Chapter 5 Flashcards
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What are macromolecules and what types are included?
Macromolecules are large biological molecules essential for life, including carbohydrates, proteins, and nucleic acids. They are composed of smaller units called monomers, which form long chains known as polymers.
What are polymers and monomers, and how are they related?
Polymers are long chain-like molecules formed by covalent bonding of repeating units called monomers. Monomers are the fundamental building blocks of polymers. For example, glucose is a monomer that can form polysaccharides like starch.
Describe the dehydration reaction in polymer synthesis.
A dehydration reaction, also known as a condensation reaction, occurs when two monomers bond together through the loss of a water molecule. One monomer provides a hydroxyl group (—OH), and the other provides a hydrogen atom (—H), forming water. This process is repeated to create long polymer chains.
Explain the process of hydrolysis in the breakdown of polymers.
Hydrolysis is the process that breaks down polymers into monomers by adding water. The water molecule breaks the bond between monomers, reversing the dehydration reaction. This process is essential during digestion, where enzymes hydrolyze food polymers into absorbable monomers.
What role do enzymes play in the synthesis and breakdown of polymers?
Enzymes are specialized proteins that accelerate the chemical reactions involved in both the synthesis (polymerization) and breakdown (depolymerization) of polymers. They lower the activation energy required for these reactions, making them more efficient.
How does the diversity of polymers arise, and why is it significant?
The diversity of polymers arises from the unique linear sequences of monomers. Although there are only about 40–50 common monomers, countless polymer combinations can be formed, similar to how numerous words are created from a limited alphabet. This diversity allows for a wide range of structures and functions in biological macromolecules.
What are the four levels of protein structure, and what characterizes each level?
Primary Structure: The sequence of amino acids in a polypeptide chain, determined by genetic information.
Secondary Structure: Localized folding into structures like alpha-helices and beta-pleated sheets, stabilized by hydrogen bonds.
Tertiary Structure: The overall three-dimensional shape of a single polypeptide chain, determined by interactions between side chains (R groups).
Quaternary Structure: The assembly of multiple polypeptide chains (subunits) into a functional protein.
What are amino acids, and how are they classified?
Amino acids are the building blocks of proteins, consisting of an amino group (—NH2), a carboxyl group (—COOH), and a variable side chain (R group). They are classified based on the properties of their side chains into nonpolar (hydrophobic), polar (hydrophilic), acidic (negatively charged), and basic (positively charged) groups.
Describe the formation of a peptide bond.
A peptide bond is formed when the carboxyl group of one amino acid reacts with the amino group of another amino acid through a dehydration reaction. This bond links the amino acids together in a polypeptide chain.
How do the tertiary and quaternary structures of proteins contribute to their stability and function?
Tertiary Structure: Stabilized by hydrophobic interactions, van der Waals interactions, hydrogen bonds, ionic bonds, and disulfide bridges. These interactions determine the protein’s three-dimensional shape, crucial for its function.
Quaternary Structure: Involves the assembly of multiple polypeptide subunits, enhancing the protein’s stability and functionality. Examples include hemoglobin, which consists of four subunits that work together to transport oxygen.
What is protein denaturation, and what causes it?
Protein denaturation is the loss of a protein’s functional shape due to changes in environmental conditions such as pH, temperature, or salt concentration. This process breaks the weak bonds holding the protein together, rendering it biologically inactive. For example, cooking an egg white causes it to change from clear to opaque due to denaturation.
What is the significance of proper protein folding, and what can result from misfolding?
Proper protein folding is essential for function. Misfolding can lead to diseases such as Alzheimer’s, Parkinson’s, and cystic fibrosis. Misfolded proteins can accumulate and disrupt normal cellular functions, highlighting the importance of correct protein folding.
How is the three-dimensional structure of a protein determined?
The three-dimensional structure of a protein is determined using techniques like X-ray crystallography and NMR spectroscopy. These methods visualize the exact arrangement of atoms within a protein, providing insights into how proteins perform their specific functions.
What are nucleic acids, and what roles do they play in genetic information?
Nucleic acids, such as DNA and RNA, are essential biological macromolecules that store and transmit genetic information. DNA encodes the instructions for building proteins, while RNA plays various roles in protein synthesis and gene regulation.
Describe the structure of DNA.
DNA typically forms a double helix with two strands running in opposite 5’ to 3’ directions (antiparallel). The sugar-phosphate backbones lie outside the helix, with complementary nitrogenous bases (adenine-thymine and guanine-cytosine) on the inside, connected by hydrogen bonds.
What is the significance of the Human Genome Project?
The Human Genome Project, completed in the early 2000s, sequenced all 3 billion DNA bases of the human genome. This project revolutionized biology by providing detailed insights into genetics, evolutionary processes, and disease mechanisms, making large-scale genomic studies more accessible.
