Biology Exam 1 and 2 Review

Carbon (C), Nitrogen (N), Oxygen (O), and Hydrogen (H) are the most abundant elements in the human body. These elements are the building blocks of essential biomolecules like carbohydrates, proteins, lipids, and nucleic acids, which are crucial for life.

The evolution of eukaryotic cells from prokaryotic cells involved the development of nuclear membranes. Prokaryotes lack membrane-bound organelles, while eukaryotes have a nucleus and other internal compartments.

A reaction is nonspontaneous when the Gibbs free energy change (ΔG) is positive. In this case, the enthalpy change (ΔH) is positive (23 kJ/mol), indicating the reaction requires energy, and the entropy change (ΔS) is positive (22 J/K*mol) but relatively small, making the overall ΔG positive at 2°C.

Ionic interactions, where oppositely charged particles attract, are the strongest noncovalent interactions. They are stronger than hydrogen bonds or van der Waals forces, which involve weaker attractions.

Urea has three atoms that can function as hydrogen bond acceptors: one oxygen atom and two nitrogen atoms. These atoms have lone pairs of electrons that can accept hydrogen bonds from other molecules.

Helicase is an enzyme involved in DNA replication that separates the two strands of DNA by breaking the hydrogen bonds between them.

DNA polymerase III is the primary enzyme responsible for synthesizing new DNA strands during replication, while DNA polymerase I is involved in removing RNA primers and replacing them with DNA.

Insertions & deletions that are not in multiples of three nucleotides cause a change in the reading frame, affecting all codons downstream.

In prokaryotic transcription, the sigma factor binds to a specific DNA sequence called the promoter, facilitating RNA polymerase binding and initiating RNA synthesis.

Aminoacyl-tRNA synthetase is an enzyme responsible for attaching the correct amino acid to its corresponding tRNA molecule.

Antibiotic resistance genes are used to identify cells that have successfully taken up the plasmid. This process involves introducing a plasmid containing the antibiotic resistance gene into the cell (transformation). After transformation, cells are grown on a medium containing the antibiotic. Only those cells that have successfully taken up the plasmid will survive and grow on the medium as they can produce the protein that renders the cell, resistant to the antibiotic.

Most human proteins have been conserved through evolution, meaning they are found in other species, not just vertebrates. This indicates a shared ancestry and the importance of these proteins for basic biological functions.

Polymerase Chain Reaction (PCR) requires a specific set of components to amplify DNA segments. These include: 1. DNA template: The DNA fragment you want to amplify 2. Primers: Short DNA sequences that flank the region. 3. dNTPs: Building blocks for the new DNA strands. 4. Thermostable DNA polymerase: An enzyme that can withstand high temperatures and replicate DNA.

The formation of a dipeptide involves the removal of a water molecule from two amino acids, connecting their amino and carboxyl groups. This process is called a condensation reaction and results in the formation of a peptide bond. The combination of amino acids is always in a specific order to give a defined protein.

In proteins, conservative substitutions are replacements of amino acids with similar properties, such as a Glutamic Acid (Glu) being replaced by Aspartic Acid (Asp). Both residues have a negative charge, so substitution will not disrupt the protein's function significantly. These substitutions are commonly seen during evolution with little to no effect on the protein.

Amino acids with a configuration of groups around the C-alpha that can be related to the configuration of groups around the asymmetric carbon in L-glyceraldehyde. These amino acids are optically active and correlate with L-glyceraldehyde configuration.

The absorption of UV light at 280 nm is primarily due to the presence of aromatic amino acids within the protein.

Stereochemistry, or the spatial arrangement of molecules, is not commonly used in protein separation methods.

Disulfide bonds are covalent bonds that link cysteine residues together in proteins, forming a bridge between two polypeptide chains or within a single chain.

SDS-PAGE separates proteins primarily based on their molecular weight (mass). The negatively charged SDS coats the protein, giving it a uniform negative charge, eliminating the effect of variations in intrinsic charges.

The carboxyl group of an amino acid is covalently linked to the 3' hydroxyl group of its cognate tRNA.

Glycine's lack of a side chain makes it inflexible and can disrupt the regular hydrogen bonding pattern required for stable alpha-helix formation.

Antiparallel beta sheets are more stable than parallel beta sheets due to the optimal hydrogen bonding patterns between the strands.

Blocking the biosynthesis of 4-hydroxyproline does not affect alpha keratin since it is a specific component of collagen.

The formation of secondary structure (alpha-helices and beta-sheets) is the first step in the folding of disordered polypeptides into ordered and functional proteins.

Proteins covalently linked to long sugar chains (glycosaminoglycans), forming a bottle-brush structure. They create hydrated gels that provide resilience to tissues, especially in cartilage, where they help resist compression.

A major component of bacterial cell walls, composed of alternating sugars N-acetylglucosamine and N-acetylmuramic acid. It provides rigidity to bacteria, allowing them to survive in hypotonic environments, and contributes to virulence.

The process of adding sugar molecules (glycans) to proteins. It can occur in two ways: N-linked (adding to asparagine) and O-linked (adding to serine/threonine). Glycosylation influences protein structure, function, and cell-cell communication.

Proteins that bind to carbohydrates, facilitating cell-cell interactions. Specialized lectins called selectins are involved in immune responses, helping white blood cells recognize and bind to endothelial cells.

Major components of cell membranes, consisting of a glycerol backbone with two fatty acid tails and a hydrophilic head group. Their structure allows them to form bilayers, the foundation of all membranes.

Fatty acids are long chains of carbon and hydrogen atoms with a carboxylic acid group at one end. They can be saturated (no double bonds) or unsaturated (with double bonds).

The primary energy storage molecules in animals. They are composed of glycerol with three fatty acid chains attached.

Lipids derived from sphingosine. They play important roles in cell recognition, adhesion, and signaling.

Proteins that mediate vesicle fusion, playing a crucial role in the process of releasing neurotransmitters and other cellular components.

Toxins produced by bacteria like tetanus and botulinum that interfere with neurotransmitter release by cleaving snare proteins.

Linear polysaccharides composed of repeating disaccharide units containing uronic acid and hexosamine.

A type of GAG composed of repeating units of D-Glucuronate and N-Acetyl-D-glucosamine.

Highly sulfated GAG with a high negative charge, known for its anticoagulant properties.

Extracellular matrices secreted by bacteria, composed of hydrated polysaccharides that offer protection against the environment.

A process by which viruses fuse their membrane with the host cell membrane, allowing them to enter and infect the cell.

The initial stage of viral infection, where the virus recognizes and attaches to specific receptors on the host cell.

The final stage of viral infection, where the viral membrane fuses with the host cell membrane, allowing the viral genome to enter the cell's cytoplasm.