Campbell Unit 2: The Cell Cycle

Light Microscope (LM)

Visible light passes through a specimen and glass lenses, which refract the light in a way that magnifies the image of the specimen.

Magnification

Image Size:Real Size ratio.

Resolution

Measure of clarity of the image, inversely related to wavelength of light a microscope uses for imaging.

Organelles

Membrane enclosed compartments within cells.

Electron Microscope (EM)

Beam of electrons is shone through specimen or onto its surface.

Scanning Electron Microscope (SEM)

Electron beam scans surface of the sample which excites the surface electrons. This is detected and translated into a 3D video.

Transmission Electron Microscope (TEM)

Electron beam aimed through very thin section of the specimen which has been stained with atoms of heavy metals, which attach to certain cellular structures and thus enhance electron density in some parts more than others. Pattern of density is translated into an image.

Cell Fractionation

Take cells apart, separate major organelles and other subcellular structures from each other using a centrifuge (differential centrifugation).

Differential Centrifugation

Spins test tubes holding mixtures of disrupted cells at a series of increasing speeds.

Cytology

Study of cell structure.

Biochemistry

Study of chemical processes of cells.

Prokaryotic Cells

Bacteria and archaea. DNA is in the nucleoid, which is not enclosed by a membrane.

Eukaryotic Cells

Fungi, animals, and plants. Most DNA is in the nucleus, bounded by a double membrane.

Plasma Membrane

Selective barrier that allows passage of oxygen, nutrients, and wastes. A double layer of phospholipids and other lipids.

Nucleus

Contains most genes in the eukaryotic cell.

Nuclear Envelope

Encloses the nucleus and separates its components from the cytoplasm.

Pore complex

Intricate protein structure that lines each pore of the nuclear envelope and regulates entry and exit of proteins, RNAs, and large complexes of macromolecules.

Chromosomes

Discrete units that DNA is organized into, carry the genetic info.

Chromatin

Complex of DNA and proteins making up chromosomes.

Nucleolus

Mass of densely stained granules and fibers adjoining part of the chromatin to synthesize RNA.

Ribosomes

Complexes made of ribosomal RNAs and proteins, carry out protein synthesis.

Endomembrane System

Synthesizes proteins, transports proteins and organelles into membranes or out of the cell, metabolism, movement of lipids, and detoxification of poisons.

Vesicles

Sacs made of membrane, transfer membrane sacs.

Endoplasmic Reticulum (ER)

Extensive network of membranes, accounts for 50%+ of the cell’s total membrane.

Golgi Apparatus

Modifies and stores products, then sends them to other destinations.

Lysosome

Membranous sac of hydrolytic enzymes that are used to digest (hydrolyze) macromolecules.

Vacuoles

Large vesicles derived from ER and golgi apparatus.

Mitochondria

Sites of cellular respiration.

Chloroplasts

Sites of photosynthesis in algae and plants.

Cytoskeleton

Network of fibers extending throughout the cytoplasm.

Microtubules

Thickest cytoskeleton fiber, hollow rods, made from tubulin proteins.

Microfilaments/Actin

Thin solid rods build from two intertwined strands of the globular protein actin.

Intermediate Filaments

Intermediate diameter, specialized for bearing tension, diverse class of cytoskeletal elements.

Centrosome

Region located near nucleus, where microtubules grow out of.

Flagella

Cellular extensions that contain microtubules.

Cilia

Cellular extensions that contain microtubules.

Basal Body

Anchors cilia or flagellum microtubule assembly.

Cortex

Outer cytoplasmic layer of a cell with a gel semisolid consistency.

Myosin

Protein that makes up actin filaments and thicker filaments to cause contraction of muscle cells.

Plasmodesmata

Channels that connect cells, perforate plant cell walls.

Tight Junctions

Plasma membranes of neighboring cells are pressed very tightly against each other.

Desmosomes

Fasten cells together into strong sheets.

Gap Junctions

Provide cytoplasmic channels from one cell to an adjacent cell.

Cell Wall

Extracellular structure of plant cells, thicker than plasma membrane.

