Bisc 315 - Cell Biology - Test 3

Front 1

The capturing and using of the energy of living systems.

Back 1

Bioenergetics

Front 2

How do cells get the energy they need?

Back 2

Chemical sources (respiration) or the sun (photosynthesis)

Front 3

What are the primary energy sources that the cell can use?

Back 3

Sugar and fat molecules

Front 4

Complex carbs have storage properties. What are the two storage forms of glucose?

Back 4

Glycogen (animal cells) and Starch (plant cells)

Front 5

What component of fat is the highest source of energy?

Back 5

Their C=H tails

Front 6

When sugars and fats are broken down, their energy must be captured and stored in forms that can be readily used called:

Back 6

Activated Carriers

Front 7

Give some examples of activated carriers.

Back 7

ATP, Acetyl CoA, NADH, NADPH, FADH2

Front 8

What percentage of cellular energy is used to make proteins?

Back 8

88%

Front 9

The energy available to do work is called:

Back 9

Free energy or G (Gibbs Free Energy)

Front 10

For a chemical reaction, if a reactant/substrate X has a greater energy than product Y:

Back 10

-Energy is released

-Exothermic

-Spontaneous

Front 11

For a chemical reaction, if a product Y has a greater energy than reactant/substrate X:

Back 11

-Energy input is required

-Endothermic

-Not spontaneous

Front 12

If ΔG is negative, the reaction is:

Back 12

Spontaneous

Front 13

If ΔG is positive, the reaction is:

Back 13

Not spontaneous

Front 14

If ΔG is 0, the reaction is:

Back 14

At equilibrium

Front 15

The breakdown of glucose makes a lot of energy. The reaction:

Glucose + 6 O2 --> 6CO2 + 6 H2O = ___ kcal/Mol

Back 15

668

Front 16

Rank the energy content of the following: ATP, ADP, AMP

Back 16

ATP > ADP > AMP

Front 17

What are the three mechanisms to generate ATP?

Back 17

Photophosphorylation, Oxidative Phosphorylation, and Substrate Level Phosphorylation

Front 18

This ATP generating mechanism involves the absorption of sunlight coupled to ATP synthesis.

Back 18

Photophosphorylation

Front 19

This ATP generating mechanism involves energy from activated carriers (NADH, FADH2) coupled with ATP synthesis (paired with the electron transport chain)

Back 19

Oxidative Phosphorylation

Front 20

This ATP generating mechanism uses enzymes to catalyze reactions coupled directly to ATP synthesis.

Back 20

Substrate Level Phosphorylation

Front 21

When O2 is available, what percentage of energy may be captured and stored as ATP?

Back 21

40-50%

Front 22

Where does the Krebs cycle occur?

Back 22

In the mitochondria

Front 23

Describe the overview of Glycolysis.

Back 23

-1 Glucose --> 2 Pyruvate

-10 reactions/10 enzymes

-Occurs in the cytosol

-Occurs in both the presence and absence of oxygen

Objective: To make ATP from energy extracted from sugars.

Front 24

What are the products of glycolysis?

Back 24

2 ATP/Glucose

2 NADH/Glucose

2 Pyruvate/Glucose

Front 25

Glucose is broken down into 2 pyruvate molecules through glycolysis. From here, it can take one of three pathways. Name them and indicate their oxygen requirements.

Back 25

>Krebs Cycle (requires oxygen)

>Lactic Acid (does not requires oxygen)

>Ethanol (does not require oxygen)

Front 26

What determines the path that the pyruvates will take post-glycolysis?

Back 26

>Oxygen availability

>Cell type

>Cellular conditions

Front 27

The process by which 2 pyruvates are turned into lactic acid is also called:

Back 27

Fermentation

Front 28

Describe the process of pyruvate being converted into lactic acid.

Back 28

>2NADH consumed

>Anaerobic

>Pyruvate --> Lactate

>No additional ATP is made

>There is energy in lactate, but under these conditions, the cell cannot extract this energy.

