Unit 3 - Metabolism Flashcards
1
Q
5 Examples of cellular activities that require energy:
A
cell division
synthesis of proteins from amino acids
active transport
muscle cell contraction (in animal bodies)
transmission of nerve impulses (in animal bodies)
2
Q
Energy
A
= ability to do work
3
Q
Sum of all chemical reactions occurring in a living cell or organism
A
= it’s metabolism
4
Q
Building up rxn
A
anabolic
5
Q
breaking down rxn
A
catabolic
6
Q
Eukaryotic cells =
A
organisms that contain a nucleus surrounded by a membrane and specialized organelles not present in prokaryotic cells. These types of cells are found in trees, protozoa (amoeba), and vertebrates (animals with a backbone)
7
Q
Prokaryotic cells =
A
typically unicelllar microorganisms that do not have a distinct nucleus or membrane bound organelles. An example of this are bacteria.
8
Q
Energy from food is typically measured in
A
calories (cal), but in some scientific literature is in Joules instead.
9
Q
1 calorie =
A
amount of energy to raise temperature of 1 gram of water by 1 degree celsius.
1 cal = 4.184 kJ
10
Q
Daily energy requirements, for basic body functions, such as breathing, digesting, and thinking can be calculated
A
basal metabolic rate/BMR
11
Q
RMR
A
resting metabolic rate - amount of energy used by a person at rest over a 24-hour period. This is the amount of energy required to run the basic energetic needs of organs like the heart, lungs, liver, and kidneys.
12
Q
BEE
A
basal energy expenditure - a 24 hour estimation of the number of calories you burn maintaining your most basic bodily functions, such as breathing, circulating blood and growing and repairing cells
13
Q
REE
A
resting energy expenditure - determines the number of calories you burn in a 24 hour period maintaining basic bodily functions, but also includes the number of calories burned eating and conducting small amounts of activity.
14
Q
BMR is a more accurate measure because
A
RMR is more general than specific; BMR targets specific body functions and measures different metabolic rates after fast and at rest at different periods
15
Q
Three of the most common health problems resulting from our modern lifestyle include:
A
Diabetes
Obesity
Cardiovascular disease
16
Q
Type 2, diabetes usually results from:
A
The pancreas’s gradual inability to produce insulin
Cells becoming resistant to absorbing glucose, a type of sugar, from the blood
Individuals with the lack of ability to control blood sugar levels
17
Q
bmi
A
body mass index calculated by dividing your weight (in kilograms) by the square of your height (in metres).
18
Q
Two of the most common cardiovascular problems in Canada are
A
heart attacks and strokes.
19
Q
coronary artery disease occurs when
A
fatty materials, calcium, and scar tissue combine into a sticky substance called plaque, which is carried in the blood. The plaque can accumulate on the walls of coronary arteries and narrow their diameter.
20
Q
In the human body and ecosystems, the ‘currency’ of energy is captured and managed by one of the most basic laws of science which states that energy cannot be created or destroyed but it can be changed from one form to another. This is called the
A
the Law of the Conservation of Energy.
21
Q
All forms of energy can be divided into two types:
A
kinetic and potential energy.
22
Q
Kinetic energy
A
is the energy that causes objects to move. This is the energy that is being used up.
23
Q
Potential energy
A
is energy that is stored for later use.
24
Q
Thermodynamics =
A
science that deals with the relationship between all forms of energy.
25
First law of thermodynamics =
energy can be changed from one form to another, but it cannot be created or destroyed. Amount of energy in universe is always conserved. However when energy is transformed, there is always some loss of energy - it is not destroyed it just becomes unusable for doing any further work.
26
Second law of thermodynamics =
disorder (aka entropy) in the universe is always increasing. Each time energy is used, some will be converted (lost) to heat (random motion). Every time energy is transformed into another form, some of the potential energy is converted into heat, but the heat is not always able to do further work. Some of the heat produced becomes permanently unavailable.
This means that disorder is always more likely than order.
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Endergonic reactions
Reactions in which the reactants have less energy than their products; reaction absorbs energy
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Exergonic
when reactants have more energy than products; releasing energy
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Recall the acronym OIL RIG.
