Unit I Study Guide: Cellular Theory, Organelles, and Transport

Comprehensive practice flashcards covering cellular theory, prokaryotic vs. eukaryotic cell structure, organelle functions, membrane transport mechanisms, homeostasis, the scientific method, and biochemistry principles.

What are three main differences between prokaryotic and eukaryotic cells?

Nucleus, Organelles, size and complexity.

How do prokaryotes and eukaryotes differ in their nucleus, membrane-bound organelles, DNA structure, and examples?

Prokaryotes have DNA free-floating in the nucleoid, no membrane-bound organelles (no mitochondria, ER, Golgi), circular and single-stranded unbound DNA, and include bacteria. Eukaryotes have DNA enclosed inside a membrane, contain membrane-bound organelles (mitochondria, ER, Golgi), linear DNA organized into chromosomes, and include plant cells, animal cells, and fungi.

How does the cell theory explain the repair of a scraped knee?

After skin cells are damaged and lost from scraping a knee, the remaining healthy cells surrounding the injury undergo cell division; these pre-existing cells divide to create new identical cells which eventually layer over each other to repair the damage.

Which organelle is found in plant cells but not in animal cells, and what is its function?

A central vacuole, which functions in water storage.

What is the function of the nucleus, and why is it called the "control center" of the cell?

The nucleus acts as the control center because it stores the cell's genetic material (DNA) and directs every single functional process within the cell, coordinating activities like growth and reproduction.

Where is the nucleolus located, and what is its primary function?

It is located inside the nucleus, and its primary function is to produce and assemble the cell's ribosomes.

What is the purpose of lysosomes, and what would happen if a cell did not have them?

They act as the cell's waste disposal and recycling system; if the cell did not have them, waste products would rapidly build up.

What is the function of ribosomes?

They synthesize proteins by translating genetic code.

What is the function of the Golgi apparatus?

It modifies, sorts, and packages proteins and lipids received from the endoplasmic reticulum for transport to their destinations.

What is the function of mitochondria?

They generate the cell's energy supply in the form of adenosine triphosphate (ATP) through cellular respiration.

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

Smooth ER synthesizes lipids and metabolizes carbohydrates. Rough ER synthesizes and folds proteins using the ribosomes attached to its surface, preparing them for transport.

What is the function of cilia and flagella?

They provide movement for the cell itself or move substances across the cell's surface.

What is the function of the cell wall, and in what organisms is it found?

It provides structural support, protection, and shape to plant cells, fungi, and bacteria (it is not found in animal cells).

What role does the cell membrane play in maintaining homeostasis?

It acts as a selective barrier that controls and regulates what enters and leaves the cell, providing protection and maintaining internal balance.

What is diffusion?

The net movement of any particles from an area of higher concentration to an area of lower concentration.

What is osmosis?

The movement of water molecules from an area of higher water concentration to an area of lower water concentration.

What is facilitated diffusion?

The movement of specific molecules across a cell membrane from high to low concentration with the assistance of membrane proteins (like channels or carriers).

What is the main difference between active and passive transport?

The use of cellular energy (ATP) and the direction of movement relative to the concentration gradient.

What happens to an animal cell when placed in a hypertonic, hypotonic, or isotonic solution?

In a hypertonic solution, the animal cell will shrivel. In a hypotonic solution, the animal cell will swell and may burst. In an isotonic solution, the animal cell will stay the same size.

How does a white blood cell capture bacteria, and what type of transport is used?

The transport used is phagocytosis; the white blood cell extends its cell membrane outward to surround the bacterium, engulfing it completely.

What are the six specific types of transport and an example of each?

1. Simple diffusion: oxygen gas moving from the lungs into red blood cells. 2. Facilitated diffusion: glucose entering a cell through a glucose transporter protein. 3. Osmosis: water rushing into a cell placed in a pure distilled water environment. 4. Protein pumps: the sodium potassium pump in nerve cells. 5. Endocytosis: a white blood cell engulfing a bacterium. 6. Exocytosis: nerve cells releasing neurotransmitters to pass a signal to the next cell.

What is the difference between endocytosis and exocytosis?

In endocytosis, the cell membrane folds inward to take materials into the cell, forming a vesicle. In exocytosis, a vesicle inside the cell fuses with the membrane to release materials out of the cell.

What is a feedback mechanism, and how does it help maintain homeostasis?

It is a physiological regulatory process that helps an organism maintain homeostasis—a stable internal environment—by adjusting its systems in response to change or stimuli.

What are examples of negative and positive feedback loops?

Negative feedback loop example: regulation of blood glucose (sugar) levels. Positive feedback loop example: blood clotting.

Why is homeostasis important for cell survival?

Homeostasis maintains a stable internal environment.

Define independent variable, dependent variable, and control group.

Independent variable: the variable that the researcher changes or manipulates in an experiment to test its effects. Dependent variable: the variable that is measured or observed to see how it will respond to the change in the independent variable. Control group: the standard or baseline group that does not receive the experimental treatment.

In an experiment testing plant growth with different fertilizers, what are the independent variable, dependent variable, and control group?

Independent variable: the type of fertilizer used. Dependent variable: plant growth. Control group: a plant grown without any fertilizer.

What does the data trend "as temperature increases, reaction time decreases" mean?

It means the rate of the reaction is speeding up.

What do the terms hydrophobic and hydrophilic mean?

Hydrophobic refers to water-fearing molecules that are nonpolar and do not dissolve or mix well with water. Hydrophilic refers to water-loving molecules that are polar or charged and readily attract or dissolve in water.

What are the four macromolecules, and which one is never used by the cell for energy?

The four macromolecules are carbohydrates, lipids, proteins, and nucleic acids. Nucleic acids are never broken down by the cell to be used as an energy source.

How do lipids, proteins, and carbohydrates help build or support the cell membrane?

Lipids (phospholipids) form the core phospholipid bilayer; proteins act as channels and pumps to transport molecules across; carbohydrates serve as cellular identification tags for cell-to-cell recognition and communication.