Front 29

2 pyruvates, under anaerobic conditions, can turn into Lactate or ____ + waste ____

Back 29

Ethanol; CO2

Front 30

Where does Lactic Acid and Ethanol + CO2 production coupled with glycolysis occur?

Back 30

In the cytosol in the absence of oxygen

Front 31

True or False: Fermentation and Ethanol production both produce additional ATP when paired with glycolysis which produces 2 ATP.

Back 31

FALSE; there is a net production of 2 ATP only from glycolysis. No extra ATP is produced from fermentation or ethanol production.

Front 32

Anaerobic Respiration captures ___ % of energy from glucose.

Back 32

2

Front 33

Aerobic Respiration captures ___% of oxygen from glucose.

Back 33

40-50

Front 34

In the presence of Oxygen, Pyruvate is imported into the mitochondria and oxidized into this compound, which can enter the Krebs Cycle.

Back 34

Acetyl CoA

Front 35

TRUE OR FALSE: Though often drawn together, the Krebs Cycle and the oxidation of pyruvate are actually two separate processes.

Back 35

True

Front 36

The oxidation of pyruvate (pyruvate --> Acetyl CoA) is actually three reactions catalyzed by three enzymes at the same place. This three enzyme complex is called:

Back 36

Pyruvate Dehydrogenase Complex

Front 37

How many reactions occur in the Krebs Cycle that extract energy from Acetyl CoA?

Back 37

8

Front 38

Describe the products of the Krebs Cycle

Back 38

2 Pyruvates --> 2 Acetyl CoA -->

>6 CO2 (released as waste)

>2 ATP (used to do cellular work)

>8 NADH (high energy; transfer electrons in ETC)

>2 FADH2 (see above)

Front 39

In what reactions is NADH produced? FADH2?

Back 39

NADH - Glycolysis, Krebs Cycle, Oxidation of Pyruvate

FADH2 - Krebs Cycle

Front 40

What kind of fats are most often used as an energy source?

Back 40

Triglycerides (3 fatty acid tails)

Front 41

Where does the β-Oxidation of Fatty Acids occur?

Back 41

Mitochondria

Front 42

What happens during the β-oxidation of fatty acids?

Back 42

-Fats and Lipids are broken down by enzymes into fatty acids

-These acids are oxidized into Acetyl CoA

-FADH2 is produced, NADH is produced, and Acetyl CoA is produced which can enter the Krebs Cycle

-Fatty acid tails have a lot of carbon atoms, so more energy can be produced

-FADH2 and NADH donate electrons in the electron transport chain

Front 43

β-Oxidation can also occur in this region, but no ATP is used.

Back 43

Peroxisomes

Front 44

Describe what happens during β-oxidation in the peroxisome.

Back 44

>Acetyl CoA is exported to the cytosol

>NADH is exported to the cytosol

>FADH2 is used to break down hydrogen peroxide

Front 45

What is the objective of the peroxisome?

Back 45

To break down toxins

Front 46

This part of the mitochondria surrounds the organelle completely and has big porins in it that allow rapid traffic to pass. It is selectively permeable, but a lot of things are allowed to cross because the porins are so big.

Back 46

Outer Membrane

Front 47

In this area of the mitochondria, many reactions occur.

Back 47

Inner membrane space

Front 48

This portion of the mitochondria runs along the outer membrane and occasionally extends finger-like projections into the outer membrane. By folding, it greatly increases surface area. Two things that happen here: Electron Transport reactions and ATP synthesis

Back 48

Inner Membrane

Front 49

This is the aqueous region inside the inner membrane that has the consistency of cytosol. Certain reactions occur here.

Back 49

Matrix

Front 50

What percentage of the organism's genome does mitochondrial DNA make up? (plants and animals)

Back 50

Plants: .2-2.5%

Animals: 0.001%

Front 51

Where are most proteins in the mitochondria made?