OIL
Oxidation is Loss of Electrons/Energy (and gain of oxygen). Substances that are oxidized are called reducing agents because they cause the reduction of other substances.
RIG
Reduction is Gain of Electrons/Energy (and loss of oxygen). Substances that are reduced are called oxidizing agents because they cause the oxidation of other substances.
30
Redox reactions occur when
both oxidation and reduction reactions occur simultaneously. When a reducing agent and an oxidizing agent react, a redox reaction takes place
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Reduced molecules or atoms are raised to higher energy levels because
electrons repel each other. Adding more electrons to an atom is like pressing down on a spring. Just as pushing on a spring increases the potential energy of the spring, adding more electrons increases the potential energy of the atom.
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Specialized molecules, called energy carriers or coenzymes, become reduced and oxidized by
electrons shuttled from one enzyme to the next through metabolic pathways, delivering or harvesting energy at each stage (ETC/Active Transport)
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how (NAD+) becomes NADH
Nicotinamide adenine dinucleotide ; becomes NADH through reduction where it accepts a H proton and 2 electrons and gains energy
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ATP
adenosine triphosphate ; currency of the cell; 54kJ of energy
35
Cells get energy from ATP by
hydrolyzing the unstable high-energy bond between the second and third phosphate of the ATP, which creates the two products, adenosine diphosphate (ADP) and inorganic phosphate (Pi), and the release of 30 kJ/mol of energy.
36
Aerobic cellular respiration is
the process of capturing the energy of the electrons that are shared in the covalent bonds (C-H) of glucose, using oxygen as a final electron acceptor. The process results in the release of energy and the formation of water and carbon dioxide as products
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Aerobic cellular respiration can be broken
down into four main stages:
Glycolysis
Pyruvate oxidation
Krebs cycle
Electron transport chain/Chemiosmosis
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energy-carrying coenzymes, enzymes, and specialized structures within the mitochondria are used by aerobic CR to
incrementally extract the energy of the electrons as they move toward their final electron acceptor, oxygen.
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cristae
folds in the inner membrane of the mitochondrion that provide greater surface area and specialized environments for energy carrying reactions
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matrix (mitochondrion)
space within the inner membrane of the mitochondrion where most reactions take place
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FADH2 is oxidized to
FAD
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describe glycolysis
- 10-step enzyme catalyzed reaction that takes place in cytoplasm of eukaryotic cells
- Each glucose (6 Carbons) enters the cytoplasm of the cell
- split into two 3-carbon molecules that eventually become pyruvate (2 × 3 Carbons).
- prepares the energy-rich glucose molecule for the extraction of the energy stored in its bonds.
- energy has first to be invested to destabilize the glucose molecule.
- Two ATP molecules are expended initially by the cell
- four ATP and two NADH molecules are then produced.
- net yield of energy-carrying products is two ATP and two NADH.
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Aerobic cellular respiration is
the process of capturing the energy of the electrons that are shared in the covalent bonds (C-H) of glucose, using oxygen as a final electron acceptor. The process results in the release of energy and the formation of water and carbon dioxide as products
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The glycolysis stage of aerobic cellular respiration does not require
oxygen
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1st stage of glycolysis
Two ATP molecules are consumed to prepare the 6-carbon glucose molecule to be broken down into 3-carbon molecules.
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2nd stage of glycolysis
- altered glucose is separated into two 3-carbon molecules called glyceraldehyde-3-phosphate (G3P).
From this point on, the metabolic reactions occur twice (once for each 3-carbon half of the original glucose molecule).
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3rd stage of glycolysis
glyceraldehyde-3-phosphate (G3P) is converted to two, 3-carbon pyruvate molecules. The energy harvested during the exothermic and enzyme catalyzed formation of pyruvate produces 2 NADH and 4 ATP molecules.
48
NET tally of the products of one molecule of glucose by the end of glycolysis:
Two (3-C) Pyruvate molecules
2 NADH
2 ATP
(4 produced – 2 consumed = 2 ATP Net)
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What is the purpose of the process of glycolysis?
Glycolysis is the first step of cellular aerobic respiration and breaks down glucose into 2 pyruvate molecules and produces high energy carriers in the amount of 2 NADH and 2 ATP molecules.
