Chapter 3 - Cellular Energy Flashcards by Aditi Iyer

catabolic processes

processes break down large macromolecules into smaller pieces and usually release energy in the form of ATP

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anabolic processes

extract ebergy from ATP and use it to build larger, more complex macromolecules, where the energy is stores

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definition of energy

the ability to do work(creating change in a biological system)

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chemical energy is a type of ____ enery

potential

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catabolic reactions ____ free energy, so they are an example of _____ reactions

release; exergonic

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true or false: catabolic reactions are not spontaneous

false - they are spontaneous because they do not require energy input to proceed

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anabolic reactions _____ free energy, so they are an example of _____ reactions

absorb; endergonic

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true or false: anabolic reactions are spontaneous

false; non-spontaneous because they require energy input to proceed to the final state

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why are ATP molecules unstable?

the three phosphate groups are all negatively charged and repel each other

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how are bonds between phosphate groups broken in ATP?

hydrolysis

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describe ATP hydrolysis reactions

spontaneous and exergonic

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mitochondria has _ membranes

two - outer and inner membranes

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the mitochondria ___ membrane contains many indentations called ___ that increase surface area

inner; cristae

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region between outer and inner membranes of the mitochondria is called the ____ ____ and is ____

intermembrane space; acidic

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the area deep to the inner membrane is called:

mitochondrial matrix

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example of cells that contain many mitochondria

myocytes (human muscle cells)

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example of cells that contain no mitochondria

red blood cells (lacks most organelles)

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the matrix contains its own:

circular DNA and ribosomes

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endosymbiotic theory

states that aerobic bacteria were internalized as mitochondria while the photosynthetic bacteria became chloroplasts

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evidence for endosymbiotic theory

size similarities and the fact that mitochondria and chloroplasts contain their own circular DNA and ribosomes.

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intermembrane space has low or high pH?

low pH (acidic)

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glycolysis

converts glucose to 2 pyruvate

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true or false: glycolysis is an anaerobic process

true - does not require oxygen

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where does glycolysis occur

cytosol

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two main phases of glycolysis

1. energy investment stage (steps 1-5) | 2. energy payoff stage (steps 6-10)

first step of glycolysis

glucose gets phosphorylated via one ATP hydrolysis to make glucose-6-phosphate. traps glucose inside the cell

first step of glycolysis enzyme name

hexokinase

true or false: 1st step of glycolysis is reversible

false - irreversible

2nd step of glycolysis

isomerase modifies G6P into F6P (fructose-6-phosphate)

3rd step of glycolysis

F6P gets phosphorylated to become fructose-1,6-bisphosphate. irreversible

3rd step of glycolysis enzyme name

phosphofructokinase (PFK)

which steps of glycolysis are irreversible

1, 3, 10

PFK is an essential ______ enzyme

regulatory - Levels of various molecules influence the speed with which phosphofructokinase functions, leading to regulation of the rate of glycolysis as a whole.

Fructose-1,6-bisphosphate is:

unstable, so it breaks down into 2 3-carbon sugars

Fructose-1,6-bisphosphate breaks down into:

dihydroxyacetone-phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P)

DHAP and G3P exist in:

equilibrium

In order to favor the conversion of DHAP into G3P, and not the opposite, the cell must keep G3P levels:

low (Le Chatelier's principle)

DHAP is converted to G3P via:

triose phosphate isomerase

Products of glycolysis are:

1. 4 ATP 2. 2 pyruvate 3. 2 NADH

Net products of glycolysis:

1. 2 ATP (since 2 ATP were used in energy investment phase) 2. 2 pyruvate 3. 2 NADH

pyruvate molecules have to travel from the ____ to ____

cytosol; mitochondrial matrix

what happens to pyruvate once it enters mitochondrial matrix?

1. decarboxylated and releases CO2 2. undergoes oxidation and becomes a 2-carbon acetyl group 3. this acetyl group binds to Coenzyme A

the three pyruvate manipulations are carried out by:

pyruvate dehydrogenase

pyruvate manipulations produce:

1. 2 CO2 2. 2 NADH 3. 2 acetyl-CoA (for each glucose that enters cellular respiration)

pyruvate oxidation step ____ and ____

indirectly depends on oxygen; reduces NAD+ to NADH

Krebs cycle occurs in:

mitochondrial matrix in eukaryotes; cytosol for prokaryotes

1st step of Krebs cycle:

acetyl-CoA joins oxaloacetate to form citrate (6 carbons)

Once citrate is formed:

goes through rearrangements. loses 2 carbons via CO2. 2 NAD+ get reduced to NADH

After citrate loses 2 carbons:

