Biochemistry - Exam 2

Front 1

What do Mb and Hb carry?

Back 1

Oxygen

Front 2

Where is Mb located?

Back 2

Myocytes

Transport of O2 through cytosol to mitochondria

Front 3

Where is Hb located?

Back 3

Erythrocytes

Transport of O2 from lungs to peripheral tissues

Transport of CO2 and H+ from tissues back to lungs

Front 4

Why does oxygen have low solubility in water?

Back 4

Oxygen is nonpolar and has little opportunities for reacting with water

Front 5

What is the oxygen carrying capacity of plasma?

Back 5

5ml O2/liter plasma

Front 6

What is the oxygen carrying capacity of whole blood?

Back 6

250ml O2/liter plasma

Front 7

What is the concentration of Hb in RBCs?

Back 7

340 g Hb/L of cytosol

Front 8

What is a simple protein?

Back 8

Polypeptide only

Front 9

What is a conjugated protein?

Back 9

Polypeptide + cofactor

Front 10

What is a cofactor?

Back 10

aka: Prosthetic Group

NON-PEPTIDE group that is essential to a protein's function

Front 11

What is a prosthetic group?

Back 11

aka: cofactor

NON-PEPTIDE group that is essential to a protein's function

Front 12

What type of protein are Mb and Hb?

Back 12

conjugated proteins --> polypeptide + cofactor (heme)

Front 13

What is the prosthetic group in Mb and Hb?

Back 13

Heme

Front 14

What is the apoprotein (polypeptide) and prosthetic group for Mb?

Back 14

apoprotein: apoMb
prosthetic: (1) Heme

Front 15

What is the apoprotein (polypeptide) and prosthetic group for Hb?

Back 15

apoprotein: (2) alpha, (2) beta
prosthetic: (4) heme

Front 16

In terms of the prosthetic group in Hb and Mb, what differs?

Back 16

In Mb, only (1) heme is present.

Hb has (4).

Front 17

Within each subunit of Hb, what is present?

Back 17

(1) polypeptide chain and (1) heme unit

Polypeptide chain can be alpha or beta

Front 18

How many subunits are needed for a functional unit?

Back 18

(4) are needed-->(4) polypeptides, each with a heme unit

Front 19

What is leghemoglobin?

Back 19

Oxygen binding protein structure found in legumes in response to infection from parasites

Front 20

How do you relate the Hb subunits to Mb?

Back 20

The (4) Hb subunits each structurally resemble the Mb as a whole.

Front 21

Within biology, what are the two types of metal bonding?

Back 21

ionic
covalent

Front 22

Describe ionic metal bonding:

Back 22

*Electrons NOT shared
*ion-ion or ion-dipole interaction
*Transient Complexes
*Examples: Na+, K+, Mg 2+, Ca 2+ (alkali metals and alkaline earth metals)

Front 23

Are ionic metal bonds long term or short term?

Back 23

Transient

Front 24

Describe covalent metal bonding:

Back 24

*Electrons shared
*Coordinate covalent bond: both electrons from other (nonmetal) atom
*Long lived
*Examples: iron, zinc, copper (transitional metals)

Front 25

What is a coordinate covalent bond?

Back 25

both electrons from other (nonmetal) atom

Front 26

Are covalent bonds short or long lived?

Back 26

Generally long lived (stable) complexes

Front 27

Describe Iron within the heme complex:

Back 27

Oxidation State: ferrous
Symbol: Fe(II)
ionic equivalent: Fe 2+
Usual coordination #: 6

Front 28

Describe Iron within the hemin complex:

Back 28

Oxidation State: Ferric
Symbol: Fe (III)
ionic equivalent: Fe 3+
Usual coordination #: 6

Front 29

What is the coordination number?

Back 29

Number of atoms nearest the metal atom.

Front 30

What is the oxidation reaction of iron?

Back 30

heme (FeII)->hemin(FeIII)+1e-

Front 31

What is the reduction reaction of iron?

Back 31

hemin(FeIII)+1e- -->heme (FeII)

Front 32

What is the organic portion of heme?

Back 32

protophyrin

Front 33

How large is heme?