50
describe pyruvate oxidation
the second stage of aerobic cellular respiration
- occurs in mitochondrial matrix
- two pyruvate molecules (2 × 3 carbons) produced in glycolysis are decarboxylated (2 × 1 carbons are removed as two CO2 are formed)
- this produces two acetyl-CoA (2 × 2 carbons), as well as reduced energy carriers.
- Also known as the oxidative decarboxylation of pyruvate
- Before this stage can occur, each pyruvate has to be actively transported across the outer mitochondrial membrane, through the intermembrane space and the inner mitochondrial membrane, finally reaching the specialized chemical environment of the mitochondrial matrix.
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3 Main Steps of Pyruvate Oxidation
1. A CO2 molecule is removed from one pyruvate.
2. Each pyruvate is also quickly oxidized by the energy carrier, NAD+, which gains two electrons and two protons, to become NADH and H+. Acetic acid is formed as the remaining product.
3. A vitamin B5 derivative called coenzyme A (CoA) bonds with the acetic acid and forms a complex called acetyl-CoA. This complex is the final product in the oxidation of pyruvate.
52
which coenzyme is involved with pyruvate oxidation and what complex does it form
Coenzyme A, CoA - bonds with acetic acid to create acetyl-CoA.
53
what vitamin does CoA derive from
Vitamin B5
54
Net tally of products from the oxidative decarboxylation of TWO pyruvate molecules (or pyruvate oxidation):
2 CO2
2 Acetyl-CoA
2 NADH
2 H+
55
describe the krebs cycle
- Two acetyl-CoA (2 × 2 carbons) molecules react in metabolic pathway to produce four CO2 (4 × 1 carbon) molecules
- energy carriers are reduced (gain energy), harvesting electrons and protons.
- occurs in the mitochondrial matrix.
- eight-step enzyme-catalyzed process
- Note that citrate is turned into isocitrate in the first step, but the number of carbons does not change and no energy is released.
- previously, the Krebs cycle was known as the citric acid cycle as citrate is one of the intermediate molecules.
- Oxaloacetate, which begins the cycle as a reactant, is regenerated as a product, during the last reactions in the cycle.
56
in krebs cycle actions of the eight different enzymes involved in the cycle result in the transformation of each acetyl-CoA molecule into which molecules:
Citrate → isocitrate → α-ketoglutarate → succinyl-CoA → succinate → fumarate → malate → oxaloacetate
57
Net tally of products from 2 acetyl-CoA (per glucose) entering the Krebs cycle:
2 co2
6 nadh
2 fadh2
2 atp
58
Explain why the Krebs cycle needs to occur twice for each glucose molecule undergoing cellular respiration
Each glucose molecule leads to the production 2 acetyl-CoA molecules at the end of pyruvate oxidation and each “turn” of the Krebs cycle uses one acetyl-CoA molecule. Thus the Krebs cycle has to occur twice for each glucose molecule.
59
Name the energy carriers in the Krebs cycle.
ATP, NADH, FADH2
60
By the end of the Krebs cycle, all of the six carbons from the original glucose molecule have been removed as
co2
61
describe the ETC and chemiosmosis
- forth stage of CR
- occurs in the cristae of the matrix, the inner membrane, and the intermembrane space.
- electrons harvested from oxidation of glucose move from electron donors (NADH and FADH2) to a final electron acceptor (O2) via a series of redox reactions called the electron transport chain (ETC).
- energy released is used to power three proton pumps that push H+ ions out across the mitochondrial matrix membrane into the intermembrane space resulting in a transmembrane proton gradientto make ATP by chemiosmosis.
-10 NADH and two FADH2 generated during the first three stages of aerobic respiration through the oxidation of glucose move into the folds of the inner membrane within the matrix, called the cristae.
. This linear series of molecules carries out coupled redox reactions to pass on electrons from the energy carriers FADH2 and NADH to oxygen.
- electrons are passed along the ETC like a baton handed from runner to runner in a relay race.
-With each transfer, the electrons occupy a slightly more stable position on the carrier molecule. The energy they give up at each transfer is used to power the proton pumps that pump the H+ ions out of the matrix into the intermembrane space.
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electron transport chain (ETC).
