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Anatomy & Physiology 12 > Enzymes > Flashcards

Enzymes Flashcards

1
Q

What is catabolism?

A

The breaking down of molecules

(hydrolysis)

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2
Q

What is anabolism?

A

The putting together of molecules.

(dehydration)

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3
Q

What causes metabolic reactions to occur in living organisms?

A

Enzymes (proteins)

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4
Q

What are protein catalysts?

A

Enzymes

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5
Q

What is a catalyst?

A

A substance that speeds up a chemical reaction without being consumed in the process.

It remains unchanged after the reaction occurs.

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6
Q

What is activation energy?

A

The energy required to initiate a chemical reaction

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7
Q

How do enzymes speed up chemical reactions?

A

They reduce the activation energy required for a reaction to occur.

They do not change the free energy of a reaction, they just encourage the reaction to happen by bringing reactants together and orienting them for a reaction.

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8
Q

What do enzymes look like?

A

They are proteins

Most are globular proteins with either tertiary or quaternary structure

Enzymes have folded surfaces that act as molds for trapping the correct substrate molecules, aligning them to cause the desired chemical reactions.

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9
Q

What are exothermic reactions?

A

Reactions that give off energy

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10
Q

What are endothermic reactions?

A

reactions that require energy

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11
Q

What type of reaction is Hyrdolysis? EXOTHERMIC or ENDOTHERMIC

A

EXOTHERMIC

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12
Q

What type of reaction is dehydration/Condensation? EXOTHERMIC or ENDOTHERMIC

A

Endothermic

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13
Q

What is entropy?

A

The measure of randomness or disorder in energy or in a collection of objects

The universe favours an increase of entropy

The universe favours disorder

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14
Q

Anabolic reactions are reactions that put molecules together. Do they Increase or decrease entropy?

A

Decrease

They are not favoured

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15
Q

Catabolic reactions are reactions that take molecules apart. Do they increase or decrease entropy?

A

Increase

They are favoured

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16
Q

What are coenzymes?

A

non-protein cofactors that bind with the substrate in the active site in order to catalyze the reaction.

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17
Q

What are some examples of coenzymes?

A

Zinc ions

manganese ions

the derivatives of many vitamins (like B3)

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18
Q

What are the factors that affect the rate of enzyme driven reactions called?

A

Yield Factors

They include:

Denaturation
(Temperature & pH)
The concentration of Enzymes/Substrates
Competitive inhibition

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19
Q

How do enzymes work together in metabolic pathways to synthesize a reaction?

A

Enzyme 1 creates a substrate that Enzyme 2 then works on, Enzyme 3 is next….

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20
Q

What factors can denature an enzyme?

A

Heavy Metals (Lead & Mercury)

Temperature Extremes (hot or cold)

pH Extremes

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21
Q

What are substrate molecules?

A

Molecules that attach to the enzyme

22
Q

What are cofactors?

A

inorganic ions that help enzymes combine with substrate molecules.

23
Q

What is the active site of an enzyme?

A

The area of the protein that combines with the substrate.

24
Q

What are some examples of cofactors?

A

Iron

Zinc

Potassium

Copper-Containing compounds

25
Q

How does temperature affect enzyme reactions?

A

the reaction rate increases as the temperature increases.

But then the reaction rates peak at about 37o Celcius

And then the reaction rate drops

At high temperatures, proteins denature or change shape. Any change in enzyme shape will have an effect on the formation of the enzyme-substrate complex.

26
Q

Why are high fevers so dangerous?

A

fevers raise the body temperature so high that the active sites on enzymes become so severely altered that the substrate can no longer bind with the enzyme.

The reaction is no longer catalyzed by the enzyme so it proceeds at a much slower rate.

27
Q

How does pH affect enzyme reactions?

A

Remember that the folds in a protein molecule are created by hydrogen bonds between negatively charged acid groups and positively charged amino groups.

The addition of H+ ions (acidic) or OH- ions (basic) will affect the hydrogen bonds - affecting the 3D shape of the molecule.

When the folds in the proteins change, the active site of the enzyme is transformed, altering the reaction.

28
Q

Which enzyme functions best in a low (2.5) pH range?

A

Pepsin

It is found in the stomach

29
Q

Which enzyme functions best at a high (9.0) pH range?

A

trypsin

it is found in the small intestine

30
Q

How does the substrate molecule concentration affect enzyme reactions?

A

the greater the number of substrate molecules, the greater the number of collisions and the greater the rate of the reaction

The reaction rate will level off because there is a limit to the amount of enzyme available.

