AP Bio Unit 2 Vocab (Cell Structure & Function)

Cells

The basic structure & fictional units of every organism

Prokaryote

A cell that does NOT contain a membrane-bound nucleus or other membrane-bound organelles

Eukaryote

A cell that contains a membrane-bound nucleus and other membrane-bound organelles (ie - mitochondria)

Chromosomes

Genetic information made of DNA (They are segments of DNA)

Organelles

Membrane-bound structures in eukaryotes

Nucleolus

The dense region of the nucleus where ribosomal DNA is synthesized

Ribosomes

Essential cellular machines that produce proteins by translating mRNA sequences into amino acid chains

Rough ER

A network of sacs and tubules within the cytoplasm of eukaryotic cells, distinguished by its surface studded with ribosomes (the “rough” appearance)

Smooth ER

A network of sacs and tubules within the cytoplasm of eukaryotic cells. They do NOT have ribosomes

Cisternae

Flattened, membranous sacs that form the basic structural units of the ER and golgi

Autophagy

When lysosomes can recycle their own cell;s damaged material (proteins and organelles) and reuse them as building blocks or energy

Lysosomes

Membranous sacs with hydrolytic enzymes that hydrolyzes macromolecules in animal cells

Peroxisomes

Membrane-bound metabolic compartment

Golgi

Cellular organelle that modifies, sorts, and packages proteins and lipids from the ER and delivers them to other organelles

Nucleus

Center organelle in eukaryotic cells that contains the cell’s genetic material

Vacuoles

Large vesicles that stem from the ER and golgi

Mitochondria

The site of cellular respiration

Chloroplasts

Specialized organelles in photosynthesis

Stroma

The fluid around thylakoids

Microfilaments

Thin, solid rods made of the protein actin

Grana

Stacks of thylakoids

Thylakoids

Membranous sacs that can organize into stacks (grana)

Intermediate filaments

Fibrous proteins made up of varying subunits

Microtubules

Hollow, rod-like structures made of the protein tubulin

Actin

The most abundant protein in eukaryotic cells, forming tin filaments of the cell’s cytoskeleton

Cilia

A Hair-like structure found on surfaces of many cells (important for cell movement)

Flagella

An appendage on the s urface of some cells (Provide motility and navigation)

Plasma Membrane

The boundary separating the interior of the cell to the outside environment

Krebs Cycle

A series of chemical reactions in cells that catalyzes cellular respiration and produces ATP

Electron Transport Chain (ETC)

Uses energy from passed electrons to create a proton gradient in the inner mitochondrial membrane, which creates ATP

Calvin Cycle

A series of enzyme-catalyzed chemical reactions within the chloroplast that uses energy from the light-dependent reactions (ie - ATP from photosynthesis) to convert CO₂ from the atmosphere into usable sugars (glucose)

Light Reactions

The initial stage of photosynthesis, where light energy is captured by pigments like chlorophyll and is converted into chemical energy (ie - ATP)

Endosymbiotic Theory

Eukaryotic cells (plants and animals) evolved when a larger host cell engulfed smaller, free living prokaryotic cells (bacteria)

Photosynthesis

The process where plants use sunlight, water, and CO₂ to create sugars and release oxygen as a byproduct

Amphipathic

Molecules possess both hydrophobic and hydrophilic components

Fluid Mosaic Model

A model to describe the structure of cell membranes. The “fluid” refers to how the membrane is held together by weak hydrophobic interactions (tails) and can therefore move and shift. The “mosaic” refers to how cells are made up of many macromolecules

Integral Proteins

Proteins that are embedded into the lipid bilayer

Peripheral proteins

Proteins that are NOT or are slightly embedded into the bilayer. Instead, they are loosely bonded to the surface

Glycolipids

Carbohydrates bonded to lipids.

Glycoproteins

Carbohydrates bonded to proteins (most abundant)

Hydrophilic

Water-loving

Hydrophobic

Water-avoiding

Selective permeability

The trait of a membrane to allow some substances to pass through the molecule easier than others

Polar

Has an unequal sharing of electrons in covalent bonds (ie - H₂O)

Nonpolar

Equal sharing of electrons in covalent bonds (ie - O₂)

Charged

Has an unequal number of protons, resulting in a net electrical charge. These are called ions

Passive transport

The transport of a molecule that does not require energy from the cell because a solute is moving with its concentration/electrochemical gradient

Active Transport

The transport of a molecule that requires energy (ATP) because it moves a solute against its concentration gradient

Concentration Gradient

The difference in concentration of a substance in two different areas

Endocytosis

The uptake of molecules from vesicles fused from the plasma membrane

Diffusion

The spontaneous process resulting from the constant motion of molecules

Exocytosis

The secretion of molecules via vesicles that fuse to the plasma membrane

Pinocytosis

The nonspecific uptake of extracellular fluid containing dissolved molecules

Facilitated Diffusion

The diffusion of molecules through the membrane via transport proteins (passive transport)

Carrier proteins

Undergo conformational changes for substances to pass

Channel proteins

Provide a channel for molecules and ions to pass

Aquaporins

A specific channel protein for water

Osmosis

The diffusion of water down its concentration gradient (low solute concentration → high concentration gradient)

Tonicity

A solution’s ability to change the water level inside a cell, causing it to swell, shrink, or stay the same

Hypertonic

When the cell’s solute concentration is LOWER than the solute concentration outside the cell, causing water to EXIT the cell

Isotonic

When the cell’s solute concentration is EQUAL to the solute concentration outside the cell. Water enters and exits the cell regularly

Hypotonic

When the cell’s solute concentration is HIGHER than the solute concentration outside the cell, causing water to ENTER the cell

Osmoregulation

The process of maintenance of salt and water balance (Osmotic balance) across membranes within the body’s fluids

Plasmolysis

The process in a plant where water leaves he cell (hypertonic) and the cell membrane pulls away from the cell wall (due to shrinkage)

Turgidity

The state of a cell being swollen and rigid due to high turgor pressure