Biology Exam 2 Study Guide 5

michelleburkee2's version from 2015-10-07 06:09

Section 1

Question Answer
what type of connections are plasmodesmata? cytoplasmic connections in plants connecting cells
what are plasmodesmata?plant cells have holes in the walls of adjacent cells forming cytoplasmic connection
allows direct communication between cells in plants plasmodesmata
what are the channels of gap junctions made of? Protein
what do gap junctions allow the passage of?hormones, nutrients, and ions
what are gap junctions? cell-to-cell protein channels allowing for passge of hormones, nutrients, and ions in animal cells
allow direct communication between cellsgap junctions
stomach and the urinary bladder are examples of?*tight junctions*
where are tight junctions found where tubes and sacs must hold contents without leaking
what are tight junctions formed from?by proteins that span the plasma membrane at corresponding sites on adjacent cells
make cell attachements leakprooftight junctions
skin, intestine and heart are examples of*desmosomes*
desmosomes are found where cells need to adhere tightly together under the stresses of movement
desmosomes extend to where beyond the plasma membrane and attatch to other cell's desmosomes
desmosomes are anchored to intermediate filaments of the cytoskeleton
attach cells together desmosomes
which types of cell connecting structures are only found in plant cells?---plasmodesmata---
which types of cell connecting structures are only found in animal cells?desmosomes, tight junctions, and gap junctions
four types of cell connecting structures desmosomes, tight junctions, gap junctions, and plasmodesmata

Section 2

Question Answer
the transfer of energy to an object which causes the object to movework
the capacity to do workenergy
stored energy (a penguin poised to plunge)potential energy
the energy of movement (the penguin jumping into the water)kinetic energy
the energy that is contained in molecules and released by chemical reactionschemical energy
molecules that provide chemical energysugar,glycogen, and fat
the laws of thermodynaics describe the quantity and the quality (usefulness) of energy
As cells absorb energy, some of it is lost as heat
entropydisorder of the universe
Energy can neither be ___________ nor _______ but cancreated nor destroyed but can change form
the total amount of energy within a closed system remains constant unless energy is __________added or removed from the system
is a cell a closed system?no
the universe always tends towards increasing disorder (entropy)
useful energy tends to be stored inhighly organized matter
when energy is used there is an overall increase in entropy
creating order (going against entropy) requiresenergy input
exergonic reactionsrelease energy
endergonic reactionsrequire an input of energy
reactants have more energy than productsexergonic reactions
what is the favorable reaction*exergonic reaction*
reactants have less energy than productsendergonic reactions
what is the unfavorable reaction?*endergonic reactions*
ball moving up hill#endergonic reaction#
ball going down hill#exergonic reaction#
where are energy carrier molecule synthesized?at the site of an exergonic reaction, capturing some of the released energy

