Biochem-Midterm#1

Front 1

What are enantiomers?

Back 1

-2 biomolecules containing 1 or more chiral centers which are nonsuperimposable mirror images of each other

Front 2

What is definition of conformation?

Back 2

-the spatial arrangement of substituent groups that are free to assume different positions in space WITHOUT BREAKING BONDS

-elcipse
-staggered
-boat
-chair

Front 3

How do you spot oxidation?

Back 3

-molecule gains an O

Front 4

How do you spot reduction?

Back 4

-molecule gains H

Front 5

What does it mean if G is +'ve?

Back 5

-not spontaneous, needs input of free energy to proceed; endergonic

Front 6

What does it mean if G is -'ve?

Back 6

-spontaneous, releases free energy which can be used to do work; exergonic

-continues until equilibrium is reached

Front 7

What does it mean if H is -'ve?

Back 7

-exothermic; heat is released

Front 8

What does it mean if H is +'ve?

Back 8

-endothermic, heat is absorbed

Front 9

What does it mean if S is -'ve?

Back 9

-less random, more structured

Front 10

What does it mean if S is +'ve?

Back 10

-more random, less structured

Front 11

What are enzymes?

Back 11

-biological catalyests which allow chemical reactions to proceed quickly and efficiently

Front 12

How is information transfered living organisms?

Back 12

DNA->transcription->RNA->translation->
PROTEIN->function

**the 3-D shapes of proteins are unique and important. if the shape changes, due to mutations, the function changes**

Front 13

What are some characteristics of water?

Back 13

-has high heat of vaporization
-has high heat capacity
-solvent for polar and ionic biomolecules
-contributes to structure and function of biomolecules
-medium for biochemical processes and reactions
-Hydrogen bonding gives water its unusual properties

Front 14

What is electronegativity?

Back 14

-the ability of an atom to attract electrons to its nucleus

**the greater the difference in electronegativity between 2 atoms, the greater the polarity of the bond**

Front 15

What 2 behaviors of water affect the behavior of biological molecules?

Back 15

1)Polarity: it's cohesive and it likes other polar molecules too

2)Tendency to dissociate into OH and H

Front 16

How many H-bonds can a single water molecule form?

Back 16

-4

Front 17

What is hydration/solvation?

Back 17

-the insulation of charged particles by water

Front 18

What does amphipathic mean?

Back 18

-molecules with a polar group (hydrophilic) and a nonpolar region (hydrophobic)

Front 19

Consider bilayers and micelles. Which allows water to have more entropy?

Back 19

-micelles allow water to have more entropy

**just in case, micelles are those globular amphipathic balls**

Front 20

What are the 4 major types of noncovalent interactions that influence the structure and function of biomolecules?

Back 20

1)Ionic Interactions: attract and repel

2)Hydrogen Bonds: H bonds

3)Van der Waals forces:
a)Dipole-Dipole
b)Dipole-Induced Dipole
c)Transient dipole-transient dipole

4)Hydrophobic interactions: nonpolar molecules create a 'water shell'. Increase in entropy of surrounding water

Front 21

How do you calculate pH? or p anything for the matter.

Back 21

pH = -log[H]

Front 22

Why is it important to maintain constant pH in living organisms? 2 reasons

Back 22

1) Maintain catalytic activity of enzymes

2) Maintain homeostasis intracellularly and extracellularly

Front 23

What does it mean if K is a large number?

Back 23

-means that the molecule is more likely to ionize

**therefore, if K is large, acid is strong**

Front 24

What does it mean if pKa is a large number?

Back 24

-means that the acid strength is decreasing

Front 25

Whats the difference between Monoprotic, Diprotic and Triprotic acids?

Back 25

-Monoprotic acids lose 1 H
-Diprotic acids lose 2 H
-Triprotic acds lose 3 H

**Monoprotic is weak, triprotic is strong**

Front 26

When is a weak acid best able to resist change in pH?

Back 26

-when pH=pK
-when [HA]=[A]

Front 27

What are the 3 main types of carbohydrates?

Back 27

1)Monosaccharides- single sugar

2)Oligosaccharides- 2 to 20 sugars

3)Polysaccarides- more than 20 sugars

Front 28

What are the 5 main functions of carbohydrates?

Back 28

1) Primary source of energy metabolism

2) Storage form of energy

3) Biosynthesis

4) Structural components

5) Informational roles

Front 29

What is an epimer?

Back 29

-2 monoscaccharides which differ only in the configuration about a SINGLE chiral center

-that chiral center is now called an epimeric carbon

Front 30

What is a hemiacetal?

Back 30

-a chiral carbon with an -OH and a -OR

**Acetals have 2 -OR's**

Front 31

What is alpha bonding?

