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Chapter 1 BC > chap 3 > Flashcards

chap 3 Flashcards

1
Q

Proteins are ____polymers of a-amino acids

A

Heteropolymers

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2
Q

Naming AA start from

A

alpha carbon( center of aa)

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3
Q

all AA alpha carbons have an acdic, basic and alpha hydrogen connected to a-carbon EXCEPT

A

Proline, has a ring, its ring is VERY CONSTRAINING

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4
Q

Name the AA for these groups

Aromatic 
Nonpolar aliphatic ,phobic
Polar, uncharged 
Pos charge
Neg charge
A

Aromatic: Phe, Tyr, Tryp
Nonpolar: Val, Iso, Leu, Pro, Gly, Ala, Met

Polar: Ser, The, Arginine, Glutamine, Cysteine

Pos: His, Lys, Arg

Neg: Arg, Glu

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5
Q

What is the unique feature about aromatic side chains

A

they ABSORB UV light at 270-280 , this is due to conjugation

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6
Q

What is the unique feature about polar side chains

A

They can for hydrogen bonds , while

cysteine for disulfide bond =cystine covalent bond very strong

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7
Q

Asparagine and glutamine are or are not good bases

A

ARE NOT goodbases, that is why they are not protonated, has amide at end

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8
Q

Adenlyation

A

is the process of attaching an AMP molecule to a protein side chain by covalent bonding.

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9
Q

Proteins 4 major biological functions

A

Catalysis-enzyme
transport : hemoglobin
Structure : collagen/keratin
Motion: myosin/cilia

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10
Q

Humans only function with L or D Steroisomers?

A

L steroisomers , cells are able to specifically synthesize L-isomer of AA because the active site of enzymes are asymmetric – cause their rxns they catalyze to be sterospecific

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11
Q

Are the active sites of enzymes asymmetric?

A

YES, causes the rxn they catalyze to be sterospcific ( favors L)

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12
Q

carbon closes to the carbxoxyl group is the

A

alpha carbon

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13
Q

which amino acid starts all protein sequences

A

methionine

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14
Q

WHAT FUNCTIONAL GROUP DOES HISTIDINE HAVE ?

A

aromatic imizidole group. histidine facilitates many enzyme catalyzed rxn by serviving as a proton acceptor or donator

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15
Q

what is the most common regulatory modification, post translational modification of AA in proteeins

A

Phosphorylations

Reversible AA modification are involved in regulation of PROTEIN ACTIVITY

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16
Q

The a-helix is disrupted

A

PROLINE RESIDUES, in which the ring imposes GEOMETRIC CONSTRAINTS , and by regions in which numerous amino acid residues have charged groups or large, bulky side chains.

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17
Q

side chains of the amino acid residues in an a-helix extend

A

OUTWARD, from the central
axis of the rodlike structure. This allows the formation of high tensile strength fibrillary
proteins.

18
Q

An a-helix is generated when each carbonyl of a peptide bond forms

A

hydrogen bond between c=o and -NH

19
Q

___ formed by hydrogen bonds between two extended polypeptide chains or between two regions of a single chain that folds back on itsel

A

B-sheets

between the carbonyl of one peptide bond and the–NH of another.

chains can runn in parallel or opp directions

20
Q

Post-translational modifications alter

A

alter the charge on proteins and the interactions between amino acid resi-
dues, altering the three-dimensional configuration and, thus, the function of the protein.

21
Q

Proteins from the extracellular environment are degraded within

A

lysozomes

Material enters the cell by endocytosis.
b. The endocytic vesicle fuses with the lysosome to form the phagolysosome.
c. The proteolytic enzymes within the lysosome digest the endocytosed material into
peptides.
d. These peptides can then be completely degraded or, in some cases, presented to cells
of the immune system.

22
Q

DEFINITION= At neutral pH ( pH=7) the carboxy group is deprotonated but the amino group is protonated. The net charge is ZERO.

A

Zwitterions

23
Q

At what ph is , the carboxy group is protonated and the amino acid is in the cationic form.

A

At Acidic pH (ph<7.4)

24
Q

At what ph is the amino group is neutral (NH2 instead of NH3) and the amino acid is in the anionic form.

A

At alkaline pH (pH>7.4),

25
Q

peptide bonds are formed by way of condensation which us

A

DEHYDRATION: water is LEAVINGto form a bond, this is a catalyzed process and DOES NOT HAPPEN SPONATENOUSLY

26
Q

is peptide formations spontaneous?

A

NO

27
Q

nucleophile is a reactant that provides

A

a pair of electrons to form a new covalent bond. AA are GOOOD NUCLEOPHILES

aka lewis bases

28
Q

An electrophile is a species that

A

accepts a pair of electrons to form a new covalent bond. The carbon on the carbonyl is a good electrophile

aka lew is acid

29
Q

How to name peptides

A

Numbering of AA always start from the Amino Terminus and all proteins should be written from N(Nh3)—> C (COO)terminus.

30
Q

Non amino acid part of an AA is called

A

Prosthetic group. They are classified by the chemical nature of their prosthetic group: lipoprotein, glycoproteins, and metalloproteins. Ex: heme in myoglobin.

31
Q

MEtal ions are usually

A

cofactor

32
Q

Coenzyme

A

usually derived from an vitamin. helper or partner that are organic molecules required for enzyme function that bind loosely to an enzyme.

33
Q

PEptide functions

A

Hormones and pheromones: Insulin, oxytocin, sex peptide
Neuropeptides: Substance P (pain mediator)
Antibiotics: polymyxin B ( for gram – bacteria) Bacitracin for (gram + bacteria)
Protection, e.g toxins

34
Q

ph dictates

A

protonationstate

deprotanated = gives up H+
protanated+ recieves H+

35
Q

Peptide bond formation is catalzed by

A

ribosomes

36
Q

prothetic groups are covalently attached __

A

cofactors

attached to protein to make it do different things, different functions

37
Q

Protein folding is entropically unvaorable or favorable?

A

Unfavorable because it minimizes the dispersal of energy and adds order to the system.

38
Q

What are the characteristics of Lodon dispersion

A
  • induced dipole-induced dipole attraction.

- is the weakest intermolecular force

39
Q

There are two kinds of Van der Waals forces

A

weak London Dispersion Forces

and stronger dipole-dipole forces.

40
Q

AMINO ACIDS CAN FUNCTION AS ampholytes BECAUSE THEY CAN BE EITHER

A

AN ACID OR A BASE

41
Q

ALIPHATIC

A

NON RING C-H BONDS

Chapter 1 BC (4 decks)

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