Proteins and Amino Acids Overview

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Questions and Answers

What functional groups are present in amino acids?

Amino and carboxylic acid groups (correct)

Amino and hydroxyl groups

Amino and methyl groups

Hydroxyl and carboxylic acid groups

What percentage of the dry weight of cells is constituted by proteins?

25%

75%

50% (correct)

20%

What characterizes most amino acids?

They contain sulfur as a standard element.

They are all non-polar.

They are typically chiral molecules. (correct)

They are all D-isomers.

What is the daily recommended intake of protein for adults?

0.8 grams per kg of body weight Signup and view all the answers

What type of bonds connect amino acids to form peptides and proteins?

Amide bonds Signup and view all the answers

What type of amino acids are most common in the human body?

α-amino acids Signup and view all the answers

Which amino acid is an exemption regarding chirality, being achiral?

Glycine Signup and view all the answers

Which of the following statements about dietary proteins is true?

They must be consumed daily. Signup and view all the answers

What is the primary function of myoglobin in muscle tissue?

To supply oxygen to the muscle Signup and view all the answers

Which protein accounts for approximately 54% of the total proteins in egg albumen?

Ovalbumin Signup and view all the answers

How is ferritin related to iron in the body?

It stores iron in a soluble, non-toxic form Signup and view all the answers

Which of these bonds is NOT involved in maintaining the tertiary structure of a protein?

Ionic bonds Signup and view all the answers

What type of structure explains the spatial relationship and interactions between subunits in a protein?

Quaternary Structure Signup and view all the answers

In terms of myoglobin content, which type of meat is considered healthier?

White meat Signup and view all the answers

What connects amino acids in proteins, facilitating their primary structure?

Peptide bonds Signup and view all the answers

What happens when ferritin levels are too high in the body?

It can damage joints, heart, liver, and pancreas Signup and view all the answers

What is the primary role of tropomyosin in muscle contraction?

Blocks myosin binding sites on actin Signup and view all the answers

Which statement about serum albumin is true?

It accounts for 50-60% of human blood protein. Signup and view all the answers

What effect does erythropoietin (EPO) have on red blood cells?

Stimulates their production Signup and view all the answers

Which of the following hormones is known as antidiuretic hormone?

Vasopressin Signup and view all the answers

How does somatotropin affect glucose levels in the body?

Decreases the rate of glucose uptake and metabolism Signup and view all the answers

Which hormones are examples of chemical messengers released in the bloodstream?

Insulin, Erythropoietin, Growth hormone Signup and view all the answers

Which structural characteristic is true for actin?

It has a myosin-binding site. Signup and view all the answers

What is the primary function of vasopressin in the body?

Conserves body water Signup and view all the answers

What is a characteristic feature of Kwashiorkor?

Bilateral extremity swelling Signup and view all the answers

What is the primary cause of Phenylketonuria (PKU)?

Change in the PAH gene Signup and view all the answers

Which of the following symptoms is most associated with Marasmus?

Marked muscle atrophy Signup and view all the answers

What dietary factors are commonly linked to Kwashiorkor?

Diets based mainly on maize, cassava, or rice Signup and view all the answers

Which symptom is NOT typically associated with Kwashiorkor?

Severe muscle wasting Signup and view all the answers

What role does HCl play in protein digestion?

It denatures proteins, making them easier to digest. Signup and view all the answers

Which enzyme is responsible for cutting proteins into smaller polypeptides in the stomach?

Pepsin Signup and view all the answers

Which of the following enzymes is secreted as procarboxypeptidase?

Carboxypeptidase Signup and view all the answers

What condition is characterized by a deficiency of one or more essential amino acids?

Hypoproteinemia Signup and view all the answers

In which part of the digestive system does the neutralization of chyme primarily occur?

Small intestine Signup and view all the answers

Which of the following enzymes is involved in the digestion of proteins in the small intestine?

Aminopeptidase Signup and view all the answers

Which amino acids are specifically mentioned in relation to protein digestion?

Aromatic amino acids Signup and view all the answers

What is a common consequence of protein deficiency in developed countries?

