Unit 1 Flashcards
The Chemistry of the Cell (Ch 3,4,5,7) (210 cards)
1
Q
What’s the matter?
A
anything that takes up space and has mass
2
Q
What’s the difference between molecule an compound
A
molecule: 2 atoms + held together by covalent bonds
compound: molecules of different element
(H2= molecule, CH4= compound)
3
Q
Which are the most abundant elements in your body?
A
Hydrogen
Carbon
Nitrogen
Oxygen
Calcium
4
Q
How do isotopes differ from each other?
A
same element
same number of protons
same atomic number
different atomic mass
different mass numbers
different number of neutrons
C12 = 6 protons, 6 neutrons
C14= 6 protons, 8 neutrons
5
Q
Difference between atomic number vs atomic mass vs atomic number?
A
atomic number = # of protons (constant in isotopes)
atomic mass = # neutrons + # protons (differs in isotopes)
atomic number = # protons + # electrons + # neutrons (differs in isotopes)
6
Q
What is the relationship between valence electrons and chemical bonds?
A
the number of valence electrons indicate the number of bonds that an atom can make
i.e: hydrogen has 1 v.e and thus can make 1 bond
7
Q
Which bonds are formed between atoms in a molecule? Which bonds are formed between
molecules?
A
between atoms: covalent bonds
between molecules: hydrogen bonding
8
Q
What two types of strong bonds? How are the two different from each other?
A
covalent bond : sharing of electrons
ionic bond : transfer of electrons
9
Q
What is the relationship between covalent bonds, electronegativity, polar and nonpolar
compounds?
A
covalent bonds can be polar or nonpolar.
the greater the difference in electronegativity = the more polar the bond
10
Q
Of the most abundant elements in your body, what is the relative electronegative to each other?
A
O > N > C = H
11
Q
What are examples of non-polar molecules and polar molecules?
A
CH4 vs H2O
12
Q
What type of compound can form ions? Under what circumstances?
A
13
Q
What are the purposes of weak bonds?
A
allow :
- interactions between molecules
- molecules to adhere to each other when they collide
- stability within large molecule (DNA)
14
Q
What is hydrogen bonding (1st of the 3 types of weak bonds). give an example regarding DNA
A
Hydrogen Bonding:
-> bond between atom with a partial negative charge and an hydrogen that is covalently bonded with an electronegative element (N, O, F. Often -OH, -NH, -SH groups)
-> individually weak, but collectively very strong
-> important, bc a lot of water molecules in our body
-> interactions between a pair of bases (between cytosine and guanine / adenine and thymine)
15
Q
What is Van deer Walls interactions (2nd of the 3 types of weak bonds). give an example regarding DNA
A
Van Der Waals Interactions:
-> nonpolar molecule with temporarily induced dipole moment caused by random movement of electrons
-> weak
-> interactions between the stack bases in DNA (between cytosine and thymine/ thymine and guanine, etc.)
-> helps keeps the DNA structure intact
16
Q
What is ionic bonds with water (3rd of the 3 types weak bonds)
A
Weak since each ion gets shielded by its interactions with water molecules
dry, salt crystal has strong bonds,but in water its bonds get much weaker
17
Q
Why do ionic bonds weaken in water?
A
Because each ion gets shielded by water molecules that exhibits oppositely charged ions.
18
Q
Where does oxygen come from in the reaction called photosynthesis?
A
Oxygen originates from water in photosynthesis NOTTT from CO2
19
Q
Why do all organisms need water?
A
dehydration and hydrolysis reactions need water
cells are 70/95% made of water
20
Q
Describe the unique structure and polarity of water. How many H-bonds can it make
A
water molecule = 2 positive ends (H) + 1 negative end (O)
water = has poles of partial charges = is a polar molecule
each water molecule can form max 4 Hydrogen bonds with neighboring molecules (2 lone pairs on O + 2x1 electron pair on H). these hold liquid water together, making water very cohesive.
21
Q
Describe how water acts as a solvent in :
- large molecules
A
-water= solvent for cells, blood & plant sap
- water dissolves mostly polar/ionic substances
large molecules:
-> they will dissolve in water if they have a polar functional group
22
Q
Describe how water acts as a solvent in :
- non-ionic polar substances (ie: hydration of glucose)
A
-> glucose is polar bc of its oxygen atoms
-> water forms H-Bonds with the molecule and removes individual monosaccharides from the solid until it is a homogenous solution
23
Q
Describe how water acts as a solvent in :
- ionic substances (ie: hydration of NaCl)
A
-> Cl- will orient itself with H+ of water molecule
-> NA+ will orient itself with O- of water molecule
24
Q
What is the difference between solvation and hydration?
A
Solvation: solid is dissolved into a solution
Hydration: solvation where the solvent is water
25
Describe the property of water (C in CAT)
Cohesion:
- how well molecules of the same substance stay together
- collectively, h-bonds hold a substance together = cohesion
- ex: water = good cohesion bc of H-Bonding
- plants get water from the roots to the leaves, fighting gravity
26
Evaporation exerts pulling force on water within what tissue?
cell walls??? capillary tissue???
27
Describe the property of water (A in CAT)
Adhesion:
- clinging of one substance to another (stronger adhesion if they have charged group of atoms on their surface)
- responsible of the meniscus of a graduated cylinder
- water makes thing wet, bc water clings to things
28
Describe the property of water (T in CAT)
Surface Tension:
- how difficult it is to break/stretch the surface of a liquid, due to cohesion
- strong attraction between water molecules (H-bond) = strong surface tension
- tension of the surface of a liquid= much stronger attractions than those between water molecules or between air molecules
29
Describe capillary action
tendency of water to move in narrow tubes, against gravity; can be explained by cohesion and adhesion.
- plants: water clings to the cells that forms the veins. it allows it to defy gravity up to the roots.
- water clings to the walls of a capillary tube (adhesion) and can pull more water up the tube (cohesion)
30
Describe moderation of temperature
- the way water responds to temperature changes depends on the h-bonds
- water heats up -> breaks h-bonds and reduces the degree of cohesion
- water cools down -> opportunity to form h-bonds
31
What are the 4 advantages of water's high specific heat?
1. it allows water to resist to temperature changes and act like a temperature buffer
1.oceans absorb heat & only increase a few degrees during day and release stored energy to warm the air at night.
-> explains why coastal areas = moderate climate that don't switch up a lot
3. oceans have a constant temperature = stable environment for aquatic life
4. most biological reactions only take place within a narrow temperature range. = good for biological reasons
32
What's the number of hydrogen bonds in water per molecule in each physical state?
