Cell Biology and Genetics Practice Flashcards

A comprehensive set of vocabulary flashcards covering cell biology concepts, biochemistry, metabolism, organelle function, and molecular genetics based on the lecture transcript.

Cell Theory

The conceptual framework stating that all organisms are composed of one or more cells, the cell is the structural unit of life, and cells arise only by division from pre-existing cells, with the modern addition that cells contain genetic information ($DNA$) passed to the next generation.

Nucleoid

The "nuclear area" in prokaryotic cells where genetic material is located, lacking a surrounding membrane.

Reductionism

An approach to studying biological systems by examining the individual parts of a whole to explain the character of the entire system.

HeLa Cells

The first cultured human tumor cells, derived from Henrietta Lacks, which are essential for biological research.

LUCA

An acronym for the Last Universal Common Ancestor of all living organisms.

Metagenome

The collective genome of all microbes present in a particular habitat.

Covalent Bonds

The strongest type of chemical bonds, formed by the sharing of electron pairs between atoms.

Hydrogen Bonds

Weak interactions that occur when a partially positive hydrogen, bonded to an electronegative atom like $O$ or $N$, is attracted to another electronegative atom.

Hydrophobic Interactions

A driver of protein folding where nonpolar molecules aggregate to minimize their contact with water.

Buffers

Substances in living systems that resist changes in $pH$ to maintain homeostasis by accepting or releasing protons ($H^+$).

Glycosidic Bonds

The chemical bonds that link monosaccharides together to form carbohydrates.

Peptide Bonds

Bonds that link amino acid monomers together to form proteins.

Molecular Chaperones

"Helper proteins" that assist in the proper folding of other proteins and prevent their aggregation.

Denaturation

The process of unfolding a protein using heat or chemicals, causing it to lose its specific biological function.

Second Law of Thermodynamics (Entropy)

The principle stating that events in the universe proceed toward a state of lower energy and higher randomness, represented as $S$.

Exergonic Reaction

A spontaneous chemical reaction where the change in free energy is negative ( ext{\Delta} G < 0), resulting in a release of energy.

Activation Energy ($E_a$)

The initial energy required to reach the unstable transition state in a chemical reaction, which enzymes work to lower.

Michaelis Constant ($K_M$)

The specific substrate concentration at which a reaction reaches $1/2\,V_{max}$; it serves as a measure of the enzyme's affinity for its substrate.

Competitive Inhibitors

Molecules that compete with the substrate for the enzyme's active site, increasing the $K_M$ without changing the $V_{max}$.

Noncompetitive (Allosteric) Inhibitors

Molecules that bind to a site other than the active site, decreasing the $V_{max}$ without changing the $K_M$.

Redox Reactions

Chemical reactions involving the loss of electrons (oxidation) and the gain of electrons (reduction).

Fluid Mosaic Model

The model of the plasma membrane describing it as a dynamic lipid-protein assembly where proteins are embedded in a fluid lipid bilayer.

Amphipathic Lipids

Molecules, such as phosphoglycerides, that possess both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions.

Lipid Rafts

Specialized microdomains within the plasma membrane enriched in cholesterol and sphingolipids that provide an environment for cell-surface receptors.

Sodium-Potassium Pump ($Na^+/K^+\,ATPase$)

An active transport mechanism that uses energy from $ATP$ hydrolysis to push $3\,Na^+$ out of the cell and pull $2\,K^+$ into the cell.

Saltatory Conduction

The process in myelinated neurons where the action potential "jumps" between Nodes of Ranvier, significantly increasing the speed of nerve impulses.

Cardiolipin

A unique lipid found in the highly impermeable inner mitochondrial membrane ($IMM$).

Tricarboxylic Acid (TCA) Cycle

A series of reactions in the mitochondrial matrix that converts Acetyl $CoA$ into $CO_2$, primary producing high-energy electron carriers $NADH$ and $FADH_2$.

