Metabolism, Cellular Processes, and Biological Systems Review

Vocabulary-style flashcards covering metabolic pathways (glycolysis, Krebs cycle, photosynthesis), cellular structures, plant hormones, and human physiological systems as described in the lecture notes.

Glycogenolysis

The breakdown of glycogen into glucose-6-phosphate ($G6P$) molecules, which occurs when the body needs more glucose.

Glucose-6-phosphate ($G6P$)

The first intermediate of glycolysis, formed after hexokinase adds one phosphate group onto glucose.

Chemiosmosis

The movement of ions down their concentration gradient across a semipermeable membrane; in cellular respiration, it refers to the flow of protons through ATP synthase down their electrochemical gradient.

Stroma

The fluid portion of the chloroplast, synonymous with the cytosol, where the Calvin Cycle takes place.

Glycogenesis

The process of storing extra carbohydrates and glucose by converting monosaccharides into $G6P$ and linking them to form glycogen.

Rubisco

The enzyme responsible for carbon fixation in the Calvin Cycle, which can also fix oxygen during photorespiration.

Photorespiration

A process where RuBisCo fixes oxygen instead of carbon dioxide, which is unfavorable because it does not produce ATP or glucose.

CAM Plants

Plants that store $CO_2$ as malic acid in vacuoles at night to power the Calvin Cycle during the day when stomata are closed.

Tight Junctions

Cell-cell junctions that form a seal between adjacent cells to prevent material leakage; they are critical for the blood-brain barrier.

Alcohol Fermentation

A cytoplasmic process occurring in yeast and some bacteria where pyruvate is converted to ethanol and $CO_2$ to regenerate $NAD^+$.

Acetaldehyde

The final electron acceptor in alcohol fermentation that accepts electrons from $NADH$ to form ethanol.

Periplasmic Space

The area between the plasma membrane and outer cell wall in prokaryotes where protons are pumped during the electron transport chain.

Cori Cycle

The metabolic process where lactate produced in muscles is transferred to the liver to be converted back into glucose.

Oxidative Deamination

A process in the liver where amino groups are removed from amino acids, producing toxic ammonia ($NH_3$) which is then converted to urea.

Beta Oxidation

A catabolic process in the mitochondrial matrix that breaks down fatty acids into $acetyl-CoA$ molecules.

Insulin

A hormone produced by the pancreas that promotes glucose uptake into cells and stimulates the synthesis of glycogen and proteins.

Catabolism

The set of metabolic reactions that break down complex organic molecules into simpler ones, releasing energy in the process.

Anabolism

Metabolic reactions, such as photosynthesis, that build complex molecules from simpler ones and require energy.

Cristae

Folded structures of the inner mitochondrial membrane that increase surface area for more efficient cellular respiration.

Proton Motive Force

The flow of protons from the intermembrane space to the mitochondrial matrix that directly powers ATP synthase.

Substrate Level Phosphorylation

The process in which an enzyme directly transfers a phosphate group from one molecule to $ADP$ to form $ATP$, occurring in glycolysis and the Krebs cycle.

Phosphofructokinase ($PFK$)

The major regulatory enzyme of glycolysis that converts Fructose 6-phosphate to Fructose 1,6-Bisphosphate; it is negatively regulated by high levels of $ATP$.

Pyruvate Decarboxylation

A process in the mitochondrial matrix where a 3-carbon pyruvate is oxidized into a 2-carbon $acetyl-CoA$, releasing $CO_2$ and reducing $NAD^+$ to $NADH$.

Amylase

An enzyme that breaks down starch, a complex carbohydrate, into the disaccharide maltose.

Abscisic Acid

A plant hormone that inhibits growth and promotes seed dormancy to prevent germination during unfavorable conditions.

Autonomic Nervous System

A division of the peripheral nervous system responsible for involuntary movements and innervating cardiac and smooth muscle.

Sympathetic Nervous System

The division of the autonomic nervous system involved in the "fight or flight" response, featuring short pre-ganglionic and long post-ganglionic nerve fibers.

Type IIb Muscle Fibers

Fast-twitch fibers with the fastest contraction speed that primarily use glycolysis, appear white due to low myoglobin, and fatigue quickly.

Conjugation

A method of horizontal gene transfer where DNA is transferred between bacterial cells via a pilus.

F-plasmid

The fertility factor required for a bacterium to assemble a pilus and donate genetic material during conjugation.

Notochord

A distinguishing feature of chordates that induces neurulation and develops into portions of the spinal vertebrae in vertebrates.

Michaelis Constant ($K_m$)

The substrate concentration at which the reaction rate is half of the maximum velocity ($1/2 V_{max}$); it inversely represents binding affinity.

Zymogens

Inactive precursors to enzymes, such as pepsinogen, that require cleavage to become active enzymes.

Second Law of Thermodynamics

States that energy transfer in closed systems leads to an increase in the total entropy of the universe over time.