Solid: 4 hydrogen bonds per water molecule
Liquid: 3-1 hydrogen bonds per water molecule
Gas: 1-0 hydrogen bond per water molecule
33
Types of evaporative cooling? Give 2 examples in biology.
1. water cools down = heat evaporates = h-bond can be formed
2. water heats up = water molecules break their h-bonds. some bonds break faster than other and escape liquid phase to enter gas phase. the molecules that contains more energy are evaporated thus making the temperature of liquid water less high.
= cool down process (water evaporating takes the heat away)
human= sweat
plants = water transpires from leaf
34
Describe the relationship between polar/nonpolar covalent bonds in organic molecules and their
solubility in water. (ie. can they dissolve in water? Why/why not?)
polar = soluble
nonpolar = insoluble bc there are no dipoles, which prevents the molecules from making interaction with water molecules.
like dissolves like
35
Explain the pH of an aqueous solution (ie: what happens when you add acid/base in soln)
the product of the H+ and OH- concentrations in any aqueous solution is constant at 10^-14.
an acid added to a solution will:
1. add hydrogen ions
2. remove OH- ions (since they will combine to the newly added H+)
3. lower the pH
4. digestive liquid in stomach = ph of 2 (only acidic place in our body)
a base added to a solution will:
1. add OH- ions
2. remove H+ ions (since they will combine to the newly added OH-)
3. increase the pH
4. biological fluids, ie. blood/saliva = ph of 6-8
36
Describe a pH buffer. What is it and what does it do?
addition of acid have much less effect on the pH of blood than the pH of water because blood contains several substances biological buffers. (ie. H2CO3)
pH buffer:
-> substance that minimizes changes in [H+] and [OH-] in a solution by accepting H+ from the solution when they are in excess and donating H+ to the solution when they are in excess.
37
Why is it important for pH in cells and in other body fluids to be tightly regulated?
change in pH alter the shape of proteins = denaturation = affects function
38
How does
carbonic acid (H2CO3) play a role in the fluids of the body? Give one nutritional example.
H2CO3 -> HCO3- + H+
this equilibrium rxn acts as a pH regulator
shift right = response to rise in pH (want more H+)
shift left = response to drop in pH (want less H+)
after eating a lot of meat = acidity in stomach = shift to the left to form more carbonic acid and get rid of the acidity in the stomach
39
What about amino acids/proteins? (see
class notes on proteins)
amino acids also act as biological ph buffers
carboxyl end = acid that donates protons
amino end = base that accepts protons
40
Explain pH homeostasis regulation by the respiratory system.
pH below normal range:
-> due to respiratory issues
-> to much [CO2] in blood
-> CO2 -> H2CO3 (in water)
-> HCO3 + H+
-> CO3 2-
-> more CO2 = more H+
-> result = acidosis
-> response = faster breathing to exhale more CO2
pH above normal range:
-> due to hyperventilation or diarrhea
-> not enough CO2
-> CO2 -> HCO3 -> H+ -> CO3 2-
-> less CO2 = les H+
-> result = alkalosis
-> response = slower breathing to accumulate more CO2
41
Explain pH homeostasis regulation by the urinary system
low pH:
- acidosis
- kidney will :
1. excretes excess H+ into the urine
2. absorb HCO3-
high pH:
- alkalosis
- kidney will:
1. excrete HCO3-
2. absorb H+ back into the blood
42
Why do shells in aquatic animals thin and become fragile as oceans become more and more acidic?
(the H+ + CO3 2- —> HCO3- step is important)
1. CO2 dissolves in water -> CO2 with water forms H2CO3 (carbonic acid)
CO2 + H2O -> H2CO3
2. more carbonic acid = more H+ (H2CO3-> H+ + CO3 2- ) = lowers ocean's pH = "ocean's acidification
3. acidic water = extra H+ available that will bind to CO3 2- to form HCO3 -
this will reduce the [CO3 2-] in the water
4. less CO3 2- = less calcium carbonate (CaCO3) available for animals' shells
(Too much CO2 in air
CO2 + water = H2CO3 (alot of CO2 creates an excess of H2CO3)
H2CO3 = H+ + HCO3- (excess of H2CO3 leads to more H+ released than what the ocean can buffer
H+ + CO3 2- = HCO3-
excess H+ = more CO3 is needed to complete the reaction = less CO3 2- is available in the ocean for the creation of shells.)
43
Where do autotrophs obtain organic carbon? Heterotrophs? (Not in class notes but you are
expected to know this from previous bio courses)
44
How does carbon enter living organisms?
45
What's the difference between a biomolecule and an organic molecule ?
Biomolecule
Organic molecule2
46
Which properties of carbon make it a good building block for organic biomolecules? Which other
elements make up the major atoms used to build these molecules?
it is very versatile (can make single, double,triple bonds)
&
4 single bonds possible -> characteristic called "tetravalence" that makes large complex molecules possible
47
When carbon is bound to four other atoms, what shape does the molecule generally take?
tetrahedral shape
48
Review polar and non-polar bonds. Would the following bonds: C-O; C-H; C-N; C-C be considered
polar or non-polar? Why?
C-O polar
C-H non polar
C-N polar
C-C non polar
49
Describe carboxyl group
R - COOH
C with one double bond to an O and one single bond to an hydroxide.
-> provides polarity
-> BUT, provides certain stability
ie: often COOH -> COO-
-> molecules with carboxyl groups are weakly acidic
-> all amino acids contain a carboxyl group that has the capacity to donate an hydrogen
50
Give 2 examples of compounds that contain a carboxyl group.
-> formic acid (organic molecule released by formicine ants as a defence mechanism)
-> acetic acid
51
Describe hydroxyl group
R-OH
provides polarity to molecule that will depend on how many OH groups there are relative to the molecule's size (C2H5OH + polar than C6H13OH bc smaller chain compared to hydroxyl group)
organic compounds with hydroxyl group = "alcohol"
ie: methanol, ethanol, etc.
glucose = 5 -OH groups & small chain (6 carbons) = highly polar
52
What do sugars owe their solubility in water to ?
their presence of hydroxyl groups (ie. glucose = 5 hydroxyl groups)
53
Describe carbonyl group
R- C=O
-> aldehydes = carbonyl carbon bonded to at least 1 hydrogen (extremity of chain)
-> monosaccharides with aldehydes = aldoses
-> ketones = carbonyl carbon bonded to 2 other carbons (middle of chain)
-> monosaccharides with ketones = ketoses
-> provide polarity to the parent molecule since electronegative oxygen attracts covalent electrons
54
Describe amino group
R-NH2
-> generally weakly basic molecules
-> all amino acids contain an amino group that can accept a hydrogen
-> provide some polarity due to the polar covalent bond between N and H (Hydrogen bond)
ex: nitrogenous bases in DNA/RNA contain amino group
55
How does amino acid act as a buffer?
