Midterm 2 Flashcards
What is metabolism?
A combination of catabolism and anabolism
chemical reactions/pathways that result in breakdown or synthesis of molecules
What is bioenergetics?
the process involved in converting food into energy
What is the difference between cellular work and mechanical work in a cell?
Cellular work - normal cell functioning
Mechanical work - contraction and relaxation of muscle
Where is energy lost to when converting chemical energy (food) into other types of energy (ATP)?
Heat
What is the goal of all of the body’s energy systems?
to create ATP
How is ATP used to make energy?
the adenosine triphosphate is together, but to get the energy out, the high energy bond between the second and third phosphate is cleaved, releasing energy
what is created when the energy in ATP is released?
ADP (adenosine diphosphate [inorganic]) + 1 phosphate + the energy from the bond
How is ADP reconverted to ATP?
energy is required to phosphorylate ADP back into ATP
What is a substrate level phosphorylation and what are some characteristics?
usually occur in the cytoplasm
are very fast
anaerobic
What is an oxidative phosphorylation and what are some characteristics?
occurs in the mitochondria
quite slow
aerobic
What is the difference between the anaerobic and aerobic energy systems?
aerobic required oxygen and anaerobic doesn’t
how many seconds of ATP are stored w/in the cell?
~2-3 seconds
What does the power of an energy system mean?
power = the rate at which energy can be produced by the system
what is the capacity of an energy system mean?
capacity = the total amount of ATP that an energy system can produce?
Describe the power and capacity of the three energy systems.
Anaerobic alactic - high power, low capacity
Anaerobic lactic - highish power, lowish capacity (middle of the road)
Aerobic - lower power, near infinite capacity
How does the body decide which energy system is dominant? and what happens to the other systems while not dominant?
the dominant energy system depends on the rate and amount of ATP needed by the body at any given time
the other systems still generate ATP but will generate less than the dominant system
what is the most efficient fuel source for the body to use for creating energy?
lipids
Why is the creatine phosphate system the most powerful (fastest rate of ATP production)?
- b/c creating ATP from CP doesn’t rely on a long chemical reaction
- ATP & CP are stored near where they are used (contractile muscle)
- oxygen isn’t involved
Why does the creatine phosphate system have low capacity?
CP stores are more than ATP stores but are not regenerated the same as ATP leading to running out of CP very quickly
used for its speed b/c low amount of steps and no travel time
How are creatine phosphate stores replenished?
ATP is required to resynthesize creatine phosphate
C + Pi + Energy -> CP
How can we increase the rate of creatine phosphate recovery?
decrease the amount of ATP requirement everywhere else so ATP can be used to resynthesize CP
What two energy systems use glycolysis?
anaerobic lactic system & aerobic system
How many carbon molecules are in glucose?
glucose is a 6 carbon molecule
How many carbon molecules does pyruvate have?
pyruvate has 3 carbon molecules as it is 1/2 of the original glucose
How many hydrogen molecules are produced per molecule of glucose?
1 hydrogen molecule is produced per molecule of pyruvate, meaning 2 hydrogen per glucose
What happens to pyruvate after glycolysis?
It either goes to the Krebs cycle (normal) or is converted to lactic acid if used in anaerobic glycolysis
How many times does each pyruvate molecule go through the Krebs cycle?
each pyruvate molecule goes through the krebs cycle once, leading to each molecule of glucose leading to two turns of the krebs cycle
Why does the anaerobic lactic system begin to shut down over time?
the build-up of end products (lactate) changes ph which leads to the enzymes of glycolysis not functioning
trained people can last longer than others as they develop cellular buffers to deal with end products
What does lactate dehydrogenase do?
converts pyruvate into lactate -or- lactate into pyruvate
works to balance lactate and pyruvate
What is an oxidative reaction?
the process of removing electrons
(organic compounds just give up a whole atom [hydrogen] instead of one electron)
ex. dehydrogenation
what is a reduction reaction?
adding electrons (often adding a hydrogen)
ex. hydrogenation
What is the role of NAD and FAD coenzymes?
hydrogen ion / electron carriers (transport hydrogen ions)
often take them to the electron transport chain in the inner membrane of the mitochondria
Where does NAD drop off its hydrogen ions (and electrons) in the electron transport chain?
right at the start. leading to 3 ATP generated per hydrogen ion taken to the electron transport chain by NAD
where does FAD drop off its hydrogen ions (and electrons) in the electron transport chain?
a couple steps into the process. leading to 2 ATP generated by each hydrogen ion taken to the electron transport chain by FAD
why do NAD and FAD drop off their hydrogen in different places?
NAD drops off at the start as it takes the higher potential hydrogen ions compared to the ions that FAD carries
what is a co-factor?
a non-protein component that some enzymes need to function as a catalyst
what is end product inhibition?
end product build-up causes an inhibition in an enzyme earlier in the pathway to slow down/stop the pathway
what is a flux generating enzyme?
an enzyme that controls the rate of which enzymes in a pathway work, therefore controlling the ‘flux’ of the pathway
flux = total movement
What is the main stimulator, inhibitor, and rate limiting enzyme of the ATP-PC system?