Back 51

They are nuclear encoded and synthesized in the cytosol, then transported into the mitochondria

Front 52

List processes that occur within the mitochondria.

Back 52

>Oxidation of pyruvate

>Citric Acid/Krebs Cycle (matrix)

>Beta Oxidation of fatty acids

>Protein synthesis

>Electron transport chain (inner membrane)

>Oxygen consumption

>ATP synthesis (Inner membrane)

Front 53

Describe the electron transport chain's composition.

Back 53

A chain/group of large protein complexes and some smaller proteins that are embedded in the membrane. They accept and donate electrons from FADH2 and NADH. This is a series of REDOX reactions that move substances through the complexes.

Front 54

NADH has to enter the electron transport chain (moved from cytosol into mitochondria) but it is NOT permeable to the membrane. How does it enter?

Back 54

The Malate Shuttleh

Front 55

How does the malate shuttle work?

Back 55

The energetic equivalent of NADH is moved across the inner membrane because NADH cannot get across.

Oxaloacetate picks up the high energy electrons from NADH and gives them to something else that can carry them across. Oxaloacetate is converted to malate which CAN move across, and when it is across the membrane, it reclaims its electrons.

Front 56

This mechanism moves pyruvate from the cytosol into the mitochondrial matrix.

Back 56

Proton/pH Gradient

Front 57

True or False: The glycolysis products (NADH and pyruvate) are moved into the mitochondria with a proton gradient and malate shuttle. The products of pyruvate oxidation and the citric acid cycle (NADH, FADH2, ATP, Acetyl CoA) are in the mitochondria, but in the wrong part.

Back 57

True

Front 58

This is a protein complex that uses the energy of a proton gradient to make ATP. All the energy from FADH2 and NADH is converted to ATP through this. It is located in the inner membrane.

Back 58

ATP synthase

Front 59

True or False: The energy used to move protons from one side of the electron transport chain to the other is used to generate a pH gradient.

Back 59

True

Front 60

True or False: NADH and FADH2 donate their electrons at the same location in the electron transport chain.

Back 60

False

Front 61

What is the role of Oxygen in the electron transport chain?

Back 61

Oxygen is the terminal electron acceptor (at the end of the chain). Electrons must be pulled out of the chain. As electrons are donated and passed through complexes, water is formed and holds onto some electrons.

Front 62

What is the reaction corresponding to oxygen's purpose in the electron transport chain?

Back 62

4 e- + 4 H+ + O2 => 2 H2O

Front 63

Which protein allows oxygen to act as the terminal electron acceptor?

Back 63

Cytochrome oxidase complex

Front 64

True or False: The electron transport chain converts one type of active carrier into another.

Back 64

True; NADH or FADH2 into ATP

Front 65

The ATP synthase is coupled to the proton gradient. How do these two work together?

Back 65

1. The energy of the electron transport chain is used to pump protons across the membrane.

2. The energy in the proton gradient is harnessed by ATP synthase to make ATP

Front 66

What is the coupling of the proton gradient and synthesis of ATP called?

Back 66

Chemiosmosis

Front 67

Where does chemiosmosis occur and what type of phosphorylation occurs in each area?

Back 67

Mitochondria (oxidative phosphorylation)

Chloroplasts/thylakoid membrane (photophosphorylation)

Front 68

This concept is described as the electron flow through the electron transport chain pumps protons across the membrane.

Back 68

Chemiosmotic Hypothesis

Front 69

How are proton gradients used in bacterial cells?

Back 69

To move flagella

Front 70

There are certain molecules that, when embedded in the membrane, they collapse the ion gradients. It's like poking holes into the membrane, and the energy source is suddenly lost. Molecules that do this are called:

Back 70

Uncouplers

Front 71

How much ATP is generated by aerobic metabolism for one molecule of glucose per product?

Back 71

-Some ATP is produced directly by substrate level phosphorylation (Glycolysis?)

-1 NADH => 3 ATP

-1 FADH2 => 2 ATP

Front 72

What are the products of glycolysis, the oxidation of pyruvate, and the krebs cycle? How much ATP do they produce?

