Biochem Lecture 4

This is the 4th and final lecture for the unit, discussing proteins, enzymes, and the Miller-Urey experiment.

And here’s the link to the more recently agreed-upon theory of life’s origins.

Proteins, Enzymes, and Miller-Urey Quiz

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This is the 5-question quiz over the final lecture of the unit; Biochem Lecture 3 (Honors Lecture 4).

Start

Question 1

Which of the following is the monomer of a protein?

A	Amino acid
B	Monosaccharide Hint: This is actually the monomer for a carbohydrate.
C	Glycerol and 3 fatty acids Hint: These are actually the monomers of a lipid.
D	Nucleotide Hint: his is actually the monomer of a nucleic acid.

Question 1 Explanation:

Great job! I hope, by now, you recognize the other choices as the monomers of the other 3 major organic compound groups.

Question 2

Which of the following is not a major function of a protein?

A	Makes up many hormones of the human body Hint: This is a major function of proteins, as very important hormones like insulin and adrenaline (epinephrine) are made of protein.
B	Provides structural support (muscles). Hint: This is an important function. Muscle fibers are made primarily of protein, which is why you see bodybuilders drinking protein shakes.
C	Speeds up chemical reactions. Hint: Proteins that speed up chemical reactions are known as enzymes, which are critical for metabolism.
D	Slows down chemical reactions.

Question 2 Explanation:

Good job! Enzymes are proteins that lower the activation energy of a chemical reaction, and therefore allow that reaction to happen more quickly!

Question 3

What determines if an enzyme will work to speed up a certain reaction (substrate)?

A	The color of the enzyme. Hint: Color has no effect. In fact, most things found in the body have no color.
B	The shapes of its active sites.
C	The size of the enzyme. Hint: The size of the entire enzyme has no effect, but the size of the grooves on the enzymes surface do...
D	How old the enzyme is. Hint: Actually, enzymes can be used over and over again and do not break down when used to speed up a reaction.

Question 3 Explanation:

Yup! When proteins fold over themselves after production, they leave unique grooves on the surface called active sites. If the active site fits a substrate like a lock-and-key, the enzyme will lower the activation energy!

Question 4

What type of organic compounds were produced from the Miller-Urey experiment?

A	Lipids Hint: No, lipids are thought to have developed later in evolutionary history.
B	Sugars Hint: No, sugars are thought to have developed later in evolutionary history.
C	Amino acids
D	Nucleotides Hint: No, but it's now believed that nucleotides were the first organic monomers produced on Earth.

Question 4 Explanation:

That's right! After this experiment, it was widely agreed that proteins (the polymer of amino acids) must have been the first major organic compounds that all others developed from. Of course, that has changed, recently.

Question 5

Even though it's now more universally agreed upon that nucleic acids developed before proteins, the Miller-Urey experiment is still considered significant. Why?

A	Because it was the first time that organic compounds were produced from inorganic substances in a lab.
B	Because scientists are stubborn and don't want to believe new ideas. Hint: Some maybe, but most scientists are fascinated by new ideas that go against what they may already believe to be true.
C	Because it was the first time heat was used in an experiment. Hint: Heat's been around for a very, very long time. This was in the 1950's.
D	Because Miller and Urey wrote our textbooks. Hint: Good guess, but no.

Question 5 Explanation:

You got it! It's now more agreed upon that nucleic acids developed first, but this experiment proved a concept that had not been proven before. Could organic compounds have come from components in the Earth's atmosphere a long, long time ago?

There are 5 questions to complete.

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