Stim - ADP
Inhibitor - ATP
Rate limiting enzyme - creatine kinase
What is the main stimulator, inhibitor, and rate limiting enzyme of glycolysis?
Stim - AMP, ADP, P, ph level ^
Inhibitor - ATP, CP, citrate, ph level down
rate limiting enzyme - phosphofructokinase
What is the main stimulator, inhibitor, and rate limiting enzyme of the Kreb’s cycle?
Stim - ADP, Ca++, NAD
Inhibitor - ATP, NADH
rate limiting enzyme - isocitrate dehydrogenase
What is the main stimulator, inhibitor, and rate limiting enzyme of the electron transport chain?
Stim - ADP, P
Inhibitor - ATP
rate limiting enzyme - cytochrome oxidase
What is the Cori cycle and how is it used to help energy systems work?
uses diffusion of lactate into the blood (using concentration gradients) where its taken to the liver where gluconeogenesis converts lactate into glucose
why does active recovery help with recovery?
maintaining some small amounts of movement allows for ATP to be generated by the aerobic system to help clear lactic acid
whats the fate of pyruvate during the use of anaerobic alactic system?
it’s moved to the mitochondria where it is converted to acetyl units for the krebs cycle
Under what condition pyruvate converted to lactic acid?
if oxygen is limited or if there is too much pyruvate to be converted into acetyl units for the krebs cycle
Where do the different phases of the aerobic system happen?
glycolysis - cytoplasm
krebs cycle & electron transport chain - mitochondria
How many cycles of the krebs cycle happen per 1 molecule of glucose in the aerobic system?
1 glucose -> 2 pyruvate -> 2 acetyl units -> 2 cycles
How many CO2 are created per glucose molecule?
- 1 per pyruvate as they are converted to acetyl units
What does the process of beta oxidation do?
allows fatty acids (lipids) to be converted into acetyl units for the krebs cycle
what does the process of deamination do?
allows for amino acids to be converted to acetyl units to be used in the krebs cycle
What is the main product of the Krebs cycle?
hydrogen ions that are taken to the electron transport chain
what is oxidative phosphorylation?
the use of movement of electrons down the electron transport chain to rephosphorylate ATP
(*requires oxygen)
how does the electron transport chain create ATP?
chemiosmotic coupling.
chain creates concentration gradient on the membrane of mitochondria, on three spots of the membrane, ATP synthase allows hydrogen back into the chain, using the energy to rephosphorylate ATP
How many ATP does aerobic metabolism create during each phase?
Glycolysis - 2 ATP
Krebs Cycle - 1 per round (2 total)
Electron transport chain - 34 ATP
(more glucose efficient than anaerobic systems)
how does ATP get out of the mitochondria?
ADP/ADP translocases - carrier proteins (translocases) exchange cytosolic ADP for mitochondrial ATP across the inner mitochondrial membrane
what is glycogenesis?
‘creation of glycogen’
formation of a covalent bond between glucose molecules
what is gluconeogenesis and where does it primarily occur?
synthesis of new glucose using; glycerol, lactate, or amino acids
primary site - liver
what is glycogenolysis and where does it take place?
breakdown of glycogen
(glycogen -> glucose)
happens in muscle tissue and liver (b/c glycogen is stored in both locations)
how is most energy stored and why?
most energy is stored as triglycerides in adipose tissue as lipids have higher energy-to-weight ratios than carbs or proteins
what is lipolysis?
separation of fatty acids from glycerol
(triglycerides = glycerol + 3 fatty acid chains)
how many acetyl units are produced during beta oxidation?
of carbon molecules in fatty acid chain / 2
what is deamination and where does it occur?
breakdown of amino acids for energy metabolism (*only happens if absolutely needed)
happens in the liver
what is the difference between ketosis and ketoacidosis?
ketosis is done ‘on purpose’ through keto diets or intermittent fasting
ketoacidosis is when the body ‘thinks’ its starving and breaks down fats and proteins
What are the three substrates used in the three energy systems?
creatine phosphate - anaerobic alactic
glucose - anaerobic lactic
glucose, lipids, proteins - aerobic
what limits capacity of the three energy systems?
small stores of CP - anaerobic alactic
build-up of lactic acid - anaerobic lactic
no limit - aerobic
what limits power in the three energy systems?
not much ATP produced per molecule (1 ATP/ 1 substrate) - anaerobic alactic
low ATP per molecule (2 ATP/substrate) - anaerobic lactic
lots of steps (takes time) - aerobic
What are the three types of cellular communication?
gap junctions, cell-to-cell binding, extracellular messengers
how do gap junctions function to allow cell to cell signaling?
membrane proteins called connexins from tunnels between cells to allow for rapid diffusion b/w cells
(allows cells to work as a unit)
how does cell to cell binding function to allow cell to cell signaling?
surface molecules on two cells bind to eachother, allowing for communication
how do extracellular messengers function to allow for cell to cell signaling?