- sequence of molecules called cytochrome complexes that release energy from the electrons each step in chain.
- Various membrane-associated proteins and special compounds called cytochromes comprise a series of increasingly strong reducers
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Step 1 of ETC + chemiosmosis
-called electron and proton removal (from NADH)
membrane-bound enzyme in the cristae called NADH dehydrogenase removes the high-energy electrons from NADH (creating NAD+). The protons ( 𝐻+ ) associated with the electrons are now free to be moved by the enzyme into the matrix. The energy released is used to drive the three proton pumps that pump the H+ ions out of the matrix into the intermembrane space.
- The NAD+ produced goes back into the Krebs cycle, where it gets turned again into NADH.
64
Step 2 of ETC + chemiosmosis
- called Electron Transport by Ubiquinone
- The FADH2 has its high-energy electrons removed by the next molecule in the chain, ubiquinone. The low-energy FAD molecule is also returned to the Krebs cycle.
- The mobile electron carrier, ubiquinone, moves within the membrane. It carries electrons to the proton pump, called the b-c1 complex, which forces more H+ out of the matrix into the intermembrane space (increasing proton concentration)
65
Step 3 of ETC + chemiosmosis
- called Electron transport by Cytochrome C
- The electron carrier, cytochrome C, carries electrons to the third proton pump, called cytochrome C oxidase.
- Most of the energy of the high-energy electrons carried by ubiquinone and cytochrome C is used to pump H+ out of the matrix into the intermembrane space, while the rest is lost as heat. The H+ that are pumped out become concentrated as they build up in the intermembrane space. These charged atoms cannot easily move back across the membrane into the matrix.
- The result is that an electrochemical gradient is built up across the membrane, with H+ concentrated on the outside. This gradient contains potential energy, which eventually gets used to make ATP.
66
Step 4 of ETC + chemiosmosis
- Electron Acceptance and the Formation of Water
- electrons that were stripped from glucose in the Krebs cycle have had their energy used to pump protons (H+) out of the matrix and are now at a very low energy level.
- lower energy electrons must be accepted by an atom for the preceding electrons to continue to flow through the ETC.
- At the end of the ETC, two electrons passing through the final complex (cytochrome oxidase) are donated to the final electron acceptor, oxygen.
- As one oxygen atom accepts two electrons, it also binds two protons (2H+) together, resulting in the formation of one molecule of water (H2O).
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Step 5 of ETC + chemiosmosis
- Production of ATP by Chemiosmosis
- Inside the matrix, the H+ concentration is low, so the trend is for the H+ to equalize its concentration (as with diffusion/osmosis).
- Specialized H+ channel proteins that span the inner membrane open to let the H+ flow into the matrix. As with busy commuters rushing through turnstiles in a train station, the protons stream through the protein channel, to the end of which the enzyme ATP synthase is attached.
- The kinetic energy delivered by the movement of the H+, called the proton motive force (PMF), powers ATP synthase to phosphorylate ADP with Pi to form ATP.
68
what is PMF and what does it power
Proton motor force, kinectic energy created through the movement of H+ protons across the membranes that powers enzyme ATP synthase
69
what does ATP synthase do during chemiosmosis
phosphorylates ADP with Pi (single/inorganic phosphate) to make ATP
70
why is oxygen needed for chemiosmosis
H+ concentration must remain high for the PMF to occur, which means electrons need to keep moving, which means oxygen needs to be accepting the electrons at the end of ETC without which will stop the CR and stop energy production
71
describe beta oxidation of fats
Enzymes in the matrix add CoA (coenzyme A) to the terminal ends of fatty acid tails, alloing for the stripping of electrons from the numerous C-H bonds via NAD+ to NADH. The end result is the production of acetyl-CoA molecules (acetyl coenzyme A).
These eneter the Krebs cycle and respiration continues as usual with its regular production of NADH and FADH2 as seen below.
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deanimation of proteins
Proteins can be broken down into amino acids, which can then be deaminated to produce energy-rich molecules that feed into cellular respiration pathways.
