BIL 150 Chapters 6–8 Detailed Study Guide (umiami)

Comprehensive practice flashcards covering cell structure and organelles, membrane dynamics and transport, thermodynamics, and cellular metabolism based on Chapters 6–8 study guide.

What are the three core principles of Cell Theory?

1. All living organisms are made of cells. 2. The cell is the basic unit of life. 3. All cells come from preexisting cells.

What are the major structural differences between prokaryotic and eukaryotic cells?

Prokaryotic cells (bacteria and archaea) lack a nucleus, have DNA in a nucleoid region, are generally smaller, and lack membrane-bound organelles. Eukaryotic cells (animals, plants, fungi, and protists) have a nucleus and many membrane-bound organelles.

What are the primary functions of the Nucleus, Nucleolus, and Ribosome?

The nucleus stores most of the cell's DNA; the nucleolus produces ribosome components; ribosomes carry out protein synthesis.

What distinguishes the functions of free ribosomes from bound ribosomes?

Free ribosomes generally make proteins used within the cell, whereas bound ribosomes on the rough ER generally make proteins for secretion, membranes, or certain organelles.

What distinguishes the functions of the Rough ER and Smooth ER?

Rough ER has ribosomes and produces and processes proteins. Smooth ER lacks ribosomes and synthesizes lipids, participates in carbohydrate metabolism, carries out detoxification, and stores $\text{Ca}^{2+}$.

What is the sequence of the protein secretion pathway through the endomembrane system?

Ribosome $\rightarrow$ rough ER $\rightarrow$ transport vesicle $\rightarrow$ Golgi $\rightarrow$ secretory vesicle $\rightarrow$ plasma membrane $\rightarrow$ exocytosis.

What are the primary roles of the Golgi apparatus, lysosomes, and central vacuoles?

The Golgi apparatus modifies, sorts, and packages proteins and other molecules. Lysosomes contain digestive enzymes to break down macromolecules, damaged organelles, and foreign materials. Central vacuoles in plant cells store materials, balance water, and maintain pressure against the cell wall.

What structural features characterize mitochondria and chloroplasts?

Mitochondria contain an outer membrane, inner membrane, intermembrane space, matrix, and cristae (folds of the inner membrane). Chloroplasts contain thylakoids (membrane sacs for light reactions), grana (stacks of thylakoids), and stroma (surrounding fluid).

What prokaryote-like features support the endosymbiotic theory for mitochondria and chloroplasts?

Mitochondria and chloroplasts have their own DNA, contain ribosomes, divide in a manner resembling bacterial cell division, have double membranes, and are similar in size to bacteria.

What are the key functions and relative sizes of the three cytoskeletal elements?

Microtubules are the largest cytoskeletal elements and handle cell shape, intracellular transport, chromosome movement, cilia, and flagella. Microfilaments are the smallest (made primarily of actin) and handle cell shape, movement, muscle contraction, and cytoplasmic streaming. Intermediate filaments provide structural support and stabilize cell shape and organelles. Size order: microfilaments < intermediate filaments < microtubules.

What are the four major types of intercellular junctions and their functions?

Tight junctions seal neighboring cells to prevent leakage; desmosomes strongly attach neighboring cells; gap junctions allow communication between animal cells; plasmodesmata are channels connecting neighboring plant cells.

Why are phospholipid molecules in the membrane described as amphipathic?

Because they contain both a hydrophilic (polar) head that is attracted to water and hydrophobic (nonpolar) tails that avoid water.

How does cholesterol regulate membrane fluidity across different temperatures?

At higher temperatures, cholesterol restrains phospholipid movement; at lower temperatures, it helps prevent phospholipids from packing too tightly.

How do fatty acid saturation levels influence membrane fluidity?

Unsaturated fatty acids have bends that prevent tight packing and increase fluidity. Saturated fatty acids pack more tightly and decrease fluidity.

How do animal and plant cells respond to hypotonic, hypertonic, and isotonic solutions?

In a hypotonic solution, water moves into the cell (animal cells swell/burst; plant cells become turgid). In a hypertonic solution, water moves out of the cell (animal cells shrivel; plant cells undergo plasmolysis). In an isotonic solution, there is no net water movement (animal cells are normal size; plant cells become flaccid).

How does active transport function, and what does the sodium-potassium pump accomplish per ATP?

Active transport requires cellular energy (usually ATP) to move substances against their concentration gradient. The sodium-potassium pump uses ATP to move $3\text{ Na}^+$ out of the cell and $2\text{ K}^+$ into the cell per ATP.

What are the three main types of endocytosis?

Phagocytosis ('cell eating' of large particles), pinocytosis ('cell drinking' of fluid), and receptor-mediated endocytosis (binding of specific molecules to cell receptors).

How do catabolic pathways differ from anabolic pathways?

Catabolic pathways break down complex molecules and release energy. Anabolic pathways build complex molecules and require energy input.

What are the First and Second Laws of Thermodynamics?

The First Law states that energy cannot be created or destroyed, only transferred or transformed. The Second Law states that every energy transfer increases the entropy (disorder/randomness) of the universe.

What are the characteristics of exergonic and endergonic reactions regarding free energy change ($\Delta G$)?

Exergonic reactions release free energy, have \text{\Delta G} < 0, and are spontaneous/thermodynamically favorable. Endergonic reactions require free energy input, have \text{\Delta G} > 0, and are nonspontaneous/thermodynamically unfavorable.

What is activation energy ($E_a$), and how do enzymes affect it and $\Delta G$?

Activation energy ($E_a$) is the initial energy barrier required to start a reaction. Enzymes lower $E_a$ to accelerate reactions, but they do not alter \text{\Delta G} or convert endergonic reactions into exergonic ones.

How do competitive inhibitors differ from allosteric (noncompetitive) inhibitors?

Competitive inhibitors bind directly to the active site and compete with the substrate. Allosteric (noncompetitive) inhibitors bind away from the active site, altering the enzyme's shape and activity.

What is feedback inhibition and why is it important?

Feedback inhibition occurs when the final product of a metabolic pathway inhibits an enzyme at an earlier step, preventing the cell from wasting energy and raw materials when enough product is present.

What is the chemical reaction for ATP hydrolysis and how is it used in energy coupling?

The reaction is $\text{ATP} + \text{H}_2\text{O} \rightarrow \text{ADP} + \text{P}_i + \text{free energy}$. Cells couple this exergonic release of energy to drive endergonic processes such as mechanical work, transport work, and chemical work.

What defines oxidation and reduction, and what roles do $\text{NAD}^+$ and $\text{FAD}$ play?

Oxidation is the loss of electrons; reduction is the gain of electrons (OIL RIG). $\text{NAD}^+$ and $\text{FAD}$ act as electron carriers that accept high-energy electrons (becoming $\text{NADH}$ and $\text{FADH}_2$) to transfer them between metabolic reactions.