or inhibit enzyme activity but is not the active site

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4
Q

Allosteric inhibition

A

Inhibitor molecules bind to enzymes in a location where binding induces a confirmational change that reduces an enzymes affinity for its substrate

Substrates bond with less efficiency

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5
Q

Cofactors

A

Inorganic ions that act as helper molecules to enzymes. They promote optimal conformation and function

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6
Q

Coenzymes

A

Organic helper molecules with a basic structure of carbon and hydrogen required for enzyme action. They help promote optimal conformation and function

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7
Q

Feedback inhibition

A

A reactant to regulate its own further production

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8
Q

Induced fit

A

A mild shift that occurs at an active site to optimize reactions and fit to substrates

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9
Q

Active site

A

The location within an enzyme where the substrate finds to the enzyme and a reaction occurs

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10
Q

What affects the active site’s micro-environment?

A

The different properties depend on the unique combination of amino acid residues, R group, their possessions sequences, structures and properties

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11
Q

Denature

A

A process that changes the substances, natural properties, and may affect function

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12
Q

Increasing the substrate concentration in an enzymatic reaction could overcome what?

A

Competitive inhibition

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13
Q

According to the induced fit hypothesis of enzyme catalysis, what can be deduced?

A

The binding of the substrate changes the shape of the enzymes active site

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14
Q

The lock and key analogy for enzymes applies to the specificity of enzymes….doing what?

A

Binding to their substrate

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15
Q

What is the difference in Delta G (Gibbs Free Energy) between a catalyzed reaction to the same reaction without a catalyst?

A

The catalyzed reaction will have the same Delta G

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16
Q

Delta G stands for what

A

Change in Gibbs Free Energy

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17
Q

What is the active site in an enzyme?

A

It is the region involved in the catalytic reaction of the enzyme

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18
Q

Fluid mosaic model

A

The plasma membrane is made up of many parts, including carbohydrates, proteins, cholesterol and phospholipids, made up of even smaller parts.

These parts are in constant motion.

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19
Q

The function of phospholipids in it the cell membrane

A

Phospholipids help the cell membranes to function and keeping it toxins out and organelles in

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20
Q

Cholesterol in the plasma membrane

A

Cholesterol helps act as a buffer where the plasma membrane is not too tight or too loose when made a phospholipids, either saturated or unsaturated

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21
Q

The function of protein channels in the plasma membrane

A

Protein channels exists as paths in and out of the cell

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22
Q

Carbohydrates in the plasma membrane

A

Carbohydrates bond with glycoproteins and glycolipids for cell receptors to initiate cell responses and adhesion to cells

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23
Q

The two types of proteins associated with plasma membranes

A

Integral protein and peripheral protein

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24
Q

Peripheral protein

A

The protein found on a membrane surface that helps with many functions of the cell, including communication with other cell parts. It may also help with enzymes acting as catalysts for reactions in the cell

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25
Q

Integral protein

A

The protein found inside of the plasma membrane made of hollow tubes. They allow nutrients in or toxins out of the cell. Different parts of the protein may be hydrophobic or hydrophilic.

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26
Q

Glycerol in the plasma membrane

A

The sugar that is the backbone to phospholipids and helps create the hydrophilic characteristic of a membrane.

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27
Q

Glycoprotein

A

This protein may act as a receptor on the plasma membrane to help cell to cell recognition and attachments. They may also initiate immune responses but can be co-opted by viruses, such as HIV.

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28
Q

Passive transport

A

This transport requires no energy as a type of diffusion, but it is only able to allow small non-polar molecules through protein channels in the membrane. These include molecules like lipid hormones, carbon dioxide, and oxygen.

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29
Q

Active transport

A

The type of transport through the plasma membrane used for a larger or polar molecules. This requires energy or ATP.