Amino acids all contain an amino group (-NH2), which is removed during the process of deamination. Because of their unique functional groups, when different amino acids are deaminated, they form products that can feed into glycolysis or the Krebs cycle, such as pyruvate but this process can also create toxins
73
Anaerobic cellular respiration
simply glycolysis which only generates 2 atp vs 32 by aerboic CR
74
how much energy lost as heat in aerobic CR
2052 kJ
75
efficiency of aerobic CR
32%
76
efficiency of anaerobic CR
2%
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formula for photosynthesis
6CO2 + 6H2O + light energy → C6H12O6 + 6O2
Carbon dioxide + water + light energy → glucose + oxygen gas
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Chloroplast -
The chloroplast is the organelle that is responsible for carrying out photosynthesis in plants. Its appearance is like that of a miniature cell with an outer membrane.
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Thylakoids -
The chloroplast contains stacks of membranous disks called thylakoids. The thylakoid membrane is embedded with many proteins.
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Granum
Thylakoids are grouped into columns, each called a granum (plural: grana, from Greek, meaning “stack of coins”).
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Lumen
The internal environment of the thylakoid is called the lumen.
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Lamellae
Some thylakoids from different grana are connected together by flat bands of ribbon-shaped membrane, called lamellae (stroma lamellae)
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Stroma
- All of these structures are suspended in an aqueous medium called the stroma.
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special light-sensitive pigments, that give chlorplast ability to absorb light and it's green colour
chlorophyll
85
chlorophyll a vs chlorophyll b
a - has a methyl group (CH3), absorobs 400-500 nm, ability to absorb energy and transfer electrons for Photosynthesis
b- has a carbonyl group (-CHO), absorbs 600-700), can absorb energy and pass electrons to chlorophyll a
86
action spectrum
combined range of spectrum that can be actively used to absorb energy by pigments (like chlorophyll)
87
2 stages of photosynthesis
Light-dependent and light independent (aka Light reactions and Calvin cycle
88
3 steps of light dependent reactions
1. Capture light energy
2. transfer light energy by intermediate energy carriers
3. Transform light energy to chemical potential energy (ATP and NADPH)
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3 steps of light independent reactions
1. Carbon fixation
2. Reduction of PGA
3. Regeneration of RuBP
90
Step 1 of light reactions
- capturing light energy
- photon of light energy hits a chlorophyll molecule bound to thylakoid membrane, an electron absorbs much of this energy.
- electron becomes excited to a higher energy level and leaves the chlorophyll a in order to move to neighbouring pigments. This association of several chlorophyll a and carotenoids, called an antenna system (photosystem I/700 or II/680), passes on the excited electron to the reaction centre.
- excited electron is captured by a primary electron acceptor which oxidizes the reaction centre to gain the electron.
91
Step 2 of light reactions
- transfer of light energy to intermediate carriers
- electrons that went through photosystem 680 are used to remove electrons from water (releasing H+ and O) via photolysis
- oxygen is released
- protons from photolysis are pumped into the lumen (interior) of thykaloid to create a chemiosmotic gradient
- photosystem 680/II feeds transfer electrons to photosystem 700/I via ETC
- high energy electron ends up being NADPH
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photolysis
enzyme-catalyzed process used to remove electrons from water and also releases oxygen
93
identify parts of the chloroplast
94
Step 3 of light reactions
Transformation of Light Energy into chemical potential energy (ATP and NADPH)
- PS 680/II -- in step 1, protons feul atp synthase to make ATP
- PS 700/I in step 2, NADPH is produced via ETC
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cyclyic vs non cyclic photophosphorylation
cyclic is when electrons donated from chlorophyll a during photophosphorylation are returned to chorophyll to continue ATP generation, but then NADPH is not produced. non cyclic requires photolysis and water to donate electrons which then can also generate the NADPH
96
Compare the roles of photosystems I and II in photosynthesis
- Photosystem II functions to harvest photon energy and donate high-energy excited electrons to the first of the electron carriers of the ETC.
- Photosystem I accepts the electrons passed along from photosystem II and, using more light energy from photons, re-excites those electrons to an even higher energy level, before passing them on to the rest of the electron carriers of the ETC.
97
List the path of an electron excited by light photons during the light reactions, identifying each cellular component it passes through.
