Mtc Week 1

Front 1

Cystic Fibrosis

Back 1

abnormal secretion in lungs, pancreas, sweat glands; chronic pulmonary disease generally leading to death in children or young adults

Effected enzyme or protein: Chloride channel

Front 2

Lesch-NyhanSyndrome

Back 2

Effect: Neurological defects, self-mutilation, mental retardation

Effected enzyme or protein: Hypoxanthine-guanine phosphoribosyltransferase

Front 3

Immunodeficiency Disease

Back 3

Effects:

Severe loss of immune response

Effected protein or enzyme: Purine neucleoside phosphorylase

Front 4

Immunodeficiency Disease

Back 4

Effects: Severe loss of immune response (children must live in a sterile bubble)

Effected protein or enzyme:

Adenosine deaminase

Front 5

Gaucher’s Disease

Back 5

Effects: Erosion of bones, hip joints; sometimes brain damage

Effected protein or enzyme:

Glucocerebrosidase

Front 6

Gout, Primary

Back 6

Effects: overproduction of uric acid resulting in recurring attacks of acute arthritis

Effected protein or enzyme:

Phosphoribosyl pyrophosphate synthetase

Front 7

Rickets, Vitamin D-dependent

Back 7

Effects: short stature, convulsions

Effected protein:

25-Hydroxycholecalciferol-1-hydroxylase

Front 8

Familial Hypercholestrolemia

Back 8

effects: Atherosclerosis resulting from elevated cholesterol levels in blood; sometimes early death from heart failure

effected protein:

low-density lipoprotein receptor

Front 9

Tay-Sachs Disease

Back 9

effects: motor weakness, mental deterioration, often death by age 3

effected protein:

Hexosaminidase-A

Front 10

Sickle-cell Anemia

Back 10

effects:

pain, swelling in hands and feet; can lead to sudden severe pain in bones or joints and death

effected protein:

hemoglobin

Front 11

Most enzymes are ___________ globular proteins which are roughly _____________________ in shape

Back 11

soluble

spherical or ellipsoidal

Front 12

The sequence of amino acids in turn determines the folding of the protein and thus its ultimate _________________. Biological function depends on the __________________.

Back 12

3D structure

3D structure

Front 13

Proteins spontaneously fold to place most ________________________ amino acids within the core and most __________________ amino acids on the surface.

Back 13

hydrophobic (apolar)

hydrophilic (polar)

Front 14

The process of folding typically follows a hierarchical sequence in which secondary structures involving __________between peptide bond carbonyl (C=O) groups and peptide bond _____________ form first (α-__________________).

Back 14

H-bonds

amide hydrogens (>N-H)

α-helices, parallel and anti-parallel β-pleated sheets

Front 15

Formation of ____________is followed sequentially by formation of _______________, and then formation of domains and ____________.

Back 15

α-helices, parallel and anti-parallel β-pleated sheets

super-secondary structures

tertiary structures

Front 16

Association of subunits form _____

Back 16

quaternary structures

Front 17

Structural proteins, on the other hand, are often __________ with unusual and very stable structures.

examples (3)

Back 17

very elongated

α-Keratin, collagenand elastin

Front 18

collagen has an unusual _____

Back 18

sequence (X-Y-Gly)

Front 19

α-Keratin and elastin have ______

Back 19

unusual crosslinks that allow it to stretch without breaking

Front 20

oxidative damage to an inhibitor of elastin _____ contributes to __________

Back 20

degradation

emphasema

Front 21

Proteins spontaneously fold into a unique three dimensional (3D) structure _________that almost always represents the ________ free energy of all possible folding patterns.

Back 21

(native structure)

lowest

Front 22

Each amino acid (except __________) has a carboxyl group, an amino group, and a distinctive side chain (often called the R group) bonded to the ___________.

Back 22

(except for proline)

α-carbon atom

Front 23

___________ is the only amino acid without _________ because its alpha-carbon is attached to 2 hydrogen atoms and is therefore not chiral).

