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
signaling molecules
endocrine versus exocrine
why don’t messenger just pile up around cells?
scavengers
3 classes of steroids? functions, transport, storage
synthesized by smooth ER or inside mitochondria, derived from cholesterol
mineralocorticoids- electrolyte and water balance, acts strong on kidneys
glucocorticoids- stress hormones, adrenal gland, can suppress pain, wide range of effects
reproductive hormones- regulate sex-specific characteristics
cell receptors- ligand-receptor interactions
affinity of receptors? down/up regulation?
down regulation of insulin receptors because cells were continuously screamed at by insulin because there was too much sugar
stages of cell signaling, processes and players involved
3 main receptor types, how do they differ, how are they similar
what are hormones
released from endocrine cell in order to travel through bloodstream and interact with a receptor or target cell to cause a physiological response
what is epinephrine and what does it do? role in glucose metabolism? role in fight or flight response?
binds to receptors on the GPCR in plasma membrane of liver cells- this triggers the release of messenger molecules that activate enzymes and result in the release of glucose in the bloodstream
activated G protein binds adenylyl cyclase causing cAMP 2nd messenger to activate protein kinase A which inhibits glycogen synthesis- leave glucose in bloodstream and promotoes glycogen breakdown- release glucose into bloodstream (fuels muscles during fight or flight)
epinephrine continued- skeletal muscle blood vessel
epinephrine binds to beta receptor on vessel causing vessel to dilate- muscle relaxes allowing for greater blood flow for fight or flight
also binds to alpha receptors on intestinal blood vessels, constricting them– diverts blood from digestive tract to muscles
negative and positive feedback loops
antagonistic hormone pairs
insulin and glucagon
insulin and glucagon, source, pathways, actions
antagonistic pair
insulin lowers blood glucose levels (encourages glycogen formation/glucose uptake and prevents glycogen breakdown in liver, promotes fat storage)
glucagon raises blood glucose levels (acts on liver cells, tells glycogen to breakdown and release glucose into blood stream, stimulates breakdown of fat and muscles)
pancreatic cells:
clusters of endocrine cells = islets of Langerhans
alpha cells- produce glucagon
beta cells- produce insulin
type 2 diabetes, contributing factors, basic pathology
adult onset diabetes
blood glucose too low- brain cannot function
blood glucose too high- osmotic balance of blood disturbed; glucose will punch out capillaries to move toward lower concentrations
insulin deficiency or reduced response of target cells due to change in insulin receptors
additivity versus synergism
additivity: response of target cell to some combination of hormones is the sum of each of their separate responses
synergism: amplified; response of a target cell to a combination of hormones is more than the individual responses
hypothalamus, pituitary, thyroid, adrenals
hypothalamus: “top dawg”, endocrine and nervous organ, receives info from the nervous system and initiates responses through the endocrine system
pituitary: attached to hypothalamus, composed of posterior and anterior pituitary
-posterior pituitary: stores and secretes hormones that are delivered from the hypothalamus
-anterior pituitary: makes and releases hormones under regulation of the hypothalamus
posterior pituitary hormones
act directly on non-endocrine tissues
oxytocin: induces uterine contractions and the release of milk
positive feedback loops-stimulus leads to an even greater repsonse
increases suckling, increases stimulus, more hormone and milk
anterior pituitary hormones
thyrotropin releasing hormone (TRH) in the hypothalamus stimulates secretion of the thyroid stimulating hormone (TSH) from the anterior pituitary
tropic hormones
regulates the function of endocrine cells or glands
thyroid stimulating hormone (TSH)
follicle stimulating hormone (FSH)
luteinizing hormone (LH)
adrenocorticotropic hormone (ACTH)
non tropic hormones
target non-endocrine tissues
prolactin (PRL): stimulates lactation in mammals
melanocyte-stimulating hormone (MSH): influences skin pigmentation in some mammals and fat metabolism in other vertebrates
both produced by anterior pituitary
TRH to TSH to T3 to T4. where, when, why?
stimulus on a sensory neuron, hypothalamus secretes TRH into bloodstream, anterior pituitary secretes TSH/thyrotropin into bloodstream, thyroid gland secretes thyroid hormones T3 and T4 into bloodstream, hormones reach body tissues/target cells, triggers a response (increased cellular metabolism)
negative feedback loop- when enough heat is produced, pathway is shut off
how is resting potential maintained
electrochemical gradients and how they are used to trigger action potentials
depolarization
repolarization
hyperpolarization
graded potentials. what are they? what causes them? why don’t they always trigger an action potential?
sequence of events that lead to an action potential
spatial summation
temporal summation
refractory periods
how do action potentials move down axon and how is information encoded?
what are neurotransmitters
acetylcholine
antagonist
agonist
calcium ion role in transmitting signals
sequence of events at axon terminal from AP arrival to neurotransmitter clean up in synapse
inhibitory vs excitatory neurotransmitters
muscle structure and functions down to myosin and actin filaments
how does an action potential trigger a muscle contraction
role of ATP and calcium in muscle contraction
role of SR
smooth muscle versus striated muscle
