BIO 241 Terms Sheet 2

Endomembrane System

A group of membranes and organelles in eukaryotic cells that work together to make, transport, and break down proteins and lipid.

Plasma Membrane

Selectively permeable membrane surrounding a cell that regulates what enters and leaves the cell

Cytosol

Fluid portion of the cytoplasm, not organelles; where many metabolic reactions occur.

Chromosome

Structure made of DNA and proteins that contains genetic information

• Located in the nucleus or nucleoid

Nucleus

Membrane-bound organelle in eukaryotic cells that contains the cell’s DNA and is the main location of gene regulation

Nucleoid

Region of prokaryotic cell where chromosome/DNA is concentrated; NOT surrounded by a membrane

Ribosome

Molecular machine of rRNA and proteins that builds proteins by translating mRNA

• In both Prokaryotic and Eukaryotic

Endoplasmic Reticulum

a continuous membrane-enclosed network of flattened sacs and branching tubules found within the cytoplasm of all eukaryotic cells

1. Rough ER: has ribosomes; makes proteins

2. Smooth ER: NO ribosomes; makes lipids

Golgi apparatus

Membrane bound organelle that modifies, sorts, and packages proteins and lipids into vesicles for transport to other locations

Selective Permeability

Property of membrane that allows some substances to cross more easily than others; depends on size, charge, polarity

Amphipathic

Has both Hydrophilic and Hydrophobic region.

Ex: Phospholipids

Fluid Mosaic Model

Model of Plasma membrance is a fluid phospholipid bilaryer with proteins, cholesterol, and carbs embedded in it

Passive Transport

Movement of substances across membrane down the concentration gradient; NO energy input needed from cell

Active Transport

Movement of substances across membrane against the concentration gradient; REQUIRES energy such as ATP

Ex: Protein pump uses ATP

Co-transport

Movement of 2 substances across membrane through the same transport protein; the movement of 1 substance drives the movement of another (“Secondary Active Transport”)

Bulk Transport

Movement of large particles or amounds of fluid in and out of a cell using vesicles

• Endocytosis - into cell

• Exoctytosis - out of cell

Tonicity

Ability of solution to cause a cell to gain or lose water; depends on the concentrations of solutes that cannot penetrate the membrane.

• Hypertonic - water leaves cell

• Hypotonic - water eneterc cell

• Isotonic - no water movement

NOTE: water moves towards higher concentration of solute (to keep things equal); AKA osmosis

Concentration Gradient

Difference in concentration of a substance between 2 regions; susbstances tend to move down concentration gradient (high to low)