Back 23

glycine

optical activity

Front 24

chiral amino acids exist in either of _____________termed the D- (dextro; right) and L- (levo; left). The L- and D-enantiomers of an amino acid have ________ chemical properties in all respects except _________

Back 24

two mirror image forms (enantiomers)

identical

their solutions cause polarized light to rotate in opposite directions.

Front 25

designations D- and L- refer to the _____________, not to the direction polarized light is rotated (direction of light rotation is denoted in lower case letters: (d) and (l))

Back 25

actual structure

Front 26

All amino acids (except glycine) found in proteins are of the __________ configuration.

Back 26

L-configuration

Front 27

two broad amino acid classifications

Back 27

hydrophilic and hydrophobic amino acids

Front 28

The distinction is important because

Back 28

hydrophillics will be on outside of proteins and hydrophobics will be inside.

Front 29

nonpolar amino acids

proline is an ______________amino acid

Back 29

Methionine, Isoleucine, leucine, valine, glycine and alanine

MILVGA

imino, amino acid

Front 30

aromatic amino acids

Back 30

tryptophan, tyrosine and phenylalanine

Front 31

The aromatic side chains of these amino acids result in their having characteristic UV absorbance spectra. Consequently, protein concentrations can be estimated by their __________.

Back 31

absorbance at 280 nm

Front 32

The –OH on tyrosine is important because it can be _________________, which are important regulatory enzymes responding to _____________

Back 32

phosphorylated by tyrosine kinases

growth factors

Front 33

Several recently developed cancer drugs___________ are inhibitors of __________

Back 33

[imatinib (Gleevac), sunitinib(Sutent), sorafenib (Nexavar), and several more]

tyrosine kinases.

Front 34

Which absorbs more light at 280 nm wavelength? Put them in order from highest absorbance to lowest.

Back 34

tryptophan

tryptophan, tyrosine, phenylalanine

Front 35

hydrophobic polar amino acids can be grouped into _____ subgroups which are _______________

Back 35

two subgroups

aromatic and non aromatic

Front 36

hydrophillic amino acids can be grouped into ____ categories which are _______________

Back 36

two categories

uncharged polar and charged polar

Front 37

Uncharged polar amino acids have ___________ at physiological pH. Met is sometimes classified in this group because of _____________.

Back 37

side chains that do not ionize

the slightly polar nature of its sulphur-containing side chain

Front 38

uncharged polar amino acids

Back 38

glutamine, asparagine, cysteine, threonine and serine

Glu ACTS

Front 39

Note that the –NH2groups of asparagine and glutamine are ________ and never carry a + charge. Those side-chains are amides, not amines.

Back 39

not ionic. Their amid groupd do not have dissociable protons (they are NH2 not NH3+)

Front 40

Charged polar amino acids have side chains that can carry either a positive charge (the basic amino acids ____________)or a negative charge (the acidic amino acids _______)

Back 40

Lys, Arg, and His (+)

Asp and Glu (-)

Front 41

The pKa of a group is the pH at which it is 50% ________ and 50% __________.

Back 41

protonated

unprotonated

Front 42

The ratio of protonated (HA) to unpro-tonated (A) forms can be calculated from the Henderson-Hasselbalch Equation: __________.

Back 42

pH = pKa+ log[A]/[HA].

Front 43

Note that when the pH is _______ than the pKa, the __________; 2 pH units higher and [A]/[HA] is _____.

Back 43

one unit higher

[A]/[HA] ratio is 10;

100

Front 44

at some intermediate pH the amino acid, peptide or protein will have a net charge of zero, this is called the

Back 44

isoelectric point

Front 45

Back 45

titration curve for arginine

Front 46

pI = _____

Back 46

(pK1+ pK2)/2

Front 47

When pKa = pH __________

If you increase by 1 pH unit, you get _________

if you increase pH by 2 pH units, you get _____

What happens if you decrease by 1 unit or 2 units?

Back 47

50% prot & 50% unprot

9% prot & 91% unprot

1% prot & 99% unprot

The opposite relationship exists, where you increase the protonated species in similar proportions.

