Light Microscopy, Cell Structures, and Membrane Transport: A Biology Review

What is light microscopy?

A technique that uses visible light and a system of lenses to magnify images of small samples.

What are the main parts of a light microscope?

The main parts include the eyepiece, objective lenses, stage, light source, and focus knobs.

How can contrast be increased in microscopy?

Contrast can be increased using stains, adjusting light intensity, or using phase contrast techniques.

What is the difference between SEM and TEM?

Scanning Electron Microscopy (SEM) provides 3D images of surfaces, while Transmission Electron Microscopy (TEM) provides 2D images of thin sections.

What are the major differences between prokaryotic and eukaryotic cells?

Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have a nucleus and organelles.

What are the major functions of the endomembrane system?

The endomembrane system is involved in the synthesis, modification, transport, and degradation of proteins and lipids.

What structures are part of the endomembrane system?

The structures include the endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, and the plasma membrane.

What is the function of the smooth and rough ER?

The rough ER synthesizes proteins, while the smooth ER synthesizes lipids and detoxifies certain chemicals.

What are lysosomes and their function?

Lysosomes are organelles that contain digestive enzymes to break down waste materials and cellular debris.

What are phagocytosis and autophagy?

Phagocytosis is the process of engulfing large particles, while autophagy is the degradation of damaged organelles.

What is the structure and function of mitochondria?

Mitochondria have a double membrane and are responsible for ATP production through cellular respiration.

What is the structure and function of chloroplasts?

Chloroplasts contain chlorophyll and are involved in photosynthesis, converting light energy into chemical energy.

What are peroxisomes and their function?

Peroxisomes are organelles that contain enzymes for oxidation reactions and detoxifying harmful substances.

What are the generalized functions of the cytoskeleton?

The cytoskeleton provides structural support, aids in cell movement, and facilitates intracellular transport.

What are the three main types of cytoskeletal elements?

The three types are microfilaments (actin), intermediate filaments (various proteins), and microtubules (tubulin).

What are the major extracellular structures and their functions?

Major extracellular structures include the extracellular matrix (support and adhesion) and cell walls (protection and structure).

What are the different types of intracellular junctions in plants and animals?

Types include tight junctions (prevent leakage), desmosomes (adhesion), and gap junctions (communication).

Why is the plasma membrane considered selectively permeable?

It allows certain substances to pass while restricting others, maintaining homeostasis.

What are the major components of the plasma membrane?

The plasma membrane consists of a phospholipid bilayer, proteins, cholesterol, and carbohydrates.

What is the structure of phospholipids?

Phospholipids have a hydrophilic head and two hydrophobic tails, making them amphipathic.

What does the fluid mosaic model of membrane structure mean?

It describes the membrane as a flexible layer of lipid molecules with embedded proteins that can move laterally.

How do temperature and hydrocarbon tail type affect membrane fluidity?

Higher temperatures increase fluidity, while saturated tails decrease fluidity compared to unsaturated tails.

What is the function of cholesterol in the plasma membrane?

Cholesterol stabilizes membrane fluidity, preventing it from becoming too rigid or too fluid.

What is an integral membrane protein?

Integral membrane proteins span the membrane and are involved in transport and communication.

What is a peripheral protein?

Peripheral proteins are attached to the membrane surface and play roles in signaling and maintaining the cell's shape.

What are the major functions of membrane proteins?

Functions include transport, enzyme activity, signal transduction, cell-cell recognition, and attachment to the cytoskeleton.

How do membrane carbohydrates contribute to cell-cell recognition?

Membrane carbohydrates act as identification tags that are recognized by other cells.

Why do polar/charged/hydrophilic substances not cross the membrane effectively?

They cannot easily pass through the hydrophobic lipid bilayer.

What is diffusion?

Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration.

What is passive transport?

Passive transport is the movement of substances across a membrane without the use of energy, down their concentration gradient.

What is osmosis?

