Cell Biology: Organelles, Transport, and Tonicity

Flashcards covering organelle functions, mitochondria versus chloroplasts, endosymbiosis, surface area-to-volume ratios, cellular transport mechanisms, tonicity, and water potential.

What is the structure and function of the plasma membrane?

It is described by the fluid mosaic model with proteins and controls what goes in and out of cells.

What is the function of the nucleus?

Known as the "control center," it stores DNA and decides what gets made.

What is the primary function of ribosomes?

They act as protein factories that build proteins with mRNA.

How do the structures and functions of the Rough ER and Smooth ER differ?

The Rough ER has ribosomes coating it and folds proteins, whereas the Smooth ER makes lipids and detoxes chemicals.

What is the role of the Golgi Apparatus in the cell?

It acts as the shipping department, packaging proteins and sending vesicles.

What role do mitochondria play in cellular function?

Known as the powerhouse of the cell, they break down glucose to make ATP.

What are lysosomes and what do they contain?

They are the recycling bins of the cell that contain enzymes to break down old organelles and molecules.

What are the three main functions of the cytoskeleton?

It gives the cell shape, holds organelles in place, and moves things around.

What do vacuoles store, and how do they differ between plant and animal cells?

Vacuoles store water, food, and waste; animal cells have small vacuoles, whereas plant cells have a big vacuole.

How do mitochondria and chloroplasts compare in terms of location and their specific DNA?

Mitochondria are found in both plant and animal cells and have mtDNA, whereas chloroplasts are found only in plant cells and have cpDNA.

What energy conversion occurs inside chloroplasts during photosynthesis?

$$\text{Light} \rightarrow \text{glucose and oxygen}$$

What is endosymbiosis?

A process where a single-cell organism goes inside another single-cell organism and stays there, adding a new function to the host cell.

Which surface area to volume ratio ($6:1$, $3:1$, $1.5:1$, or $1:1$) is most optimal, and why?

$6:1$, because a higher surface area to volume ratio is more optimal for the transport of nutrients in and out of the cell (more surface area > more volume).

When cell size increases, how does the growth rate of surface area compare to volume?

Surface area increases by $4\times$, while volume increases by $8\times$ (volume grows faster than surface area).

What are the key characteristics and examples of passive transport?

Molecules move from high to low concentration (down the gradient) without requiring ATP; examples include simple diffusion, facilitated diffusion, and osmosis.

What are the key characteristics and examples of active transport?

Molecules move against the gradient and require ATP; examples include endocytosis and exocytosis.

How many ions does the $\text{Na}^+/\text{K}^+$ pump transport per ATP, and what type of gradient does it create?

It moves $3\,\text{Na}^+$ out of the cell and $2\,\text{K}^+$ into the cell per ATP, creating an electronegative gradient because more positive charge exits than enters.

How do hypertonic, hypotonic, and isotonic solutions differ in their solute and water composition?

Hypertonic solutions have more solute and less water, hypotonic solutions have less solute and more water, and isotonic solutions have equal parts solute and water.

How is osmosis defined?

The movement of water from high to low concentration.

What is the formula for water potential, and what do the variables represent?

$\text{water potential} = -iCRT$, where $i$ is the ionization constant, $C$ is the molar concentration, $R$ is the pressure constant, and $T$ is the temperature.

In which direction does water move with respect to water potential, and what outside factors affect the formula?

Water moves from high water potential to low water potential; outside factors like heat and air quality affect the formula.