Front 48

methionine and cysteine are the only two amino acids with ______. They have unique______

Back 48

Sulfer

sensitivities

Sometimes methionine (always the starting amino acid) can become oxidized which impairs its function.

Front 49

The ______ or sulfhydryl group of cysteine can spontaneously _____ to form a _______two cysteine residues within a protein.

When linked cysteine residues are called cystine

Back 49

thiol

oxidize

disulfide bond, linking

Front 50

Disulfide bonds are important in stabilizing the circulating peptide hormone ____________

Back 50

insulin

Front 51

Two features of a peptide bond limit the number of conformational states possible for a polypeptide:

Back 51

The strong electronegativity of the carbonyl oxygen relative to the amide nitrogen within the peptide bond and create resonance by delocalizing electrons.

&

For each peptide bond, the R groups of the two adjacent amino acids could exist in either a cisor transconfiguration

Front 52

one of the amino acid resonance structures make a double bond character between the C-N- making amino acids _______ about _____ of the time

Back 52

planar, with little rotation

40%

Front 53

the two bonds flanking the alpha-carbon of each amino acid are _________, limited only by possible _________. Their orientations are referred to as __________.

Back 53

relatively free to swivel

steric hindrance between atoms of the polypeptide chain and R groups

phi (; N-C) and psi (; C-C) angles.

Front 54

he sequence of amino acids in a protein contains all of the information necessary for _______________________

Back 54

it to fold into its final, native 3D shape

Front 55

What influences protein folding - major one

Back 55

1- Hydrophobic forces have a large role in driving folding(i.e., apolar side chains of amino acids associate with each other because their exposure to water is energetically very unfavorable).

Front 56

The right-handed alpha helix is a secondary structure. It contains ____residues per turn and is stabilized by hydrogen bonds between the carbonyl and the amide proton of amino acid i+4. The H-bonds are parallel to the helix axis and the amino acid side chains (R groups) project __________ Significant R group steric hindrance destablizes alpha helices having a left-handed screw sense. Alpha helices on the surface of a protein are ______.

Back 56

3.6 (5.4 A in height)

radially outward, minimizing steric repulsion

amphipathic

Front 57

The beta pleated sheet is distinguished from the α-helix by being stabilized by H-bonds running between _____ parts of the polypeptide chain.

Hydrogen bonds are ________ with the beta sheet. _________ alternately project above and below the plane of the sheet. Beta sheets often form ___________

Back 57

carbonyl oxygen atoms and amide protons of non-contiguous

co-planar

Side chain R groups

the hydrophobic core of proteins

Front 58

The ring structure of ___________ prevents it from forming the H-bonds required for α-helices or β-pleated sheets. So it's found ____________

Back 58

proline

where secondary structures end.

Front 59

Ramachandran was the first to notice the limitation of ________ and plots of favored combinations bear his name.

Back 59

psi and phi bonds

Front 60

secondary structures to make stable associations with one another (e.g., folding over on top of each other). These are called __________

Back 60

super-secondary structures

Front 61

Domains are the smallest ____________ of protein structure and they often account for a particular part of an ______________ or they may even catalyze one part of a complex reaction sequence.

Back 61

thermodynamically stable units

enzyme’s active site

Front 62

Tertiary structure is the term that describes the final thermodynamically stable structure of a single polypeptide chain (___________, then that is the tertiary structure)

Back 62

if there is only one domain

Front 63

an example of a metamorphic protein is ______

an immunological signaling protein that induces _____________

Back 63

human chemokine lymphotactin,

leukocyte migration

Front 64

Fibrous proteins are characterized by sequences rich in ________ and by regular, repeating secondary structural elements. examples:

Back 64

specific amino acids

alpha keratin, elastin, collagen

Front 65

α-Keratin: α-Keratin, the primary component of _________, consists of two ___________ α-helices that are intertwined in a ___________ called an α-coiled coil

Back 65

hair an nails

right handed

left handed super coil

Front 66

the most abundant protein in the body

Back 66

collagen

Front 67

A typical collagen molecule is a long, rigid structure in which ______________

Back 67

three polypeptides are wound around each other in a rope-like triple helix.