each amino acid can :
1. donate an H+ into the solution -> acid solution
2. accept an H+ -> basic solution
carboxyl group = acidic (this end can donate an H+)
amino group = basic (this end can accept an H+)
= amino acid = pH buffer
56
Describe sulfhydryl group
R- SH
-> stabilize the internal structure of proteins
-> can form disulphide bridges with another -SH (very strong bond)
-> disulphide bridges form cross-links that stabilize protein structures
57
Where can sufhydryl groups be found?
in some proteins that contain cysteine amino acids
58
What is responsible for the stabilization of the straight/curly nature of hair ?
the disulfide bridges between two sulfhydryl groups
59
Describe phosphate group
R - OPO3 2-
-> constituents of phospholipids (reason for polar heads)
-> provides polarity
-> phosphates can donate H+ into solution and make the molecule weakly acidic
-> this ionization gives a negative charge to the parent molecule
60
What is the reason for the high energy bonds between the phosphate groups in ATP?
ATP = 3 phosphate groups
-> each phosphate group = negative charge (PO4 3-)
-> negative-negative = they each naturally repel each other and thus create a lot of instability
-> instability + repelling = high energy covalent bonds necessary to hold the phosphate groups together
-> high energy covalent bonds can be used for cell work
61
In phosphate groups, how many hydrogen ions can each phosphate give up into solution?
2
62
Describe methyl group.
R -CH3
-> non polar group
-> methyl groups can be added to molecules to act as a identity tag or signal for enzymes
-> ie: methylated DNA affect gene expression
63
Describe how each of the following contributes to the diversity of organic biomolecules:
o Carbon skeleton
o Functional groups
1. carbon skeleton diversity
-> degree of branching
-> ie. butane = straight chain vs isobutane= branched
-> double bonds' different possible locations
2. functional groups
-> atom groups that provide a molecule with a particular characteristic/function
-> different # or position of functional groups = different properties
-> most functional groups can form ionic & hydrogen bonds with other molecules and thus give the organic molecule hydrophilic properties.
-> some functional groups are non-polar and give the molecule hydrophobic properties
64
Define an isomer. Compare a structural isomer and a stereoisomer.
compounds with the same molecular formula but different structures and properties.
yes, because organisms are sensitive to even subtle variations in molecules.
cells will recognize one enantiomer (an isomer that mirror images of each other) but not the other
65
What are the 3 kinds of isomers?
structural isomer
-> 2 C5H12 molecules but different covalent arrangements (different structures)
stereoisomers (2 kinds) :
1. geometric isomer
2. optical isomer
66
Describe geometric stereoisomers
-> same covalent arrangement but different spatial arrangement
-> The spatial arrangement differs around the double bond between 2 Carbons
-> cis isomer = both sides of the double bonds mirror each other. ie: 2 hydroxyl groups are on the upper half bond.
-> trans isomer = 2 hydroxyl groups are on opposite sides, across each other (diagonally)
-> ex: rhodopsin (visual pigment in the eye), when hit by light, changes from cis isomer to trans isomer.
67
Describe optical stereoisomers
-> enantiomers
-> isomers that are mirror images of each other
-> a carbon attached to 4 different functional groups
-> Cells will recognize one enantiomer but not the other
-> 2 drugs enantiomers = different effects
-> We are sensitive to even subtle variations in molecules
68
List 3 examples of optical stereoisomers and their different biological effects.
R -(+)- Thalomide = sedative
S-(-)- Thalomide = malformation of babies
L-Dopa = helps fighting Parkinson's disease
D-Dopa = biologically inactive
D- Alanine VS L-Alanine
69
Would you expect
stereoisomers to have different biological properties than isomers?
70
Define a monomer and a polymer.
monomers are building blocks of polymers
A, C, H, T = monomers
CHAT = polymer
71
Describe a hydrolysis and condensation reaction. Which require(s) energy and/or a catalyst?
Hydrolysis
-> breakdown of polymers into monomers by adding a water molecule
-> require catalyst
Condensation (dehydration synthesis)
-> monomers form larger molecules by removing a water molecule and forming a new bond
-> requires energy & catalyst
72
Describe the major functions of carbohydrates in cells. Give some specific examples for each
1. energy storage
-> starch (plants)
-> glycogen (animals)
2. structural components
-> cellulose in a plant's cell wall
-> Chitin in fungi's cell walls and exoskeleton
-> peptidoglycan in bacteria
3. Energy source
4. Protection
-> glycoproteins = mucus = protects respiratory and digestive tracts
73
What are the 2 types of polysaccharides? Give examples
1. Energy storage
-> starch (plants)
-> glycogen (animals)
2. structural polysaccharides
-> cellulose in a plant's cell wall
-> chitin in fungi's cell walls and exoskeleton
-> peptidoglycan in bacteria
74
What is the general ratio of the three main atoms in a carbohydrate?
carbon, hydrogen and oxygen in a 1:2:1 ratio
75
Describe the structure of a monosaccharide
monosaccharides = [CH2O]n where n is between 3-7
76
Describe the structure of a disaccharide.
disaccharides = 2 monosaccharides bonded by glycosidic linkage by dehydration synthesis
77
Describe the structure of an oligosaccharide
-> Small sugar polymers formed from 2-6 monosaccharides
-> found attached to glycoproteins or glycolipids
78
Describe the structure of a polysaccharide.
-> 100-1000 monosaccharides linked by dehydration synthesis
-> mostly made of glucose
-> vary in properties due to their different isomers and differently arranged units
79
What is the bond that links two monosaccharides together called? What type of bond is it?
glycosidic linkage
covalent bond
80
Why does a monosaccharide have high chemical energy making it a good fuel in cellular respiration?
(The bond between which atoms can be broken?)
its numerous C-H and C-O bonds makes it useful to fuel cellular respiration
when C-H bonds are broken, they release aloottttt of energy that can be used to produce ATP
monosaccharides are stable which allow them to store the energy until needed
81
What are three monosaccharides that mammals can metabolize? How do they differ from each
other?
glucose
-> carbonyl group at the first carbon
fructose
-> carbonyl group at the second carbon
galactose
-> carbonyl group at the first carbon
all have different arrangement of hydroxyl groups
82
List the four structural characteristics of a monosaccharide that can vary.
position of carbonyl group
number of carbon atoms
configuration of hydroxyl group
ring or linear form
*confirm with teacher
83
Define (and identify) an aldose, ketose, triose, pentose, and hexose
2 types of sugar : aldose and ketose
aldose: carbonyl group is located on the first carbon (top end of the chain).
ex: glucose
ketose: carbonyl group is located within the carbon chain, such as on the second carbon
ex: fructose
triose: 3 carbons -> smallest sugar
pentose: 5 C-> in DNA
hexoses; 6 C ->common sugar
84
Explain why monosaccharides have isomers. Identify whether a monosaccharide pair is a structural
isomer or stereoisomer
glucose, galactose and fructose are all structural isomers of one another.
