BIO-168 The Cell, Histology & The Integument

Extracellular

Outside of a cell.

Intercellular

Between cells.

Intracellular

Inside a cell.

Phospholipid

A molecule with a hydrophilic phosphate head and two hydrophobic fatty acid tails.

Hydrophilic

Attracted to water.

Hydrophobic

Repelled by water.

Phospholipid bilayer

A double layer of phospholipids forming the basic structure of the cell membrane.

Fluid Mosaic Model

Model describing the cell membrane as a flexible phospholipid bilayer containing proteins, cholesterol, and carbohydrates that move within it.

Cell membrane structure

Phospholipids form the structural framework of the membrane.

Cell membrane function

Membrane proteins provide most of the membrane's specific functions.

Integral/Intrinsic protein

Protein embedded in or extending through the phospholipid bilayer.

Peripheral/Extrinsic protein

Protein attached to the inner or outer surface of the membrane.

Channel protein

Membrane protein that allows specific substances to cross the membrane.

Ligand-gated channel

Channel that opens or closes when a specific chemical binds to it.

Voltage-gated channel

Channel that opens or closes in response to a change in membrane voltage.

Receptor

Membrane protein that binds a specific chemical and triggers a cellular response.

Marker

Membrane protein or carbohydrate that identifies a cell and helps distinguish self from non-self.

Cellular attachment protein

Protein that attaches cells to one another or to extracellular structures.

Membrane enzyme

Protein that catalyzes a chemical reaction at the cell membrane.

Nucleus

Membrane-bound organelle containing DNA and controlling many cellular activities.

Nuclear envelope

Double membrane surrounding the nucleus.

Nuclear pores

Openings in the nuclear envelope that regulate movement of substances between the nucleus and cytoplasm.

Chromatin

DNA combined with proteins in a less-condensed form.

Chromosome

Highly condensed form of chromatin, especially visible during cell division.

Nucleolus

Region of the nucleus where rRNA is synthesized and ribosomal subunits are assembled.

Cytoplasm

Everything inside the cell membrane except the nucleus.

Cytosol

Fluid portion of the cytoplasm.

Organelle

Specialized structure within a cell that performs a specific function.

Smooth ER

Membranous network without ribosomes that synthesizes lipids, detoxifies chemicals, and stores calcium.

Rough ER

Membranous network with ribosomes that synthesizes proteins for secretion, membranes, or certain organelles.

Golgi apparatus

Organelle that modifies, sorts, and packages proteins and lipids.

Lysosome

Organelle containing digestive enzymes that break down waste, damaged organelles, and foreign material.

Peroxisome

Organelle involved in fatty acid breakdown and detoxification; produces and breaks down hydrogen peroxide.

Mitochondria

Organelles that produce ATP through aerobic cellular respiration.

Krebs cycle location

Mitochondrial matrix.

Electron Transport Chain location

Inner mitochondrial membrane.

Centrioles

Paired structures that organize the cytoskeleton and help form spindle fibers during cell division.

Cilia

Short, hairlike structures capable of movement that move material across a cell surface.

Power stroke

Movement of a cilium that pushes material across the cell surface.

Recovery stroke

Return movement of a cilium to its original position with minimal movement of material.

Flagella

Long, whiplike structures that move cells.

Microvilli

Non-motile projections that increase a cell's surface area.

Microvilli examples

Small intestine and kidney tubules.

Diffusion

Movement of substances from an area of high concentration to an area of low concentration.

Concentration gradient

Difference in concentration between two areas.

Factors affecting diffusion rate

Magnitude of concentration gradient, concentration, temperature, molecular size, and viscosity.

Magnitude of concentration gradient

A greater concentration difference causes faster diffusion.

Temperature and diffusion

Higher temperature generally increases the rate of diffusion.

Molecular size and diffusion

Smaller molecules generally diffuse faster.

Viscosity and diffusion

Lower viscosity allows faster diffusion.