Front 68

The individual collagen chains (called α-chains) are _______________helices

They are wound into a _____________helix

Back 68

left handed helices (not alpha helices!!!!)

right handed triple

Front 69

Collagen is rich in _________and each plays an important role in triple helix formation. The ____ stack along the outside of the helix giving it rigidity. __________ having ______ is found at every ________ position of the polypeptide chain so that it can fit into the restricted central space where the three strands come together.

Back 69

proline and glycine

proline rings

glycine

Smallest R group

3rd

Front 70

In X-Y-Gly- the X is often _______ and the Y is often _______________or _____________

Back 70

proline

hydroxyproline or hydroxylysine

Front 71

the two Y molecules are formed after their incorporation into the polypeptide chain and serve to stabilize the triple-helical structure. The enzymes that catalyze the hydroxylation reactions require _______________, a deficiency of which results in __________.

Back 71

ascorbate(vitamin C),

scurvy

Front 72

The symptoms of scurvy () are due in part to the decreased _________________.

Back 72

bleeding gums

tensil strength of their collagen

Front 73

vitamin c deficiency can have physical ramifications as seen in scurvy (2 examples)

Back 73

poor gums

easy bruising

due to inability to make hydroxyproline and hydroxylysine for collagen.

Front 74

alcoholics and food fadists in the US sometimes get _________

Back 74

scurvy

Front 75

after synthesis, post translational modification and triple helix assembly, the almost ready collagen molecule is called ______ before leaving the cell.. Once secreted out, the N and C proterminal peptides are cleaved and its called ________

Back 75

procollagen

tropocollagen

Front 76

___________ is a connective tissue protein with rubber-like properties that is found in ________.

Back 76

Elastin

the lungs, large arterial walls, and elastic ligaments

Front 77

Elastin is comprised predominantly of ____________. It's also rich in ________________ NOT___________________

Back 77

small, nonpolar amino acids(e.g., glycine, alanine, and valine)

proline and lysine but not hydroxyproline or hydroxylysine.

Front 78

Elastin precurser

Back 78

tropoelastin

Front 79

In elastin _____________________residues crosslink with ________________

In collagen __________________ residues cross link as well but not as much- it mostly links due to R group interactions

Back 79

allysine and lysine

allysine and lysine

Front 80

example of a crosslinked elastin

Back 80

desmosine

Front 81

_____________is a small protein that inhibits a number of proteolytic enzymes in bodily fluids.It inhibits _______________.

Back 81

alpha1-antitrypsin (alpha1-AT)

elastase

Front 82

alpha1-AT (inhibits what inhibits elastin) contains a methionine residue that is essential for binding to target proteins (________). Elements in cigarette smoke cause the oxidation of this Met residue, which renders it unable to bind and inactivate elastase. So cigarette smokers can develop

Back 82

elastase

emphysema even if they have no mutant α1-AT alleles

Front 83

Back 83

Oxidants in cigarette smoke convert a methionine residue (left) of α1-AT to methionine sulfoxide (right). With that change α1-AT is no longer an effective inhibitor of elastase.

Front 84

O2 binding to Hb is cooperative such that binding of each O2 molecule to the tetramer increases the affinity with which tO2binding to Hb is cooperative such that binding of each O2molecule to the tetramer increases the affinity with which the next O2binds__________binds. This is also true for dissociation (the release of one decreases affinity and leads to the release of more)

Back 84

the next O2 molecule

Front 85

The cooperative binding curve greatly supports the release of ___________ into __________

Back 85

O2 into tissues

Front 86

The affinity of Hb for O2 is decreased by _______

Back 86

H+ (lower pH),

CO2,

2,3-diphosphoglycerate (DPG)

and increasing temperature (fever)

Front 87

Sickle cell disease is an inherited mutation of the __________ gene causing a change from _______ to _________________.

