Questions and Answers
What is the primary function of hormones?
What is the term for the process of a protein losing its shape and function?
denaturation
All proteins are fibrous in nature.
False
There are approximately __________ types of amino acids that comprise all proteins.
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What is the role of enzymes in living cells?
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Match the following proteins with their characteristics:
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All proteins have the same molecular weight.
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What is the term for the molecules that bind to enzymes?
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What type of enzymes are responsible for breaking down substrates?
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All amino acids are essential for human health and must be obtained through diet.
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What components make up the basic structure of an amino acid?
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Salivary amylase is an enzyme that hydrolyzes ______, a component of starch.
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Match the following amino acids with their nature:
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Which of the following amino acids is nonpolar?
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Proline is an exception to the standard structure of amino acids because its amino group is separate from the side chain.
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How many common amino acids are present in proteins?
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Study Notes
Proteins
- Proteins are among the most abundant organic molecules in living systems and exhibit the widest variety of functions among macromolecules.
- Functions of proteins include structural, regulatory, transport, storage, protective, enzymatic, and toxic roles.
- Each cell may contain thousands of distinct proteins, each serving a unique function based on its specific amino acid sequence.
- Proteins are polymers made up of amino acids organized in a linear sequence, exhibiting diverse shapes and molecular weights.
- Globular proteins (e.g., hemoglobin) are typically more rounded, while fibrous proteins (e.g., collagen in skin) have elongated structures.
- Protein shape is crucial for its function; many types of chemical bonds help maintain this shape.
- Changes in temperature, pH, or chemicals can permanently alter a protein’s shape, resulting in loss of function (denaturation).
- All proteins are composed of arrangements of 20 standard amino acids, plus two rare amino acids: selenocysteine and pyrrolysine.
- Hormones, often small proteins or steroids secreted by endocrine cells, play key roles in regulating physiological processes (e.g., insulin regulates blood glucose levels).
- Enzymes are complex or conjugated proteins produced by living cells that act as catalysts in biochemical reactions, such as digestion.
- Each enzyme is substrate-specific, facilitating breakdown (catabolic enzymes) or synthesis (anabolic enzymes) processes.
Amino Acids
- Amino acids are the monomers that make up proteins, each containing a central carbon (α carbon), an amino group (NH2), a carboxyl group (COOH), a hydrogen atom, and a unique R group.
- The term "amino acid" reflects the presence of both an amino and a carboxyl group in their structure.
- There are 20 common amino acids, with nine being essential for humans, as they cannot be synthesized by the body and must be obtained through diet.
- The R group determines the characteristics of each amino acid, categorizing them as acidic, basic, polar, or nonpolar.
- Nonpolar amino acids (e.g., valine, methionine, alanine) are hydrophobic, while polar amino acids (e.g., serine, threonine, cysteine) are hydrophilic.
- Lysine and arginine possess positively charged side chains, classifying them as basic amino acids.
- Proline is atypical, as its R group forms a ring structure linked to the amino group, differing from standard amino acid composition.
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Description
Learn about the diverse range of functions of proteins in living systems, including structural, regulatory, contractile, and protective roles. Discover how proteins vary in structure and function in each cell.