PROKARYOTE VS. EUKARYOTE
What is the most fundamental structural difference between a eukaryotic cell and a prokaryotic cell?
Eukaryotic cells possess a true, membrane-bound nucleus that houses their DNA, while prokaryotic cells lack a nucleus, with their DNA floating freely in the cytoplasm in a region called the nucleoid.
What is the "control center" of the cell, and what key molecule does it store?
The nucleus is the control center, containing the cell's DNA, which holds the instructions (genes) for all cell activities and protein synthesis.
What's the difference between passive and active transport?
Passive transport (diffusion, osmosis) moves substances down their concentration gradient (high to low) without cell energy (ATP). Active transport moves substances against their gradient (low to high) and requires cellular energy (ATP).
qWhat is osmosis, and in which direction does water move?
Osmosis is the passive diffusion of water across a selectively permeable membrane, moving from an area where water concentration is high (low solute) to an area where water concentration is low (high solute) to achieve equilibrium.
Q: What are the main inputs (reactants) and outputs (products) of photosynthesis and cellular respiration, and how do they relate?
Photosynthesis uses 6CO₂ + 6H₂O + Light Energy to produce C₆H₁₂O₆ (glucose) + 6O₂, while cellular respiration uses C₆H₁₂O₆ + 6O₂ to produce 6CO₂ + 6H₂O + ATP (energy). They are inverse processes: one's products are the other's reactants, forming a cycle of energy and matter.
Name key organelles found in eukaryotes but not in prokaryotes.
Eukaryotes have membrane-bound organelles like mitochondria, endoplasmic reticulum (ER), Golgi apparatus, lysosomes, and chloroplasts (in plants/algae), which are absent in prokaryotes.
Which organelle is known as the "powerhouse" and produces most of the cell's energy (ATP)?
The mitochondrion (plural: mitochondria) generates energy through cellular respiration, making it vital for cell function.
1.
What is osmosis, and why is it important?
What happens to a red blood cell (animal cell) placed in pure (distilled) water?
The cell is in a hypotonic environment (more water outside). Water rushes into the cell, causing it to swell and eventually burst (lyse) because animal cells lack a rigid cell wall.
Where do these processes occur in a eukaryotic cell?
How does the DNA differ between the two cell types?
Eukaryotic DNA is typically linear and organized into multiple chromosomes, whereas prokaryotic DNA is usually a single, circular molecule.
What are ribosomes, and what is their primary job?
Ribosomes are tiny structures that act as protein factories, reading messenger RNA (mRNA) to build proteins needed by the cell.
How do large molecules enter or exit the cell?
Large molecules use vesicular transport, a form of active transport. Endocytosis brings things in (like phagocytosis/pinocytosis) via engulfing vesicles, while exocytosis moves substances out by fusing vesicles with the membrane.
Q3: What happens to a plant cell in a highly salty (hypertonic) solution?
A3: Water moves out of the plant cell into the salty solution. This causes the cell membrane to pull away from the cell wall, making the cell flaccid or wilted (plasmolysis), as seen in wilting leaves.
Q: Why do plants need to perform both photosynthesis and cellular respiration, while animals only perform respiration?
Plants perform photosynthesis to create their own food (glucose) from sunlight. They then use cellular respiration to break down that glucose to get usable energy (ATP) for growth and life functions. Animals can't photosynthesize, so they must eat plants or other animals for glucose and perform respiration to power their cells.
Give examples of organisms that are eukaryotic and organisms that are prokaryotic.
Eukaryotes include animals, plants, fungi, and protists. Prokaryotes include all bacteria and archaea.
What's the difference between the Rough and Smooth Endoplasmic Reticulum (ER), and what does the Golgi apparatus do?
The Rough ER has ribosomes and makes proteins, while the Smooth ER makes lipids and detoxifies; the Golgi apparatus (or Golgi complex) then sorts, modifies, and packages these proteins and lipids for transport.
What role do transport proteins play in the cell membrane?
Define isotonic, hypotonic, and hypertonic solutions.
A4:
What is ATP, and why is it crucial for cells?
What are the main differences in how these cells reproduce?
Prokaryotes primarily reproduce asexually via binary fission (simple splitting). Eukaryotes can reproduce both asexually (mitosis) and sexually (meiosis), leading to genetic variation.
What are lysosomes and vacuoles, and how do they differ in animal vs. plant cells?
Lysosomes digest waste and old cell parts, while vacuoles store water/nutrients. Plant cells usually have large central vacuoles for support, whereas animal cells have smaller, temporary ones.
What happens if a cell is in a hypertonic solution?
A: In a hypertonic solution (higher solute outside), water leaves the cell through osmosis. Animal cells shrink (crenate), while plant cells become flaccid as the central vacuole loses water, pulling the membrane away from the wall (plasmolysis).
What two main things determine the rate and direction of osmosis?
The water potential gradient (difference in water/solute concentration) and the presence of a partially permeable membrane that allows water but restricts solute movement. Temperature also affects the rate.
Q: How do the carbon cycle and energy flow connect photosynthesis and respiration?