Hypoproteinemia is rare Signup and view all the answers

Study Notes

Proteins

A group of complex organic macromolecules containing carbon, hydrogen, oxygen, nitrogen, and usually sulfur.
Linear polymers of amino acids connected by peptide bonds.
Most important of all biological compounds.
Constitutes about 50% of the dry weight of cells.
Must be consumed daily because they are not stored.
Dietary protein usually comes from meat and dairy products.
Recommended daily intake for adults: 0.8 grams of protein per kg of body weight.

Amino Acids

Organic compounds containing an amino group (NH2) and a carboxylic acid group (COOH).
Building blocks of protein.
Most are chiral molecules.
Chiral carbon centers are carbon atoms attached to four different substituents.
Most common amino acids are α-amino acids.
All amino acids in the body are L-isomers.
Glycine is the simplest amino acid.
Peptides and proteins are formed when amino acids are joined together by amide bonds.

Types of Proteins

Actin: Spherical protein, thin filament, two long chains, each has a myosin-binding site.
Serum Albumin: Largest protein component of human blood (50-60%), regulates plasma volume and tissue fluid balance.
Tropomyosin: Blocks myosin binding sites on actin molecules, preventing contraction in a muscle without nervous input.
Troponin: Globular protein, protein complex that binds to tropomyosin, helps position tropomyosin on the actin molecule.
Erythropoietin: Glycoprotein hormone, naturally produced by the peritubular cells of the kidney, acts on red blood cells to protect them against destruction, stimulates stem cells of the bone marrow to increase RBC production.
Growth Hormone: Secreted by the anterior lobe of the pituitary gland, stimulates the growth of essentially all tissues of the body, keeps blood glucose levels within set levels, decreases the rate of glucose uptake and metabolism.
Vasopressin: Antidiuretic hormone, produced in the hypothalamus, helps control blood pressure by acting on the kidneys and blood vessels, conserves body water by reducing the loss of water in urine.
Immunoglobulin: Antibodies.
Fibrinogen: Involved in blood clotting.
Thrombin: Involved in blood clotting.
Ovalbumin: Major egg white protein, responsible for egg white formation.
Casein: Storage protein found in milk.
Ferritin: Protein complex that stores iron in a soluble, non-toxic form.
Myoglobin: Monomeric protein found mainly in muscle tissue, serves as an intracellular storage site for oxygen.

Levels of Protein Structure

Primary Structure: Linear sequence of amino acids connected by peptide bonds.
Secondary Structure: Local folding patterns of the polypeptide chain.
Tertiary Structure: Complete 3D arrangement of the atoms in a protein, held together by peptide bonds, hydrogen bonds, disulfide bonds, and salt bridges.
Quaternary Structure: The spatial relationship and interactions between subunits in a protein that has more than one polypeptide chain, held together by peptide bonds, hydrogen bonds, disulfide bonds, and salt bridges.

Protein Digestion

Begins in the stomach with the help of pepsin, which cuts proteins into smaller polypeptides.
Continues in the small intestine where chyme is neutralized and trypsin, chymotrypsin, and elastase are activated.

Enzymes Involved in Protein Digestion

Carboxypeptidase: Released from the pancreas as procarboxypeptidase, breaks down aromatic and branched amino acids.
Aminopeptidase: Released from the small intestine as proaminopeptidase, breaks down peptides from the amino end.

Diseases Associated with Proteins

Protein Deficiency: State of relative or absolute deficiency of body proteins or one or more of the essential amino acids.
Hypoproteinemia: A state of relative or absolute deficiency of body proteins or one or more of the essential amino acids.
Marasmus: Severe form of malnutrition, visible wasting of fat and muscle under the skin.
Kwashiorkor: Severe form of protein malnutrition, characterized by bilateral extremity swelling, abdominal distension, round face, subcutaneous fat retention, thin, dry, peeling skin, growth retardation, psychic changes, skin lesions/dermatitis.
Phenylketonuria: Rare inherited disorder, causes an amino acid called phenylalanine to build up in the body, caused by a change in the phenylalanine hydroxylase (PAH) gene.

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Description

Explore the fundamental concepts of proteins and amino acids in this quiz. Learn about their structures, importance, and daily intake recommendations. Discover the types of proteins and the key role amino acids play in building these essential macromolecules.