AP Biology Unit 2

Cytoplasm

inside substance of cells, in both prokaryotes and eukaryotes

plasma membrane

Outer envelope of the cell; consists of a phospholipid bilayer; is semipermiable, allowing only certain substances

Proteins associated with the cell membrane

Peripheral proteins are loosely associated, surface of membrane; intergral proteins are firmly bound to the plasma membrane; transmembrane proteins go all the way through the membrane

Fluid-mosaic model

Says each layer of phospholipids are flexible, a “mosaic” of proteins and carbohydrates

Adhesion proteins

In phospholipid bilayer, forms junctions between adjacent cells

Receptor proteins

docking sites for arrivals at the cell in the plasma membrane

Transport proteins

Form pumps that use ATP to transport solutes across the plasma membrane

Cell surface markers

exposed on the extracellular surfce and play a role in cell recognition

Carbohydrate side chains

Found on outer surface of plasma membrane, attached to the surface of some peripheral proteins

Nucleus

Usually the largest organelle, home to DNA and chromosomes and nucleolus, where rRNA and ribosomes are assembled

Ribosomes

Sites of protein synthesis; made of rRNA and proteins

Endoplasmic Reticulum

Attached to the nucleus, provides mechanical support and helps with intracellular transport

Rough ER

Studded with ribosomes, generates proteins

Smooth ER

No ribosomes, makes lipids, hormones, steroids, and breaks down toxic chemicals

Golgi Apparatus

Stacks of flattened sacs, like the “factory”, modifies, processes, and sorts out the products; packages final products into vescicles

Vescicles

Little “sacs” that transport substances within the cell

Mitochondria

The powerhouse of the cell!! Makes ATP, useful energy for the cell; has many folds to maximize surface area:volume ratio

Cristae

Folds within the mitochondria and separates the inner matrix from the intermembrane space

Lysosomes

The cell’s “clean up crew”; carries digestive enzymes; essential during programmed cell death (apoptosis)

Centrioles

small, paired cylindrical structures found within microtubule organizing centers; most active during cellular division, where it produces microtubules that pull the chromosomes apart

Vacuole

fluid filled sacs that store water, food, wastes, etc. biggest organelle in plant cells

Peroxisomes

detoxify various substances, producing peroxide (H2O2) as a byproduct

Cytoskeleton

holds the cell together and enables it to hold its shape; creates a path for vacuoles to “walk on” via motor proteins

MIcrotubules

Integrao parts of centrioles, cilia, and flagella; helps chromosomes separate

Cilia

used for locomotive properties; more of like rowing; often many

Flagellum

used for locomotive properties in single-celled organisms ex. sperm; back and forth back and forth; often just a few

Plant cells

different from animals because they have cell walls and chloroplasts

Central vacuole

only plants have it, contains the cell sap

Facilitated transport

If substance is hydrophillic, must use channel proteins in facilitated transport

Aquaporins

water-specific channels

Passive transport

down the concentration gradient; like riding a bicycle downhill

Osmosis

water is diffusing, most concentrated to least concentrated; if substance cannot move across a barrier, water diffuses across to get equillibrium; used in plant cells because plant cell walls cannot expand nor shrink

Isotonic

Solution has the same concentration inside and outside

Hypertonic

Solution has MORE dissolved solutes than the cell

Hypotonic solution

Solution has LESS dissolved solutes than the cell

Water potential

Measures potential water in water; eagerness to flow from high water potential to an area with low water potential

Active transport

Movement against the concentration gradient; riding a bicycle uphill, gets its energy from ATP

Endocytosis

When the cell engulfs a substance with the cell membrane, forming a vacuole or vesicle

Pinocytosis

Endocytosis for water (pee-no)

Phagocytosis

Endocytosis for food

Receptor-mediated endocytosis

endocytosis involving cell surface receptors , works with endocytic pits lined with a protein called clathrin, causing the folding of the cell membrane

Bulk flow

one-way movement of fluids via pressure; ex. blood through blood vessel

Dialysis

Diffusion of solutes across a selectively permeable membrane

Exocytosis

Cell ejects waste or secretion products; reverse endocytosis