Back 33

>70 atoms

Front 34

Describe the bond structure of heme and the results of it:

Back 34

*alternating double bonds
*aromatic
*planar (flat)
*pi electrons: intensely colored
*non-polar except for (2) COO-

Front 35

Is heme completely non-polar?

Back 35

No, (2) COO- are present

Front 36

Within heme, there are unpaired electrons of Nitrogen. Are they available for interaction?

Back 36

No, they are delocalized in the ring system.

Front 37

Iron is attached to ________ in heme.

Back 37

(4) nitrogens

Iron is tightly bound at center of (4) Nitrogens

Covalent bonds
->Both electrons come from N

Front 38

When iron is within heme, it is bonded to ____ atoms. It is capable of bonding to ___ more atoms.

Back 38

4, 2

Front 39

When iron is attached to heme, what state is it in?

Back 39

Ferrous - Fe(II)

Front 40

Spatially within heme, where are the two additional bonding positions on iron?

Back 40

The heme molecule is planar, the two additional bonding positions are perpendicular to this plate.

Front 41

Within heme, what are the non-polar interactions?

Back 41

Folded peptide has a pocket complementary in size and shape to heme

Front 42

Within heme, what are the coordinate covalent bond interactions?

Back 42

Coordinate covalent bond exists between a histidine side chain and iron

5th coordinate position (proximal histidine)

Front 43

At what coordinate covalent position does iron bond with the main polypeptide chain of heme?

Back 43

5th

Front 44

Within heme, what his does iron bond with?

Back 44

Proximal his

Mb - #93??
Hb - #8??

Front 45

Within heme, what ion pairing occurs?

Back 45

heme COO- groups paired with (2) cationic side chains:

*arginine (R) - 45
*histidine (H) - 97

Front 46

Where is the oxygen binding site on heme?

Back 46

On the iron atom, 6th coordination position

Front 47

How is the Fe-O bond formed?

Back 47

Fe-O bond formed via an electron pair on oxygen

Front 48

How is the distal his chain involved in oxygen binding?

Back 48

distal his binds to O2, stabilizing Mb-O2 binding

Front 49

Describe oxidation in heme:

Back 49

irreversible
e is transferred
hemin unable to bind O2 (not an O2 carrier)

When heme is bound to Mb and Hb, oxidation occurs very slowly due to inhibition by apoprotein

Front 50

What is the rxn of oxidation of heme?

Back 50

heme-O2 → hemin + O2–*

*O2- is called superoxide, it is a reactive oxygen species

Front 51

What is metHb?

Back 51

Methemoglobin

Hb or Mb with hemin instead of heme

Front 52

How does metHb occur and how is it taken care of?

Back 52

metHb naturally forms via oxidation very slowly

Heme is ferric instead of ferrous

Unable to carry oxygen

It is normally reversed via enzymes & reductants (metHb->Hb)

Front 53

What is methemoglobinia and how is it caused?

Back 53

Clinically significant build up of metHb

Causes:
*Food additives (nitrites)
*drugs (sulfonamides, some local anesthetics)
*deficiency in reversing enzymes

Treatable with reducing agents such as Vitamin C

Front 54

How is methemoglobinia treated?

Back 54

Treatable with reducing agents such as Vitamin C

Front 55

Within Mb, how much is alpha helix?

Back 55

75%

Front 56

How many alpha helix does Mb have and how are they arranged?

Back 56

8

arranged in 2 layers

Front 57

For Mb, where are the polar and non-polar side chains located?

Back 57

Polar - Exterior

Non-polar - Embedded

Front 58

What is important regarding heme and the folded structure of Mb?

Back 58

The folded polypeptide has a pocket for heme

When heme is bonded to the folded Mb protein, it is less oxidizable

Front 59

What about Hb over Mb gives it unique characteristics?

Back 59

The tetrameric structure and lack of quaternary

Front 60

When Hb and Mb go from oxygenated to deoxygenated state, how much O2 is released?

Back 60

Hb - 4 O2
Mb - 1 O2

Front 61

How do you define fractional saturation of oxygen?

Back 61

Y= pO2/[pO2+P50]

P50 - pO2 where 50% is saturated

Front 62

What is the descriptive word used to describe the shape of the graph of pO2 v. saturation in Hb and Mb?

