Biology Chapter on Proteins and Enzymes

<p>Bind to antigens (C)</p> Signup and view all the answers

<p>Transport proteins (A)</p> Signup and view all the answers

<p>They can take significantly longer. (D)</p> Signup and view all the answers

<p>By the levels of iron (C)</p> Signup and view all the answers

<p>Presence of nucleic acids (C)</p> Signup and view all the answers

<p>Amino acid sequence formed by peptide bonds (A)</p> Signup and view all the answers

<p>Secondary structure (C)</p> Signup and view all the answers

<p>Stimulates production of adrenal hormones (D)</p> Signup and view all the answers

<p>The primary structure remains unchanged (D)</p> Signup and view all the answers

<p>Spatial arrangement of multiple polypeptide chains (C)</p> Signup and view all the answers

<p>Myoglobin functions to store oxygen, while hemoglobin transports it (D)</p> Signup and view all the answers

<p>Acid or base, water, and heat (B)</p> Signup and view all the answers

<p>It is formed by hydrogen bonding between amide hydrogens and carbonyl oxygens. (D)</p> Signup and view all the answers

<p>The helix is left-handed. (B)</p> Signup and view all the answers

<p>It consists of chains that are nearly completely extended. (C)</p> Signup and view all the answers

<p>Interactions among side chains or R groups. (C)</p> Signup and view all the answers

<p>Disulfide bridges (C)</p> Signup and view all the answers

<p>It consists of fibers or sheets with one type of secondary structure. (A)</p> Signup and view all the answers

<p>They are ionic interactions between positively and negatively charged side chains. (C)</p> Signup and view all the answers

<p>All carbonyl O and amide H are involved in hydrogen bonding. (B)</p> Signup and view all the answers

<p>Hydrogen bonding between amide and carbonyl groups. (A)</p> Signup and view all the answers

<p>It binds and transports iron safely in the bloodstream. (D)</p> Signup and view all the answers

<p>Following a conformational change induced by decreased pH. (B)</p> Signup and view all the answers

<p>Hemoglobin and myoglobin (B)</p> Signup and view all the answers

<p>Control metabolic and reproductive functions. (B)</p> Signup and view all the answers

<p>They provide mechanical support in multicellular organisms. (B)</p> Signup and view all the answers

<p>Severe chronic blistering from birth. (A)</p> Signup and view all the answers

<p>Insulin and glucagon (D)</p> Signup and view all the answers

<p>It interacts dangerously with cellular structures. (A)</p> Signup and view all the answers

<p>Internalization via receptor-mediated endocytosis. (A)</p> Signup and view all the answers

<p>It provides structural support in hair and nails. (C)</p> Signup and view all the answers

<p>pH 6.02 (D)</p> Signup and view all the answers

<p>To observe migration of amino acids based on their charge (D)</p> Signup and view all the answers

<p>Net negative charge (A)</p> Signup and view all the answers

<p>Alanine (A)</p> Signup and view all the answers

<p>Lysine (D)</p> Signup and view all the answers

<p>The amino acid becomes negatively charged (A)</p> Signup and view all the answers

<p>To react with amino acids producing colored products (A)</p> Signup and view all the answers

<p>Aspartic Acid (C)</p> Signup and view all the answers

<p>pKa 2.34: +1; pKa 9.60: 0 (C)</p> Signup and view all the answers

<p>At its pI (A)</p> Signup and view all the answers

Proteins are essential for life and are made up of amino acids. They are crucial for a wide variety of functions in the body.

The name 'protein' comes from the Greek word 'proteios' meaning 'first', reflecting their central role in living organisms.

There are 20 commonly occurring amino acids that form the building blocks of proteins. The diversity of proteins arises from the unique properties of these amino acids.

Enzymes are biological catalysts that speed up chemical reactions in the body. Most enzymes are proteins.

Pepsin, trypsin, and chymotrypsin are examples of digestive enzymes that break down proteins in our food. These enzymes allow our bodies to absorb nutrients.

Antibodies are specialized protein molecules produced by the immune system that bind to foreign antigens, like bacteria and viruses, to help eliminate them from the body.