Back 72

10 NADH @ 3 ATP = 30 ATP

2 FADH2 @ 2 ATP = 4 ATP

2 ATP = 2 ATP

TOTAL = 36 ATP (theoretical yield)

Front 73

What is the theoretical yield and observed yield of aerobic respiration?

Back 73

Theoretical yield: 36 ATP

Observed yield: 30 ATP

Front 74

What are some causes of lower ATP yield in aerobic respiration?

Back 74

Inner mitochondrial membranes leak protons and proton gradient is used for other purposes

Front 75

Compare efficiency in aerobic and anaerobic respiration

Back 75

AEROBIC -> 36 ATP -> 40%

ANAEROBIC -> 2 ATP -> 2%

Front 76

We break down glucose, carbons, hydrogens and oxygens end up in water, and the energy associated with all chemical bonds is captured in ATP. What happens to the rest of the energy?

Back 76

Lost as heat

Front 77

What do we call organisms that can retain the heat produced by ATP production?

Back 77

Endotherms

Front 78

This is the outermost structure of the plant cell, residing outside of the cell membrane. It is made of cellulose and other types of polysaccharides. It's very complex and does not break down well.

Back 78

Cell Wall

Front 79

This structure of the plant cell is found in mature cells and is surrounded by a membrane. It can sometimes be so big that it can push all other organelles against the cell membrane. It can occupy 80-95% of the cellular space. It contains water, and the hydrostatic pressure is what gives plant cells their support.

Back 79

Vacuole

Front 80

This is a group of double-membrane enclosed organelles.

Back 80

Plastids

Front 81

There are two kinds of plastids discussed in class. What are they?

Back 81

Amyloplasts and Chloroplasts

Front 82

These plastids hold starch and sometimes can hold so much starch that they look like they are empty. They are used by plant cells to detect gravity and are similar to statoliths in the inner ear.

Back 82

Amyloplasts

Front 83

These plastids are found in plants and algae. Their numbers vary from 20-50 per cell. Some bacteria are photosynthetic but do not contain these.

Back 83

Chloroplasts

Front 84

How are mitochondria similar to chloroplasts?

Back 84

They both have double membranes (envelope)

They both contain their own DNA

They both have ribosomes

They can make proteins, but not a lot of proteins. Most are made in the cytosol and are imported into the organelle.

Front 85

This chloroplast component is the part that is not occupied by the membranes. It is aqueous based.

Back 85

Stroma

Front 86

The stroma is similar to what component of the mitochondria?

Back 86

Matrix

Front 87

This component of the chloroplast is sometimes stacked up like pancakes, but sometimes they are individual in the cell.

Back 87

Thylakoid Membrane

Front 88

If we took the thylakoid membrane and sliced them open, we see that they have spaces inside. These spaces, cavities, or openings are called:

Back 88

Thylakoid Lumen/Thylakoid spaces

Front 89

What percentage of cellular DNA is the DNA in chloroplasts?

Back 89

10-15%

Front 90

In what three places can we find DNA in cells

Back 90

Mitochondria, chloroplasts, nucleus

Front 91

In what three places can proteins be synthesized?

Back 91

In cytosol, in mitochondria, in chloroplasts

Front 92

What are the three objectives in photosynthesis?

Back 92

a.) Capture solar energy and convert it into chemical energy for the use of other living things

b.) Can use inorganic carbons (CO2) and convert them to organic carbon (sugars)

c.) Source of atmospheric oxygen (O2); released as waste

Front 93

What is the summary equation of photosynthesis?

Back 93

6 CO2 + 6 H2O --> 6 (CH2O) + 6 O2

Front 94

What does each component in oxygenic photosynthesis do?

Back 94

CO2 -> Synthesize sugars

H2O -> Used as a source of electrons and hydrogens

O2 - Released from the water molecule

Front 95

The type of photosynthesis that releases oxygen, particularly by plants, algae and cyanobacteria is called

Back 95

Oxygenic Photosynthesis

Front 96

What is the alternative form of photosynthesis called and what is its equation?