Back 62

Hb - Sigmoidal
Mb - Hyperbolic

Front 63

For Mb, what is the p50?

Back 63

1 torr

similar to Hb

Front 64

What is the significance of p50?

Back 64

Defines O2 affinity of an O2 binder

Front 65

Does a higher p50 value correspond to higher or lower O2 affinity?

Back 65

lower O2 affinity

Front 66

Describe the affinity curve of Mb vs Hb:

Back 66

Mb has a hyperbolic shape

Hb has a sigmoidal shape

Implications:
Hb curve is steeper in middle
Hb more sensitive to changes in pO2 in middle

Front 67

What is the saturation of blood as it leaves healthy lungs?

Back 67

.98

Same in tissue arteries

Front 68

What is the saturation of blood as it leaves the tissues?

Back 68

.62

Front 69

During exercise what is the saturation of blood as it leaves the tissue?

Back 69

.26

Front 70

What is the relationship between changes in pO2 and changes in saturation?

Back 70

small changes in pO2 doubles change in saturation

Front 71

What is cooperative binding in hemoglobin?

Back 71

Binding of oxygen to hemoglobin increases affinity of molecule to bond the next molecule of oxygen

Likewise for release of Oxygen

Front 72

Define allosterism in regards to hemoglobin:

Back 72

change in one site of a structure leads to changes elsewhere in the molecule

*Increased affinity as more Oxygen binds

Front 73

What is degree of cooperativity?

Back 73

Can range from 1-># of binding sites/molecule

Front 74

How are the subunits in Hb joined?

Back 74

Via:
ionic (salt links)
H-bonds
nonpolars

Front 75

Why is Hb a dimer of dimers?

Back 75

dimer 1 - alpha1beta1
dimer 2 - alpha2beta2

Front 76

When O2 binds, how does the Hb molecule shift?

Back 76

The dimers shift relative to each other, not within though

Relative to one dimer, the other dimer:
rotates 15 degrees counterclockwise and translates .8 angstrums

Front 77

What happens to the interactions between dimers as oxygen binds?

Back 77

several intersubunit salt bridges break

Front 78

What happens during the iron movement due to O2 bonding?

Back 78

*in deoxyHb, iron is out of plane of heme, towards proximal his (dome shaped)

*O2 binds, drawing iron into heme plain

*proximal his is pulled along

*parts of the polypeptide chain attached to proximal his move as well

Front 79

As oxygen binds to hemoglobin, shifts occur and bonds break? How many and of what kind break?

Back 79

8 intersubunit ion pairs break

Front 80

Describe O2 binding energy and how it changes as more oxygen binds:

Back 80

Some O2 binding energy is used in polypeptide movement/breakage

First O2 requires more breakages-->weaker bond

Later O2 requires less breakages-->stronger bond

Front 81

What two forms does Hb exist in?

Back 81

Tense and Relaxed

Tense (T):
low O2 affinity
many intersubunit interactions

Relaxed:
high O2 affinity
few intersubunit interactions

Front 82

How does the affinity of Hb for O2 change?

Back 82

Changes with metabolic needs

Front 83

What does BPG directly do?

Back 83

BPG lowers O2 affinity by binding to deoxyHb, not oxyHb

Front 84

What state is Hb when BPG binds?

Back 84

Binds only to tense state

Front 85

Can Hb bind BPG and O2?

Back 85

No, only one of a kind

Front 86

What type of molecule is BPG classified as?

Back 86

Allosteric effector

binds at a seperate site than O2 (allosteric site)

Acts as a regulator of O2 affinity

Front 87

At physiological pH, what is the charge of BPG?

Back 87

4-5 negative charges

Front 88

How and where is BPG manufactured?

Back 88

synthesized and degraded in RBCs by side reaction of glycolysis

Front 89

How many BPG binding sites are available per Hb?

Back 89

Only 1 is available per HbT

None are available in relaxed state

Front 90

Is the BPG binding site cationic or anionic?

Back 90

Cationic

Front 91

What subunits create the BPG binding site?

Back 91

(2) beta chains

(or gamma in fetal)

Front 92

Why is Hbr have little affinity for BPG?