Back 87

β-globin gene

Glu

Val at position 6.

Front 88

Hemoglobin (Hb) is a tetramer comprised of

Back 88

2 alpha subunits (from 2 alpha genes)

(chromosome 16)

and 2 beta subunits from one beta globin gene

(chromosome 11 )

Front 89

O2 has very ____________ in plasma (the non-cellular part of blood). As a consequence,________of the O2 that reaches tissues is carried in ___________ bound to _____________.

Back 89

low solubility

>98%

reb blood cells

hemoglobin

Front 90

_______________ contain ________________which catalyzes the rapid reversible hydration of _______ to ________ (H2CO3). H2CO3 then rapidly and spontaneously dissociates to __________(HCO3-) and a H+.

Back 90

RBCs

carbonic anhydrase

CO2

carbonic acid

bicarbonate

Front 91

CO2 and, especially, HCO3- are ________ in ________and most of the CO2 made in tissues returns to the ___________ as those species.

Back 91

soluble

plasma and RBC cytosol

lungs

Front 92

Hb carries more than 98% of O2 where it needs to go but only about ______ percent of CO2 back to the lungs

Back 92

14%

Front 93

The alpha and βsubunits of hemoglobin have similar ___________. Both subunits are evolutionarily related to ________, a monomeric protein abundant in muscle that is designed to store O2

Back 93

sequences and tertiary structures

myoglobin

Front 94

Note that ________is the ________ form of iron that is capable of binding O2; Fe3+ is the _________ form of iron that cannot bind O2and is present in an inactive form of hemoglobin called _______________.

Back 94

Fe2+, ferrous

ferric

methemoglobin

FERRICK makes ya sick! ferrous works best

Front 95

what is significant about this chart

Back 95

This chart shows that at pO2 pressures where myoglobin has a high affinity for O2, hemoglobin has a much lower. This is why hemoglobin can release O2 to resting and working tissues.

Front 96

whats significant

Back 96

fetal hemoglobin has a higher affinity for O2 at =PO2

increase PCO2, increase in temp and deccrease in pH lowers Hb affinity for O2 *shifting the curve to right.

Front 97

Carbon monoxide (CO) has a much higher affinity for Hb than does O2. When bound to the heme group of one subunit, it causes all four subunits to “lock”in the R conformation. What effect would this have on O2delivery?

Back 97

This would cause the R locked heme groups to hold on tight to their O2 and not release it in the tissues.

Front 98

Metabolically active tissues need more _______; they generate more __________ which causes hemoglobin to release its O2

Back 98

O2

CO2 and H+

Front 99

2,3-Bisphosphoglycerate is a negative effector. • A single 2,3-BPG binds to a _____________ and stabilizes it by interacting with __________.

Back 99

a central pocket of deoxyhemoglobin

three positively charged aa of each β-chain

Front 100

Fetal hemoglobin has 2 α and 2 chains

Back 100

γ

Front 101

The binding affinity of fetal hemoglobin for _________ is significantly lower than that of adult hemoglobin

Back 101

2,3-BPG

Front 102

Without O2 bound, the heme Fe2+ is __________ the plane of the ___________ by a _______ residue of the Hb polypeptide chain (a His ring N is bound to the Fe2+). When O2 binds, it ________ the plane of the ring and that moves ___________ and its whole section of the polypeptide chain.

Back 102

pulled away from, porphyrin ring, His

pulls the Fe2+ back into

the His residue

Front 103

DPG--HHb--CO2 +O2 <--->?

Back 103

HbO2 + CO2 + DPG + H+

That is, protons (H+), CO2, and 2,3-diphosphoglycerate (DPG) ALL can bind to Hb and reduce its affinity for O2(i.e., if CO2, H+and DPG are high, the equilibrium shown is driven to the left and O2comes off Hb). Correspondingly, if O2is high, then the equilibrium is driven to the right and H+and CO2and DPG will dissociate from Hb as O2binds

Front 104

H+and CO2are ________________effectors that decrease the affinity of ______ for O2. They are heterotropic because they __________; negative because they decrease affinity for O2; and allosteric because they bind to a site other than the O2site(s) affected.

