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Biochemistry > Peptides and Proteins > Flashcards

Peptides and Proteins Flashcards

1
Q

Proteins

A

are very important biological molecules that play important roles in almost ALL biological processes

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2
Q

Proteins provide many essential functions in the body, such as:

A
  • antibodies supporting the immune system
  • digestive enzymes help facilitate chemical reactions
  • support muscle contraction & movement
  • hormones help coordinate bodily function
  • provide support to the body
  • move essential molecules around the body
  • support the regulation and expression of DNA and RNA
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3
Q

Proteins are

A

polymers of amino acids

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4
Q

A peptide bond results from the linkage of the

A

carboxyl group of 1 amino acid to the amine group of its neighbor

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5
Q

Water is

A

eliminated to form a peptide bond

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6
Q

Each amino acid links to the next with

A

a peptide bond

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7
Q

Amino acids are connected

A

head to tail

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8
Q

Dipeptide=
Tripeptide=
Polypeptide=

A

2 joined amino acids
three
many

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9
Q

A polypeptide becomes a protein at

A

50 amino acids

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10
Q

Naming peptides

A

-name from the free amine (
NH3+)
-use -yl endings for the names of amino acids

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11
Q

Naming peptides 2

The last amino acid with the free carboxyl group (COO-)

A

uses its amino acid name

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12
Q

Representation of a peptide or protein:

A peptide or protein can be represented using the

A

3 letter codes of the residues, written in the order in which they are linked together

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13
Q

Why do we represent peptides/proteins link this:?

A

this convention is to orient the sequence of amino acids so that N-terminal residue is on the left and the C-terminal residue is on the right.

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14
Q

Many hormones are

A

peptides

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15
Q

Oxytocin has

A

9 residues

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16
Q

Bradykinin has

A

9 residues

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17
Q

Insulin has

A

30 residue chain + 21 residue chains + glucagon 20 residues

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18
Q

Antibiotics polymyxin B is for

A

grambacteria

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19
Q

Bacitracin is for

A

gram + bacteria

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20
Q

Amanitin =
Conotoxin=
Chlorotoxin=

A

mushrooms
cone snails
scorpions

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21
Q

Protein folding is

A

the physical process by which a protein chain acquires its native 3-dimensional structure, a conformation that is usually biologically functional

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22
Q

Protein folding occurs _______ in a cellular compartment called the ______

A

spontaneously

ER

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23
Q

Why is protein folding necessary?

A

because proteins must be correctly folded into specific, 3D shapes in order to function correctly

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24
Q

When does folding occur?

A

begins during the translation of the polypeptide chain

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25
Q

Amino acids interact with each other to produce a ………….
The folded protein is known as the ———–

A

well-defined 3D structure

native state

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26
Q

Primary Structure

A

linear sequence of amino acids

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27
Q

Secondary Structure

A

localized folding

28
Q

Tertiary Structure

A

overall 3-D structure

29
Q

Quaternary Structure

A

association of 2 or more protein subunits into a protein

30
Q

Primary structure is the

A

order in which amino acids are joined together by peptide bonds

31
Q

Secondary structure of protein includes

A

alpha helix
b pleated sheet (3 strands)
b turn

32
Q

Alpha Helix

A

held by H bonds between the H of –N-H group and the -O of C (double bond) O of the fourth amino acid along the chain

33
Q

The alpha helix looks like a

A

coiled ‘telephone cord’

34
Q

The 2 very important secondary structures of proteins are:

A

a- helix

b-pleated sheet

35
Q

Both of these structures depend on ________ ______ between the _____ H and the _______ O further down the chain or on a parallel chain.

A

hydrogen bonding
amide
carbonyl

36
Q

What is a common secondary structure of proteins?

A

alpha helix (a-helix)

37
Q

The a-helix is a

A

right hand coiled or spiral conformation

38
Q

What must happen in a alpha helix bond?

A

every backbone N-H group donates a hydrogen bond to the backbone C=O group of the amino acid 4 residues earlier (hydrogen bonding)

39
Q

Each turn of a-helix contains

A

3.6 amino acids

40
Q

In a B-pleated sheet

A

all of the peptide bond components are involved in a hydrogen bonding

41
Q

In a B-pleated sheet , the surface of the sheet appears

A

pleated

42
Q

All of the carbonyl O and amide H are involved in the __ _____ with the chain are nearly completely ________.

A

H bonds

extended

43
Q

In a B-pleated sheet, the 2 possible orientations are

A

parallel

antiparallel

44
Q

What are the differences between B-pleated sheets and A-helix sheets?

A
  • unlike the a-helix, B-sheets are composed of 2 or more peptide chains
  • the peptide chains of B-sheets are fully extended
45
Q

There are several types of ______ and ________ that hold a protein in its tertiary structure

A

bonds and forces

46
Q

Quaternary Structure:

Association of

A

more than one polypeptides

47
Q

Each unit of a quaternary structure protein is called a

A

subunit

48
Q

Subunits (________) can be identical (__________) or different (__________)

A

monomers
hompolymeric
heteropolymeric

49
Q

Hemoglobin is made up of

A

2 alpha globins

2 beta globins

50
Q

We can classification of proteins according to

A

shape and nutritional value

51
Q

According to shape:

A

globular

fibrous

52
Q

According to nutritional value:

A

complete protein

non-complete protein

53
Q

Globular proteins ‘spherical’ shape include:

A 
HEMAI
Hemoglobin
Enzymes
Myoglobin 
Antibodies
Insulin
54
Q

Fibrous proteins ‘long, thin fibers’ include:

A

KEC
keratin
elastin
collagen

55
Q

Complete Proteins

A

proteins that provide all the essential amino acids (most animal proteins)

56
Q

Incomplete Proteins

A

proteins that are missing one or more essential amino acids (most plant proteins except soy protein)

57
Q

Incomplete proteins can be served with a

A

complementary protein to make it complete

58
Q

Why are animal products thought to be higher quality proteins compared to plant products?

A

because animal proteins are complete proteins

59
Q

Not only do animal proteins contain all of the essential amino acids,

A

they’re in larger amounts and in the proper proportions

60
Q

Can plant proteins provide the human body with all the amino acids needed for optimal growth and development?

A

yes

61
Q

The proteins in plant proteins are usually in much

A

smaller amounts

62
Q

Most plant proteins have ____ or ________ ________ acid making them ________ proteins.

A

one or more limiting amino acid making them incomplete proteins.

63
Q

While most plant proteins are considered to be incomplete amino acid sources, they

A

may be combined and eaten in proper combinations to provide complete proteins

64
Q

The only protein that is an exception to this rule is

A

the soybean

65
Q

The soybean is considered a

A

complete protein and is comparable to animal protein

Biochemistry (25 decks)

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