Back 92

The conformational changes result in the BPG being covered up

Front 93

Within Hb, what are the most important characteristics of the BPG site?

Back 93

Arrangement of cationic groups:

N-terminal of alpha-NH3+ grou

(3) basic side chains from each beta chain

Front 94

When oxygen binds, what happens to the bonded BPG?

Back 94

The ion pairing breaks

Front 95

Name some ways fetal Hb is different than adult Hb:

Back 95

BPG site differs

P50 of fetal Hb is lower than adult

No matter the pO2, transfer to fetal Hb occurs

Front 96

What are the isoforms of Hb in adults and fetus?

Back 96

HbA: alpha2beta2
HbF: alpha2gamma2

Front 97

Does HbF has lower or higher affinity for BPG, and chemically why?

Back 97

Lower

Due to fewer cationic groups at BPG site

his 143 of each betachain replaced by ser in each gamma chain

Front 98

Does Hb and Mb's affinity for Oxygen change with pH?

Back 98

Hb - YES
Mb - NO

Front 99

Describe the bohr effect:

Back 99

lowering pH increases P50, promoting O2 release, while raising pH decreases P50

Front 100

Why does the bohr effect take place?

Back 100

Increase in [H+] is due to increase in metabolism --> increase in Oxygen needs of muscles and increased Oxygen unloading

Front 101

How is some H+ removed from the tissue?

Back 101

carried by deoxyHb

Front 102

What are the (3) antagonists for O2 binding?

Back 102

BPG
H+
CO2

Front 103

For various groups, what is the affinity (pKa) based upon?

Back 103

local environment

Front 104

is H+ affinity higher for HbT or HbR, and why?

Back 104

HbT

pKa values of a few basic groups are higher on HbT than on HbR

Front 105

Does CO2 react preferentially with HbT or HbR?

Back 105

HbT is more likely to react

Front 106

What groups does CO2 react with on Heme?

Back 106

amino groups

Front 107

Where does CO bind to Hb?

Back 107

On the Oxgyen binding sites

Front 108

What are the relative affinities of Oxygen and CO with hemoglobin?

Back 108

Hb=200xs
Free Heme=25,000xs

Front 109

Within free heme, the affinity for CO is much higher than in physiological form.

Why is this?

Back 109

Steric hindrance by distal his, preventing optimal CO binding

Front 110

How much CO does it take to become fatal?

Back 110

.1% CO for ~1hr ties up ~50% of the Hb

Front 111

The dissociation of CO from Heme is catalyzed by?

Back 111

light

Front 112

Comparing T vs. R forms:

Binds?
Salt Bridges?
Temperature?

Back 112

T:
*binds H+, CO2 & BPG
*contains 8 salt links that break on oxygenation
*favored by ↑ temperature

R:
*binds O2, CO
*fewer intersubunit interactions

Front 113

What are the signs and symptoms of Sickle Cell Disease?

Back 113

*susceptibility to infection
*recurring pain
*chronic fatigue
*swollen lymph nodes
*cardiac enlargement
*kidney damage
*jaundice
*anemia
*misshapen erythrocytes

Front 114

What are the codons for HbA and HbS?

Back 114

A: GAG
S: GTG

Front 115

What are the sticky patches on Heme?

Back 115

Differing side chains on Beta chain:

HbA has a surface glu
HbS has a surface val

Front 116

What are complementary patches on Heme?

Back 116

deoxyHb (on both HbA and HbS) have surface sites complementary to the val on each Betachain

(val is substituted for the correct one)

Front 117

What has both sticky patches and complementary patches?

Back 117

deoxyHbS

Front 118

How does the aggregation occur in Sicke Cell Disease?

Back 118

deoxyHbS has both sites and so they aggregate together

binding causes precipitation as fibers

this occurs where increase in [deoxyHbS]

Front 119

Aggregation of deoxyHbS is based upon:

Back 119

aggregation rate is extremely
concentration-dependent:
proportional[deoxyHbS]10


e.g., 7%↑ [deoxyHbS] produces rate doubling

Front 120

Where does deoxyHbS increase?

Back 120

deoxyHbS increases at regions where there is a decrease in [O2]

Front 121

Is precipitation of HbS self regulating?