Proton-Motive Force

The electrochemical gradient created by the Electron Transport Chain ($ETC$) through the pumping of protons ($H^+$) into the intermembrane space.

Warburg Effect

The observation that cancer cells often rely on aerobic glycolysis even when oxygen is present, rather than using mitochondrial respiration.

Thylakoids

Flattened membranous sacs within chloroplasts where the light-dependent reactions of photosynthesis occur.

Rubisco

The most abundant protein on Earth, responsible for the carboxylation step of the Calvin Cycle where $CO_2$ is attached to $RuBP$.

Photorespiration

A wasteful process in plants where Rubisco binds with $O_2$ instead of $CO_2$, typically occurring in hot, dry weather.

Glycocalyx

A layer of carbohydrate projections on the outer surface of the plasma membrane that mediates cell-cell interactions and provides protection.

Integrins

Animal-specific membrane proteins that handle cell adhesion and transmit signals between the extracellular environment and the cell interior.

Hemidesmosomes

The strongest attachment sites in the body, which anchor epithelial cells to the underlying basement membrane using keratin filaments.

Cadherins

Calcium-dependent glycoproteins that act as "glue" to join similar cell types together into cohesive tissues.

Tight Junctions (TJs)

Junctions located at the apical end of epithelial cells that form a "gasket" to prevent solutes and water from leaking between cells.

Gap Junctions

Intercellular "pipelines" made of connexin proteins that allow small molecules and ions to pass directly between adjacent animal cells.

Plasmodesmata

Cytoplasmic channels through plant cell walls that allow the passage of proteins and $RNA$ between cells.

Zellweger Syndrome

A clinical condition caused by the lack of peroxisomal enzymes, leading to severe neurological damage.

Signal Recognition Particle (SRP)

A particle that binds to the signal sequence of a growing polypeptide, halting translation and directing the ribosome to the rough endoplasmic reticulum ($RER$).

ERAD (Endoplasmic Reticulum Associated Degradation)

A quality control pathway that exports misfolded proteins from the $ER$ to the cytosol to be destroyed by a proteasome.

COPII-coated Vesicles

Vesicles that move materials in an anterograde fashion from the Endoplasmic Reticulum to the Golgi complex.

Acid Hydrolases

Digestive enzymes found in lysosomes that function optimally at a low $pH$ of approximately $4.6$.

Autophagy

The regulated process by which a cell degrades and recycles its own worn-out organelles.

Microtubules

Stiff, hollow tubes made of $GTP- ext{\alpha} ext{\beta}-tubulin$ subunits that serve as tracks for kinesin and dynein motor proteins.

Axoneme

The structural core of cilia and flagella characterized by a "9 + 2" arrangement of microtubules.

Taxol

A mitotic inhibitor drug that stabilizes microtubules to prevent their shrinkage, thereby stopping cancer cell division.

Linkage Groups

Sets of genes located on the same chromosome that do not assort independently.

Chargaff’s Rules

The principle stating that in any double-stranded $DNA$ molecule, the amount of Adenine equals Thymine ($[A] = [T]$) and the amount of Guanine equals Cytosine ($[G] = [C]$).

Topoisomerases

Enzymes that regulate the supercoiling of $DNA$ by cutting and resealing one or both strands.

Melting Temperature ($T_m$)

The temperature at which $DNA$ strands separate, which is higher for sequences with greater $G-C$ content.

Retrotransposons

Mobile genetic elements that move within the genome via an $RNA$ intermediate using reverse transcriptase.

Alternative Splicing

A regulatory mechanism that allows one gene to produce multiple different proteins by joining different combinations of exons.

Telomerase

An enzyme that prevents the shortening of linear chromosomes by adding repeated sequences to the telomeres.

Nucleotide Excision Repair (NER)

A $DNA$ repair mechanism that fixes bulky lesions, such as pyrimidine dimers caused by $UV$ light exposure.