Once the number of substrate molecules exceeds the number of enzyme molecules, the reaction rate levels off

31
Q

What are competitive inhibitors?

A

molecules that have shapes very similar to that of the substrate

They compete with the substrate molecule for active sites of the enzyme

32
Q

What are metabolic pathways?

A

orderly sequences of chemical reactions, with enzymes regulating each step of the reaction.

33
Q

What is feedback inhibition?

A

the inhibition of an enzyme in a metabolic pathway by the final product of that pathway.

It slows the reaction rate, preventing the accumulation of final products

The final product of the metabolic pathway interferes with the enzyme by combining with its regulatory (allosteric) site which alters the active site and prevents the union of the enzyme and substrate

34
Q

What is an example of a hydrolytic enzymatic reaction? Explain with the lock and key theory.

A

Sucrose (substrate) attaches to the enzyme

Add water

Chemical reaction takes place to split the sucrose molecule into glucose and fructose

The enzyme remains unchanged.

35
Q

What is the allosteric site?

A

A site on the enzyme that allows molecules to either activate or inhibit (turn off) enzyme activity.

It’s different then the active site

When allosteric activators bind to the allosteric site, the enzyme binds the substrate better, and the reaction becomes faster

36
Q

What three glands in the body are primarily responsible for regulating metabolism in our bodies?

A

Thyroid Gland

Parathyroid Gland (behind the thyroid)

Pituitary Gland (in the brain)

37
Q

What at the 2 important hormones that are released by the thyroid and serve to regulate body metabolism and growth?

A

Thyroxine (T4)

Triodothyronine (T3)

38
Q

What does thyroxine do?

A

stimulates the tissues (cells) in our bodies to utilize (oxidize) the sugars we consume

39
Q

Once the sugars are oxidized how are they used?

A

60% of the energy produced is released as heat to maintain our body temperature

40% is utilized in the process of creating ATP (cellular respiration)

40
Q

What is hypothyroidism?

A

low thyroid hormones

41
Q

What do people with hypothyroidism experience?

A

weight gain, feeling cold all the time, lethargic (feel tired), weakness, etc..

42
Q

What controls the release and production of T4 by the thyroid gland?

A

Thyroid stimulating hormone (TSH)

it’s another hormone produced in our brains at the pituitary gland

If T4 production is low, TSH encourages the thyroid to grow and produce more hormones

This is an example of a negative feedback loop

43
Q

What is going on in this image

A

Negative feedback loop

The thyroid hormones T4 and T3 are synthesized and secreted by thyroid glands.

the hypothalamus secrete thyroid releasing hormone (TRH), which stimulates cells in the anterior pituitary to secrete thyroid-stimulating hormone (TSH).

TSH binds to receptors on the thyroid gland, stimulating synthesis and secretion of thyroid hormones.

When blood concentrations of T3 and T4 increase above a certain threshold, TRH-secreting neurons in the hypothalamus are inhibited and stop secreting TRH.

Inhibition of TRH secretion leads to shut-off of TSH secretion, which leads to shut-off of thyroid hormone secretion. As thyroid hormone levels decay below the threshold, negative feedback is relieved, TRH secretion starts again, leading to TSH secretion.

44
Q

What does the hormone T4 do?

A

increases energy usage in the body by oxidizing sugars

45
Q

What happens to those with low levels of thyroid hormones?

A

May have even more excess sugar left in their bloodstreams, which will be taken up by the cells and stored as glycogen.

Once glycogen stores are full, cells convert glycogen to adipose tissue (fat)

46
Q

What can cause low thyroid hormone levels?

A

autoimmune conditions (the body attacks its own thyroid and destroys it)

Having a diet low in iodine (iodine is an essential element found in T4)

47
Q

What is hypothyroid disease?

A

occurs when someone does not produce enough thyroid hormone

Symptoms - feeling cold, tired, high heart rate, low heart rate, hair loss, weight gain

48
Q

What is hyperthyroidism?

A

occurs when someone produces too much thyroid hormone

symptoms - anxious, high heart rate, weight loss, bug eyes

49
Q

What is cellular respiration?

A

includes all the chemical reactions that provide energy for life.

50
Q

What happens during oxidation in cellular respiration?

A

high-energy compounds like glucose are converted into low-energy compounds such as carbon dioxide and water.

The chemical energy of glucose can be converted into heat or other forms of chemical energy storage such as ATP

Anatomy & Physiology 12 (27 decks)

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