Back 121

No, it is amplifying, vicious cycle

Front 122

What is one positive thing of the heterozygous sickle cell trait?

Back 122

Protection against malaria

Front 123

What is the heterozygous sickle cell trait and characteristics?

Back 123

1/2 - HbA
1/2 - HbS

Protection against Malaria
Minimal SCD symptoms

Front 124

What is the treatment for Sickle Cell Disease?

Back 124

Marrow transplant - RBC progenitor cells replaced

Front 125

What is the functional relationship between oxygen binding by myoglobin and oxygen concentration?

Back 125

Y=pO2/(pO2+p50)

Front 126

What is the HbS sticky patch?

Back 126

a surface anionic side chain (glu) on b chains of HbA is replaced by a nonpolar side chain (val )

On beta chain:
glu (anionic)-> val (nonpolar)

Front 127

What is the HbS complementary site?

Back 127

also on b chains ala 70 & leu 88

Front 128

What two sites interact on HbS?

Back 128

occurs via intermolecular binding of surface val of one. HbS to a complementary site on another HbS

Front 129

What is the relationship between O2 consumed and CO2 expired?

Back 129

For each O2 consumed,
.8 CO2 is produced

Front 130

How is most O2 in blood carried?

Back 130

Bound to protein Hb

Front 131

How is most CO2 transported?

Back 131

12% is bounded to Hb in form of carbamino groups

Majoraty is soluble in H2O

Front 132

Compare the solubility of O2 and CO2 in water:

Back 132

CO2 is 20xs more soluble in water than O2

Front 133

Does O2 react with water?

Back 133

No

Front 134

Does CO2 react with water?

Back 134

Yes

CO2 (gas) <--> CO2 (liq) + H2O
<--Carbonic Anhydrase--> H2CO3 <--> HCO3-

Front 135

What is the enzyme involved in CO2 transport?

Back 135

carbonic anhydrase

Front 136

Where is carbonic anyhdrase located?

Back 136

RBC cytosol

NOT in plasma

Front 137

For every HCO3- produced, how many H+ are produced?

Back 137

1 for 1

Front 138

When attempting to measure CO2 levels, which ones are hard to measure seperate?

Back 138

CO2liq & H2CO3

Together, they are called disolved CO2

Front 139

What is dissolved CO2 composed of?

Back 139

CO2liq and H2CO3

Front 140

What is the simplified equilibrium equation for CO2 dissolving?

Back 140

CO2gas <--> disCO2 <--> H+ + HCO3–

Front 141

What is the H-H equation for CO2 dissolving?

Back 141

pH = pKa + log([HCO3– ]/[disCO2])

Front 142

What is the ratio of basic:acidic form in CO2?

Back 142

19-20

Front 143

What form of dissolved CO2 is the highest?

Back 143

HCO3-

Front 144

What are the percentages of the dissolved CO2?

Back 144

HCO3- - 84%
carbaminoHb - 12%
disCO2 - 4%

Front 145

Can dissolved CO2 levels change w/o detremental effects on health?

Back 145

Yes, pH (dissolved H+) must stay constant though

Front 146

What are some harmful effects of pH change?

Back 146

malfunction of enzymes, receptors, neurons

Front 147

How much of H+ is carried bound by buffers?

Back 147

60% is carried bound to buffers

Front 148

Isohydric carriage of CO2:

Back 148

CO2 is carried with minimal change of pH

pKa shifts of Hb side chains upon O2 dissociation
(deoxy-Hb/ HbT formation) enable Hb to bind & carry more H+

Front 149

If pH rises, what is likely to happen to excitable cells and why?

Back 149

hyperexcitability likely

due to effects on membrane proteins

Front 150

If pH lowers, what is likely to happen to excitable cells and why?

Back 150

hypoexcitability likely

due to effects on membrane proteins

Front 151

What are some important buffers in blood and their pKas?

Back 151

***buffers

Front 152

What are the important buffers for intracellular and extracellular regions?

Back 152

Intracellular:
Protein (Hb in RBC)
CO2-bicarb
Pi
Phosphesters

Extracellular:
CO2-bicarb (in plasma, protein also)

Front 153

What are (3) key things of buffers?

