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Biology 108 Test #2 > Metabolism > Flashcards

Metabolism Flashcards

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1
Q

What is metabolism? Is this a emergent component of life?

A

The totality of an organisms chemical reactions. YES, this describes the interactions between molecules within the cell.

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2
Q

Describe a metabolic pathway, what do you start with and what do you end with? How can these reactions be catalyzed?

A

starts with a starting molecule (substrate) and ends with a product. Enzymes can help to catalyze reactions.

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3
Q

What is catabolism? an example?

A

the release of energy by breaking down complex molecules into simpler ones. THINK “Cleave” Cellular respiration - breakdown of glucose in the presence of oxygen

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4
Q

What is anabolism? What is an example of this?

A

consuming energy to build complex molecules from simpler ones think “absorb” making proteins from aminos acids

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5
Q

What is energy and what are the forms of energy?

A

Energy is that capacity to cause change, some can do work. Kinetic energy - the energy of motion Heat energy (thermal) - energy associated with the random movement of molecules Potential energy - positional energy, matter possess this due to its position or location Chemical energy - POTENTIAL energy available for release in a chemical reaction

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6
Q

What is thermodynamics?

A

The study of energy transformations that occur in a collection of matter.

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7
Q

What is considered the universe?

A

this is the SYSTEM (what is being studied) and its surroundings (everything outside the system)

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8
Q

What is special about a closed system? What is an example of this?

A

A closed system is isolated from its surroundings A liquid in a thermos

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9
Q

What is special about an open system?

A

Energy and matter can be transferred between the system and its surroundings.

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10
Q

Are organisms open or closed systems?

A

OPEN, which means that energy and matter can be transferred between it and its surroundings.

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11
Q

What is the first law of thermodynamics? What is this also called?

A

ENERGY CAN BE TRANSFERRED AND TRANSFORMED, BUT CANT BE CREATED NOR DESTROYED. (this means the energy of the universe is constant) It is also called the principle of conservation of energy

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12
Q

What does the second law of thermodynamics state? Elaborate?

A

Every energy transfer or transformation increases the entropy (disorder) of the universe. Energy transfer or transformation causes the lost of some unusable energy in the form of heat. Heat is released into the environment which increased the entropy (randomness).

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13
Q

How is it possible for a process to occur SPONTANEOUSLY? are they fast or slow?

A

For a process to be spontaneous it must increase the entropy of the universe. they can be fast OR slow

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14
Q

What is an example of cells creating ordered structures from less ordered structures (biological order and disorder)?

A

Forming amino acids into polypeptide chains.

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15
Q

What is an example of an organism replacing an ordered matter with a less ordered form of matter?

A

When animals eat a plant and obtain its starch, proteins, and other complex molecules.

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16
Q

Does the evolution of more complex organisms violate the second law of thermodynamics?

A

NO NO NO Think of the total system: while the entropy of the organism may decrease, the entropy of the environment increases (the organism is a small island of decreased entropy in a sea of increasing randomness).

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17
Q

What is free energy?

A

This is energy in a living system that can do work when temperature and pressure are uniform, like in a living cell.

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18
Q

What is the equation for free energy change? What does each value represent?

A

^G = ^H-T^S

^G is the change in free energy

^H is the change in enthalpy (total energy)

T is temperature

^S is the change in Entropy

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19
Q

Does a positive ^G or negative ^G mena that a reaction is spontaneous?

A

NEGATIVE

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20
Q

How does a -^G equal a spontaneous reaction (this is represented as an equation in the powepoint)?

A

^G = G final state - G initial state

In a spontaneous change, free energy decreases while the stability of a system increases

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21
Q

What type of reaction is considered to be spontaneous (-^G)?

A

EXERGONIC reactions

there is a net release of free energy

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22
Q

Must a spontaneous reaction occur instantaneously or even rapidly?

A

NO

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23
Q

If an exergonic reaction is spontaneous, then that means that an ENDergonic reaction is…?