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30
Q

Three types of active transport

A

Uniporter
Symporter
Antiporter

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31
Q

Uniporter

A

One molecule passes through one way through a plasma membrane

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32
Q

Symporter

A

Two molecules pass the same way through the plasma membrane

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33
Q

Antiporter

A

One molecule goes in one way and another goes up the other way through a plasma membrane

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34
Q

Three factors that affect diffusion rates

A

Temperature
Concentration gradient
Pressure

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35
Q

Two types of transport proteins

A

Carrier protein
Channel protein

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36
Q

Channel protein definition

A

Protein tubes through a plasma membrane that allow ionized and polar molecules in and outs through opposite sides. These molecules tend to be small and may require specific signals.

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37
Q

Two types of channel proteins for polar molecules

A

Aquaporin
Ion channels

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38
Q

Aquaporin channels

A

Channels used for water to travel through membranes quickly

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39
Q

Ion channels

A

Channels in specific tissues where molecules need to pass quickly under specific circumstances for bodily functions to occur. One example is calcium passing through these channels quickly for muscle tissues

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40
Q

Carrier proteins

A

Turnstile type channels that exist for specific molecules. A molecule will fuse to this protein in the protein. Carries it to the other side of the membrane. o
Once it is dropped off another molecule is capable of fusing to this protein to be carried to the other side.

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41
Q

One example of carrier proteins

A

Glucose transporter

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42
Q

Two types of active transport

A

Primary
Secondary

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43
Q

Primary active transport

A

ATP is the energy source. One example is an ion or molecule moving from a low concentration to a high concentration gradient using a uniporter

Sodium potassium pump

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44
Q

Secondary active transport

A

Energy is required as molecules, ions or atoms are trying to go from a low electrochemical gradient to a high electrochemical gradient. The energy comes from the electrochemical gradient.

One example is the sodium glucose symporter

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45
Q

Two types of metabolic pathways

A

Anabolic
Catabolic

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46
Q

Metabolism

A

All chemical reactions of a cell

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47
Q

Anabolic pathway

A

Taking small molecules and converting them into large molecules that are usable for energy such as glucose. The stored energy will typically have a greater output of energy.

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48
Q

Catabolic pathway

A

Taking large molecules and breaking them down into small molecules to release energy

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49
Q

Two types of energy

A

Kinetic
Potential

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50
Q

Kinetic energy

A

Objects in motion. Examples in the cell include chemical and electrochemical gradients as plasma membranes are dynamic

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51
Q

Potential energy

A

Potential to move and energy may be stored. And human cells cellular respiration helps to store energy in the form of ATP, which is potential energy. It will later be broken down for kinetic energy.

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52
Q

Endergonic reactions

A

Energy is added to a chemical reaction and has a positive Delta G

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53
Q

Exergonic reactions

A

Energy is really released in chemical reactions. Delta G is less than zero.

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54
Q

Catabolism is to anabolism as x is to y

A

Exergonic is to endergonic x is to y

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55
Q

What is one deducement of the second law of thermodynamics?

A

Cells require a constant input of energy to maintain their high level of organization

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56
Q

What is a logical consequence of the second law of thermodynamics?

A

Every chemical reaction must increase the total entropy of the universe

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57
Q

What type of reaction would decrease the entropy within a cell?

A

Anabolic reaction

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58
Q

For a living organism, what is an important consequence of the first law of thermodynamics?

A

The organism ultimately must obtain all of the necessary energy for life from its environment

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59
Q

What structure is most similar to ATP?

A

An RNA nucleotide

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60
Q

When ATP releases some energy, it also releases inorganic phosphates. What happens to the inorganic phosphate in the cell?

A

And maybe used to form phosphorylated intermediate

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61
Q

10,000 molecules of ATP are hydrolyzed to ADP and inorganic phosphate in a test tube. About half as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Why?

A

The reactant and production concentrations in the test tube are different from those in the cell

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62
Q

What happens to the heat generated when chemical transport or mechanical work is done by an organism?

A

The heat is lost to the environment

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63
Q

What is the structure of ATP?

A

Adenine base
Five carbon ring
Ribose
Three phosphate groups (alpha, beta, gamma from low to high energy bonds)

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64
Q

ATP hydrolysis reaction

A

ATP + water → ADP + inorganic phosphate + free energy

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65
Q

If ATP hydrolysis is not coupled with an inorganic reaction, what will happen to the free energy?