Back 104

heterotropic negative allosteric

Hb

are not O2

Front 105

The reciprocal relationship between O2 and H+ binding is termed the Bohr effect or ________

Back 105

isohydric shift.

Front 106

Changes in H+ binding result from a shift in the ______________ due to microenvironment effectstriggered by ________________.

Back 106

pKa of specific residues (mostly histidines)

conformational changes in the hemoglobin molecule

Front 107

2,3-DPG binds to a specific site in a central cavity between the_________.

Back 107

βsubunits.

Front 108

lots of _______________ charges on 2,3-DPG allow it to bind to __________________________.

Back 108

negative

positively charged groups of Hbβ-chains

Front 109

There are 2 important things to notice about the effect of 2,3-DPG on the O2 binding curves shown in the figure. First, ______________, Hb would be much more like myoglobin and nearly useless for delivering O2 from lungs to tissues. 2,3-DPG stabilizes _________-state, making it easier for Hb to release O2. Second, 2,3-DPG levels increase at high altitudes.

Back 109

without any 2,3-DPG,

the T

Front 110

Hemoglobin Milwaukee (Hb M) is a rare dominant mutation of the β-subunit (Glu replaces Val at amino acid _________). The change allows the Fe to be more easily oxidized and affected patients have high levels of MetHb (15-30%). Few consequences in everyday life.

Back 110

67

Front 111

Hemoglobin is caused by a point mutation in the adult β-globin gene that causes substitution of valine (Val) for glutamic acid (Glu) at amino acid ____. So patients RBCs containing mainly________, which is comprised of two normal adult alpha-globin subunits and two ______ subunits. The amino acid at position 6 is on the surface of the β-chain and it should be a ____. Valine is _____ and its presence creates a sticky patch on deoxyHbthat leads to polymerization of Hb tetramers into long chains.

Back 111

6

hemoglobin S (HbS)

sickle adult β-globin

hydrophilic amino acid (Glu is)

hydrophobic

Front 112

what structural changes lead to a shorter erythrocyte half-life and chronic hemolytic anemia?

Back 112

The replacement of val by Glutamine (nonpolar) makes the surface of beta globin chain sticky and cause a fibers and the erythrocyte to sickle- this leads to....

Front 113

A critical contact is made by the β6 VAL of one molecule and a hydrophobic acceptor pocket of the βsubunit of another molecule formed by Leu88 and Phe85 surrounded by hydrophilic residues. The presence of a __________________in HbA prevents this interaction.

Back 113

charged amino acid (Glu)

Front 114

___________________ HbS forms insoluble polymers]

Back 114

Deoxygenated

Front 115

__________ inhibits polymerization owing to a GLU residue at position 87 of the __________, which prevents a critical lateral contact in the sickle cell fiber. HbF decreases with post-partum age but varies from ______ of total Hb in sickle cell individuals.

Back 115

HbF

gamma chain

1-30%

Front 116

Sickling leads to Membrane Distortion leads to Ca2+-leakage

The Gardos Effect: increased intracellular Ca2+activates the Gardos channel leads to export of K+

Loss of _____________ leads to dehydration leads to [HbS]

Back 116

K+, Cl-and H2O

Front 117

_________________, an antitumor drug, is currently the only drug in widespread use for the treatment of sickle cell anemia. It stimulates _______production.

Back 117

Hydoxyurea

fetal hemoglobin

Front 118

an imbalance in the concentration of alpha -globin or β-globin chains

Back 118

Thalassemias

Front 119

alpha thalassemia is normally asymptomatic. beta thalesemias can affect _________

Back 119

chain termination, transcription activation, and RNA processing.

