Bio 225 Exam 1 - Metabolism and Cell Signaling - Lloyd

Metabolism and Cell Signaling

Gluconeogenesis input, output, and location

starts with amino acid, pyruvate, or small lipids

output is glucose or glycogen

occurs in mitochondria and cytoplasm

(aerobic) Glycolysis input, output, and location

starts with glucose (or glycogen)(other hexoses are converted to glucose)

end product is 2 pyruvate; 2 ATP; and 2 NADH; H20

occurs in cytoplasm

anaerobic glycolysis outcomes are

3 possible outcomes: ethanol, propionate, or lactate

species and condition dependent

pyruvate oxidation anaerobic and aerobic product

lactic acid; acetyl CoA

Lipids are

composed of glycerol and up to 3 fatty acids

fatty acids are

long chains of hydrocarbons

highly non-polar

Hydrocarbon chains saturated v. monounsaturated v. polyunsaturated

no double bonds

one double bond

more than one double bond

Steroid molecules and the blood…

steroid molecules require something to carry them so that they do not form lipid “rafts”

Fatty acid oxidation

fatty acids are broke down to produce acetyl-CoA; each pair of carbons in FA chain are used to produce 1 acetyl-CoA

Acetyl-CoA can also be

used to make ketone bodies

Acetyl-CoA can be produced from diverse metabolites

amino acids, glucose (dietary starch, dietary sucrose), glycogen, lactate (lactic acid), pyruvate, fatty acids, ketone bodies

Citric Acid Cycle other names

Kreb’s cycle

tricarboxylic acid cycle

Citric acid cycle input, output, and location

Acetyl CoA

3NADH, FADH2, GTP, 2CO2

mitochondria

Oxidative phosphorylation / Electron Transport Chain

Complex I collects electrons from NADH produced by various mitochondrial dehydrogenases

Complex II, or succinate dehydrogenase, transfers electrons from succinate to FAD

Both complex I and II, as well as other FAD-linked dehydrogenases not shown, transfer electrons to ubiquinone (Q)

Electron transfer continues through complex III, cytochrome c, and finally complex IV, cytochrome oxidase

During electron transport, complexes I, III, and IV also pump protons out of the mitochondrial matrix, creating the proton motive force

The mitochondrial F1F0 ATPase (complex V) uses proton motive force to fuel ATP synthesis

Oxidative phosphorylation occurs where

within the inner mitochondrial membrane of eukaryotic cells

Why don’t cells always do TCA cycle and oxidative phosphorylation if it produces so much more ATP than glycolysis alone?

oxidative phosphorylation is obligated to be aerobic

Types of cell signaling

direct cell signaling, autocrine and paracrine signaling, endocrine signaling, neural signaling

a ligand is

a chemical message sent from one cell to another

a receptor is

a target for a ligand and binding elicits (causes signal transduction) or prevents a response (stops/prevents signal transduction)

agonist

mimics the natural ligand

antagonist

binds to prevent ligand binding

natural ligand is

endogenously (internally) produced

signal transduction ia

a cascade of molecular events triggered by ligand/receptor binding

receptors have two different domain types

binding domains and functional domains

functional domains do what

determine the effect of the ligand/receptor binding

What determines the effect of ligand-receptor binding

the receptor type

receptors can be

external (transmembrane) or internal

Gap junctions

provide direct connections b/w cells that are in contact; traffic is generally controlled by diffusion and ligands are usually hydrophilic (not always); fast, and efficient

What molecules are transported via gap junctions

generally small molecules such as ions and cell messengers (ex: cAMP)

Desmosomes

non-communicating; generally for connection only; found in tissues which are exposed to high levels of stress

ex: cardiac tissue; skin

True gap junctions (function, types of transported molecules, example)

allow exchange of substances from one cell to another (small molecules, ions, metabolites); mostly functionally bilaterally; might be a chemical or an electrical synapse

ex: gap junctions in cardiac cells

autocrine/paracrine/endocrine signaling all involve and are differentiated by

the release of chemical messenger into the extracelullar matrix

target of the chemical messenger determines the type

autocrine signaling

the target receptor is on the releasing cell

ex: IGF, IL-1

paracrine signaling

the target is cells very near the releasing cell

ex: Wnt family of signals (carcinogenesis, embryonic development, etc)

Endocrine

the target is cells (relatively) distant to the releasing cell

ex: estrogens, thyroid hormones, cortisol, insulin

neural signaling (electrochemical) involves (what cells)

always involves connection b/w neural cells and other neural cells or tissues/sensors

neural signaling (electrochemical) how it works basic

involves the change in membrane potential due to changes in ion locations inside or outside neural cells

endocrine v. neural signaling

neural is faster than endocrine but it is targeted

endocrine is slower, longer lasting, and sent everywhere