Week 4 Biochem Flashcards Preview

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Flashcards in Week 4 Biochem Deck (18):
1

Collagen is an example of a _____ protein that exhibits a tightly wound _____ structure.

1. Fibrous
2. Triple helix

2

Globular proteins are considered highly water soluble because _______.

They have:
1. Polar AA Side Chains facing OUT
2. Non-polar side chains interiorly (hydrophobic core)

3

______ is considered the prosthetic group for Hemoglobin.

Heme

4

Define the structure of Heme:

A porphyrin ring (4 cyclic rings containing nitrogen) with a ferrous (Iron in the 2+ state --> Fe2+) ion in the center.

5

What 2 forces hold the heme group of myoglobin to its structure?

1. Histidine forms a covalent bond to Fe2+.
2. Hydrophobic Interactions with the porphyrin ring.

6

What is the importance of the Fe2+ being buried deep inside the porphyrin ring of heme in myoglobin?

It ensures that oxygen only travels through the globular protein and is released as O2, not superoxide.

7

Sperm whale myoglobin is identical to _______ in humans. But what is different between the two structures and why is it remarkable?

1. Beta-Globin
2. The Primary Sequence is very different, but the few CONSERVED amino acids are able to give the same shape and function.

8

The _____ histidine of hemoglobin is covalently bonded to the heme group, while the ______ histidine is free to act as a buffer for pH and a/b-dimer linkage.

1. Proximal
2. Distal

9

Cooperative Binding:

O2 acts as an ALLOSTERIC regulator of its own binding to Hb because binding of one molecule of O2 increases Hb's affinity for more O2 binding.

10

Bohr Effect:

Describes how Hb responds to changing pH by changing its O2-affinity.

11

2,3-BPG acts to ______ the O2 affinity of Hb, therefore it is considered to be a ________ of Hb.

1. Decrease
2. Negative Allosteric Regulator

12

4 Allosteric Regulators of Hb:

-pO2
-pCO2
-pH
-2,3-BPG

13

Titration of a strong acid with a strong base yields __________.

The formation of Salt Water (Salt + H20) at the equivalence point of pH=7.

14

A ______ Ka implies a stronger acid, while a _____pKa implies a stronger acid ________.

1. Higher Ka = Stronger
2. Lower pKa = Stronger

15

When titrating a weak acid with a strong base, the pKa is the pH range at which ________.

50% dissociation has occurred
i.e. [HA] = [A-] ....AND....[weak acid] = 1/2[strong base]

16

The buffer range is seen at ________.

(+/-) 1 pH unit from the pKa

17

The pKa of Acetic Acid is ________.

pH = 4.75

18

Titratable Acidity for weak acids is _______ compared to strong acids.

The same