4C molecule progresses, GTP is produced. 4C molecule passes electrons to FAD, FAD is reduced to FADH2

After FADH2 is made:

the 4C molecule transforms back into oxaloacetate, NAD+ is reduced

Krebs cycle products for each glucose:

1. 4 CO2 2. 6 NADH 3. 2 FADH2 4. 2 GTP

Krebs cycle occurs _ types per glucose

Krebs cycle ____ depends on oxygen

indirectly

last step in cellular respiration

oxidative phosphorylation (ETC and chemiosmosis) synthesizes ATP and water

___ is the final electron acceptor for aerobic ETCs

oxygen. produces water

where is the ETC?

eukaryotes - inner membrane of mitochondria | prokaryotes - along cell membrane

ETC operate through

redox reactions

enzyme that synthesizes ATP

ATP synthase

ATP spins via

proton motive force

full aerobic respiration is ____

exergonic (-686 kcal/mol glucose)

eukaryotic cells can generate ___ ATP/glucose if they are entirely efficient

36-38

single NADH can contribute to synthesis of _ ATP

single FADH2 can contribute to synthesis of _ ATP

prokaryotes make __ ATP if entirely efficient

Lactic acid fermentation

regenerates NAD⁺ from NADH by reducing pyruvate into lactic acid. NADH transfers its electrons to pyruvate, regenerating NAD⁺

once oxygen has become available again, humans can use ____ ___ to convert lactate back into glucose

cori cycle

Cori cycle:

transports lactate from the myocyte through the bloodstream to liver cells (hepatocytes). Once at a hepatocyte, the lactate can oxidize back into pyruvate. Pyruvate can form glucose through gluconeogenesis.

gluconeogenesis from pyruvate in the Cori cycle requires:

6 ATP

which organ can release glucose into the bloodstream

liver - since it contains an enzyme that "undoes" the hexokinase reaction of glycolysis

1st step of gluconeogenesis

formation of oxaloacetate by carboxylation of pyruvate

1st step of gluconeogenesis enzyme

pyruvate carboxylase (activated by high levels of Acetyl-CoA)

alcohol fermentation

1. pyruvate is decarboxylated to make acetaldehyde | 2. NADH reduces this to ethanol, reforming NAD+ to contine glycolysis

obligate aerobes

organisms that can only metabolize their fuel sources via aerobic respiration, cannot do fermentation

obligate anaerobes

only metabolize via anaerobic respiration or fermentation; oxygen is toxic

facultative anaerobes

can utilize aerobic respiration, anaerobic respiration, or fermentation; they will undergo aerobic respiration if they are able to (if oxygen is present).

microaerophiles

cannot live without oxygen. Therefore they cannot undergo anaerobic respiration or fermentation. However, high concentrations of oxygen are harmful to them.

aerotolerant organisms

cannot use oxygen; therefore, they only utilize anaerobic respiration or fermentation. However, the presence of oxygen does not poison them.

the ___ stores 2/3 of all the body's glycogen

liver

___ contain 1/3 of glycogen

muscles

true or false: humans need to digest fats before absorbing them

true

___ convert triglycerides into FFA and alcohols

lipases

how do humans absorb digested fats?

through enterocytes of small intestine

once in the enterocyte, what happens to FFA and monoglycerides?

they will reform into triglycerides, which then pair up with proteins, phospholipids, and cholesterol and form chylomicrons

chylomicrons leave enterocytes and enter:

lacteals - small lymphatic vessels that take fats to the rest of the body

fatty acids can also travel in their free state via

binding to albumin

Which enzymes are involved in the stages of glycolysis that require ATP investment?

hexokinase; phosphofructokinase (steps 1 and 3)

Amino acid byproducts can be incorporated into cellular respiration as which molecule? A. Pyruvate B. Acetyl-CoA C. Krebs Cycle Intermediates

all of the above

Which molecule can undergo direct conversion to glycogen or glucose?

glycerol

``` Which of the following can undergo alcohol fermentation? A. Human muscle cells B. Yeast C. Human liver cells D. Erythrocytes ```

Yeast

Which of the following best describes aerobic respiration?

Exergonic and spontaneous

What molecule is toxic to vertebrates?

NH3

During fermentation, what is the net ATP yield for every glucose?

At which point of lactic acid fermentation is NAD+ regenerated?

when pyruvate is converted to lactate

Which molecule is released from glycogen as a result of glycogenolysis?

G6P

What do lipases convert triglycerides into during lipolysis?

free fatty acids and alcohol

What is the net GTP yield from the Krebs cycle processing one molecule of glucose?

Which of the following receives electrons from FADH2?

Complex II