Back 31

-occurs when monosaccharides form a ring
-OH group is trans to the CHHOH on the 6 carbon (across the O)

**Remember: When 2 rings join, the bond type of the leftmost ring takes priority and that bond is used in the final name!**

Front 32

What is Beta bonding?

Back 32

-occurs when monosaccharides form a ring
-OH group is cis to the CHHOH on the 6 carbon (across the O)

**Remember: When 2 rings join, the bond type of the leftmost ring takes priority and that bond is used in the final name!**

Front 33

What are reducing sugars?

Back 33

-sugars which contain a potentially reactive aldehyde group that can be oxidized (ie: has a free OH at the anomeric carbon)

-reducing sugars are the rightmost group of sugar when drawn properly (ie: from left to right)

Front 34

What's the difference between linear and branched polysaccharide chains?

Back 34

-linear chains are in a straight, single line

-branched chains branch off from main chains

**sugars are removed from the non-reducing end**

Front 35

What's the difference between amylose and amylopectin in terms of linkage?

Back 35

-amylose is a linear polysaccharide, composed of 10->1000 D-flucose residues. Bonds are alpha(C1->C4)

-amylopectin is a branched polysaccaride composed of 300->6000 sugars or more. Bonds are alpha(C1->C4) on linear sugars but are alpha(C1->C6) on branching sugars.

Front 36

What is glycogen?

Back 36

-it's like amylopectin but with way more branches (I'm talking about a branch every 8-10 glucoses!!!)

Front 37

What is cellulose?

Back 37

-linear polysaccharides
-differs from the rest because it has Beta(C1->C4) bonding

Front 38

What are the 7 amino acids that belong to the 'nonpolar, aliphatic R groups'?

Back 38

-glysine
-alanine
-proline
-valine
-leucine
-isoleucine
-methionine

Front 39

What are the 3 amino acids that belong to the 'aromatic R groups'?

Back 39

-phenylalanine
-tyrosine
-tryptophan

Front 40

What are the 5 amino acids that belong to the 'polar, uncharged R groups'?

Back 40

-serine
-threonine
-cysteine
-asparagine
-glutamine

Front 41

What are the 3 amino acids that belong to the 'positively charged R groups'?

Back 41

-lysine
-arginine
-histidine

Front 42

What are the 2 amino acids that belong to the 'negatively charged R groups'?

Back 42

-aspartate
-glutamate

Front 43

What's so special about tyrosine. serine and thereonine?

Back 43

-there OH group can be phosphorylated

Front 44

Are amino acids S or R configured?

Back 44

-they are 'S' configured

-remember: CORN
[1]CO=COO
[2]R=R group
[3]N=NH3

Front 45

What so special Proline, Glycine and Cysteine?

Back 45

-Proline has a rigid backbone

-Glycine has a flexible backbone

-Cysteine can form S-S (disulphide bonds)

Front 46

What are zwitterions?

Back 46

-result of amino acid being dissolved in water
-a dipolar ion, with spatially separated positive and negative charges
-can act as an acid or a base

Front 47

What is pI?

Back 47

-it is the isoelectric point
-the point at which the net electric charge is zero

**so if pH is less then pI, amino acid is more acidic therefor have a relatively larger postive charge. if pH is greater than pI, amino acid is more basic therefor having a relatively larger negative charge**

Front 48

How does an amino acid titration curve work... or any titration curve for the matter?

Back 48

-farthest right is where it is most acidic.
-as the titration plateaus (ie hits a pK value), the original amino acid becomes more basic (ie: loses an H) when more base is added

**so... curve rises, plateaus, turns more basic, rises, plateaus, turns more basic, etc.**

Front 49

How do amino acids form peptide bonds?

Back 49

-amino acids join head to tail by dehydration. OH of carboxylic head makes off with H of tail.

Front 50

What is the 'direction' of amino acids?

Back 50

N---> Residues---> C

Front 51

What is residue?

Back 51

-each amino acid in the chain is referred to as residue
-proteins are about 60-800 residues long
-average weight is 110 Daltons

Front 52

What are some characteristics to peptide bonds?

Back 52

*Consists of O=C-N-H
-O and H are trans 99% of the time
-rigid and planar
-has partial double bonds (ie:O or N can be double bonded to C at any time)
*N-C[alpha] bonds are called phi
*C-C[alpha] bonds are called psi
-phi and psi bonds are free to rotate

Front 53

For amino acids, what is the alpha carbon?

Back 53

-the central, chiral carbon is referred to as the alpha carbon

Front 54

How do you calculate G?

Back 54

G = G + RT(lnKeq)

G = H - TS