AP Biology Unit 2: Cell Structure and Function Flashcards

Comprehensive question-and-answer study flashcards covering AP Biology Unit 2: Cell Structure and Function, Cell Size, Plasma Membrane, Membrane Permeability, Transport, Facilitated Diffusion, Tonicity, Osmoregulation, Compartmentalization, and Endosymbiosis.

What are the components of a ribosome?

Ribosomal proteins and rRNA (ribosomal RNA).

What three types of RNA are involved in protein synthesis?

mRNA, tRNA, and rRNA.

What is the structure and function of a ribosome?

Two subunits that work together to synthesize proteins.

What are the components of the endomembrane system?

Nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, and plasma membrane.

What is the overall function of the endomembrane system?

Makes, modifies, packages, and transports materials throughout the cell.

What is the structure and function of the rough ER?

A folded membrane network covered with ribosomes that makes and processes proteins.

What is the structure and function of the smooth ER?

A membrane network without ribosomes that makes lipids, detoxifies chemicals, and stores calcium.

What is the structure and function of the mitochondria?

A double-membrane organelle that produces ATP through cellular respiration.

What are cristae and how do they contribute to mitochondrial function?

Folds of the inner mitochondrial membrane that increase surface area for the reactions involved in ATP production.

What are the functions of a central vacuole, a contractile vacuole, and a food vacuole?

A central vacuole stores water and maintains turgor pressure; a contractile vacuole removes excess water; a food vacuole stores and digests food.

What is the structure and function of a chloroplast?

A double-membrane organelle containing thylakoids that carries out photosynthesis.

What happens to volume compared to surface area as a cell increases in size?

Volume increases faster than surface area.

How can a cell increase surface area without increasing volume?

By developing folds in its membrane.

What is the relationship between organism size, heat exchange, and metabolic rate per unit body mass?

Smaller organisms lose heat faster relative to their body mass and generally have higher metabolic rates per unit body mass.

What are the surface area and volume formulas for a sphere?

Surface area is $SA = 4\times\times\text{r}^2$ (or $SA = 4\times\times\text{r}^2$) which is $SA = 4\times\times\text{r}^2$ and volume is $V = \frac{4}{3}\times\times\text{r}^3$.

What are the surface area and volume formulas for a sphere in standard notation?

$SA = 4\times\times\text{r}^2$ ($SA = 4\times\times\text{r}^2$) and $V = \frac{4}{3}\times\times\text{r}^3$.

What are the surface area and volume formulas for a cube?

Surface area is $SA = 6s^2$ and volume is $V = s^3$.

What are the surface area and volume formulas for a rectangular prism?

Surface area is $SA = 2lw + 2lh + 2wh$ and volume is $V = lwh$.

What are the surface area and volume formulas for a cylinder?

Surface area is $SA = 2\times\times\text{r}h + 2\times\times\text{r}^2$ and volume is $V = \times\times\text{r}^2h$.

Which geometric shape among a sphere (radius 2), cube (side 3), rectangular prism ($2 \times 3 \times 4$), and cylinder (radius 2, height 4) has the highest surface area-to-volume ratio?

The rectangular prism ($2 \times 3 \times 4$), with a ratio of approximately $2.17$.

What are the main components of the cell membrane?

Phospholipids, proteins, cholesterol, and carbohydrates.

How are phospholipids arranged in the cell membrane in an aqueous environment?

Hydrophilic heads face the watery environments inside and outside the cell; hydrophobic tails face inward toward each other.

What is the fluid mosaic model?

A model describing the membrane as a flexible phospholipid bilayer with proteins and other molecules that can move within it.

What types of materials easily pass through the phospholipid bilayer?

Small nonpolar molecules, such as oxygen ($O_2$) and carbon dioxide ($CO_2$), because they dissolve in the hydrophobic interior.

What types of materials require transport proteins to cross the membrane?

Large, polar, or charged molecules (such as glucose and sodium ions).

What types of materials require bulk transport via vesicles?