85
Define a glycosidic linkage and describe 2 ways that they can vary. What kind of reaction makes and
breaks these bonds?
glycosidic linkage: the covalent bond of two monosaccharides formed by a dehydration reaction
alpha configuration
-> -OH group on the first Carbon is on the opposite side of CH2OH
-> can be metabolized and used as an energy source=useful
-> in sugar and starch
beta configuration
-> -OH group on the first Carbon is on the same side as CH2OH
-> cannot be digested = useless
-> in structural molecules, i.e cellulose
86
What is a trick to recognize the 2 configurations of glycosidic linkage?
if the -OH group is attached on the bottom of each monosaccharide -> alpha
if every monosaccharide is upside down compared to the previous one -> beta
you count the carbons starting from the one on the extreme right C1 and count CCW.
87
Which is more soluble, glycogen or starch? Why?
Glycogen, because it has much more branching than starch
88
What does glycogen break down (with the help of glucagon) into?
glycogen -> glucose-6-phosphate
89
What type of isomers are the 2 different kinds of glycosidic linkage? Which one is useful vs useless biologically?
spatial isomers
useful = alpha configuration
useless = beta configuration
90
How does your body maintain homeostasis of glucose in your blood? Which organs and tissues are
involved? Which two hormones are responsible for this balance?
high sugar levels:
-> trigger the pancreas to release insulin that will bind to receptors on fat, muscle and liver cells, forcing them to absorb glucose and store it as glycogen.
low sugar levels: liver releases glucagon. the glucagon receptors in the liver will bind to glucagon and stimulate the conversion of glycogen into glucose or the breakdown of fats in adipose tissue.
91
What is the difference between the breaking down of glycogen in the muscle vs the liver?
liver: glycogen -> glucose-6-phosphate and is released in the blood = use for the whole body's cells
muscles: glycogen->glucose-6-phosphate and stays in muscle = use for the muscle cell only
92
Which glycosidic linkage configuration allows more hydrogen bonds? Link this idea to cellulose.
beta configuration, because the -OH groups are up in one glucose and down on the other = h-bond possible between two stacked chains.
this phenomenon makes the cellulose fibers in clusters/stacked tightly together bc of the h-bonds (cellulose = B-1-4 linkages)
93
What are the functions of insulin?
1. stimulate the storage of glucose in adipose cells and in muscle cells
2. stops the breakdown of glycogen->glucose in the liver
94
What are the functions of glucagon?
stimulate the breakdown of :
1. glycogen-> glucose (in the liver)
2. proteins -> amino acids (muscle cells)
3. fats -> fatty acids (adipose tissue)
95
List the monosaccharides and the specific linkage involved for the following disaccharides: maltose,
sucrose, lactose.
lactose = made of 2 monomers galactose and glucose
maltose= made of 2 glucose monomers
sucrose = made of 2 monomers glucose and fructose
96
Describe the cause of lactose intolerance. Why can’t another enzyme fill in? What is the treatment
for lactose intolerance?
lactose = glucose + galactose
lactase = enzyme that breaks down lactose found in our digestive system.
an inherited lack of lactase = lactose intolerance
the lactose disaccharide that is undigested (bc of the lack of lactase) will pass into the large intestine. the bacteria that digest the disaccharide in the large intestine will produce gas (bloating, cramps)
also, lactose going in the large intestine creates an osmotic pull which draws water from surrounding tissue into the large intestine. this causes diarrhea
97
What is the cause of flatulence from eating legumes?
humans don't have the enzymes to fully break down the legumes' oligosaccharides in the small intestine, so they go into the large intestine, pull water from surrounding tissue into the intestine and thus create diarrhea.
the oligosaccharides get digested only by the bacteria in the large intestine which creates gas.
98
Describe the two functional classes of polysaccharides. Discuss how the overall structure for each
class correlates to its function. For instance, discuss how cellulose forms strong, elastic structural materials that resist degradation and glycogen is an efficient storage molecule that is easily
hydrolyzed.
1. energy storage
- starch
-glycogen (found in animals only) : a branched polysaccharide and formed by a alpha-1-4 and a alpha-1-6 glycosidic linkages. it has much more branching that starch, which makes it more soluble.
2. structural polysaccharides
- cellulose
-chitin (exoskeletons in insects or in fungus)
alpha glucose isomers are digestible, not the beta glucose isomers
99
For each of the following polysaccharides: starch, glycogen, cellulose, chitin, and peptidoglycan list
the functional class it belongs to, the organisms that make and use it, and its specific function in
these organisms.
starch
- energy storage
- main storage for plants
- hydrolyzed (broken down) into disaccharide maltose by enzyme amylase (found in saliva and intestine)
cellulose
- structural
- its chain is unbranched and not easily broken down.
- most animals/humans lack cellulase and cant break the beta-1-4 link
chitin
- unbranched polysaccharide
- very flexible and strong = used for surgical threads
100
What is dietary fiber? Describe its importance in our diet
group of carbohydrates, such as cellulose.
carbs that humans need to digest
humans lack the enzymes to break these carbs into monosaccharides = they cant be used for energy
fibers:
-> absorbs water = softer & larger feces = less pressure when shitting = less risks of hemorrhoids
-> lower cholesterol = less colon cancer, heart disease
-> slows down the rate of carb absorption = less diabetes, obesity
101
What polysaccharide is used for flexible surgical threads?
chitin (decomposes as incision heals)
102
Define peptidoglycans
Polysaccharides in bacterial cell walls
used in gram-staining to check infections:
-> gram-positive = lot of peptidoglycan= purple
-> gram-negative = a little of peptidoglycan= pink
103
Define a glycoprotein. Describe its structure and indicate where you find these proteins. Describe
the major functions of glycoproteins.
104
Identify the classes of lipids discussed in class (neutral, steroids and phospholipids) and summarize
their functions in organisms.
neutral fats
-> large molecule assembled from small molecules by dehydration synthesis (not a polymer!!)
-> called triglyceride = 3 fatty acids + 1 glycerol
- store energy
- insulation
- cushion for injury
steroids
-> carbon skeleton of 4 hydrocarbon rings with functional groups attached
-> 3 hexagons & 1 pentagon
-> Steroids hormones (estrogen/testosterone), vitamin D/E and cholesterol
phospholipids
-> lecithin
105
What are anabolic steroid?
group of hormones that promote muscle growth
more masculine traits but health damages
106
Discuss the different fatty acid forms.
saturated
-> no double bond = max # of hydrogen
-> solid at room temp.
monounsaturated
-> contains one double bond
-> liquid at room temp.
polyunsaturated
-> More than one double bond
-> liquid at room temp.
