Proteins Flashcards Preview

BIOL 141 > Proteins > Flashcards

Flashcards in Proteins Deck (43)
Loading flashcards...
1
Q

4 parts of an amino acid

A

*all are bonded to common carbon core

  1. H - hydrogen atom
  2. NH2 - amino functional group
  3. COOH - carboxyl functional group
  4. a distinctive “R-group”
2
Q

What happens to amino acids in water?

A

They ionize due to the pH of 7

3
Q

What acts as a base in an amino acid?

A

Amino group (NH2)

4
Q

What acts as an acid in an amino acid?

A

Carboxyl group (COOH)

The two highly electronegative oxygens pull the hydrogen away

5
Q

What makes the amino acids unique?

A

The r-group

6
Q

What happens if an R-group just contains carbon and hydrogen?

A

They will not participate in many chemical reactions

7
Q

Hydrophilic R-groups

A

Polar and electrically charged

8
Q

Hydrophobic R-groups

A

Nonpolar R-groups or highly electronegative atoms capable of forming hydrogen bonds with water

9
Q

Does the R-group have a negative charge?

A

If yes, it is acidic and will lose a proton

10
Q

Does the R-group have a positive charge?

A

If yes, it is basic and will pick up a proton

11
Q

If the R-group is uncharged, does it have an oxygen atom?

A

If yes, then the highly electronegative oxygen atom will form a polar covalent bond, thus making it uncharged

12
Q

Dehydration reactions

A

also called condensation reactions

newly formed bond results in the loss of water

13
Q

What type of bond is a peptide bond?

A

Covalent

14
Q

What do peptide bonds occur between?

A

carboxyl group of one amino acid and the amino group of another amino acid

2 hydrogens from (NH2) react with one oxygen from (COOH) to form the peptide bond

15
Q

Are peptide bonds stable?

A

Yes due to the degree of electron sharing

16
Q

Residues

A

amino acids that are linked together in a chain

17
Q

R-group orientation in residue

A

Side chains (R-group) stick out which makes it possible for them to react with eachother and to react with water

18
Q

What is the directionality of the residue?

A

N-terminus (amino group) to C-terminus (carboxyl group)

19
Q

Oligopeptide

A

a polymer with fewer than 50 amino acids

20
Q

Polypeptide

A

a polymer with more than 50 amino acids

21
Q

Primary structure

A

refers to the distinct amino acid sequence

R-groups affect chemical reactivity and solubility

22
Q

Secondary structure

A

distinctively shaped sections that are stabilized by hydrogen bonding that occurs between the oxygen on the C=O group of one amino acid residue and the N-H groups on another

23
Q

a-helix

A

the polypeptide’s backbone is coiled

24
Q

B-pleated sheet

A

segments of the peptide chain fold in the same plane

25
Q

Proline

A

rarely found in a-helixes

26
Q

Tertiary structures

A

form using a variety of bonds and interactions between R-groups or between R-groups and the backbone

27
Q

Types of interactions used for tertiary structures

A
  1. Hydrogen bonding
  2. Hydrophobic interactions
  3. van de Waals interactions
  4. Covalent bonding
  5. Ionic bonding
28
Q

Hydrogen bonding

A

form between polar side chains and opposite partial charges either in the peptide backbone or other R-groups

29
Q

Hydrophobic interactions

A

water molecules force the hydrophobic nonpolar side chains to merge into globular masses

30
Q

van der Waals interactions

A

once hydrophobic side chains are close to one another, electrical attractions take place

constant motion of elections produces tiny asymmetry in charge this makes nonpolar molecules slightly attracted to eachother

31
Q

Covalent bonding

A

can form between two cysteines

disulfide bonds create strong links

32
Q

Ionic bonding

A

form between groups that have full and opposing charges

33
Q

Quaternary structure

A

proteins that involve multiple polypeptides

34
Q

Dimers

A

proteins with two polypeptide subunits

35
Q

Macromolecular machines

A

groups of multiple proteins that assemble to carry out a particular function

ex: ribsome

36
Q

Is folding spontaneous?

A

It tends to be

37
Q

Denatured

A

unfolded proteins

38
Q

How do we know that folding affects function?

A

Anfinsen studied denatured proteins and found that they could not function

39
Q

Molecular chaperones

A

special proteins that can facilitate protein folding

40
Q

Prions

A

proteins that can be induced to fold into infectious, disease causing agents

shapes are different

Ex: mad cow disease

41
Q

What are proteins used for?

A
Catalysis
Defense
Movement
Signaling
Structure
Transport
42
Q

Active site

A

location where substrates bind to enzyme and react

43
Q

Where can hydrogen bonding occur to form the secondary structure?

A

Every 4th amino acid

Between carboxyl (-) and amino (+) group