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Biochem > Ch. 3 Proteins > Flashcards

Ch. 3 Proteins Flashcards

1
Q

The “first in rank” macromolecules.

A

Proteins

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2
Q

-in ending reflects the presence of _______.

A

Amino groups

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3
Q

_____ from amino groups contributes significantly to protein mass (16% on average).

A

Nitrogen

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4
Q

Two key aspects of proteins

A
  1. structure: from building blocks to three-dimensional shape
  2. function: diverse roles in biological systems
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5
Q

Proteins are composed of a limited set of ____ fundamental amino acids.

A

20

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6
Q

Modified amino acids exist but arise from the 20 fundamental ones after __________.

A

Protein synthesis

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7
Q

How many amino acids are essential?

A

8

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8
Q

How are essential amino acids obtained in the body?

A

Through the diet, because they cannot be synthesized through the body.

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9
Q

How many amino acids are “non-essential”?

A

12

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10
Q

How does the body synthesize the 12 non-essential amino acids?

A

Through compounds already present in our cells.

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11
Q

The general formula of amino acids includes:

A

central (alpha) carbon atom with 4 attached groups: carboxyl group COO-, amino group +H3N, hydrogen H, variable group (side chain) R.

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12
Q

Amino acids are ionized in _______ solutions.

A

Aqueous

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13
Q

What is an amino acid’s predominant form at physiological pH?

A

Neutral (zwitterionic)

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14
Q

Side chains vary in ______

A

Size, charge, polarity, and chemical reactivity

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15
Q

Amino acids link ____ to form proteins.

A

Covalently

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16
Q

Short stretches of amino acids are known as ________.

A

Peptides

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17
Q

Peptides are _______.

A

Proteins digested to produce shorter chains.

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18
Q

What indicates the number of amino acids in a peptide chain? Give 3 examples.

A

Prefixes - di, tri, tetra

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19
Q

What term describes 10-20 amino acids in a chain?

A

Oligopeptide

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20
Q

What term describes more than 20 amino acids in a chain?

A

Polypeptide

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21
Q

Proteins are often referred to as ________.

A

Polypeptide chains

22
Q

How do peptide bonds form?

A

Via a synthesis condensation reaction, producing water.

23
Q

How do peptide bonds break?

A

A hydrolysis reaction, requires the addition of water.

24
Q

The left side of a Lewis structure is known as _______.

A

N-terminus

25
Q

The right side of a Lewis Structure is known as _______.

A

C-terminus

26
Q

What is a residue?

A

The part of the amino acid involved in peptide formation (what is left over after linking with others to become a larger polymer).

27
Q

A free carboxyl group deriving from aspartate and a free amino group belonging to phenylalanine.

A

Dipeptide Asp-Phe (isomer of Phe-Asp)

28
Q

What are the four levels of protein structures?

A

Primary, secondary, tertiary, and quaternary

29
Q

The most basic level of protein structures.

A

Primary

30
Q

Humans can have around ______ to ______ proteins.

A

100,000 to 200,000

31
Q

Primary structure is determined by ________.

A

Genetic information in genes encodes the amino acid sequences.

32
Q

3D arrangements within proteins, polypeptide chain folding in specific patterns.

A

Secondary structure

33
Q

Key Players - Noncovalent with some covalent character; Forms between δ+(H) and δ-(O or N) atoms, because O and N have a higher electronegativity than H; Stabilizes the secondary structure.

A

Hydrogen Bonds

34
Q

The two common types of secondary structures

A

Alpha (α) helix, Beta (β) sheet

35
Q

Resembles a right-handed spiral staircase, backbone forms a spiral, side chains point outward, stabilized by hydrogen bonds between adjacent turns.

A

Alpha (α) Helix

36
Q

Resembles a crinkled bedsheet, strands are segments of stretched polypeptide chain, strands undulate with parallel peptide unit planes, adjacent residue side chains point in opposite directions.

A

Beta (β) Sheet

37
Q

Conformation of the entire polypeptide chain, flexible and can fold to bring distant residues together, stabilized by various (four) interactions.

A

Tertiary structure

38
Q

4 different types of tertiary interactions

A

Electrostatic Bond, Van Der Waals Interaction, Disulfide Bond, Hydrophobic Interaction

39
Q

Formed between oppositely charged groups; weaker than hydrogen bonds.

A

Electrostatic Bonds

40
Q

Positively charged groups of electrostatic bonds

A

Terminal amino group, lysine, arginine, and possibly histidine

41
Q

Negatively charged groups of electrostatic bonds

A

Terminal carboxyl group, aspartate, and glutamate

42
Q

Noncovalent attraction due to electron movements, momentary asymmetries induce electrostatic forces, weaker than electrostatic bonds

A

Van Der Waals Interaction

43
Q

Covalent bond between cysteine residues (sulfur atoms from two cysteine residues), forms through shedding of H atoms, stronger than peptide bonds, remains united as cystine after protein breakdown.

A

Disulfide bonds

44
Q

Side chains (alanine, valine, leucine) cluster together, driven by repulsion by surrounding water, more stable than exposure to water, weakest interaction discussed

A

Hydrophobic Interaction

45
Q

The process of altering a protein’s structure, causing it to unfold or break up.

A

Denaturation

46
Q

Two main factors of leading to denaturation, provide 2 examples of this process.

A

High temperature and extreme pH values - cooking eggs, yogurt formation.

47
Q

Why does high temperature lead to denaturation? Is it reversible or irreversible?

A

Thermal movement disrupts protein structure , alteration of the polypeptide chain - often irreversible.

48
Q

Why do extreme pH values lead to denaturation? Is it reversible or irreversible?

A

Addition or removal of protons (H+) from chemical groups, affects hydrogen and electrostatic bonding - typically irreversible.

49
Q

Consists of multiple polypeptide chains (known as subunits/simply chains), stabilized by the same bonds as tertiary structures.

A

Quaternary Structure

50
Q
A

Biochem (8 decks)

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