-> best type of lipid nutritionally
107
What is the difference between cis vs trans unsaturated fatty acids?
cis
-> double bond between 2 C
-> each C is attached to one another C and one H
-> the H is on the same side of the chain for both C
-> this gives the chain a more pronounced bend
trans
-> each H of the double bonded Carbons are on diagonally opposite sides
-> this gives the chain a less pronounced bend, more straight
108
What is the structure of fatty acids and of glycerol?
fatty acid
= long hydrocarbon (C-H) chain with a carboxyl group at one end
glycerol
3 carbon alcohol with one hydroxyl group attached to each carbon
109
What type of bond links fatty acids and glycerol together?
3 fatty acids + 1 glycerol -> ester linkages-> triglyceride (this requires 3 dehydration reactions)
110
Why does a monosaccharide have high chemical energy making it a good fuel in cellular respiration?
(The bond between which atoms can be broken?)
monosaccharides are mostly C-H and O-H bonds, which are very high in energy bonds. the C-H bonds can be broken and the energy released fuels cellular respiration and helps make ATP
monosaccharides are very stable yet reactive, which allows store energy until needed.
111
Describe the basic structure a phospholipid.
1 glycerol + 2 fatty acids
amphipathic=
1 hydrophilic head (glycerol + phosphate group + organic and polar base)
2 hydrophobic tails (2 fatty acids chain)
112
What structural differences produce a solid or liquid fat at room temperature?
unsaturated fats = bent chain = at room temp, the molecules cannot pack their chains close enough together to solidify
saturated fats = straight chain = stackable and chains can pack closely to form a solid at room temp.
113
Describe the two outcomes of hydrogenation
process where H atoms are added to unsaturated fats by hydrogenation
results :
-> makes the fat more solid at room temp.
-> converts cis bonds -> trans bonds = more straight
ex: converting liquid vegetable oils into solid margarine
114
From what molecule are steroids derived? What molecules in the body are made from steroids?
cholesterol
steroids hormones and sex hormones are made from steroids
115
Explain the digestion of triglycerides (fats).
1. emulsification of fats
-> Fat is mixed with an aqueous solution (ie. bile salts in the liver)
2. hydrolyzation of fats
-> fats are broken down into fatty acids and monoglycerides
3. absorption of fatty acids and monoglycerides
-> These can be absorbed by the inner wall of the small intestine
4. reassembling into chylomicrons
-> fatty acids + monoglyceride = lipoproteins called chylomicrons
-> Chylomicrons then enter the blood and fat gets delivered to the cells of the body
116
Describe the cycle of the digestion of triglycerides with LDLs and IDLS.
-> excess proteins and carbohydrates in the body go to the liver and get converted to fats (Very-Low-Density-Lipoproteins, VLDLs).
1. Lipoproteins exit the small intestine and get to the liver
2. exit the liver as VLDL
3. lipoproteins travel through the body in the form of IDL
4. stop at fat cells, muscle cells, etc (density of proteins increases)
5. IDLs slowly become LDLs
6. lipoproteins go back to the liver in the form of HDLS (almost only the proteins of the lipoprotein exterior are left)
117
What is the structure and function of lipoproteins?
->fatty acids + monoglycerides
-> a spherical molecule with hydrophobic interior (carries fat) and hydrophilic exterior composed of water-soluble proteins
-> a particle that carries lipids to the cells of the body through blood
-> This form is water-soluble and is the only way fats & cholesterol (insoluble) can be transported in the blood
118
Describe the functions of HDL and LDL in the human body. Describe “bad” and “good” cholesterol
and discuss its link with diet and health.
lipoproteins (LDL and HDL) transport cholesterol in the blood
LDL
-> bad cholesterol
-> causes a malformation of the plasma membrane that will create a "leak" of LDL in the blood and risk blocking arteries
-> Eating lots of trans fats (unsaturated) = more LDLs and less HDLs
HDL
-> good cholesterol
-> HDLs pick up excess cholesterol from the body and get it back to the liver = less cholesterol in the blood
-> omega-3, omega-6 fatty acids = HDLs
119
What is the name of the health issue of cholesterol blocking arteries?
atherosclerosis
120
Describe the structures that phospholipids form in water. Indicate whether an energy input is
required to form these structures.
121
What two types of lipids make up the phospholipid bilayer?
1. phosphoglycerides
contain glycerol, fatty acids, phosphate and an alcohol
2. sphingolipids
contain sphingosine (a long chain of amino alcohol) instead of glycerol
122
Which cells have a higher abundance of sphingolipids? What happens to sphingolipids in patients
with Tay-Sachs disease?
brain, nerves, lungs, spleen tissue
cell cannot produce enzyme to correctly breakdown sphingolipids = accumulation of sphingolipids in the nerve cells of the brain
autosomal recessive allele codes for this enzyme
123
Draw the basic structure of an amino acid. Identify the central carbon. Identify the four groups
attached to the central carbon. Which group is responsible for the amino acids specific properties?
1 carboxyl group, 1 amino group and 2 functional groups
The central carbon is the alpha carbon and is always bound to the carboxyl group and can sometimes be bound to the amino group.
the 2 side chains (R groups) are responsible for the specific function and properties of an amino acid
124
What are alpha and beta forms of amino acids?
alpha form: only an alpha carbon bonded to the carboxyl group
beta form: if you have a second carbon bonded to the amino group, other than the alpha carbon that means you have the beta form.
125
Why are some amino acids biological buffers? How do they maintain pH levels? What is a
zwitterion?
amino acids maintain the narrow pH range of cells.
the carboxyl and amino group can donate protons into the solution and make the solution acidic. they can also take the proton out of the solution to neutralize the acidity.
zwitterion: amino acids at physiological pH (7.4) (bc 1 negative and 1 positive end).
