CH 18

Question 1

Amino acids contain…

Answer 1

acidic grp -COOH

basic grp -NH3

can undergo intramolecular acid-base RXN

Question 2

Zwitterion

Answer 2

Neutral dipolar ion that has one (+) charge and one (–) charge

Question 3

acid- base properties

-zwitterions, amino acids have physical properties w/ salts…….and those are…

Answer 3

• can form crystals
• high melting points
• soluble in water but not hydrocarbon solvents

Question 4

What is the isoelectric point?

Answer 4

pH @ which 2 amino acids exists as a zwitterion

Question 5

In acidic solution (low pH)…

Answer 5

Amino acids zwitterions accept protons on their basic -COO- groups

acidic= has positive charge

Question 6

In a basic solution (high pH)…

Answer 6

Amino acid zwitterions lose protons from their acidic -NH3+ groups

basic has negative charge

Question 7

Chiral

Answer 7

having right or left handedness w/ two different mirror images = doesn’t match

Question 8

Achiral

Answer 8

opposite of chiral having superimposable mirror images and thus no right or left handedness

SYMMETRY= achiral

Question 9

CHIRAL OR ACHIRAL?
CHAIR
BABY POWDER BOTTLE
SPOON
SCISSORS

Answer 9

CHAIR-chiral

BABY POWDER BOTTLE-chiral

SPOON- achiral

SCISSORS- chiral

Question 10

Molecular handedness and amino acids

Answer 10

• when a carbon has four different groups, it becomes a chiral carbon atom- or chiral center

Question 11

Enantiomers (optical isomers)

Answer 11

two mirror image forms of a chiral molecule

Question 12

Steroisomers

Answer 12

isomers that have the same molecular and structural formula but different spatial arrangements

Question 13

How many amino acids are chiral out of the 20? Which one is the exception?

Answer 13

19 out of 20

Glycine

Question 14

Primary PRO structure

Answer 14

sequence in which amino acids are linked by peptide bonds in a PRO

Question 15

Primary PRO structure combining

Answer 15

a pair of amino acids can be combined to form 2 different dipeptides

-when combining as a product you get H20 and amino acid residue

Question 16

how are peptides and PRO always written?

Answer 16

w/ amino-terminal amino acid on the LEFT

carboxyl- terminal amino acid on the RIGHT

Question 17

Residue

Answer 17

and amino acid unit in a polypeptide bond

Question 18

Hydrogen bonds along the backbone…

Answer 18

cause a sheet or helix shape

Question 19

Hydrogen of R groups with each other or with back bone atoms…

Answer 19

can cause FOLDING over of THE SHEET OR HELIX

Question 20

Ionic attraction b/t R groups

Answer 20

Salt bridges

similar to H+ of R groups w. each other or backbone atoms

Question 21

Hydrophobic interxns b/t R groups

Answer 21

create a H20 free “pocket” to carry H20 insoluble substances thru H20

Question 22

Covalent sulfer-sulfer bonds

Answer 22

can loop or tie chains together

Question 23

Secondary PRO structure

Answer 23

regular and reporting structural patterns
ex:
alpha helix, Beta sheet
-created by hydrogen bonding b/t backbone atoms in neighboring segments of PRO chains

Question 24

Alpha (a) helix…

Answer 24

SECONDARY PRO structure in which a PRO chain forms a right-handed coil stabilized by H+bonds b/t peptide groups along backbone

-ex: telephone wire
clockwise coil from ‘C’ terminal

Question 25

Beta (B) sheet

Answer 25

SECONDARY PRO struct. in which adjacent PRO chains either in the same molecule or in diff. molecules are held together by H+ bonds along the backbones -->forming flat street structure Ex: little fan unfolded

Question 26

Secondary PRO structure classified as.

Answer 26

globular | fibrous

Question 27

Fibrous PRO

Answer 27

``` tough insoluble PRO whose PRO chains form fibers or sheets ex: nails hair wool skin wood spider web ```

Question 28

Globular PRO

Answer 28

WATER SOLUBLE PRO whose chain is folded in a compact shape w/ HYDROPHILIC grapes on the outside ``` ex: eggs milk cheese insulin ```

Question 29

Tertiary PRO structure

Answer 29

the way in which an entire PRO chain is coiled and folded into specific 3D shape

Question 30

Native PRO

Answer 30

PRO w/ the shape (secondary, tertiary, & quaternary) which it exists NATURALLY in living organism

Question 31

Simple PRO

Answer 31

PRO compose of ONLY amino acids

Question 32

Conjugated PRO

Answer 32

PRO that incorporates one or more non-amino acid units in its structure

Question 33

Quaternary PRO structure

Answer 33

the way in which TWO or MORE PRO chains aggregate to form LG, ordered structures EX: HEMEGLOBIN

Question 34

Collagen

Answer 34

Fibrous PRO most abundant of all PROs in mammals MAJOR constituent of skin, tendons, bones, blood vessels, and other connective

Question 35

PRO denaturation

Answer 35

LOSS of secondary, tertiary, quaternary PRO structure due to disruption of noncovalent interns and/or disulfide bonds that leaves peptide bonds and PRIMARY STRUCTURE INTACT **When PRO denatured ONLY PRIMARY STRUCTURE REMAINS!**

Question 36

Chemical Properties of PRO | Heat

Answer 36

Disrupts the weak side chain intern FRYING AN EGG= IRREVERSIBLE

Question 37

Chemical Properties of PRO | Mechanical agitation

Answer 37

whipping air bubbles into a foam- air is held in place by disrupted protein WHIPPING EGGS/ CREAM

Question 38

Chemical Properties of PRO | Detergents

Answer 38

disrupt HYDROPHOBIC side chain DAWN, AJAX

Question 39

Chemical Properties of PRO | Organic Compounds

Answer 39

polar solvents can interfere w/ H+ bonds

Question 40

Chemical Properties of PRO | pH change

Answer 40

can disrupt salt bridges MILK SOURING

Question 41

Chemical Properties of PRO | Inorganic salts

Answer 41

can disrupt salt bridges Na+CL-

Question 42

Curling/ straightening hair w/ hot plates...?

Answer 42

Reversible denaturing