A

This energy is lost as heat

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66
Q

If ATP hydrolysis is coupled with an inorganic reaction, what happens to the free energy?

A

The free energy can be used to drive the endergonic reaction

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67
Q

What are enzymes?

A

Protein catalysts that speed up reactions by lowering the required activation energy by binding with reactant molecules

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68
Q

Activation energy

A

Energy required for a reaction to proceed

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69
Q

What is heat energy the main source for in a cell

A

Activation energy in a cell to reach the transition sites for a reaction

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70
Q

Metabolic pathway

A

A series of biochemical reactions that converts one or more substrates into a final product

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71
Q

Transition in a reaction

A

And unstable state which happens quickly in a reaction, especially as the heat energy increases

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72
Q

The law of thermodynamics

A

The study of energy and energy transfer involving physical matter

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73
Q

The two rules of the law of thermodynamics

A

Energy cannot be created or destroyed

Some energy is lost and unusable energy forms such as heat energy. This results an increased entropy

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74
Q

Four different ways active sites can lower an EA barrier

A
  1. Orienting substrates properly
  2. Straining substrate bonds
  3. Providing a favorable micro environment
  4. Covalent bonding to the substance
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75
Q

Allosteric enzyme regulation is usually associated with _____.

A

An enzyme with more than one subunit

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76
Q

Besides turning enzymes on or off, what other means does a cell use to control enzymatic activity?

A

Localization of enzymes into specific organelles or membranes

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77
Q

Six major functions of membrane proteins

A

Transport
Enzymatic activity
Signal transduction
Cell-cell recognition
Intercellular joining
Attachment to the cytoskeleton and extracellular matrix (ECM)

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78
Q

Membrane potential

A

the voltage difference across a membrane
Voltage is created by differences in the distribution of positive and negative ions across a membrane

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79
Q

Two combined forces, collectively called the electrochemical gradient, drive the diffusion of ions across a membrane

A

A chemical force (the ion’s concentration gradient)

An electrical force (the effect of the membrane potential on the ion’s movement)

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80
Q

An electrogenic pump

A

a transport protein that generates voltage across a membrane

help store energy that can be used for cellular work

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81
Q

Two types of electrogenic pump

A

The sodium-potassium pump is the major pump of animal cells

The main pump of plants, fungi, and bacteria is a proton pump

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82
Q

Phagocytosis

A

A cell membrane surrounds the particle and engulfs it.

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83
Q

Pinocytosis

A

the cell membrane surrounds a small volume of fluid, and pinches off

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84
Q

Receptor-mediated endocytosis

A

the cell’s uptake of substances targets a single type of substance that binds to the receptor on the cell membrane’s external surface to carry it in vesicles

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85
Q

Exocytosis

A

vesicles containing substances fuse with the plasma membrane. The contents are then released to the cell’s exterior.

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86
Q

Bioenergetics

A

the study of energy flow through a living system

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87
Q

Metabolism

A

all chemical reactions of a cell or organism

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88
Q

A metabolic pathway

A

series of biochemical reactions that converts one or more substrates into a final product

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89
Q

Two types of reactions/pathways

A

Anabolic and catabolic

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90
Q

Anabolic

A

Those that require energy and synthesize larger molecules

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91
Q

Catabolic

A

Those that release energy and break down large molecules into smaller molecules

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92
Q

Is photosynthesis an anabolic or catabolic pathway?

A

Anabolic

93
Q

Thermodynamics

A

the study of energy and energy transfer involving physical matter

94
Q

1st Law of Thermodynamics

A

The total amount of energy in the universe if constant: energy cannot be created or destroyed

95
Q

2nd Law of Thermodynamics

A

The transfer of energy is not completely efficient.

With each chemical reaction, some energy is lost in a form that is unusable, such as heat energy. The result is increased entropy (disorder)

96
Q

What provides the energy for a cell’s endergonic reactions?

A

Usually, the hydrolysis of ATP.