126
List the 3 classes of amino acids based on their chemical properties. Classify an amino acid into one
of those groups based on the chemical structure of its side chain.
nonpolar, polar and electrically charged
127
Can you recognize some of the names of nonpolar amino acids (4)
methionine
tryptophan (gives serotonin and makes you sleepy i.e:after eating beef)
leucine
isoleucine
128
What is an essential amino acid?
amino acids that animals cant synthesize
-> your body cannot make essential amino acids and synthesize them from scratch so they have to obtain it from food.
ex: asparagine in asparagus
129
Define a polypeptide and state the type of bond involved in linking monomers.
polypeptide = 2+ amino acids linked via a peptide bond
= polypeptide backbone with side chains popping out
the peptide bond is formed between the carboxyl of one aa's and an amino group of the following aa's
= bond between the N-terminus (free amino end) and the C-terminus (free carboxyl end)
130
Describe the difference between a polypeptide and a protein.
aa's linked together form a polypeptide
one twisted and folded polypeptide is a functional protein
two or more twisted and folded polypeptides are a functional protein
131
Describe the first level of protein structure
amino acid sequence
order is determined genetically
132
Describe the second level of protein structure
coiling and folding in a polypeptide chain
-> very stable structure with hydrogen bonds between amino groups and carboxyl groups
-> beta pleated sheets (fold form)
-> alpha helix (coil form)
133
Examples of beta pleated sheet and alpha helix
alpha helix
keratin in hair and nails
beta pleated sheet
globular proteins
fibrous proteins such as fibroin (silk protein made by spiders)
134
Describe the third level of protein structure
overall 3D shape
the interactions of the side chains/ r-groups determines the position of the folds ohh this 3D shape
thus, the tertiary structure is determined by the primary structure (the chemical nature of the r-groups)
135
What are the 4 types of interactions in the tertiary structure of proteins?
1. hydrogen bonds (between 2 functional groups)
2. hydrophobic interactions (many C-H non polar bonds "hide" from water and coils inward)
3. ionic bond
4. disulfide bridges
136
What are the 2 common forms of tertiary structure?
1. Globular
-> compact combinations of alpha helix et beta sheets
-> spherical
2. fibrous
-> only alpha helix
-> long and straight
137
Describe the fourth level of protein structure
association of multiple polypeptide chains
138
Discuss the relationship between protein structure and function. Explain how sickle cell disease
highlights this point.
one amino acid in the wrong position alters the function of the cell and leads to sickle-cell anemia.
139
Describe the function of molecular chaperones in cells.
transformation occurs in steps within protein complexes called chaperonins (hollow cylinder with a "cap")
chaperonins create an environment where folding occurs and eliminates any unwanted hydrogen bonds/ionic bonds. = creates a favourable environment for folding
misfolding = dysfunctional protein
140
Monomeric VS oligomeric ?
monomeric
proteins made of a single polypeptide (no 4th structure)
oligomeric
2+ polypeptide chains
141
Simple protein VS conjugated protein?
simple protein
only made of aa's
conjugated protein
contain aa's & a prosthetic group (not an aa's)
142
Define a prion. Where are they located?
= a misfolded protein that becomes an infectious agent & affect other proteins by attaching to them and forcing them to fold differently.
= untreatable and always fatal. = mistake in folding leads to death.
prions are associated with neurological disease bc they target the nervous system.
143
Define denaturation of a protein and list some environment conditions that will promote
denaturation.
disruption and possible destruction of the 2nd AND 3rd (and 4th).
= changes the normal alpha-helix and beta-sheets in a protein.
not strong enough to break the primary structure. (changing primary structure = mutation)
conditions:
- heat (disrupts hydrogen bonds and nonpolar hydrophobic interactions.)
- alcohol (auses new H-bonds to form)
- change in pH
- change in salt concentrations
144
Why do biologists want to determine the structure of proteins?
145
Describe the eight major functional classes of proteins. List some specific examples for each:
o Enzymatic
o Storage
o Chemical messenger
o Contractile and motor
o Defensive
o Transport
o Receptor
o structural
146
Enzymatic proteins
accelerate chemical rxns
sucrase enzyme that breaks down sucrose
147
Transport proteins
move substances within the body in/out of cells
hemoglobin
148
Structural proteins
provide support (in cell membrane, muscle tissue, tendons and ligaments)
collagen and elastin (skin, tendons and ligament)
keratin
149
Storage proteins
provide a source of aa's for developing embryos or infants
ovalbumin (egg)
casein (milk)
150
Contractile and motor proteins
movement
actin and myosin (muscle movement)
contractile proteins are responsible for cilia and flagella undulations
151
Receptor proteins
regulate the response of the cell to chemical stimuli
receptors of the membrane of a nerve cells detect chemical signal of other nervel cells
152
Chemical messenger
coordinate organism's activities such as hormones (endocrine system) and neurotransmitters (nervous system)
insulin
acetylcholine
153
Defensive proteins
defensive substances within the body
antibody proteins fight antigens (foreign substance)
154
Why do organisms require energy? Describe some of the types of work required in cells.
155
Describe some forms of energy and energy transformations important in life.
chemical energy:
a form of potential energy
is stored in molecules
bond energy:
form of potential energy
chemical rxn occurs-> atoms of molecules are rearranged-> chemical energy -> kinetic energy
156
Describe energy coupling in cells. What is its importance?
catabolic reactions release energy that fuels anabolic reactions.
never ending cycle where anabolic/endergonic process are driven by the energy of a catabolic/exergonic process.
ex: you eat a lot proteins, break it down (catabolic), form an energy molecule, take the ATP from the broken down proteins to form new proteins, etc.
157
What is the difference between a spontaneous and nonspontaneous biological process?
spontaneous = dont need external energy to amorce the rxn and are due to a decrease in free energy (release in energy)
non-spontaneous = need external energy to amorce the rxn
158
How does the first law of thermodynamics apply to biological systems?
conservation of energy :
- energy can be transformed/transferred but not created/destroyed
- chloroplast creates bonds in sugar molecules.
= convert light energy (kinetic) -> stored chemical (potential) energy
- mitochondria uses chemical energy (potential) in glucose, aa's and fatty acids to make ATP (potential)
- energy transfer in the food chain
- eating process
159
How does the second law of thermodynamics apply to biological systems?
Entropy is increasing:
energy transferred/transformed = more entropy/disorder released in the universe
loss of heat during energy transfers -> + entropy
ex: animal running = you're releasing energy, heat, CO2 = more disorder released in universe
160
Which characteristics of a process (such as a chemical reaction) determine whether it is
spontaneous or nonspontaneous?
G = H- TS (G more negative= more spontaneous)
delta S
-> increase in entropy = more spontaneous (large delta S)
delta H
-> exothermic rxn are more spontaneous (negative delta H)
temperature
-> large temperature increases spontaneity
161
What is the Gibbs free energy equation? What can it be used for?
delta G = G final - G start
the more order there is in a system, the more free energy there is
free energy = energy available to do work
ex: man diving:
before dive; high potential energy = less stable = higher G
during dive; lower potential energy= more stable = lower G
162
What does a negative, positive,
and zero ΔG indicates about a process?
negative = spontaneous; less energy stored at the beginning than at the end; will happen on their own ;
positive = non-spontaneous
0= system is at equilibrium
163
Explain why many chemical reactions in cells do not reach equilibrium. Compare equilibrium
concentrations of reactants and products to steady-state concentrations.