Back 96

Anoxygenic photosynthesis

CO2 + H2S --> CH2O + 2S + H2O

Front 97

What does each component in anoxygenic photosynthesis do?

Back 97

CO2 - Synthesizes sugars

H2S - Source of protons and electrons (rotten egg smell)

Sulfur - waste product

Front 98

Where do light reactions occur?

Back 98

Thylakoid membrane

Front 99

Where do dark reactions occur?

Back 99

Stroma

Front 100

What occurs during the light reactions?

Back 100

Light energy is absorbed and converted to chemical energy (ATP, NADH) using various pigments

Front 101

Chlorophyll and other pigments function to absorb light energy in a structure/unit called a:

Back 101

PhotosystemW

Front 102

What are the three components of a photosystem?

Back 102

-Chlorophyll acting as an antennae

-Chlorophyll acting as a reaction center

-Proteins

Front 103

What occurs in the reaction center in the photosystem?

Back 103

Light energy in the chlorophyll molecules excite the electrons, bringing them to a higher energy levelP

Front 104

Photosystems are part of the

Back 104

Electron Transport Chain

Front 105

Photosystem II can break apart water molecules and extract the electrons and proteins from this water. The electrons are used to replace the electrons lost in the reaction center chlorophyll. This is called

Back 105

Photolysis

Front 106

What happens to the products of photolysis

Back 106

Electrons are donated to chlorophyll to replace lost electrons

Hydrogen accumulates in the thylakoid lumen (later will made a proton gradient)

Oxygen is released in the atmosphere

Front 107

ATP synthesis is this type of phosphorylation.

Back 107

Photophosphorylation

Front 108

Photophosphorylation is a type of

Back 108

Chemiosmosis

Front 109

What are the three major pathways involved in dark reactions?

Back 109

C3, C4, and CAM pathways

Front 110

Describe the process of the C3 pathway

Back 110

First reaction: CO2 + RuBP --> 2 PGA

Catalyzed by Rubisco

PGA is further metabolized by the calvin cycle which requires a lot of ATP and NADPH to produce G3P

Front 111

Rubisco catalyzes two reactions. What are they?

Back 111

CO2 + RuBP --> PGA

O2 + RuBP --> PGA + PGLY

Front 112

CO2 + RuBP --> PGA is the first step in what process?

Back 112

Photosynthesis

Front 113

O2 + RuBP --> PGA + PGLY is the first step in what process?

Back 113

Photorespiration

Front 114

The photorespiration pathway metabolizes what?

Back 114

PGLY

Front 115

The photorespiration pathway occurs in three organelles. What are they?

Back 115

Chloroplast, peroxisome, mitochondria

Front 116

This is the idea what photorespiration results in the loss of CO2 and therefore lowers the rate of photosynthesis.

Back 116

The Warburg Effect

Front 117

What determines whether rubisco uses CO2 or O2?

Back 117

The relative amount closest to Rubisco

Front 118

What does C4 and CAM do?

Back 118

C4 and CAM attempt to shove carbon dioxide closer to rubisco and prevent photosynthesis from being reduced. C4 is the basic carbon fixation pathway (Calvin Cycle). C4 and CAM modify the C3 pathway, elevating CO2 at rubisco. This reduces photorespiration and increases photosynthesis.

Front 119

This is the degradative process by which large molecules are broken down into smaller ones. Usually energy is released, starting with high energy through a step by step process. Energy is captured and stored in activated carriers.

Back 119

Catabolism

Front 120

This is a biosynthetic pathway used to build up substances. It requires energy.

Back 120

Anabolism

Front 121

Pathways can be one of three formats.

Back 121

Branched, linear, or cyclic

Front 122

What is the general formula for enzyme actions?