97
Q

ATP Structure

A

An an adenosine backbone with three phosphate groups attached

98
Q

ATP Hydrolysis

A

ATP + H2O → ADP + Pi + free energy

99
Q

An example of energy coupling

A

The Sodium Potassium Pump

100
Q

Enzymes

A

protein* catalysts that speed up reactions by lowering the required activation energy

bind with reactant molecules promoting bond-breaking and bond-forming processes

*ribozymes also exist

101
Q

Substrate

A

reactants to an enzyme that interact at the enzyme’s active site

102
Q

Induced fit

A

a mild shift in shape of an enzyme that optimizes reactions

103
Q

Four ways an enzyme can affect a reaction

A
  1. position two substrates so they align perfectly for the reaction
  2. provide an optimal environment, i.e. acidic or polar, within the active site for the reaction
  3. contort/stress the substrate so it is less stable and more likely to react
  4. temporarily react with the substrate (chemically change it) making the substrate less stable and more likely to react.
104
Q

Three ways enzymes are regulated

A

Modifications to temperature and/or pH
Production of molecules that inhibit or promote enzyme function
Availability of coenzymes or cofactors

105
Q

Competitive inhibitors

A

Molecules that have a similar shape to the substrate, competing with the substrate for the active site rates but do not affect the maximal rate

106
Q

Noncompetitive inhibitors

A

Molecules that bind to the enzyme at a different location, causing a slower reaction rates and affect the maximal rate

107
Q

Maximal rate

A

speed of a reaction when substrate is not limited

108
Q

Allosteric inhibitors

A

They modify the active site of the enzyme so that substrate binding is reduced or prevented

109
Q

Allosteric activators

A

They modify the active site of the enzyme so that the affinity for the substrate increases

110
Q

Feedback inhibition

A

Where the end product of the pathway inhibits an upstream step, is an important regulatory mechanism in cells

111
Q

Diffusion

A

The tendency for molecules to spread out evenly into the available space

112
Q

Concentration gradient

A

the region along which the density of a chemical substance increases or decreases

no work must be done to move substances down the concentration gradient

113
Q

Facilitated transport

A

substances move down their concentration gradients

114
Q

Osmosis

A

water always moves from an area of higher water concentration to one of lower concentration

115
Q

Redox reactions

A

chemical reactions where electrons are transferred from one molecule to another

116
Q

Reducing agents

A

Molecules that can donate electron(s) in a redox reaction

117
Q

Oxidizing agents

A

Molecules that can accept electron(s) in a redox reaction

118
Q

The reduced product

A

Molecules that gain electron(s) after the reaction

119
Q

The oxidized product

A

Molecules that lose electron(s) after the reaction

120
Q

Electron carrier

A

Very important molecules in cellular respiration and photosynthesis.

They shuttle electrons to electron transport chains where ATP is produced.

121
Q

Dephosphorylation

A

The loss of a phosphate group from a molecule

122
Q

Phosphorylation

A

The process of adding a phosphate group is to a molecule

They tend to be less stable and more likely to react

123
Q

ADP undergoes what to create ATP

A

Phosphorylation

124
Q

Where does the energy for ADP to ATP come from

A

a coupled exergonic reaction (substrate-level phosphorylation) (10%)

a process called chemiosmosis, which requires the enzyme ATP synthase (90%)

125
Q

Where does ATP formation occur

A

Occurs in mitochondria, chloroplasts, and plasma membrane of aerobic prokaryotes

126
Q

What metabolic pathways are involved in cellular respiration

A

Glycolysis
Oxidation of Pyruvate and Citric Acid Cycle
Oxidative Phosphorylation

127
Q

Glycolysis

A

the first metabolic pathway of glucose metabolism; includes 10 enzymatic reactions

Nearly all organisms perform glycolysis
occurs in the cytoplasm
O2 is not required

128
Q

What are the inputs of glycolysis

A

1 Glucose, 2 NAD+, 2 ATP, 4 ADP

129
Q

What are the outputs of glycolysis

A

2 Pyruvate, 2 NADH, 4 ATP, 2 ADP

130
Q

Substrate-level phosphorylation occurs where?

A

in both glycolysis and the citric acid cycle

131
Q

When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is what? (Think oxidation and laws of thermodynamics)

A

reduced, and energy is released

132
Q

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?

