Exam 2 Flashcards
what are carbohydrates? types?
monosaccharides- used for energy and biosynthesis (glucose and fructose)
disaccharides- two monosaccharides connected by a covalent bond, bonds broken during metabolism (sucrose)
polysaccharides- complex carbohydrates, energy storage(glycogen and starch) and structural molecules (chitin, cellulose)
what are lipids? types?
used for energy metabolism, long-term energy storage, cell structure, and signaling
hydrophobic
fatty acids, triglycerides, phospholipids, steroids (testosterone, cortisone, vitamin D, cholesterol)
cell membrane structure
isolate cells from the environment- control intracellular conditions
organize intracellular pathways into sub-cellular compartments
contains membrane proteins
-integral membrane proteins: tightly bound to the membrane, embedded in bilayer or spanning the entire membrane
-peripheral membrane proteins: weaker association with the lipid bilayer
-glycoproteins and their sugar residues
cell membrane permeability
cell membrane receptors
cell membrane transport and channels
passive diffusion: lipid soluble molecules, no specific transporters needed, molecules cross bilayer, no energy needed, depends on concentration gradient
facilitated diffusion: hydrophilic molecules that cannot diffuse through bilayer, protein transporter–ion channel, porin (like ion channel, for larger molecules), permease (function more like enzyme, carrie molecules across membrane– is needed, no energy is needed, depends on concentration gradient
active transport: protein transporter needed, energy is required, molecules can move against concentration gradient
chemical concentration gradients
electrical gradients
electrochemical gradient relationship
membrane potential
the relative charge of the inside of the cell compared to the outside of the cell, standardly negative
varying permeability
mostly dependent on Na+, K+, Cl- gradients
pumps
Na+/K+ ATPase pump maintains Na+ and K+ gradients across membrane using ATP
ion channels
voltage gated
ligand gated
mechano gated
equilibrium potential
unique to each ion
electrochemical equilibrium potential
ion does not want to move anymore with completely open pores
ion diffuses down its own concentration gradient but also responds to the overall electrical gradient
mechanisms for influencing membrane potential
depolarization and repolarization
depolarization
cell becomes more positive on the inside- Na+ entering cell
repolarization
cell becomes more negative on the inside- K+ leaving cell
hyperpolarization
K+ channels are slow to react- too much K+ flows out of cell causing the membrane potential to become too negative
what kind of work do cells do?
chemical, transport, mechanical
anabolic reactions: muscle building
catabolic reactions: cracking sugar molecules requires some ATP investment
what is the main energy source for work?
ATP- adenosine triphosphate
the energy from the exergonic reaction of ATP hydrolysis can be used to power an endergonic reaction–> overall the coupled reactions are exergonic (releases heat)
what is ATP? what does it look like? where is energy stored? what is hydrolysis? phosphorylation?
adenosine triphosphate
composed of ribose (sugar), adenine (a nitrogenous base), and three phosphate groups
the phosphate groups repel each others negative charges- bonds are very easy to break (via hydrolysis) and release energy upon breakage
why are exergonic and endergonic reactions coupled?
ATP drives endergonic reactions by phosphorylation, transferring of a phosphate group to another molecule- changes confirmation and affinity for other molecules
building high energy molecules
how is ecosystem respiration similar to cellular respiration?
energy flows into an ecosystem as sunlight and leaves as heat
photosynthesis releases oxygen gas and builds organic molecules which are used in cellular respiration
cells use chemical energy stored in organic molecules to regenerate ATP, which powers work
aerobic respiration
consumes organic molecules and oxygen gas
yields ATP
anaerobic respiration
consumes non-oxygen compounds
what are redox reactions? oxidation? reduction? reducing agents versus oxidizing agent?
the transfer of electrons during chemical reactions releases energy stored in organic molecules
lost electrons- oxidized; the oxidized is the reducing agent
gain electrons- reduced; the reduced is the oxidizing agent
in cellular respiration: glucose becomes oxidized to carbon dioxide and oxygen gets reduced to water
what is NAD? NADH?
coenzyme that gain electrons from organic compounds= reduced form is NADH (stored energy that is tapped to synthesize ATP)
NADH passes electrons to the electron transport chain
glycolysis?
what is produced that is necessary for aerobic respiration?
glucose is cleaved into 2 three carbon pyruvate and NADH and electrons through investment of 2 ATP–> produces 4 ATP, net 2 ATP
2 pyruvate enter citric acid cycle/krebs cycle = 2 net ATP
NADH and electrons enter ETC= hydrogen ions pumped across membrane- gradient will be used to generate ATP (34-36)
direct versus indirect signaling
direct: signal and target cell connected by gap junctions, directly from one cell to another–specialized protein complexes create an aqueous pore between adjacent cells
indirect: signaling cell releases a chemical messenger into extracellular fluid, chemical messenger binds to a receptor on target cell–activation of signal transduction pathway–action inside cell via signal reception on outside membrane
indirect signaling over short and long distance
short
-paracrine: chemical messenger diffuse to nearby cells
-autocrine: chemical message diffuses back to signaling cell
long
-endocrine system: chemical messenger transported by circulatory system
-nervous system: electrical signal, axon terminal, neurotransmitter, action
structures associated with direct and indirect signaling
gap junctions in direct signaling