involves multiple steps, chemical secreted from one cell and binds to a receptor of a target cell, eventually eliciting a cellular response
what are three types of extra cellular messengers?
hormones, neurotransmitters, local mediators
what is a hormone and how does it travel?
an extracellular chemical messenger carried by the blood to its distant target cells
water soluble hormones travel freely in the blood whereas lipid soluble hormones are bound to carrier proteins in the blood
what is a neurohormone?
a transmitter released from a neuron into the blood that acts like a hormone
(essentially a neurotransmitter that uses the blood to travek)
what is a local mediator and what are the two types of cells that use them?
extracellular transmitter that is released by cells
paracrine cell - a cell that releases transmitters into the extracellular fluid to get to target cells
autocrine cell - a cell that releases transmitters but also has receptors for the transmitter (used in negative feedback)
what kinds of messengers can cross the plasma membrane?
lipophilic/hydrophobic can cross the plasma membrane
lipophobic/hydrophilic cant
what affinity receptor (high or low) will be the dominant response within a cell?
low affinity. this is due to the cell knowing that there must be a lot of the messenger if the lower affinity receptor receives some
what is downregulation?
when an excess of a messenger leads to number of receptors decreasing
what is signal transduction?
sequence of events that begins with a messenger binding to a receptor and ends with a cellular response
what are the two possible responses when a first messenger binds to a receptor?
it can: open/close ion channels - or - activate another messenger system
how do you tell the difference between a first and second messenger?
first messenger is extracellular and second messenger is intracellular
how does a message get terminated?
the messenger and the receptor are separated through: enzymatic degration of the messenger, internalization of the messenger and receptor, or removal of calcium from the cytoplasm
why are lipid soluble messengers receptors inside the cell?
b/c they can cross the plasma membrane
where must a water soluble messengers receptor be?
on the membrane (membrane bound receptors)
what is it called when a receptor acts as an ion channel and what is the reaction when a messenger binds to it?
a fast ligand-gated channel
reaction - ion channel opens and allows ions in down the concentration gradient
what is the reaction when a messenger binds to a receptor acting as an enzyme?
enzyme portion of the receptor (inside the cell) creates a chemical reaction in the cytosol
what is the difference between an enzyme-coupled receptor and a receptor acting as an enzyme?
enzyme-coupled - enzyme is associated but considered SEPERATE from receptor
what is a g protein receptor and what does it do?
a receptor bound to a g protein on the inner surface of plasma membrane
serves as a ‘switch’ to couple a receptor to an ion channel or enzyme
why are g proteins called g proteins and what are the subunits of a g protein?
called g protein b/c it binds to GDP or GTP
three subunits; alpha, beta, gamma
what can the activated g protein do?
- directly gate ion channels (slow gating)
g protein (or subunits) move from receptor and directly open OR close ion channel
- indirect slow gating
g protein activates second messenger which opens/closes ion channel
(*has the ability to open/close more ion channels than direct gating)
what is a protein kinase?
any protein that phosphorylates other proteins
what is signal amplification?
a system that creates a ‘cascade’ to amplify initial effect
what is cAMP and what does it do?
cAMP = cyclic AMP (second messenger)
travels through the cell and activate protein kinases
what is cyclic GMP?
comes from guanosine-triphosphate
also activates protein kinases
what is the function of the PIP2 system?
second messenger system activated by g protein that acts as an amplifier enzyme
makes DAG and IP3 when activated by a g protein
what do DAG and IP3 do?
DAG role: activates protein kinase c
IP3 role: binds to calcium ion channel and directly opens it
where are glut 4 receptors mainly found?
cardiac, muscle and adipose tissues
what makes up the different parts of the double helix DNA ‘ladder’?
‘rungs’ - nucleotides
‘outside’ - sugar phosphate backbone
what are the three letter words made up by nucleotides called?
codons
what is transcripton?
the process of transferring genetic info from DNA to mRNA
what direction is DNA read in and what direction is mRNA built in?
DNA read: 3’ -> 5’
mRNA created: 5’ -> 3’
what amino acid does AUG (the start codon) code for?
methionine
what is rRNA and what does it do?
ribosomal RNA combines with other proteins to form subunits of the ribosome
what is tRNA and what does it do?
transfer RNA grabs amino acids from the cytosol and brings them to the ribosome
*each tRNA can only carry one type of animo acid
what is the difference between a charged tRNA and a free tRNA?
charged = has amino acid bound
free = no amino acid bound
what is mRNA and what does it do?
messenger RNA carries the codons from the nucleus to specify which amino acids go where in the protein chain
what is an intron?
parts of the DNA that don’t contain any useful information and are removed before leaving the nucleus
what is an exon?
the remaining parts of transcribed RNA that must be spliced together using spliceosomes to form mRNA
how is translation initiated?
starts at the nearest AUG codon to the 5’ cap of the mRNA
then small subunits binds to AUG and first nucleotide binds to the ‘p-site’ before the large subunit binds to the small subunit