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Glycoproteins

Membrane carbohydrates covalently bonded to proteins

Selective Permeability

Allows some substances to cross more easily than others

Transport Proteins

Help hydrophilic substances pass through the membrane

Aquaporins

Facilitates passage of water molecules through the membrane

Diffusion

Movement of particles from high to low concentration

Concentration Gradient

Region along which the density of a substance increases or decreases

Passive Transport

Transport that requires no energy

Osmosis

Diffusion of free water across a selectively permeable membrane

Tonicity

Ability of a surrounding solution to cause a cell to gain or lose water

Hypotonic

Solution has less solutes than in another

Isotonic

Equal number of solutes in both solutions

Hypertonic

Solution has more solutes than another

Osmoregulation

Control of solute concentrations and water balance in organisms without rigid cell walls

Facilitated Diffusion

Polar molecules and ions diffuse passively with the help of transport proteins

Ion Channels

Channel proteins that transport ions

Gated channels

Open or close in response to a stimulus

Active Transport

Using ATP to transport a solute across a membrane

Membrane Potential

Voltage across a membrane

Electrochemical Gradient

Combination of chemical force and an electrical force acting on an ion

Electrogenic Pump

Transport protein that generates voltage across a membrane

Proton Pump

Actively transports protons out of the cell

Cotransport

Using proton gradient to power something else

Exocytosis

Secreting certain molecules by fusion of vesicles with the plasma membrane

Endocytosis

Cell takes in molecules by forming new vesicles by pinching off part of the membrane

Phagocytosis

Cell engulfs a particle by extending pseudopodia around it and packaging it in a food vacuole

Pinocytosis

Cell continually "gulps" droplets of extracellular fluid into tiny vesicles

Receptor-Mediated Endocytosis

Specialized type of pinocytosis, enables cell to acquire large quantities of specific substances

Metabolism

Totality of an organism's chemical reactions

Metabolic Pathway

Specific molecule is altered in a series of defined steps, each catalyzed by a specific enzyme, resulting in a certain product

Catabolic Pathways

Breakdown pathways, release energy

Anabolic Pathways

Consume energy to build complex molecules from simpler ones

Kinetic Energy

Energy associated with relative motion of objects

Thermal Energy

Kinetic energy associated with random movement of atoms or molecules

Heat

Thermal energy in transfer from one object to another

Potential Energy

Energy that matter possesses because of its location or structure

Chemical Energy

Potential energy available for release in a chemical reaction

Spontaneous Process

Process that can happen without input of energy, leads to an increase in entropy by itself

Thermodynamics

Study of energy transformations that occur in a collection of matter

First Law of Thermodynamics/Principle of Conservation of Energy

The energy of the universe is constant—Energy can be transferred and transformed but not created or destroyed

Second Law of Thermodynamics

Every energy transfer or transformation increases the entropy of the universe

Entropy

Measure of molecular disorder/randomness

Free Energy

Portion of energy that can perform work when temperature and pressure are uniform

Exergonic Reaction

Net release of free energy, negative ΔG

Endergonic Reaction

Absorbs free energy from its surroundings, positive ΔG

ATP (Adenosine Triphosphate)

Sugar ribose + nitrogenous base adenine + chain of 3 phosphate groups (like a compressed spring)

Phosphorylated Intermediate

Recipient molecule of phosphate group from ATP, which is made less stable

Enzyme

Macromolecule that acts as a catalyst

Catalyst

Chemical agent that speeds up a reaction without being consumed by it

Activation Energy

Energy required to contort reactant molecules so bonds can break—amount of energy needed to push the reactants to the top of a barrier so the downhill part can begin

Substrate

Reactant an enzyme acts on

Active Site

Restricted region of the enzyme that actually binds to the substrate

Induced Fit

Tightening of binding after initial contact

Cofactors

Nonprotein helpers for catalytic activity,

Chemiosmosis

Process where energy stored in the hydrogen ion gradient across a membrane is used to drive cellular work (such as ATP synthesis)

Proton Motive Force

H+ gradient