An excited electron takes the following path during the light reactions: photosystem II, chlorophyll a, pheophytin, plastoquinone (Q), cytochrome b6-f complex, plastocyanin (pC), photosystem I, ferrodoxin (Fd), NADP reductase, NADP/ NADPH. (Also, a new electron from water replaces the lost electron).
98
uses the ATP and H+ protons from the light-dependent reactions to reduce carbon from CO2 to form carbohydrate molecules like glucose.
the calvin cycle
99
Carbon reduction involves
- a series of enzyme-mediated reactions in the stroma of the chloroplast.
- To eventually build complex organic molecules containing many carbon atoms, must start by attaching single carbon atoms to smaller carbon-containing molecules.
100
phase one of light independent reactions
carbon fixation
- CO2 is added to ribulose 1,5-bisphosphate (RuBP/rubisco) in stroma
- RuBP carboxylase catalyzes reaction to create unstable compound that splits into 3-phosphoglycerate (PGA).
- 3 CO2 and 3 RuBC creates six PGA
101
type of reaction to RuBp and CO2
carbon fixation
102
phase two of light independent reaction
- six PGA from from phase 1 are raised to a higher energy level by addition of a phosphate group to make 1,3-biphophoglycerate (PGAP)
- PGAP is reduced into glyceraldehyde-3-phosphate (G3P) using the NADPH
- one of the six G3P are removed from the cycle, while the other 5 return to replensish RuBP
- the one G3P is produced to make carbohydrates
103
how many ATP and NADPH are used to produce one G3P
- six each
104
phase three of light independent reactions
Regeneraiton of RuBP
- the 5 G3P plus 3 phosphates and 3 ATP synthesize 3 RuBP which is used for phase 1 to continue calvin cycle
105
Where does the energy in NADPH and ATP that feeds the Calvin cycle come from?
The energy in ATP and NADPH comes from the light-dependent reactions. It is transferred to the Calvin cycle during the dark reactions.
106
Summarize the events of the light-independent reactions by referring to the reactants, products, and cellular components involved.
CO2 molecules enter into a three-step metabolic pathway called the Calvin cycle. ATP provides energy for enzymes to add the carbon from the CO2 to intermediate carbon- and phosphate-rich molecules, eventually yielding the energy-rich G3P molecule, which leaves the Calvin cycle. NADPH is then used with more ATP to regenerate the carbon-rich intermediate RuBP, so that the cycle can begin again with the entry of more CO2.
107
What is the relationship between the light reactions and the Calvin Cycle?
The light reactions use light energy and water to provide the energy (in the form of ATP and NADPH) for the Calvin Cycle, which fix carbon from gaseous carbon dioxide into energy-rich sugar molecules.
108
Photorespiration
- process that reduces the efficiency of photosynthesis, preventing photosynthesis when unfavourable temperatures are present. - Rubisco, is required to fix carbon dioxide. However, Rubisco can also react with oxygen instead of carbon dioxide leads to a less efficient photosynthetic rate.
- Photorespiration results when plants try to conserve water loss when the temperature rises above the optimal temperature
109
C4 Plants
Plants that fix carbon into molecules containing four carbon atoms are called C4 plants.
- more efficient in higher temperatures than lower temperatures
110
C3 Plants
Plants that fix carbon into molecules containing three carbon atoms (like G3P via the Calvin Cycle, as described previously) are called C3 plants.
- dont grow well in hot dry areas, more photorespiration
111
Crassulacean acid metabolism (CAM)
another way that some water-storing succulent plants like pineapples, cacti, aloe vera, and orchids cope, especially in hot and dry climates.
These plants limit photorespiration by carrying out the C4 pathway at night and switching to the Calvin cycle during the day.
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similarities between chloroplast and mitochondria
- Both have a double membrane.
- A cyclic process occurs in both organelles - Krebs cycle in mitochondria and Calvin cycle in the stroma of the chloroplast.
- An electron transport chain (ETC) occurs in both thylakoid and inner mitochondrial membranes, and it contains some proteins and cytochromes that are identical or very similar.
- ATP synthase uses proton motive force to power chemiosmosis during the main ATP generation phase (oxidative phosphorylation), both in the final stage of the light reactions (in the chloroplast) and in the final stage of respiration (in the mitochondria).