Section 3

Question Answer
hydrolysis of ATP is a exergonic reaction
breakdown of some metabolites is ________ because ________exergonic reaction because it releases energy
synthesis of complex molecules and many other metabolic reactions is ________ because _________endergonic reaction because it requires an input of energy
photosynthesis is a _______ reactionendergonic
most organisms are powered by the breakdown of which moleculeglucose
Can energy in glucose be used directly to fuel endergonic reactions?no
energy released by glucose it first transferred to _________an energy carrier molecule
high energy, unstable molecules that are synthesized at the site of an exergonic reaction, capturing some of the released energyenergy carrier molecules
what two things capture energy within cells?ATP and electron carriers
the formation of ATP is an ___________endergonic reaction
Energy is stored in the ________ of ATPphosphate bonds
what two molecules are combined to form ATPADP and phopshate
energy released in cells during glucose breakdown is thenused to make ATP (endergonic reaction)
ATP is stored _______ before being broken downvery briefly
fat and glycogen are stored ________ before being broken downfor a long time
during glucose metabolism and photosyntheis, energy is transfered in the form of electrons to electron carriers
the two types of electron carriersNAD and FAD
transport high energy electrons to machinery in the cell that leads to ATP synthesiselectron carriers
_______________ allows otherwise unfavorable reactions to occurchemical coupling of exergonic and endergonic reactions
in chemical coupling the _______ reacts with the ______ that needs _______ATP reacts with the substrate that needs activation
speed of reactions depends onactivation energy
What are two ways to increase reaction rate which are used by living organismslower activation barrier by catalyst (enzymes) and change the reaction by coupling to a fast one
four ways to increase reaction ratehigh temperatures, higher concentration of reactants, change the reaction by coupling to a fast one, and lower activation barrier by catalyst
ATP hydrolysis to drive an unfavorable reaction is an example ofchange the reaction by coupling to a fast one
enzymes are a catalyst
how do enzymes speed up chemical reactionsthey lower the activation energy needed to start the reaction
in a biological catalyst reaction the enzyme ______ change shapedoes not
in a biological catalyst reaction the substrate _______ change shapedoes
loctose intolerance happens when westop making lactASE=leads to accumulation of lactOSE in the body
what does lactase do in the bodyit catalyzes the hydrolysis of lactOSE into glucose and galactose
if we do not have alcohol dehydrogenase what happensethanol accumulates in our cells causing alcohol intoxication
the three properties of enzymes as biological catalysts1) they speed up reactions by lowering the activation energy required for the reactions to proceed 2) they are NOT changed or used up by the reactions they promote 3)they bind their substrate with specificity
one enzyme can convert ________ substrate molecules to products. why. many. because they are not used up or changed by the reactions they promote
how do enzymes lower the activation energy of a reaction?1) binds reacatants 2)stabilizes teh deformation of chemical bonds as they are rearranged to form a product 3)releases product $)goes back to step one
active sitethe site where the substrate binds to the enzyme
the analogy or enzymes are specifica substrate fits the enzymes like a key fits in a lock
why do animals have enzymes that can digest starch but not cellulose even though they are both polymers of glucose?the enzymes are specific to the shape of the bonds in starch-the cellulose bonds don't fit in teh enzyme active site so the enzyme can't break it
change in the shape of enzyme upon substrate binding making the interaction even strongerinduced fit

Section 4

Question Answer
what two attributes set enzymes apart from nonbiological catalysts1)enzymes are very specific for the reactions they catalyze 2)enzyme activity is regulated
can enzyme activity be turned off and on?yes. because enzymes are regulated
what type of catalysts are enzymesbiological catalysts
the sum of all chemical reactions inside a cellmetabolism
how does the breakdown of a molecule within a cell occur?it occurs in many small steps, each catalyzed by a different enzyme linked in metabolic pathways
how are metabolic pathways controlledthe regulation of enzyme activity, the regulation of enzyme production, and some are synthesized in inactive form
genes that code for enzymes may be turned on or off according to needregulation of enzyme production
a substance that is not the enzyme's normal substrate binds to the active site of teh enzyme, competing with teh substrate for the active sitecompetitive inhibition
a molecule binds to a site on the enzyme distinct from the active sitenoncompetitive inhibition
2 ways enzyme activty can be controlledcompetitive inhibition and noncompetitive inhibtion
are competitive inhibition and noncompetitive inhibtion reversable?yes
allosteric regulationa small regulator molecule binds an enzyme to either enhance or inhibit its activy, usually changing the enzymes shape. Usually these enzymes are multisubunit. Usually have both acvitaor and inhibitor sites. Usually these enzymes respond to changes in metabolism.
feedback inhibitiona negative feedback type of allosteric inhibition that causes a metobolic pathway to stop producing its product when quantities reach an optiumum level. An enzyme near the begining of a metobolic pathway is allosertically inhibited by the end product of the pathway
posions and drugs also influenceenzyme activity
denaturationthe unfolding of teh three dimensional structure of an enzyme falls apart causing it to lose activity
causes of denaturationheat, disulfide bond reduction, extremes of pH, organic solvents, urea abd guanidine, hydrochloride
the activity of an enzyme is influenced by its local environment
most enzymes only function optimally within _________a narrow range of conditions
for humans enzymes, the maximum activity occurs at96 degrees farenheit or 37 degrees celcius