Large particles and macromolecules (such as bacteria and large proteins).

How do plant, fungal, and bacterial cell walls differ in their composition?

Plants have cellulose, fungi have chitin, and bacteria have peptidoglycan.

How does the cell wall protect plant cells against hypotonic solutions?

It prevents the cell from bursting when water enters by resisting expansion.

What is the fundamental difference between passive and active transport?

Passive transport is the movement of substances from high to low concentration without using cellular energy, while active transport moves substances against their concentration gradient using energy.

What are the three types of endocytosis?

Phagocytosis (cell eating of large particles or solid material), pinocytosis (cell drinking of liquids and dissolved substances), and receptor-mediated endocytosis (selective uptake using membrane receptors).

What is exocytosis?

The process in which vesicles fuse with the plasma membrane and release materials outside the cell.

What is facilitated diffusion?

Passive movement of substances from high to low concentration through membrane proteins.

What are aquaporins and how do they function?

Channel proteins that allow large quantities of water to cross the membrane by osmosis.

What do hypotonic, hypertonic, and isotonic mean relative to a cell?

Hypotonic means a solution has a lower solute concentration than the cell; hypertonic means a solution has a higher solute concentration than the cell; isotonic means a solution has the same solute concentration as the cell.

What happens to a cell when placed in a hypotonic solution versus a hypertonic solution?

In a hypotonic solution, water enters causing the cell to swell; in a hypertonic solution, water leaves causing the cell to shrink.

In what direction does water move based on water potential?

Water moves from higher water potential to lower water potential.

What is the water potential equation?

$$\Psi = \Psi_p + \Psi_s$$

What is the pressure potential ($\Psi_p$) of a solution in an open container?

$$0$$

What is the solute potential equation?

$$\Psi_s = -iCRT$$

In the solute potential equation $\Psi_s = -iCRT$, what do the variables represent?

$i$ is the ionization constant, $C$ is the molar concentration, $R$ is the pressure constant ($0.00831\,\text{L}\cdot\text{MPa}/\text{mol}\cdot\text{K}$), and $T$ is temperature in Kelvin ($^{\circ}\text{C} + 273$).

What are the ionization constants ($i$) of sucrose and NaCl?

Sucrose has an ionization constant of $1.0$ because it does not ionize in water; NaCl has an ionization constant of approximately $2$ because it separates into two ions.

If Cell A has a water potential of $-0.2\,\text{MPa}$ and Cell B has a water potential of $0.4\,\text{MPa}$, which direction will water flow?

From Cell B to Cell A because water moves from higher to lower water potential.

What are two mechanisms cells and organisms use to perform osmoregulation?

Cells use contractile vacuoles and controlled membrane transport; organisms use salt-secreting cells and kidneys.

What is an electrochemical gradient and what are its two components?

A difference in ion concentration and electrical charge across a membrane; its components are a concentration gradient and an electrical gradient.

How does the sodium-potassium pump maintain membrane potential?

It moves $3\,\text{Na}^+$ ions out of the cell and $2\,\text{K}^+$ ions into the cell.

What is the function of ATPase in transport mechanisms?

Breaks down ATP to release usable energy that powers ion movement across the membrane.

How do internal membranes and compartmentalization facilitate cellular processes?

They divide the cytoplasm into functional regions, provide surfaces for reactions, and create specialized environments to increase efficiency.

What is the endosymbiotic theory and which organelles originated through it?

The theory that mitochondria and chloroplasts evolved from free-living bacteria that were engulfed by larger cells and formed a mutually beneficial relationship.

What are three structural similarities between prokaryotic and eukaryotic cells?

Both have DNA, ribosomes, and a plasma membrane.

What are three differences between prokaryotic and eukaryotic cells?

Prokaryotes lack a nucleus, lack membrane-bound organelles, and are generally smaller than eukaryotes.

What are nucleoid regions and plasmids in prokaryotic cells?

Nucleoid regions are areas of the prokaryotic cell that contain DNA; plasmids are small circular DNA molecules that carry additional genes.