A

nonspontaneous (+^G)

absorbs free energy.

24
Q

What ^G is equal to a system reaching equilibrium? Can this occur in in an open system?

A

^G = 0

THIS CAN ONLY OCCUR IN CLOSED SYSTEMS

Open systems are constantly experiencing a flow of materials

25
Q

What is a defining feature of life and metabolism?

A

They can never be at equilibrium.

26
Q

If exergonic reactions are spontaneous and release energy, what would that make catabolic and anabolic reactions in regards to spontaneity?

A

Catabolic - spontaneous, release free energy by breaking down larger molecules to smaller ones

Anabolic - nonspontaneous, absorb free energy to create more complex molecules from simpler ones.

27
Q

What are the three main types of work a cell does? Give an example of each.

A

Chemical - Protein production

Transport - active transport across a cell membrane

Mechanical - muscular and flagellar movements

28
Q

What is the term that describes how cells manage their energy resources? How is this process mediated?

A

ENERGY COUPLING - the use of an exergonic process to drive an endergonic process.

ATP

29
Q

What is the importance of ATP, what is it comprised of, what makes it good at its job?

A

ATP - the cells energy shuttle

Composed of a ribose (sugar), adenine (nitrogenous base), and three phosphate groups

When looking at a ATP molecule in the powerpoint you can see that the terminal phosphate group has a highly negative charge, making it very unstable. This means the covalent bond holding it together is easily broken and releases energy.

30
Q

What type of reaction breaks the covalent bond of the phosphate tail? How does this cause a release of energy? What is the addition or removal of a phophate group called?

A

HYDROLYSIS

The chemical change from a state of higher free energy to lower free energy caused the release.

Phosphorylation (addition) and dephosphorylation (removal)

31
Q

How does ATP fuel the three types of cellular work?

A

ATP hydrolysis is an exergonic reaction that releases free energy which can be used to drive an endergonic reaction

This is usually done by phosphorylation, transferring a phosphate group to another molecule. SO… ATP is dephosphorylated and the phophate group is used to phosphorylate another molecule.

32
Q

As an example of energy coupling,the powerpoint goes over the use of phosphorylation in the production of glutamine from glutamic acid and ammonia. What is the ^G for this process and how is it carried out with the use of ATP?

A

^G = +3.4 (nonspontaneous)

  1. ATP phosphorylates glutamic acid making it less stable
  2. then ammonia displaces the phosphate group and bonds to glutamic acid forming glutamine with a detached phosphate group.
33
Q

For the formation of glutamic acid, using the values of ^G for ATP -> ADP + P and ^G for Glutamic acid + ammonia -> Glutamine explain why this reaction can occur.

A

Glutamic acid + ammonia -> glutamine = ^G +3.4 (endergonic)

ATP -> ADP + P = ^G -7.3 (exergonic)

3.4 + -7.3 = -3.9 (-^G reaction can occur)

THIS IS ENERGY COUPLING

34
Q

What is an example of ATP being used in the process of transport work?

A

Sodium-potassium pumps require ATP work

Vesicles within cell require ATP to travel along cytoskeleton rail

35
Q

Where does the energy come from to recyle ATP from ADP and a phosphte group? What type of reaction would attach the phosphate group to ADP?

A

catabolic reactions within the cell

dehydration reaction

36
Q

What is an enzyme, why are these needed for spontaneous reactions?

A

This is a catalyst usually in the form of a protein (can also be RNA based).

These speed up a reaction without being consumed

Just because a reaction is spontaneous doesnt mean that it will occur immediately (example used in class is sucrose in water can take years without hydrolyzing)

37
Q

What is the activation energy barrier? What is a common supply of Ea (enorgy of activation)?

A

This is the initial energy needed to start a chemical reaction, this explains why some spontaneous reactions wont occur quickly w/o the help of a catalyst.