A

100%

133
Q

If you were to add one of the eight citric acid cycle intermediates to the culture medium of yeast growing in the laboratory, what do you think would happen to the rates of ATP and carbon dioxide production?

A

The rates of ATP production and carbon dioxide production would both increase.

134
Q

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

A

oxidation of pyruvate to acetyl CoA and the citric acid cycle and what is released?

135
Q

Which electron carrier(s) function in the citric acid cycle?

A

NADH and FADH2

136
Q

Most of the CO2 from the catabolism of glucose is released during when?

A

the citric acid cycle

137
Q

What is formed by the removal of a carbon (as CO2) from a molecule of pyruvate?

A

acetyl CoA

138
Q

If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle?

A

2/3

139
Q

Pyruvate oxidation

A

2 pyruvate molecules enter mitochondria where each is converted to Acetyl CoA before entering the CAC

140
Q

Result of pyruvate oxidation

A

a CO2 is released
pyruvate is oxidized, transferring e- to NAD+ to create NADH
coenzyme A is attached

141
Q

Pyruvate oxidation inputs

A

2 pyruvate, 2 NAD+
2 coenzyme A

142
Q

Pyruvate oxidation outputs

A

2 CO2, 2 NADH, 2 acetyl CoA

143
Q

Citric Acid Cycle

A

a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins

144
Q

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the what?

A

creation of a proton-motive force

145
Q

The electron transport chain _____.

A

is a series of redox reactions

146
Q

What takes place in the electron transport chain?

A

the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle

147
Q

Where are the proteins of the electron transport chain located for oxidative phosphorylation?

A

mitochondrial inner membrane

148
Q

During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from?

A

molecular oxygen (O2)

149
Q

During aerobic respiration, electrons travel downhill in which sequence?

A

glucose → NADH → electron transport chain → oxygen

150
Q

The chemiosmotic hypothesis is an important concept in our understanding of cellular metabolism in general because it explains _____.

A

how ATP is synthesized by a proton motive force

151
Q

During aerobic respiration, what donates electrons to the electron transport chain at the lowest energy level?

A

FADH2

152
Q

Why is glycolysis considered to be one of the first metabolic pathways to have evolved?

A

It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.

153
Q

What occurs in the cytosol of a eukaryotic cell?

A

glycolysis and fermentation

154
Q

Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing what carbon sources for energy?

A

glucose

155
Q

An organism is discovered that thrives in both the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism’s environment, even though the organism does not gain much weight.

A

facultative anaerobe

156
Q

New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to “hit the wall” and find it difficult to continue exercising. These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise. Why?

A

During anaerobic respiration, lactate levels increase when muscles cells need more energy, however muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.

157
Q

Citric Acid Cycle

A

is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.

158
Q

Outputs of the CAC

A

4 ATP (2 from glycolysis, 2 from CAC)
6 CO2 (2 from oxidation of pyruvate, 4 from CAC)
10 NADH (2 from glycolysis, 2 from oxidation of pyruvate, 6 from CAC)
2 FADH2 (from CAC)

159
Q

In glycolysis, is most of the energy from glucose stored in the ATP, the CO2, or the electron carrier molecules?

A

Electron carrier molecules

160
Q

Oxidative phosphorylation

A

a cellular process that harnesses the reduction of oxygen to generate high-energy phosphate bonds in the form of adenosine triphosphate (ATP)

The only pathway that uses O2 as an input

161
Q

Two ways of generating ATP in oxidative phosphorylation

A

an electron transport chain and chemiosmosis, which generates ATP

162
Q

The energy to power chemiosmosis in oxidative phosphorylation

A

A H+ concentration gradient created by the ETC

163
Q

An Electron Transfer Chain

A

a series of electron transporters embedded in the inner mitochondrial membrane

164
Q

The electron carriers in oxidative phosphorylation

A

NADH and FADH2 to O2

165
Q

Chemiosmosis

A

kinetic energy from protons falling down its gradient to form ATP from ADP + Pi

the complex, integral protein ATP synthase mediates this reaction

166
Q

The number of ATP generated by cellular respiration

A

30-36 per glucose

varies by species and how efficiently NADH from glycolysis enters mitochondria

167
Q

Cellular respiration in total stores

A

34% of the energy from glucose in ATP

168
Q

Glycolysis without O2

A

NAD+ is an input of glycolysis; regenerated during oxidative phosphorylation when O2 is present

