Biological molecules
What are 4 types of polysaccharides?
Starch – energy storage in plants.
Glycogen – energy storage in animals (in liver & muscles).
Cellulose – makes up plant cell walls, gives structure.
Chitin – found in fungi cell walls & insect exoskeletons.
Name 3 functions of water
1. Polarity
2. Cohesion
3. Adhesion
4. Capillary action
5. Temperature control
High specific heat
Evaporative cooling
6. Floating ice
7. Solvent
What is the two difference between passive transport and active transport?
Passive transport does not require energy (ATP) and goes with the concentration gradient. Active transport requires energy and goes against the concentration gradient.
Describe "fluid mosaic" model of plasma membrane. What might shown on it?
plasma membrane is a flexible layer of phospholipids with proteins floating
Phospholipid bilayer (hydrophobic tails + hydrophilic heads)
• Channel and carrier proteins
• Cholesterol (for stability)
• Glycoproteins and glycolipids (for cell recognition)
What is the primary energy currency of the cell?
ATP (Adenosine Triphosphate)
What type of bond connects two amino acids together during protein synthesis?
peptide bond
Why is water considered the "universal solvent"?
Because of its polarity, it can dissolve many ionic compounds and other polar molecules.
What is osmosis?
The diffusion of water across a selectively permeable membrane from an area of low solute concentration to high solute concentration.
What are the functions of the Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER)?
RER: Synthesizes and modifies proteins (has ribosomes). SER: Synthesizes lipids and detoxifies drugs/poisons (no ribosomes).
What is the function of an enzyme?
To speed up chemical reactions by lowering the activation energy.
What are the two types of nucleic acids and what are their primary functions?
DNA (stores genetic information) and RNA (transmits genetic information and makes proteins)
Explain why ice floats on liquid water. Why is this important for aquatic life?
Ice is less dense than liquid water because hydrogen bonds form a stable, open crystalline lattice. It insulates the water below, allowing life to survive in freezing temperatures.400Define "specific heat" and explain how water's high specific heat helps moderate Earth's climate.
What happens to an animal cell placed in a hypertonic solution? What about a plant cell?
Animal cell: Shrivel. Plant cell: Plasmolyze, cell membrane pulls away from the cell wall.
What is the difference between a prokaryotic and a eukaryotic cell?
Prokaryotic cells have no nucleus or membrane-bound organelles. Eukaryotic cells have a nucleus and membrane-bound organelles.
True or False: Enzymes are consumed (used up) in the reactions they catalyze. Explain.
False. Enzymes are catalysts and are not consumed. They can be reused.
Explain the difference between a saturated and an unsaturated fatty acid in terms of their chemical structure.
Saturated fatty acids have no double bonds between carbon atoms (straight chain, solid at room temp); Unsaturated have at least one double bond (kinked chain, liquid at room temp).500What are the four levels of protein structure and what type of bonds/interactions are primarily responsible for maintaining the tertiary structure?
Define "specific heat" and explain how water's high specific heat helps moderate Earth's climate.
Specific heat is the amount of heat required to raise the temperature of 1 gram of a substance by 1°C. Water's high specific heat allows it to absorb and release large amounts of heat with little temperature change, stabilizing ocean temperatures and coastal climates.
Describe the process of endocytosis. What is the difference between phagocytosis and pinocytosis?
Endocytosis is the process of taking material into the cell by infolding the cell membrane. Phagocytosis = "cell eating" (taking in large particles/solids). Pinocytosis = "cell drinking" (taking in extracellular fluid/solutes).
Describe the "Endosymbiotic Theory". What evidence supports this theory?
It explains how eukaryotic cells evolved from prokaryotic cells. Evidence: Mitochondria and chloroplasts have their own circular DNA, double membranes, and their own ribosomes.
What happens to an enzyme when it is exposed to high temperatures or extreme pH? What is this process called?
The enzyme denatures (loses its shape). This changes the shape of the active site, so the substrate can no longer bind.
How the Protein structure change in different levels?
Primary: the linear sequence of amino acids in the polypeptide chain.
Secondary: folds due to hydrogen bonding within the polypeptide backbone.
Tertiary: 3D folding, formed by interactions between R groups (like hydrophobic interactions, ionic bonds, and disulfide bridges).
Quaternary:when multiple polypeptide chains associated.
All four stages determine the function of the protein
Use plants to explain water’s properties (adhesion, cohesion and capillary action )
Cohesion: water molecules stick to each other by hydrogen bonds, forming a continuous column.
Adhesion: water sticks to the walls of the xylem, helping it climb against gravity.
Capillary action: Occurs when adhesion is greater than cohesion, the water moves upward, important for transporting water and nutrients.
In what scenario would active transport be required instead of facilitated diffusion?
Sodium ions moving against their concentration gradient via a pump
A defect in the smooth ER would have the greatest impact on what process?
Breaking down cellular waste and worn-out organelles using hydrolytic enzymes.
A plant cell is placed in a hypotonic solution. Which transport process allows water to move, and what direction will it flow?
Osmosis; into the cell