Molecules and Cells

Transport and signaling

What two cell functions do cell membranes participate in?

Unsaturated fat

one or more double bonds.

Saturated fat

no double bonds

increase fluidity

Unsaturated fats do this to the phospholipid bilayer

Down, Down

Temp ___, Membrane Fluidity ____

Change amount of hydrocarbon saturation

How do fish cell membranes respond to changes in temperature

Fasting, Hibernation

How do Mammals respond to temperature affecting cell membrane fluidity

Channel, Transporters, Enzymes, Receptors, Structural Proteins

The Five types of membrane proteins

Integral Proteins

Can’t be removed from the membrane without disruption

Peripheral Proteins

Can be removed from the membrane

Iron Channel

Protein subunits arrange to create a pore in the cell membrane that is hydrophilic all the way through and allows things to pass through

Cone Snails

Venom from these animals block iron channel transport and stop nerve function

Epithelia

Cells arranged in layers

polarized

Often times epithelial cells are ___

Apical

This side faces outwards (towards external or lumen)

Basal/Basolateral

This side Faces the blood stream

Columnal, Cuboidal, Squamous

Three types of epithelial cells

Columnal

Ex. Intestine, often have a brush border or microvilli. Tall shape

Cuboidal

Come in tubules or follicles (dead end tubules).

Squamous

Flat cells, often make up the borders of capillaries

Tight and septate

Two types of Obligate junctions, where portions of cells tough each other

Cell}{Cell

Gap Junctions

Direct channels between two cells, often used for cell communication especially in muscles

Seperate Apical and Basolateral proteins

Tight junctions do this

Transcellular

path where stuff is absorbed into the blood stream by going through a cell

paracellular

Stuff is absorbed through epithelia into bloodstream through intercellular space

Open and Close

Many protein channels can do this, ex. some do this by voltage

Proteins as Machines

ATP Synthase is like a motor for ATP generation

Metabolism

Process of acquiring, rearranging and voiding commodities to sustain life

catabolism

breakdown of large compounds

anabolism

synth of large compounds

Saturation Kinetics (Hyperbolic Kinetics)

calculation of vmax for enzyme concentration and reaction rate

Sigmoids

S shaped curve for enzyme concentration and reaction rate. Occurs when multiple substrates or bonding sites

Affinity

The more better suited an enzyme is to a substrate, the higher the reaction rate will be

Km

Affinity constant, defined as concentration of substrate needed to reach ½ of vmax

Up, Down

Affinity ____, Km ____

turnover rate

kcat

Affinity, Kcat (turnover rate), Substrate concentration

Three things that effect enzyme rate of reaction

Isozyme

Different forms of an enzyme within one organism

Homologs

Different forms of enzymes between species

anaerobic

LDH-A4 is often found in skeletal muscles because it is good in _____ environments, but would not be adapted for the heart. Heart uses LDH-B4

slow step

This step in an enzymatic pathway is prone to being regulated

Gene transcription

This can control enzymatic pathways, but is often slow (hours)

Allosteric Modulation

Inhibiting the enzyme by changing shape of protein

Constitutive

Enzyme that is always present

Inducible

Enzymes that are only present when certain genes are activated, often acclimitization/acclimation

End Product Regulation

End product inhibits prior step to create negative feedback loop

Covalent modulation

Phosphoryllation of enzymes to activate. Slower than allosteric, but can cause hugge chain reactions

Phylogenetic trees

Can build one of these based off of enzyme amino acid orders across species

Killifish

Speciation in progress: Along eastern Seaboard, LDH Ba allele better in warm temps (Florida) and LDH Bb allele better in cold temps (Maine). However still gene flow

Ligand gated channel, G-protein coupled, enzyme linked, intracellular receptores

4 types of Signal reception

Ligand channel, G protein, Enzyme linked

Which 3 are hydrophilic of the 4 signal receptions

G protein

Ligand binds to receptor on cell membrane, which then couples to G protein, and then those couple to enzymes to do a rxn

Enzyme linked

Ligand binds outside the membrane, which allows for enzymatic release of intracellular 2nd messenger