Osmosis is the diffusion of water across a selectively permeable membrane.

What are hypertonic, hypotonic, and isotonic solutions?

Hypertonic solutions have higher solute concentration, hypotonic have lower, and isotonic have equal concentrations.

What do turgid, flaccid, and plasmolyzed mean?

Turgid refers to a swollen state in plants, flaccid is a limp state, and plasmolyzed is when the cell membrane pulls away from the cell wall.

How do animal cells control water balance?

Animal cells use osmoregulation to maintain water balance, often through ion channels and aquaporins.

How do plants control water balance?

Plants control water balance through turgor pressure and the regulation of stomata.

What is facilitated diffusion?

Facilitated diffusion is the process of transporting substances across a membrane via channel or carrier proteins without energy.

What are examples of channel proteins?

Examples include aquaporins for water transport and ion channels for specific ions.

How do carrier proteins work?

Carrier proteins bind to specific molecules and change shape to transport them across the membrane.

What is active transport?

Active transport is the movement of substances against their concentration gradient, requiring energy.

What are the differences between facilitated diffusion and active transport?

Facilitated diffusion does not require energy and moves substances down their gradient, while active transport requires energy and moves substances against their gradient.

What are ion pumps?

Ion pumps are membrane proteins that transport ions across the membrane, often against their concentration gradient.

How does the sodium/potassium pump work?

It transports sodium out of the cell and potassium into the cell, using ATP for active transport.

What is membrane potential?

Membrane potential is the voltage difference across a cell's plasma membrane due to the distribution of ions.

What is coupled transport?

Coupled transport is the process where the movement of one substance drives the movement of another across a membrane.

What is secondary active transport?

Secondary active transport uses the energy from the electrochemical gradient created by primary active transport.

What are endocytosis and exocytosis?

Endocytosis is the process of taking in substances by vesicle formation, while exocytosis is the process of expelling substances from the cell.

What are the types of endocytosis?

Types include phagocytosis (cell eating), pinocytosis (cell drinking), and receptor-mediated endocytosis (specific uptake).

What is the first law of thermodynamics?

Energy can be transferred and transformed, but it cannot be created or destroyed.

What is metabolism?

Metabolism is the sum of all chemical reactions in an organism, including catabolic and anabolic reactions.

What are the different forms of energy?

Forms include kinetic energy, potential energy, thermal energy, and chemical energy.

What is the second law of thermodynamics?

The second law states that energy transformations increase the entropy of the universe.

What is free energy (G)?

Free energy is the energy available to do work in a system.

What does the formula ∆G = Gproducts - Greactants represent?

It represents the change in free energy during a chemical reaction.

What are exergonic and endergonic reactions?

Exergonic reactions have a negative ∆G and release energy, while endergonic reactions have a positive ∆G and require energy.

What are enzymes?

Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy.

What is an activation barrier?

An activation barrier is the energy threshold that must be overcome for a reaction to proceed.

How do enzymes lower activation energy?

Enzymes provide an alternative reaction pathway with a lower activation energy.

What is an active site?

An active site is the region on an enzyme where substrates bind and undergo a chemical reaction.

What are the basic steps of enzyme catalysis?

The steps include substrate binding, formation of the enzyme-substrate complex, conversion to products, and release of products.

What factors affect enzyme activity?

Factors include temperature, pH, and the presence of cofactors or coenzymes.

What is competitive inhibition?

Competitive inhibition occurs when an inhibitor competes with the substrate for the active site of an enzyme.

What is noncompetitive inhibition?

Noncompetitive inhibition occurs when an inhibitor binds to an enzyme at a site other than the active site, altering its function.

How are enzymes regulated?

Enzymes are regulated through mechanisms such as allosteric regulation, covalent modification, and feedback inhibition.

What is ATP?

ATP (adenosine triphosphate) is the primary energy carrier in cells, and its hydrolysis is coupled to endergonic reactions.