164
What is an endergonic reaction?
endergonic:
gain of free energy = non-spontaneous -> only happens if external energy or enzyme present.
ex: building larger molecules from small molecules requires an external source of energy
165
What is an exergonic reaction?
exergonic:
loss of energy; will happen on its own; spontaneously; disaccharide -> two monosaccharides;
don't need external energy, but still need enzyme
most spontaneous reactions take a long time to occur
166
Describe the structure of adenosine triphosphate
ATP (triphosphate) is made of :
1. nitrogenous base (Adenine)
2. Pentose sugar (ribose)
3. Phosphate groups (1= AMP, 2=ADP, or 3= ATP)
it is very unstable + polar.
bond between 2 phosphate groups = high energy bond bc 3 negatively charged phosphate groups repel each other, which makes it unstable and thus high in energy. the p-p bonds has a lot of potential energy stored
167
Describe the use of ATP in energy coupling
hydrolysis of ATP:
atp + water -> adp + P1 + energy (exergonic rxn)
atp acts as a mediate and links exergonic rxn to endergonic rxn OR links catabolic and anabolic rxns. atp transfers energy between these two types of rxns.
1- hydrolysis of ATP occurs
2- that energy released drives endergonic rxn
3- atp is used for cellular work
4- atp is regenerated from Pi and ADP through other processes (i.e: cellular respiration)
168
Describe phosphorylation of ATP
ATP gives a phosphate group to another molecule that becomes phosphorylated and more reactive/less stable. this will make the rxn spontaneous & release ADP + Pi.
Glucose + ATP -> Glucose-Pi + ADP
Glucose-Pi + ADP + fructose -> sucrose + ADP + Pi
this rxn has a negative total free energy
the not phosphorylated rxn has a positive total free energy
Glucose + fructose -> sucrose (endergonic)
* ATP -> ADP = exergonic
169
Is the regeneration of atp endergonic or exergonic? Why?
it is endergonic
to regenerate atp from adp + Pi, you need energy (it is a non-spontaneous rxn)
this source of energy can be provided by exergonic/catabolic rxns such as cellular respiration.
170
Comparer our body's regeneration of ATP process to the one for plants
plants use light energy to amorce the atp regeneration process.
us= cellular respiration
plants = photosynthesis
171
Describe the use of ATP for various biological work (mention the 3 types of cellular work)
ATP is used for :
1. Cellular transport
-> molecules transported across the membranes via transport proteins
2. Cellular mechanical work
-> movement of motor proteins
-> i.e : cilia, moving organelles along cytoskeleton, actin/myosin
3. Cellular chemical work
->ATP phosphorylates reactants and phosphate group is released as work is performed
172
How do redox reactions power cellular work? What are some examples of molecules that transfer
electrons in cellular respiration and photosynthesis?
electrons are transferred from one molecule (reductant) to another (oxidant).
this transfer releases energy that is then used in cellular work.
AH2 + NAD+ -> A + NADH + H+
NAD+ = reduced
it stores a lot of free energy that is then used to make ATP.
H2 = oxidized
173
What are 2 acceptor molecules in redox rxns?
FADH2 and NADH are 2 electron carriers that store high energy electrons.
in redox rxns, FADH2 and NADH donate electrons and are oxidized whereas FAD and NAD+ act as acceptor molecules and are reduced.
174
what is a reducing agent
molecule that causes another molecule to be reduced
= donates off electrons
175
what is an oxidizing agent?
molecule that causes another molecule to be oxidized
= accept electrons
176
what does it mean to be reduced (redox)?
a molecule that gains electrons and protons
177
what does it mean to be oxidized (Redox)?
a molecule that loses electrons and protons
178
In the process of NADH production, which product has gained unstable energy? which molecule is reduced? which molecule is oxidized?
NAD+ accepts electrons and is being reduced. it then forms the product NADH, which gained unstable energy by acquiring more electrons and a proton. the substrate A in AH2 is the molecule that is oxidized (loses electrons and a proton)
179
Define chemical energy and briefly explain why an abundance of non-polar bonds in organic
molecules can make them better sources of energy.
C-H bonds have high bond energies, are stable and reactive.
thus they can store energy until needed and when needed the bonds can be broken and release their high energy
180
Define anabolic pathway
anabolic: consume energy (mostly endergonic) build small -> big molecules
ex: aa's -> protein
often back and forth from catabolic to anabolic reactions and vice-versa. catabolic rxn = energy source for anabolic reactions to happen
181
Define catabolic pathway
catabolic: spontaneous and releases energy. breakdown big -> small molecules (cats = catastrophic/break everything)
ex: cellular respiration
182
Define metabolic pathway
series of chemical reactions in a cell that takes a reactant over a series of steps that gives you the wanted product (ex: cellular respiration = 12 steps pathway = glucose -> ATP)
183
Why is studying enzymes and metabolism important for understanding and treating disease?
the cell can convert energy from 1 form into another = vital to live
ex: myosin & actin convert chemical -> kinetic
184
List some types of chemical reactions that occur in cells.
redox rxns
hydrolysis rxns
dehydration synthesis
enzymatic rxns
185
Describe two events that must occur for reactants in order for chemical reactions to take place.
collisions of molecules in an effective direction
enough energy to meet the activation energy
186
Describe the two factors that can affect the direction of a chemical reaction.
concentrations of substrate and concentrations of products
(add more sucrose to the right = push to the left)
temperature
187
Describe the three factors that can affect the rate of a chemical reaction. Describe how each affects
the rate.
temperature
concentration of substrate
number of enzymes
(is this right??)
188
Define the activation energy of a reaction.
the initial energy needed to start a chemical reaction
also called free energy of activation
189
Define a catalyst and describe some characteristics of a catalyst.
unchanged by the rxn
lowers the activation energy by providing an alternative pathway
increases rxn rate
helps reach equilibrium faster, but won't change the position of the equilibrium.
190
Define an enzyme and describe its importance in life.
a type of catalyst that is a protein and that speeds up the rate of a reaction without being consumed.
no enzyme = pathways of metabolism = too slow to maintain organisms biological needs (breakdown of glucose would be too long)
191
Define an enzyme’s active site and describe its importance in the function of an enzyme. Describe
the specificity of enzymes.
the specific region of a substrate where the enzyme binds to. the rest of the protein is the "framework"
enzyme are specific ; active site's shape needs to be compatible to the substrate's shape.
192
Describe the “induced fit” model of enzyme action.
there's always an enzyme to your substrate
substrate goes to the active site and will move around and will cause the active sit to fit more snuggly around it until perfect fit.