Back 122

Enzyme + substrate -> enzyme/substrate complex -> enzyme + product

Front 123

What alters the rate of enzyme catalyzation?

Back 123

The arrangement of the enzyme

Front 124

True or False: Enzymes are soluble

Back 124

True

Front 125

In what arrangements can enzymes be found?

Back 125

-"floating" in the cytosol unattached to anything else, in a complex which allows the product to be passed to the enzyme right next to it, or in membranes where they are held together.

Front 126

What is an example of enzymes "floating" in the cytoplasm?

Back 126

Calvin cycle, glycolysis, Krebs Cycle enzymes

Front 127

What is an example of enzymes found in a complex?

Back 127

Oxidation of pyruvate enzymes

Front 128

What is an example of enzymes found in a membrane?

Back 128

Two different electron transport chains in the inner mitochondrial membrane and thylakoid membrane in the photosynthetic electron transport chain use this arrangement

Front 129

This is the production of glucose from non-sugar molecules. It is essentially the reverse of glycolysis

Back 129

Gluconeogenesis T

Front 130

True or False: Most glycolysis/gluconeogenesis pathway enzymes are reversible.

Back 130

TrueI

Front 131

What determines the direction of reversible reactions?

Back 131

Local conditions around where the reaction is found. If there is more A than B, more B will be produced. If the reverse is true, more A will be catalyzed than B.

Front 132

This is the enzyme that is found in many pathways, but may restrict the activity of one or more pathway activities. They often catalyze reversible reactions

Back 132

Rate limiting enzyme

Front 133

What are the two levels at which enzyme activity is regulated?

Back 133

The amount of enzyme present (coarse control) and the regulation of activity of pre-existing enzymes (fine control)

Front 134

Give three examples of enzyme regulation.

Back 134

1. Aerobic eukaryotic cells; krebs cycle

-ATP inhibits

-NADH does not inhibit

2. E. coli

-NADH inhibits

-ATP has no impact

3. Germinating seeds of oil-producing plants

-No ATP or NADH synthesis

BOTTOM LINE: Enzymes are regulated differently in different cells

Front 135

True or False: All of the examples of metabolic control discussed in class are examples of coarse control.

Back 135

FALSE; Fine control

Front 136

List the mechanisms of metabolic control.

Back 136

1. pH

2. Temperature

3. Substrates

4. Enzyme activation/inactivation

5. Allosteric proteins

6. Feedback inhibition

Front 137

In this mechanism of metabolic control, enzymes have optimum levels, and different enzymes have different pH optima. Ezymes in the lysosomes are regulated by this. Proton gradient creation affects this.

Back 137

pH

Front 138

In this mechanism of metabolic control, cells cannot control this on their own. Heat is created as a byproduct of inefficiency, but most of this is controlled by environmental conditions. Rate of reaction increases as this variable increases to a point where the enzymes will begin to denature and the rate will crash.

Back 138

Temperature

Front 139

In this mechanism of metabolic control, there are two different perspectives. As we provide more of this substance, the rate continues to a point, then levels off. The reason for this leveling off is that the enzyme becomes so saturated and cannot bind anymore. The second perspective is that the enzyme has a choice of these which can determine the pathway.

Back 139

Substrate control

Front 140

In this mechanism of metabolic control, activity can increase or decrease. The major regulatory process is phosphorylation/dephosphorylation. Proteins can also add/remove GTP. Competitive inhibition occurs here too in which substrate can bind to the active site and limit/eliminate activity.

Back 140

Enzyme activation/inactivation

Front 141

In this mechanism of control, proteins are shaped when a regulatory ligand (an effector) binds to the protein. The binding of the ligand changes the shape of the active site, either allowing or denying substrates to bind. The activity can be increased or decreased, positive or negative effectors. ATP is a positive effector. CTP is a negative effector.

Back 141

Allosteric proteins

Front 142

In this mechanism of control, enzymes in the pathway are affected by a product later in the pathway, stopping the production of said product.

Back 142

Feedback inhibition