Front 120

substituting Lys for glutamine at position 6 on the b globin gene creates the ______ allele which is found with the __________allele causing _____________ in patients

Back 120

HbC

HbS

HB Sc disease ( a milder form of sickle cell)

Front 121

only difference betwen thymine and uracil is

only difference between cytosine and uracil is

Back 121

Thymine has a methyl group at on C5

cytosine has nh2 coming from c 4 position instead of a double bonded O like thymine and uracil

Front 122

deoxyribose and ribose differ at _______

Back 122

C2

Front 123

The antibiotic ______________ (produced by Streptomyces antibioticus) binds to DNA duplexes, thereby interfering with the action of enzymes engaged in replication and transcription. It is an anti-cancer drug commonly used in the treatment of pediatric malignancies such as_______________________

Back 123

actinomycin D

Wilms' tumour, Ewing's sarcoma and rhabdomyosarcoma

Front 124

Two helical polynucleotide chains coiled around a common axis that run in __________ directions, resembles a twisted ladder structure

Back 124

antiparallel

Front 125

The planes of the DNA bases are“stacked” _____________ to the helix axis. ______________ helps stabilize double helix.

Back 125

perpendicular

Stacking resonance

Front 126

DNA Helical structure repeats after ______ residues at intervals of ______ angstroms.

Back 126

10.5

36

Front 127

N------O bond length between nitrogenous bases is ALWAYS _______

Back 127

Spacing constant: 2.9 A

Front 128

DNA melting can be monitored spectrophotometrically at 260 nm due to a ___________ that occurs upon base stacking annealed DNA

Back 128

hyperchromic shift

Front 129

DNA molecules can be______________.Linear and circular DNA have very different topological properties.

Back 129

linear, relaxed circular, or supercoiled circular

Front 130

Positive supercoiling of DNA occurs when the right-handed, double-helical conformation of DNA is twisted even tighter (twisted in a right-handed fashion). Negative supercoiling, on the other hand, involves twisting against the helical conformation (twisting in a left-handed fashion), which preferentially underwinds the helix at low twisting stress, and knots the DNA into negative supercoils at high twisting stress. Negative supercoils favor ____________________

Back 130

local unwinding of the DNA, allowing processes such as transcription, replication and recombination-DNA in cells is typically somewhat negatively supercoiled.

Front 131

topoisomerases type 1s : ATP independent

Back 131

1) cleaving one strand of DNA
2) passing a segment of DNA through the break
3) resealing the break.
4) DO NOT need energy donors (ie, ATP-independent)

Front 132

type 2 topoisomerases (ATP needed):

Back 132

1) two strands are cleaved2) the DNA is passed through the break3) the break is resealed.

Front 133

chromatin condensation is associated with

Back 133

phosphorylation

Front 134

Actinomycin D is

Back 134

An anticancer drug that intercelates with the minor groove of DNA to interfere with its transcription and translation

Front 135

Uracil and cytosine differ at the ____ position. There, cytosine has a substituted amid group instead of a _________

Back 135

4' position

Double bonded oxygen

Front 136

Uracil and thymine differ at the ____position. There, thymine gas ________ instead of just a hydrogen like uracil has.

Back 136

5' position

Methyl group

Front 137

Adenine and Gaunine differ in two places, at 2'(bottom left) and _______(top of the six membered ring). At the 2' guanine has an amid branch, Adenine has a hydrogen. At the top of the six mbrd ring, Adenine has _________ and Gaunine has a _____.

Back 137

6' position

An amid

Double bond O

Front 138

The major groove of the RH B form of DNA is _______ angstrums. The minor is _______

Back 138

12

Half @ 6 angstrums

Front 139

Streptomyces antibioticus makes ______

Back 139

Actinomycin. An anti cancer drug that binds minor DNA groove and interferes with replcation and transcription enzyme action

Front 140

Used in treatment if wilms tumor, Ewing sarcoma and rhabdomyosarcoma

Back 140

Actinomycin D

Front 141

The nucleotide rings are aligned ________ the phosphate backbone

Back 141

Perpendicular ....this is why there is "stacking resonance" in intact dna

Front 142

Assembly of preinitation complex (closed process) is the _________ of transcriptional initiation and transcription.

Back 142

Rate determination step