AP Biology Unit 2

What are the four main types of biomolecules that make up cells?

Nucleic acids, proteins, carbohydrates, and lipids.

Who is credited with the discovery of cells in 1665?

Robert Hooke.

What does cell theory state about living organisms?

Every living organism is made of one or more cells, the cell is the smallest unit of life, and all living cells arise from pre-existing cells.

What are the main components of prokaryotic cells?

Plasma membrane, cytosol/cytoplasm, genetic material (chromosomes), and ribosomes.

What types of organisms are classified as prokaryotic?

Archaea and Bacteria.

What is the function of the capsule in prokaryotic cells?

It helps prokaryotes stick to surfaces and provides extra protection.

What is the role of ribosomes in cells?

Ribosomes are the site of protein synthesis, assembling proteins from amino acids.

What distinguishes eukaryotic cells from prokaryotic cells?

Eukaryotic cells have internal membranes that compartmentalize functions and isolate specialized environments.

What are the two types of eukaryotic cells based on nutrition?

Autotrophic (plant-like) and heterotrophic (animal-like).

What is the function of the Golgi apparatus?

It modifies, sorts, and packages proteins for secretion or delivery to other organelles.

What is the purpose of the endomembrane system?

It coordinates the sending of proteins from ribosomes to their destinations.

What is the role of lysosomes in animal cells?

Lysosomes digest old cell parts and large food molecules, and destroy engulfed pathogens.

What is the function of large central vacuoles in plant cells?

They store water and exert turgor pressure to maintain cell rigidity.

What is the role of contractile vacuoles in unicellular eukaryotes?

They expel excess water to prevent the cell from bursting.

What are plasmids in prokaryotic cells?

Small circular chunks of DNA that contain genes easily shared with other bacteria.

What is the function of the nucleoid in prokaryotic cells?

It contains a large circular chunk of DNA that holds the bacteria's genes, not enclosed by a nucleus.

What are the main differences between plant and animal cells?

Plant cells have chloroplasts, a large central vacuole, and a cell wall, while animal cells have centrioles, lysosomes, and gap junctions.

What is the function of the smooth endoplasmic reticulum (ER)?

It synthesizes lipids, detoxifies poisons, and stores calcium ions.

What is exocytosis?

The process by which secretory vesicles fuse with the cell membrane to release their contents outside the cell.

What are peroxisomes and where are they commonly found?

Peroxisomes are organelles that break down fatty acids and are commonly found in the liver of animals and in seeds of plants.

What is the function of mitochondria?

Mitochondria are eukaryotic organelles that produce ATP through aerobic respiration.

What are the folds of the inner membrane of mitochondria called?

Cristae.

What is stored in the matrix of mitochondria?

Enzymes, proteins, ribosomes, and mitochondrial DNA.

How is mitochondrial DNA inherited?

It is inherited from the maternal lineage.

What is the primary function of chloroplasts?

Chloroplasts function in photosynthesis in plants and algae.

What pigment is contained in chloroplasts?

Chlorophyll, which captures sunlight for photosynthesis.

What are thylakoids?

Flat green structures in chloroplasts that store chlorophyll and collect sunlight.

What is the stroma in chloroplasts?

The fluid surrounding thylakoids where the second half of photosynthesis occurs.

What theory explains the presence of DNA in mitochondria and chloroplasts?

The Endosymbiotic Theory, which suggests a mutualistic relationship between early eukaryotes and prokaryotes.

What is the cytoskeleton?

A network of structural proteins extending throughout the cytoplasm, reinforcing and organizing cell structures.

What are cilia and flagella?

Extensions of the cytoskeleton that allow for cell motility.

What is the extracellular matrix (ECM)?

A network of connective proteins outside the cell membrane that provides external support.

What is the primary component of plant cell walls?

Cellulose.

What do animal cells use for cell adhesion?

The extracellular matrix (ECM) made of connective proteins like collagen.

Why is cell size important?

Cells must exchange substances with their environment efficiently to keep up with metabolism.

What happens to the surface area to volume ratio as cells increase in size?

The ratio decreases, making it harder for cells to exchange materials efficiently.

What is the structure of the cell membrane?

Made of two layers of phospholipids with hydrophilic heads facing outward and hydrophobic tails inward.

What does the Fluid Mosaic Model describe?

The organization of cell membranes where phospholipids and proteins move freely within the bilayer.

What is the role of membrane proteins?

They facilitate communication and transport across the cell membrane.

What are integral proteins?

Proteins that permanently attach to the cell membrane, including transmembrane proteins that span the membrane.

What does selectively permeable mean in relation to cell membranes?

Only certain molecules can pass through the membrane, while others cannot.

What are transmembrane proteins?

Transmembrane proteins are embedded through the plasma membrane and are used for transport or cellular communication.

How are transmembrane proteins oriented?

Transmembrane proteins are oriented the same as phospholipids, with hydrophilic ends on the inside and outside of the cell and hydrophobic regions in the membrane.

What role does cholesterol play in cell membranes?

Cholesterol maintains membrane fluidity; it makes membranes more rigid at high temperatures and prevents crystallization at low temperatures.

What are glycoproteins and glycolipids?

Glycoproteins and glycolipids are carbohydrate chains attached to proteins and lipids, respectively, used for cell recognition and communication.

What is passive transport?

Passive transport is the movement of substances down their concentration gradient from high to low concentrations without using metabolic energy (ATP).

What are the two types of passive transport?

The two types of passive transport are simple diffusion and facilitated diffusion.

What is osmosis?

Osmosis is the diffusion of water across a membrane, either through phospholipids or via channel proteins called aquaporins.

What factors affect the rate of diffusion?

The rate of diffusion depends on the size of molecules, temperature, steepness of the concentration gradient, charge of molecules, and pressure.

What is selective permeability?

Selective permeability is the ability of a cell membrane to control which substances enter or leave the cell, maintaining differences between internal and external environments.

What is active transport?

Active transport moves molecules from low to high concentrations, requiring energy from ATP.

What are protein pumps?

Protein pumps are membrane proteins that change shape when phosphorylated, allowing them to transport molecules against their concentration gradient.

What is endocytosis?

Endocytosis is the process by which cells ingest large particles or amounts of material.

What happens during hypotonic conditions for animal cells?

In hypotonic conditions, water moves into the cell, potentially causing it to swell and burst.

What happens during hypertonic conditions for animal cells?

In hypertonic conditions, water moves out of the cell, causing it to shrivel and potentially die.

What is turgor pressure in plant cells?

Turgor pressure is the outward pressure exerted by the central vacuole on the cell wall, helping maintain the plant's structure.

What is water potential?

Water potential is the potential energy of water, which moves from areas of higher to lower water potential.

What is the role of aquaporins?

Aquaporins are channel proteins that facilitate the rapid transport of water across cell membranes.

What is the significance of dynamic equilibrium in osmosis?

Dynamic equilibrium in osmosis is reached when water moves to balance solute concentrations on both sides of a membrane.

What are the effects of isotonic solutions on animal cells?

In isotonic solutions, water moves into and out of the cell at equal rates, keeping the cell happy and stable.

What is phagocytosis?

Phagocytosis is the process of a cell ingesting large particles or other cells.

What is pinocytosis?

Pinocytosis is the process of a cell ingesting liquid.

How do plant cells respond to hypotonic solutions?

Plant cells become turgid in hypotonic solutions, maintaining their shape due to turgor pressure.

What occurs when plant cells are in hypertonic solutions?

In hypertonic solutions, plant cells become plasmolyzed, leading to dehydration and potential cell death.