-> active site isn't rigid.
good position = increase chemical reaction rate = becomes chemically unstable
193
List the steps of enzyme action.
1. substrate binds to active site of enzyme
2. induced fit to provide a snugglier fit between active site and substrate
3. The enzyme acts as a template that helps to orient the substrate in the right position inside the active site
2. the enzyme adds stress to the bonds within the substrate to break them down-> this lowers the Ea
3. becomes a microenvironment that is more favourable to a particular rxn, and thus speed up the rxn. facilitate the transfer of H+ to the substrate
some enzymes act as part of the rxn for a brief moment
194
Define enzyme activity and list five factors that can affect an enzyme’s activity.
1. substrate specificity
-> binding at a specific active site only
-> compatible fit between the substrate and active site
2. induced fit
-> Active site moves for a snugglier fit
3. stress
-> The enzyme stresses the substrate's molecule bonds
-> It participates in the chemical rxn for a brief moment
4. template
-> enzyme acts as a template to allow proper orientation of the substrate
5. microenvironment
-> enzyme provides a microenvironment that is favourable to particular rxns (ex: active site becomes a pocket of low pH for acidic R-groups of amino acids)
195
Define a cofactor and its role in an enzyme’s function. Differentiate between a cofactor, coenzyme, and a prosthetic group.
cofactors: any non-protein molecule that assists enzymes to catalyze their rxn
coenzymes: organic cofactors (often derived from vitamins). loosely and temporarily bound.
prosthetic group: a type of cofactor that is tightly or permanently bound to an enzyme (unlike cofactor/coenzyme that is often temporary). (??? is it right)
196
Describe the relationship between substrate concentration and the reaction rate of an enzyme- catalyzed reaction. Define saturation with respect to an enzyme-catalyzed reaction and Vmax.
increasing the substrate concentration increases the rxn rate and makes the graph curve more pronounced.
the same # of enzymes but more products -> saturation of the enzymes' active sites -> the reaction rate graph will create a plateau.
a lot of substrates = always a plateau at some point.
to get rid of the plateau, you add more enzymes
197
Sketch a graph to compare the reaction rate vs. substrate concentration for an enzyme-catalyzed reaction and an uncatalyzed reaction.
enzyme-catalyzed rxn = kinda log shaped curve
uncatalyzed rxn = linear curve which a much less drastic slope
198
Define an enzyme’s KM. Indicate what information it provides about an enzyme.
KM: susbtrate's concentration at 1/2 Vmax. it is a concentration value, not speed.
ex: Vmax =30m/s -> find the concentration at 15m/s .
indicates the affinity of the enzyme to the substrate
high KM = low affinity = bad partners (needs a high concentration of substrate to achieve Vmax)
199
Define an enzyme’s optimum temperature. Describe the effects on enzyme structure/activity above
and below this optimum value.
the preferred temperature for an enzyme is around body temperature, and ph is between 6-8 (body ph)
the rate of rxn increases as temperature increases.
increase the temperature too much = denatures the enzyme, since its a protein
-> lost of function.
10 degrees over the preferred temperature is enough to denature the enzyme, that's why on the graph it drops drastically; the range is narrow.
200
Discuss how optimum temperature and optimum pH of enzymes are adaptations in organisms.
enzymes in the stomach (pepsin) work at a ph of 2 and enzymes in the intestine (trypsin) work at a ph of 8 -> you cant Interswitch enzymes, they work at specific conditions
nervous system tells pepsin to work when food hits the stomach (= directors of how enzymes work)
201
Describe two main ways that an enzyme’s activity (or any protein) can be regulated in cells. Mention
whether regulation is fast or slow.
A) regulation once the enzyme has been made
-> fast
1. Activators
-> cofactors
-> allosteric activators
2. Inhibitors
-> allosteric inhibitors
B) Gene regulation
-> slow, but better on the long term
202
Describe enzyme activators ; cofactors and allosteric activators
Type A of regulation -> activators-> "cofactors"
- cofactors (prosthetic groups) = organic or inorganic groups
- they bind to a part of the active site of the enzyme and catalyze the reaction.
= enzyme activator
allosteric activators
- molecules that binds to the allosteric site of an enzyme
- forces the enzyme into a change in shape; into its active form
- favorizes the reaction
203
Describe competitive inhibitors
Type A of regulation -> inhibitors
= Sit in the active site and block the substrate.
binds to the enzyme
- irreversible (if the inhibitor attaches to the enzyme by covalent bonds)
- reversible (if the inhibitor attaches to the enzyme by weak bonds)
solution : increase substrate concentration = more substrate than inhibitor = find a way to get in= good
some inhibitors regulate enzymatic activity, not always harmful
204
Describe non-competitive inhibitors
type A of regulation: inhibitor
also called allosteric inhibitor
binds to a different site than the substrate; it ignores the active site.
the binding changes the shape of the enzyme.
then the active site is no longer appropriate for the substrate.
205
Describe why metabolic pathway regulation is important and why enzymes make good targets for
this regulation.
allosteric regulation:
molecules bind to an allosteric site (= other site than the active site) which changes the shape of the active site.
allosteric regulations lead to the enzyme moving in 2 conformations (active and inactive)
metabolic pathway regulation:
1. binding of a molecule to an allosteric site
2. inhibition or stimulation of enzyme's activity
3. allosteric regulation then results in 2 conformations (active enzyme or inactive)
206
Describe allosteric regulation: enzyme location
enzymes involved in the same metabolic pathway = clustered together = faster rxn
- different steps of a metabolic complex becomes a multi-enzyme complex = facilitates the transportation of the product to the next enzyme.
- multi-enzyme complex = often in plasma membrane and mitochondria
207
Describe allosteric regulation: enzyme gene regulation
-> Stop the translation/transcription to prevent the system from making too many products. this is a slow but more long-term regulation
-> type of regulation used during adaptation to new conditions
transcription at a gene is turned on = makes more enzyme
transcription is turned off = enzyme making is stopped
208
Describe allosteric regulation: enzyme cooperation
- one substrate molecule binds to an active site which affects the other active sites in the complex
- as the substrate binds to its corresponding active site, it locks all the other active sites of the enzyme into their active conformation
- this substrate "invites" the enzyme to accept additional substrate molecules.
209
Describe allosteric regulation: enzyme feedback inhibition
- method of metabolic control
- a metabolic pathway is shut off by its end-product that becomes the allosteric inhibitor
- ex: your body detects that you are making too much isoleucine, so the following isoleucine molecule made will bind to an allosteric site. the active site of the enzyme will no longer be able to catalyze the rxn. = no more isoleucine
210
Why are isotopes important in biology?
because they can be used as tracers to follow particular atoms and molecules through metabolic pathways
