Biochemistry Lecture 7 - Protein Structure and Function Flashcards

1
Q

Proteins fold to maximize _______.

A

Weak forces (such as hydrogen bonds).

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2
Q

What test is used to identify proteins?

A

Western blot.

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3
Q

How many amino acids are there?

A

20

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4
Q

Which amino acid has the smallest R group? What function does this AA often play in proteins?

A

Glycine, the R group is a hydrogen. It is often found in tight bends in protein structure.

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5
Q

What does herceptin do?

A

Treats breast cancers.

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6
Q

What amino acids absorb UV light the strongest?

A

Tryptophan and tyrosine. The ones that have the letters T, R, and Y at the start! TRY to remember that shit.

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7
Q

What is a “molten globule” state?

A

When the nascent protein’s hydrophobic groups begin to aggregate - and at this point the protein is insoluble because it’s hydrophilic groups have not covered up the hydrophobic ones.

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8
Q

What do chaperone proteins do for regarding synthesis?

A

They assist protein folding, or they chaperone them to proteases if they get misfolded.

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9
Q

Which amino acid is the “alpha helix breaker?” Why?

A

Proline, it has a five membered ring and doesn’t fit.

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10
Q

Define amphipathic.

A

Having both hydrophobic and hydrophilic parts.

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11
Q

What are the two secondary structures of proteins?

A

Alpha helix and beta sheet.

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12
Q

Contrast side-chain proximity between AA’s in the helix vs. in the sheet.

A

R groups are relatively close to each other in the helix, whereas in the sheet the side chains are 180 degrees from each other.

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13
Q

In what major organ is elastin found?

A

Lungs

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14
Q

What part of the CFTR protein binds and hydrolyzes ATP? What does ATP hydrolysis do to the protein?

A

NBD 1 and 2. ATB binding and hydrolysis changes the conformation, allowing chloride ion to pass through.

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15
Q

What part of the CFTR protein gets phosphorylated? What effect does the phosphorylation have on the protein’s activity?

A

The Regulatory Domain gets phosphorylated. This activates the CFTR channel.

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16
Q

What is the structure of elastin? What are the links called? What amino acid is responsible for the linking and how many residues are involved?

A

Elastin forms a flexible network linked via cross-links. The links are formed by four lysine residues and are called desmosine residues.

17
Q

Where is keratin found?

A

Hair, nails.

18
Q

What structure makes up keratin?

A

Alpha helices, very tightly wound up.

19
Q

What is the major buffer inside cells?

A

Phosphate.

20
Q

What is pKa?

A

The pH at which the molecule is 50-50 acid-base form.

21
Q

At what pH is maximal buffering achieved?

A

pKa

22
Q

What is meant by the isoelectric point of a protein?

A

The pH where a protein achieves neutral charge.

23
Q

What is the major buffering system in the blood?

A

Bicarbonate.

24
Q

Why is aspirin most readily absorbed in the gut where the pH is lower?

A

It’s carboxylic acid group is protonated, resulting in a neutrally charged molecule. Uncharged molecules can pass the PM easier!