When O2 is lacking, fermentation regenerates NAD+

169
Q

Two common types of fermentation

A

Lactic acid fermentation

Alcohol fermentation

170
Q

Lactic acid fermentation

A

Occurs in muscle cells when O2 is limited, mammalian red blood cells, & some bacteria, ex. those in yogurt

Pyruvate + NADH → lactate + NAD+

171
Q

Lactic acid enzyme

A

Lactate dehydrogenase

172
Q

Alcohol fermentation

A

anaerobic yeast species

involves:
First, catalyzed by pyruvate decarboxylase
Second, by alcohol dehydrogenase

Pyruvate → CO2 + acetylaldehide
acetylaldehide + NADH → ethanol + NAD+

173
Q

Cellular respiration is regulated by many mechanisms, including

A

Hormonal control of glucose entry into the cell

Enzyme reversibility (functioning to substrate product equilibrium) or irreversibility (able to exceed equilibrium)

Enzyme sensitivity to pH changes due to lactic acid build-up

Feedback controls

174
Q

Photosynthesis

A

the process that converts solar energy into chemical energy

directly or indirectly, photosynthesis nourishes almost the entire living world

175
Q

Autotrophs

A

the producers of the biosphere, producing organic molecules from CO2 and other inorganic molecules

Almost all plants are photoautotrophs, using the energy of sunlight to make organic molecules

176
Q

Photosynthesis occurs

A

plants, algae, certain other unicellular eukaryotes, and some prokaryotes
These organisms feed not only themselves but also most of the living world

177
Q

Heterotrophs

A

the consumers of the biosphere
Almost all heterotrophs, including humans, depend on photoautotrophs for food and O2

178
Q

Chloroplasts structure

A

structurally similar to and likely evolved from photosynthetic bacteria

the structural organization of these organelles allows for the chemical reactions of photosynthesis

179
Q

The 3 Sites of Photosynthesis in Plants

A

Leaves are the major locations of photosynthesis

Chloroplasts are found mainly in cells of the mesophyll, the interior tissue of the leaf

CO2 enters and O2 exits the leaf through microscopic pores called stomata

180
Q

Stroma

A

the dense fluid in an envelope of two membranes in chloroplasts

181
Q

Thylakoids

A

connected sacs in the chloroplast which compose a third membrane system

182
Q

Grana

A

Stacks of thylakoids

183
Q

Chlorophyll

A

the pigment which gives leaves their green colour, resides in the thylakoid membranes

184
Q

Is photosynthesis ender or exergonic

A

Endergonic

185
Q

What is oxidized and reduced in photosynthesis

A

H2O is oxidized and CO2 is reduced

186
Q

Two Stages of Photosynthesis

A

Light Cycle and Calvin Cycle

187
Q

The light reactions and products (in the thylakoids)

A

Split H2O
Release O2
Reduce the electron acceptor NADP+ to NADPH
Generate ATP from ADP by photophosphorylation

188
Q

The Calvin cycle (in the stroma)

A

forms sugar from CO2, using ATP and NADPH
The Calvin cycle begins with carbon fixation

189
Q

Carbon Fixation

A

In photosynthesis, incorporating CO2 into organic molecules

190
Q

Light

A

a form of electromagnetic energy, also called electromagnetic radiation

191
Q

Wavelength

A

the distance between crestsof waves

wavelength determines the type of electromagnetic energy

192
Q

electromagnetic spectrum

A

the entire range of electromagnetic energy, or radiation

193
Q

Visible light

A

wavelengths that we can see

194
Q

photons

A

Discrete particles of light

195
Q

Pigments

A

substances that absorb visible light

196
Q

Wavelengths that are not absorbed

A

Colors reflected back

197
Q

absorption spectrum

A

a graph plotting a pigment’s light absorption versus wavelength

198
Q

absorption spectrum of chlorophyll a

A

suggests that violet-blue and red light work best for photosynthesis

199
Q

action spectrum

A

the relative effectiveness of different wavelengths of radiation in driving a process

