L4(8/27): Eukaryotic Cell Biology, Enzymology, and Metabolic Energetics

Vocabulary flashcards generated from lecture notes covering eukaryotic cell structures, endosymbiosis, cytoskeletal elements, enzymology, and metabolic classifications.

Eukaryotic cells are significantly

Larger than prokaryotic cells (nucleus & membrane-bound organelles)

Golgi Apparatus

Folds & modifies newly synthesized proteins, adds extra non-amino acid components, makes vesicles, vacuoles & lysosomes.

Vacuole

spherical eukaryotic storage organelle, phospholipid bilayer

stores excess materials such as water, starch, or iron.

Inclusion Bodies

Bacteria cells non-membrane bound localized cytoplasmic aggregations of proteins, lipids, or other substances that serve as storage deposits for nutrients or metabolic products.

Lysosome

A spherical eukaryotic organelle produced by the Golgi Body, contains acidic conditions (low pH) and hydrolytic enzymes specialized for destroying worn-out organelles and breaking down ingested materials.

Mitochondria

Rod-shaped organelles with a double membrane. Contain 70S ribosomes (bacteria-like) inside; 80S ribosomes are found outside in the cytoplasm/rough ER.

Endosymbiotic Theory

Mitochondria originated when a eukaryotic cell engulfed a prokaryotic cell, lysosome function failed, forming a mutually beneficial symbiotic relationship rather than digesting it.

70S Ribosomes

Bacterial-sized ribosomes found inside the inner mitochondrial membrane, supporting the evolutionary endosymbiotic origin of mitochondria.

Mutualism

A relationship where both organisms benefit.

• Prokaryote: Gets protection + nutrients

• Eukaryote: Gets more efficient energy production → competitive advantage

Cytoskeleton

Protein fibers that provide cell structure, shape, movement, and transport.

Microfilaments, intermediate filaments, microtubules

Microfilaments

Cytoskeletal protein fibers located along the outer edge of the cell just inside the plasma membrane that give the eukaryotic cell its shape.

Intermediate Filaments

Cytoskeletal protein fibers passing through the middle of a eukaryotic cell that provide structural attachment networks to keep organelles evenly distributed.

Microtubules

Dynamic, transient cytoskeletal fibers that crisscross the cell to transport vesicles and organelles → railroad trax (assembling, disassembling) where cellular priorities shift

form the internal structural core of eukaryotic cilia and flagella.

Eukaryotic Flagellum

A membrane-covered cellular extension containing internal microtubules that thrashes to allow direct, steered motility without using a biased random walk.

Low numbers usually 1-2

Cilia

Short, numerous extensions of the eukaryotic plasma membrane containing internal microtubules that thrash to facilitate cellular swimming or move substances across tissue surfaces.

Glycocalyx

An outer carbohydrate-rich cellular coating present on animal cells and certain protists that aids in attachment and protection without forming a rigid cell wall(no cell wall) →allows movement

Metabolism

Sum of all chemical reactions in an organism.

Catabolism

The breaking down of large molecules into smaller simpler ones; these reactions are typically exergonic(release energy) and exothermic(release heat during bond breakdown)

Anabolism

Building larger, complex molecules from smaller simpler components, these reactions are typically endergonic(requires energy) and endothermic(absorbs required heat from the environment)

Energy of Activation

Min energy threshold required to force reactants into an unstable transition state to initiate the reaction

Exergonic Reaction

Energy of reactants are higher than the energy of the products (the difference in energy is released into the cell or environment)

Endergonic Reaction

The total energy of the products is higher than the total energy of reactants (requires energy absorption from external sources)

Enzyme

A folded protein catalyst that lowers the required activation energy of a specific chemical reaction without being consumed or permanently altered in the process.

Active Site

The specifically shaped pocket or region within a folded enzyme protein whose shape matches specific reactant molecules

Substrate

The specific chemical reactant or starting material that binds to an enzyme's active site (undergoes chemical changes into distinct products molecules)

Turnover Number

The rate at which a specific enzyme processes substrate molecules into products per unit of time when fully saturated.

Factors that influence enzyme activity

Substrate concentration: As it increases, collision frequency btw substrates & active sites increases, making the reaction rate rise

Saturation limit: Reached once every active site of every available enzyme is operating @ max turnover speed

Temp: Higher temp increases Brownian motion

Denaturation

The irreversible loss of a protein's functional three-dimensional structure and active site caused by heat breaking stabilizing hydrogen bonds.

Optimum pH

The specific pH level at which an enzyme maintains its ideal active site configuration and functions at maximum rate. Deviating from it reduces enzyme function by changing the structure of the active site

Enzyme pathways

Enzymes only catalyze one minor chemical modification at a time

Assembly Line pathway

For complex metabolic transformations, enzymes function sequentially in organized pathways (the product of one enzyme is the reactant of the next)

Enzyme pathway branching

Products produced in the middle generated along the enzymatic pathway can branch into secondary pathways to synthesize different end molecules

Chemotroph ( energy source)

An organism that obtains its energy from extracting energy from organic or inorganic molecules from the environment (humans)

Phototroph ( energy source)

An organism that absorbs sunlight to power its cellular metabolic processes (plants)

Heterotroph (carbon source)

An organism that requires organic carbon sources and cannot utilize inorganic carbon dioxide ($\text{CO}_2$).

Autotroph (carbon source)

An organism capable of utilizing inorganic carbon dioxide ($\text{CO}_2$) as its carbon source to build organic macromolecules.

Chemoheterotroph

An organism metabolic classification that relies on chemical compounds for energy and organic carbon sources, including humans, animals, and all pathogenic bacteria.

Photoautotroph

An organism metabolic classification that uses light energy from the sun and inorganic carbon dioxide ($\text{CO}_2$) as a carbon source, such as plants.

Adenosine Triphosphate (ATP)

A nucleotide energy carrier molecule composed of a nitrogenous base, a ribose sugar, and three phosphate groups linked by high-energy covalent bonds.

Glycolysis

An enzymatic catabolic pathway that breaks down carbohydrates to release energy(exergonic) used for converting ADP and inorganic phosphate back into ATP.

Plant Cell Structure

Eukaryotic cells surrounded by a rigid cell wall made of cellulose, a sugar-derived carbohydrate material

Fungal Cell Structure

Eukaryotic cells surrounded by a rigid cell wall made from sugar polymers different than cellulose

Protist structure

Diverse eukaryotic cellular boundaries that, depending on the species ( glycocalyx, cellulose, or fungal-like cell walls)