Heat is a common form of activation energy

38
Q

What do enzymes do to the Ea to catalyze reactions? Do enxymes effect the ^G in the reaction?

A

They lower the energy of activation barrier

^G is NOT effected by enzymes

39
Q

What is a substrate? What is the term for when an enzyme and substrate bind? What is an active site?

A

The reatant that an enzyme acts on.

Enzyme-substrate complex

an active site is where the enzyme attaches to the substrate

40
Q

What is induced fit?

A

This is the positioning of chemical groups of the active site that enhance their ability to catalyze a reaction

41
Q

Heat can be a good way to speed up a reaction (providing activation energy), but, why woould heat not necessarily be a good thing in regards to chemical reactions?

A

Heat may speed up a reaction too much than is needed

Too much heat can denatre proteins, including enzymes that help catalyze reactions.

42
Q

In what ways do enzymes specifically reduce the activation energy of a reaction?

A
  1. Orienting substrates correctly (making rx happen more readily)
  2. Straining substrate bonds (making them break easier)
  3. Providing favorable microenvironment
  4. Covalently bonding to substrate
43
Q

How can an enzymes activity be affected?

A

changes in pH

changes in temperature

some chemical influence enzyme activity

44
Q

Why is it important to know that pH and temperature can effect enzyme activity?

A

Enzymes have an optimal temperature and pH in which they function in.

45
Q

What are nonprotein enzyme helpers called? Are these all organic? If they are organic, what are they called and what is an example of them?

A

cofactors

Dont have to be organic (can be inorganic)

Organic cofactors are called coenzymes, vitamins are an example of these.

46
Q

What is the difference between competitive inhibitors and noncompetitive inhibitors?

A

Competitive inhibitors bind to the active site of an enzyme, competing with the substrate for the active site.

Noncompetitive inhibitors bind to another part of the enzyme making the enzyme change shape and making the active site less effective or inactive.

47
Q

What are some examples of inhibitors, how is the effect of inhibiton effected?

A

toxins, poisons, pesticides, and antibiotics are inhibitors.

The substrate inhibitor ratio will effect the amount of inhibiton.

48
Q

What are two ways that enzymes are regulated in order to tightly regulate metabolic pathways?

A
  1. genes can be switched on or off that encode for specific enzymes
  2. regulation of the activity of the enzyme themselves (more rapid way to regulate), an example of this is allosteric regulation
49
Q

Describe allosteric regulation. What are the main types of enzymes effected by this?How does this occur?

A

this is the process of a regulatory molecule (activator or inhibitor) attaching to a protein at one site which effects the proteins function at another site.

The mains types of enzymes that are effected by this have multiple subunits each with an active site.

This occurs by an inhibitor or activator binding to an area of the enzyme that is not the active site. the effect it has is based on if its an inhibitor or an activator. the active sites will cange shapes accordingly and become either active or inactive.

50
Q

Describe cooperativity. How does this occur? What is an example of this?

A

This is a form of allosteric regulation that occurs when a substrate binds to one active site of an enzyme, making all of the other active sites even more favorable to bind with a substrate.

An example of this is O2 when it binds to hemoglobin, which has 4 active sites, this also occurs in the opposite when O2 is deposited into the tissues.

51
Q

How does feedback inhibition work in regards to metabolism and enzymes?

A

In some cases when too much end products of a metabolic pathway are produced the products will bind to the enzyme at a site other than the active site inhibiting the active site.

NONCOMPETITIVE

52
Q

How do some cells bring order to metabolic pathways?

A

By compartmentalizing them.

53
Q

What is it called when multiple enzymes that facilitate a certain sequence of reactions are assembled together?

A

This is called a multienzyme complex

54
Q

Can some enzymes be a structural component of membranes?

A

YES

55
Q

Can some enzymes reside in specific organelles? What is an example of this?

A

YES, for example enzymes for cellular respiration reside in the mitochondria.

Biology 108 Test #2 (5 decks)

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