Transferrin is a protein that carries iron from the liver to the bone marrow, where it is used to produce hemoglobin for red blood cells.

Iron alone is very reactive and can damage cells. Transferrin safely carries iron through the body.

Iron, a crucial element for life, is bound to the protein transferrin in the bloodstream for safe transport.

Transferrin, after binding to its receptor on cell surfaces, is internalized into cells via receptor-mediated endocytosis.

The release of iron from transferrin within cells is triggered by a decrease in pH within the endocytic vesicle.

Transport proteins facilitate the movement of various substances throughout the body. Examples include hemoglobin, which carries oxygen in red blood cells, and myoglobin, which stores oxygen in muscles.

Regulatory proteins play vital roles in controlling cellular processes like metabolism and reproduction, ensuring proper function within a specific range of conditions.

Many hormones that regulate bodily functions, such as insulin and glucagon, are proteins.

Structural proteins provide mechanical support to large organisms, giving them their shape and form. Examples include keratin in hair and fingernails, and proteins that strengthen bones, tendons, and skin.

Epidermolysis bullosa (EB) is a group of genetic disorders that affect the skin due to mutations in structural proteins.

Recessive dystrophic EB, the most severe form of EB, causes extensive blistering on the skin due to defects in structural proteins.

Defective structural proteins in the skin are the underlying cause of the severe skin blistering in individuals with Epidermolysis bullosa.

The isoelectric point (pI) is the pH at which an amino acid exists as a zwitterion with a net charge of zero.

At pH values below the pI, an amino acid will have a net positive charge because the carboxyl group is protonated (COOH) and the amino group is also protonated (NH3+).

At pH values above the pI, an amino acid will have a net negative charge because the carboxyl group is deprotonated (COO-) and the amino group is also deprotonated (NH2).

The pKa values for an amino acid correspond to the pH values at which the amino acid exists in a 50:50 ratio of protonated and deprotonated forms for each ionizable group.

The pI of an amino acid with an acidic side chain is calculated as the average of the pKa values for the carboxyl group and the acidic side chain.

The pI of an amino acid with a basic side chain is calculated as the average of the pKa values for the amino group and the basic side chain.

Electrophoresis is a technique used to separate molecules based on their charge and size using an electric field.

In electrophoresis, amino acids with a net positive charge will migrate towards the negative electrode (cathode) when an electric field is applied.

In electrophoresis, amino acids with a net negative charge will migrate towards the positive electrode (anode) when an electric field is applied.

Amino acids can be separated using electrophoresis by allowing them to migrate in an electric field at a specific pH. This method allows us to identify and distinguish different amino acids based on their charge.

The linear sequence of amino acids in a polypeptide chain, determined by the genetic code.

The three-dimensional arrangement of a polypeptide chain, formed by hydrogen bonds between the backbone amide and carbonyl groups.

The overall three-dimensional shape of a protein, determined by interactions between amino acid side chains.

The arrangement of multiple polypeptide chains in a protein complex.

The loss of organized structure in a protein, leading to a change in its function but not its primary sequence.

The breaking of peptide bonds in a protein, resulting in smaller peptides or free amino acids.

A molecule that binds to and transports oxygen in the blood.

The most common type of secondary structure in proteins, characterized by a coiled, helical shape.

A form of protein secondary structure where polypeptide chains are arranged in a pleated sheet-like structure, stabilized by hydrogen bonds.

A repeated coiling of α-helices, often found in fibrous proteins, leading to a long, extended fiber-like structure.

A covalent bond formed between two sulfur atoms of cysteine residues, playing a key role in stabilizing the tertiary structure of proteins.

Electrostatic interactions between positively and negatively charged amino acid side chains, contributing to the tertiary structure of proteins.

A secondary structure that is not easily defined or regular, occurring in regions of a polypeptide chain that lack a clear α-helix or β-pleated sheet conformation.

Proteins that are primarily composed of long, extended fibers or sheets, usually containing only one type of secondary structure. They typically have a structural role rather than a catalytic function.