Osmosis

Diffusion of water across a selectively permeable membrane.

Semipermeable membrane

Membrane that allows some substances to cross while preventing others.

Isotonic

Solution with approximately the same solute concentration as the cell; no net water movement.

Hypertonic

Solution with a higher solute concentration than the cell; water leaves the cell.

Hypotonic

Solution with a lower solute concentration than the cell; water enters the cell.

Crenation

Shrinking of a cell because water leaves it.

Lysis

Rupture or bursting of a cell due to excessive water entering.

Mediated transport

Movement across a membrane using a membrane protein.

Specificity

Property in which a transport protein transports only certain substances.

Competition

Different substances compete for the same transport protein.

Saturation

Condition in which all available transport proteins are occupied and transport reaches its maximum rate.

Facilitated diffusion

Passive movement of substances from high to low concentration using a membrane protein.

Simple diffusion

Movement of substances directly through the lipid bilayer without a transport protein.

Active transport

Movement of substances against their concentration gradient using energy, usually ATP.

Sodium-potassium pump

Active transport protein that uses ATP to move 3 Na+ out of the cell and 2 K+ into the cell.

Secondary active transport

Transport that uses the energy stored in an ion concentration gradient rather than directly using ATP.

Glucose secondary active transport

Na+ moving down its concentration gradient provides energy to move glucose against its concentration gradient.

Symport/Co-transport

Transport of two substances in the same direction.

Antiport/Counter transport

Transport of two substances in opposite directions.

Endocytosis

Process in which the cell membrane surrounds material and brings it into the cell in a vesicle.

Exocytosis

Process in which a vesicle fuses with the cell membrane and releases material outside the cell.

Metabolism

All chemical reactions occurring in a cell or organism.

Anabolism

Building larger molecules from smaller molecules; requires energy.

Catabolism

Breaking larger molecules into smaller molecules; releases energy.

Glycolysis

Breakdown of glucose into two molecules of pyruvic acid; occurs in the cytosol.

Pyruvic acid

Three-carbon product of glycolysis.

Glycolysis ATP production

Produces 2 net ATP per glucose.

Aerobic respiration

Cellular respiration that uses oxygen and occurs primarily in the mitochondria.

Krebs cycle

Stage of aerobic respiration occurring in the mitochondrial matrix.

Krebs cycle ATP production

Produces 2 ATP per glucose.

Anaerobic respiration

Energy production when oxygen is not readily available; produces lactic acid and only 2 net ATP per glucose.

Lactic acid

Product formed from pyruvic acid when oxygen is insufficient.

Protein functions

Proteins function as enzymes, receptors, transport proteins, channels, structural proteins, antibodies, hormones, and attachment proteins.

DNA and protein synthesis

DNA contains the instructions used to make proteins.

Triplet

Three DNA nucleotides that correspond to a codon.

Gene

Segment of DNA containing information for producing a functional product.

Codon

Three-nucleotide sequence on mRNA that specifies an amino acid or stop signal.

Anticodon

Three-nucleotide sequence on tRNA that pairs with an mRNA codon.

Start codon

Codon that signals the beginning of translation; AUG.

Stop codon

Codon that signals the end of translation.

mRNA

RNA that carries genetic instructions from DNA to ribosomes.

tRNA

RNA that carries amino acids to the ribosome.

rRNA

RNA that makes up much of the ribosome and helps with protein synthesis.

Transcription

Process of making mRNA from a DNA template; occurs in the nucleus.

RNA base pairing

DNA A pairs with mRNA U; DNA T pairs with mRNA A; DNA C pairs with mRNA G; DNA G pairs with mRNA C.

Number of possible codons

64.

Number of amino acids

20.

Genetic code redundancy

Multiple codons can code for the same amino acid.

Translation

Process of using mRNA instructions to assemble a protein; occurs at ribosomes.

Pro-protein/Pro-enzyme

Inactive protein that must be modified or cleaved before becoming functional.