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MCAT - Bio/Biochem > Macromolecules > Flashcards

Flashcards in Macromolecules Deck (30):
1

In an amino acid, which is the alpha carbon?

The carbon that the variable R group attaches to

2

What are the nonpolar, hydrophobic amino acids?

Glycine, Alanine, Valine, Methionine, Leucine, Isoleucine, Proline, Phenylalanine, Tryptophan

GAVIMLPPT

3

What are the polar and neutral amino acids?

Serine, Threonine, Asparagine, Glutamine, Cysteine, Tyrosine

STAGCT

4

What are the polar and acidic amino acids?

Aspartic acid and glutamic acids

Those with ACID in the name = acidic (duh)!

5

What are the polar and basic amino acids?

Histidine, Arginine, Lysine

HAL(smith) is basic ;)

6

How would you characterize polar but neutral amino acids?

Hydrophilic enough to form hydrogen bonds with water, but not polar enough to act as an acid or base.

7

Are phosphate groups hydrophilic or hydrophobic?

Hydrophilic

8

What does the mnemonic "His goes both ways" refer to?

Histidine's side chain is very close to physiologic pH so it can be in the protonated OR deprotonated form.

This makes it common in enzyme active sites.

9

What type of bond is a peptide bond?

Covalent

10

What type of bond is a disulfide bond?

Covalent

11

What is formed when two amino acids are linked and what is lost?

A peptide bond. A water molecule is formed (lost).

12

Which two amino acids form a disulfide bond? And what is another name for it?

Cysteine-Cysteine

CystINE

13

Is the inside of a cell an oxidizing environment or reducing environment?

Reducing

14

Which amino acid cannot form an alpha helix and why?

Proline, it kinks the polypeptide chain.

15

What are the two forms of secondary protein structure and what bond forms them?

Alpha helix and Beta sheet

Formed by hydrogen bonds

16

What determines tertiary protein structure?

Interaction of R groups with each other and water. i.e. hydrophobicity and hydrophilicity.
Other common bonds formed at this time = disulfide bridges and van der Waals interactions

17

What are two major non-covalent bonds?

Hydrogen bond
Van der Waals interaction

18

What defines quaternary protein structure?

Bonds between SEPARATE chains in one protein

19

What is the bond between two monosaccharides? What kind of bond is it?

Glycosidic bond.

It is a covalent bond.

20

What are the 3 most common disaccharides?

Sucrose (Glu + Fru)
Lactose (Glu + Gal)
Maltose (Glu + Glu)

21

Why can't mammals break down cellulose?

We are incapable of hydrolyzing the beta linkages.

22

What makes a fatty acid saturated vs unsaturated?

Saturated = no double bonds, full of maximum number of carbons and hydrogens.

Unsaturated = one or more double bonds, causes a kink.

23

Which type of fatty acid (saturated or unsaturated) has stronger Van der Waals forces?

Saturated. The kinks in unsaturated FA's are disruptive.

24

What 3 things increase membrane fluidity?

1. Unsaturation
2. Shorter tails
3. Cholesterol

25

How do steroid hormones act in/on the cell and why?

Steroid hormones act intracellularly because they are cholesterol-derived and are thus hydrophobic and can travel across the PM.

26

What type of hormone is insulin and what is the significance of this?

Peptide hormone -> must act on the cell SURFACE because it cannot pass PM.

27

Are pyrophosphate bonds high energy?

YES!! Think of them like compressed springs waiting to bust open and release their energy to catalyze a reaction.

28

What are 3 common monosaccharides?

1. Glucose
2. Fructose
3. Galactose

29

What type of macromolecule is a terpene?

Lipid

30

How does cholesterol affect plasma membranes?

At low temperatures, it improves fluidity (lowers the freezing temp).

At high temperatures it sticks and reduces fluidity so its not all melty (increases melting temp).

In summation, cholesterol serves to maintain the membrane status quo.