200
Q

chlorophyll b

A

Accessory pigments that broaden the spectrum used for photosynthesis

201
Q

The difference in the absorption spectrum between chlorophyll a and b

A

to a slight structural difference between the pigment molecules

202
Q

carotenoids

A

Accessory pigments that absorb excessive light that would damage chlorophyll

203
Q

An excited pigment

A

a pigment absorbs light which is unstable

204
Q

fluorescence

A

excited electrons fall back to the ground state, photons are given off

205
Q

illuminated

A

an isolated solution of chlorophyll will fluoresce, giving off light and heat

206
Q

photosystem

A

of a reaction-center complex (a type of protein complex) surrounded by light-harvesting complexes that transfer the energy of photons to the reaction center

207
Q

reaction-center complex

A

a type of photosynthesis protein complex

208
Q

light-harvesting complexes

A

pigment molecules bound to proteins

209
Q

primary electron acceptor

A

the reaction center for photosynthesis accepts excited electrons and are reduced as a result

210
Q

Photosystem II (PS II) best wavelength

A

best at absorbing a wavelength of 680 nm

211
Q

reaction-center chlorophyll a of PS II

A

P680

212
Q

Photosystem I (PS I)

A

best at absorbing a wavelength of 700 nm

213
Q

reaction-center chlorophyll a of PS I

A

P700

214
Q

During the light reactions, there are two possible routes for electron flow

A

cyclic and linear

215
Q

Linear electron flow

A

the primary pathway, involves both photosystems and produces ATP and NADPH using light energy

216
Q

Step 1 in linear electron flow

A

A photon hits a pigment and its energy is passed among pigment molecules until it excites P680

217
Q

Step 2 in linear electron flow

A

An excited electron from P680 is transferred to the primary electron acceptor (we now call it P680+)

218
Q

Step 3 in linear electron flow

A

H2O is split by enzymes, and the electrons are transferred from the hydrogen atoms to P680+, thus reducing it to P680
P680+ is the strongest known biological oxidizing agent
O2 is released as a by-product of this reaction

219
Q

Step 4 in linear electron flow

A

Each electron “falls” down an electron transport chain from the primary electron acceptor of PS II to PS I

220
Q

Step 5 in linear electron flow

A

Energy released by the fall drives the creation of a proton gradient across the thylakoid membrane
Diffusion of H+ (protons) across the membrane drives ATP synthesis

221
Q

Step 6 in linear electron flow

A

In PS I (like PS II), transferred light energy excites P700, which loses an electron to an electron acceptor
P700+ (P700 that is missing an electron) accepts an electron passed down from PS II via the electron transport chain

222
Q

Step 7 in linear electron flow

A

Each electron “falls” down an electron transport chain from the primary electron acceptor of PS I to the protein ferredoxin (Fd)

223
Q

Step 8 in linear electron flow

A

The electrons are then transferred to NADP+ and reduce it to NADPH
The electrons of NADPH are available for the reactions of the Calvin cycle
This process also removes an H+ from the stroma

224
Q

Cyclic Electron Flow

A

electrons cycle back from Fd to the PS I reaction center

Cyclic electron flow uses only photosystem I and produces ATP, but not NADPH

No oxygen is released

225
Q

Which light reaction (cyclic and linear) is thought to have come first

A

Cyclic electron flow

226
Q

ATP and NADPH are produced on the side facing the stroma, where at in the cycle of photosynthesis

A

Calvin cycle

227
Q

The Calvin cycle has three phases

A

Carbon fixation (catalyzed by rubisco)
Reduction
Regeneration of the CO2 acceptor (RuBP)

228
Q

Calvin cycle reactants

A

Take place in the stroma

Use ATP and NADPH to convert to CO2 to the sugar G3P

Return ADP, inorganic phosphate, and NADP+ to the light reactions

229
Q

CAC Input

A

Acetyl CoA

Intro to Molecular and Cellular Biology (5 decks)

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