Chapter 3: The Cellular Level of Organization

cell membrane

phospholipid bilayer

When a cell regulates what comes in and what comes out

Selective Permeability

Integral Membrane Proteins

Span the membrane, form channels & bind

Peripheral Membrane Proteins

Cell signaling mediators, aid in transport & support

Diffusion

High concentration to low concentration, passive transport

Facilitated Diffusion

passive diffusion that moves polar + large nonpolar molecules

Osmosis

water moves through semipermeable membrane from low concentration area to high concentration area

Tonic

Stress of osmolality

Isotonic

net zero movement of water

Hypertonic

water is leaving the cell in an attempt to fix equilibrium

Hypotonic

water goes into the cell, causes swelling and bursting

Sodium-Potassium Exchange Pump

Electrochemical gradient; K+ high inside cell and Na+ high outside cell

Active Transport

ATP used/required

Endocytosis

Substances actively moving into cell

Phagocytosis

large particle consumed, uses a lot of energy

Pinocytosis

Cellular processes where a cell swallows extracellular fluids + dissolved small molecules

Receptor-Mediated Endocytosis

cells absorb specific extracellular molecules using receptor proteins on their plasma membrane

Exocytosis

Cells make and release things instead of bringing them in

Organelle

“Little Organ”

Endoplasmic Reticulum

smooth and rough, roles are tissue and cell type specific

Golgi apparatus

Packages, modifies, and manufactures proteins

Lysosome

Vesicle important to protein transfer that contains a protein pump and functions at LOW pH

Mitochondria

Creates energy, contains a matrix which performs inmportant biochemical functions

Peroxisome

Prevents or limits oxidative stress

Cytoskeleton

Structural protein fibers that support morphology of cell

Microtubules

Largest fibers of cytoskeleton that resist compresssive forces

Microfilaments

Monomer actin that resists tension and is a structural component

Intermediate filaments

Keratin and junction between cells

Nucleus

Houses genetic info in DNA, ribosomes made in nucleolus

DNA macromolecule

DNA wrapped around histome

Chromosome

Densely packed DNA in prep for cell division

Chromatin

Loosely packed DNA to be transcribed

Complementary Pairs

Thymine binds Adenine, Guanine binds cytosine

Transcription

Cellular process where an enzyme copies a DNA sequence into an RNA molecule

Translation

Ribosomes send mRNA to build proteins out of amino acids (peptide bonds)