Key Concepts in Cell Theory and Functions

What are the three main parts of the cell theory?

The cell is the basic unit of life; all living things are made of cells; all cells come from preexisting cells.

How has scientific investigation impacted the cell theory?

New technology and discoveries have expanded and supported cell theory over time.

How are scientific claims evaluated in biology?

Through scientific argumentation, critical and logical thinking, and considering alternative explanations.

What’s the difference between a theory and a law in science?

A law describes what happens; a theory explains why or how it happens, supported by evidence.

How are prokaryotic and eukaryotic cells different?

Prokaryotes have no nucleus or membrane-bound organelles; eukaryotes do.

What are similarities between prokaryotic and eukaryotic cells?

Both have DNA, a cell membrane, cytoplasm, and ribosomes.

How are plant and animal cells different?

Plant cells have cell walls, chloroplasts, and large central vacuoles; animal cells do not.

How are plant and animal cells similar?

Both are eukaryotic and share structures like the nucleus, mitochondria, Golgi apparatus, ER, etc.

What is the function of the cell wall?

Provides support and protection; found in plants, fungi, and some prokaryotes.

What is the function of the cell membrane?

Controls what enters and leaves the cell; helps maintain homeostasis.

What is the function of the cytoplasm?

Jelly-like substance where cell processes occur.

What is the function of ribosomes?

Produce proteins by linking amino acids.

What is the function of cilia and flagella?

Help cells move or move substances past cells.

What is the function of the nucleus?

Stores DNA and controls cell activities.

What is the nuclear envelope?

Membrane around the nucleus that regulates what enters and exits.

What is chromatin?

Uncoiled DNA and proteins found in the nucleus.

What does the endoplasmic reticulum (ER) do?

Processes and transports proteins (rough ER) and makes lipids (smooth ER).

What does the Golgi apparatus do?

Modifies, packages, and ships proteins.

What do mitochondria do?

Produce energy (ATP) through cellular respiration.

What do chloroplasts do?

Carry out photosynthesis to make food (in plant cells).

What do vacuoles do?

Store water, nutrients, and waste; large central vacuole in plants.

What do lysosomes do?

Break down waste and cell parts using enzymes.

What is passive transport?

Movement of substances across a membrane without energy (e.g., diffusion, osmosis).

What is active transport?

Movement of substances using energy (ATP), often against the concentration gradient.

What is osmosis?

Diffusion of water across a membrane.

What is diffusion?

Movement of molecules from high to low concentration.

What are the four macromolecules?

Carbohydrates, lipids, proteins, nucleic acids.

What is the function of carbohydrates?

Provide short-term energy and structural support.

What is the function of lipids?

Long-term energy storage and make up cell membranes.

What is the function of proteins?

Do most of the cell's work (enzymes, transport, structure).

What is the function of nucleic acids?

Store and transmit genetic information (DNA and RNA).

What do enzymes do?

Act as catalysts to lower activation energy and speed up reactions.

How do pH and temperature affect enzyme activity?

Extreme pH or temperature can denature (damage) enzymes and reduce their function.

What are key properties of water that support life?

Cohesion, temperature moderation, expansion when frozen, good solvent, hydrogen bonding, polarity.

How are photosynthesis and cellular respiration connected?

The products of one are the reactants of the other.

What is the photosynthesis equation?

6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂

What is the cellular respiration equation?

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

What are the reactants and products of aerobic respiration?

Reactants: glucose and oxygen; Products: CO₂, water, and ATP.

What are the reactants and products of anaerobic respiration?

Reactants: glucose; Products: less ATP + lactic acid or alcohol + CO₂.

What is the role of ATP in the cell?

ATP stores and transfers energy for cell functions.

What is the energy difference between photosynthesis and respiration?

Photosynthesis stores energy in glucose; respiration releases energy as ATP.