Chpt 2 Flashcards
Protein
- Linear, unbranched polymer of 50 or more amino acids
- Amino acids are connected through peptide bonds
- the linear sequence of amino acids folds into a 3 Dimensional structure
Functions of proteins (7)
- Enzymatic Catalysis
- Transport and storage
- Mechanical Support
- Coordinate Motion
- Generate and transmission of nerve impulses
- Control of growth and differentiation
- Immune protection
Function of proteins: Enzymatic Catalysis
- most chemical reactions in the cell are carried out by enzymes, which are globular proteins
- they increase the rate of chemical reactions by reducing the energy of activation
Function of proteins: Transport and storage
-small molecules are moved throughout the cell by specific transporters
Ex: hemoglobin transports O2 in the blood
Function of proteins: Mechanical support
-the high tensile strength of bone and skin is due to the presence of collagen, a fibrous protein
Function of proteins: Coordinate motion
- muscles are made mostly of proteins
- contraction of muscles relies on the sliding motion of two types of proteins, actin and myosin.
- Motion of a flagella and movement of chromosomes in mitosis also relies on proteins
Function of proteins: Generate and transmission of nerve impulses
-sending and receiving messages between nerve cells requires receptor proteins that detects the presence of acetylcholine
Function of proteins: Control of growth and differentiation
-proteins turn the expression of other proteins on and off by binding to specific sequences on DNA
Function of proteins: Immune protection
-antibodies are highly specific proteins that identify and remove foreign substances from the cell
Amino Acid Backbone
- 20 naturally occurring amino acids are incorporated into proteins
- proteinogenic amino acids
-other amino acids found in the cell
what form of amino acids are found in living systems
L amino acids
Glucogenic vs Ketogenic Amino Acids
Glucogenic Amino Acids
-Carbon skeleton is converted into intermediate(s) that can be used to synthesize glucose
Ketogenic Amino Acids
- Carbon skeleton is converted into intermediate(s) (acetyl CoA or Acetoacetyl CoA) that can form ketone bodies or fatty acids
- Not substrate for glycogenesis
Essential vs Nonessential Amino Acids
Nonessential Amino Acids:
-enzymes present for de novo synthesis of these amino acids
Essential Amino Acids- (Human= TV FILM HWK)
- Organisms lacks enzymes to synthesize the amino acids
- Must be obtained from diet
Which amino acids are Glucogenic/nonessential
- Alanine (A, Ala)
- Arginine (R, Arg)
- Asparagine (N, Asn)
- Aspartate (D, Asp)
- Cysteine (C, Cys)
- Glutamate (E, Glu)
- Glutamine (Q, Gln)
- Glycine (G, Gly)
- Proline (P, Pro)
- Serine (S, Ser)
Which amino acids are both glucogenic/ketogenic and nonessential
-Tyrosine (Y, Tyr)
Which amino acids are ketogenic and nonessential amino acids
None
Which amino acids are glycogenic and essential
Val (and) His Thr(ee) Met(hods)
- Histidine (H, His)
- Methionine (M, Met)
- Threonin (T, Thr)
- Valine (V, Val)
Which amino acids are both glucogenic/ketogenic and essential
ile(y) Trp(ped) BOTH Phe(sants)
- Isoleucine (I, ile)
- Phenylalanine (F, Phe)
- Tryptophane (W, Trp)
Which amino acids are ketogenic and essential
KETONES in Leu of Lys(ine)
- Leucine (L, Leu)
- Lysine (K, Lys)
Which R groups have dissociable protons?
-undergo change
Ryan Harris, Do You Even Know Connor? (7) (R) Arginine (12.5) (H) Histidine (6.0) (D) Aspartic acid (3.9) (Y) Tyrosine (10.9) (E) Glutamic acid (4.3) (K) Lysine (10.8) (C) Cysteine (8.3)
If pH is above pKa what happens to the R group?
the R group will deprotonate
if pH is below pKa what happens to the R group?
the R group will be protonated
Zwitterionic Form
-just looking at amino backbone (Nitro group and Carboxyl group)
Neutral Charge
- Nitro group Protonated
- Carboxylic acid Oxygen is deprotonated
pKa of Terminal alpha carboxyl group
3.1
pKa of terminal amino group
8.0
Peptide bonds
- linear and planar
- uncharged
- not free to rotate (due to resonance–>double bond like-steric hindrance)
- Trans configuration-hydrogen of substituted amino group is trans to the oxygen of carbonyl group
What is the only Amino acid that is in the cis configuration instead of trans?
Proline
Cyclic Amino Acids
Proline
Aliphatic Def
Nonaromatic Hydrocarbon (C and H only) -nonpolar hydrophobic
Aliphatic Amino Acids
Glycine Alanine Valine Leucine Isoleucine
Sulfur containing Amino Acids
Cysteine
Methionine
Aromatic Amino Acids
Phenylalanine
Tryptophane
Tyrosine
Hydroxyl Containing Amino Acids
Serine
Threonine
Acidic Amino Acids
Aspartic Acid (aspartate-deprotonated form) Glutamic Acid (Glutamate-deprotonated form)
Neutral Amide Acids
Asparagine
Glutamine
what is the pKa of the terminal alpha-carboxyl group
3.1
what is the pKa of the terminal alpha-amino group
8.0