Back 153

Act Instantaneously

Only minimize pH changes

Are overwhelmed with continuous base or acid production

Front 154

Does ventilation adjust pH quickly or slowly?

Back 154

Quickly, usually within seconds

Front 155

What are lungs capable of excreting?

Back 155

They only DIRECTLY extrect CO2

Fixed "non-volatile" acids must be extreted by the kidneys

Front 156

Why are the lungs considered open system for buffering?

Back 156

The rate of excretion can be varied

Front 157

What basis are used for excretion of H+ by the kidneys?

Back 157

***kidney

Front 158

What are the characteristics of renal compensation to pH?

Back 158

slow (hrs->days)

permanent

Front 159

Respiratory Acidosis:

Back 159

Hypoventilation

Cause: Lung disorders

Compensation: Increased renal acid excretion

Note: [HCO3-] & pCO2 still high

Front 160

Respiratory Alkalosis:

Back 160

Hyperventilation

Cause: anxiety

Compensation: decrease renal acid excretion

Front 161

Metabolic Acidosis:

Back 161

Causes: diabetes mellitus, renal failure

Compensation: increase excretion of CO2 from lungs

Front 162

Metabolic Alkalosis:

Back 162

Cause: vomiting, antacids

Compensation: Decrease excretion of CO2 by lungs

Front 163

What are genes made of?

Back 163

DNA

Front 164

A complete copy of all DNA is in which cells?

Back 164

All Cells

Front 165

What does DNA determine?

Back 165

cellular structure and function.

Front 166

What is the diameter and length of a single round of DNA double helix?

Back 166

Diameter - 20 angstrums
Length - 34 angstrums

Front 167

What is the backbone of DNA?

Back 167

Deoxyribose Phosphate

Front 168

What is the sugar in DNA?

Back 168

Beta-D-2-deoxyribose

Front 169

On the DNA sugar, where are the hydroxal groups?

Back 169

1',3',5'

Front 170

Why is it deoxy instead of oxyneucleic acid?

Back 170

2' position has a hydrogen instead of a hydroxal

Front 171

What connects the sugars within DNA?

Back 171

Phosphate

Front 172

What are the purine bases?

Back 172

Adenine
Guanine

Front 173

What are the Pyrimidine bases?

Back 173

Thymine
Cytosine

Front 174

What is a deoxynucleoside?

Back 174

A deoxynucleoside is a deoxyribose with a base (purine or pyrimidine) attached at the 1' carbon by an N-glycoside bond

1' hydroxyl group has been replaced by a hydrogen

Front 175

What is a deoxynucleotide?

Back 175

Deoxynucleoside that is phosphorylated at the 5' hydroxyl

There are deoxynucleoside mono-, di-, and tri- phosphates

Front 176

What type of deoxynucleoside phosphates are there?

Back 176

Mono, Di-, Tri phosphates

dNTP's (where N is base [T,A,G,C])

dNTP's are relatively unstable

Front 177

DNA is a polymer of:

Back 177

deoxynucleotide monophosphates

Front 178

What is the backbone a repeating unit of?

Back 178

Repeating identical units of deoxyribose and phosphate connected by a diester linkage

Front 179

What are the ends of DNA called?

Back 179

3' (bottom)
5' (top)

called 3' and 5' hydroxals of the deoxyriboses

Front 180

How are complementary bases paired?

Back 180

Via Hydrogen bonds

Front 181

How are the phosphates within DNA arranged?

Back 181

They are arranged on the outside of the helix to maximize their distance from each other

also helps reduce hydrolysis of the phosphate ester bond

Front 182

What does cooperativity do for the DNA molecule?

Back 182

Cooperativity makes small changes in structure energetically unfavorable

Front 183

How many degrees does each base pair rotate the helix?

Back 183

36 degrees

Front 184

What type of replication is DNA?

Back 184

Semiconsurvative

Front 185

What end is the dNMP added?

Back 185

3' end via the 5'->3' polymerase

Front 186

Addition of dMNP to DNA requires how much energy?

Back 186

zero, addition of dMNP to DNA is energetically neutral

Hydrolysis of pyrophosphate drives the reaction

Front 187

What are the polymerization energetics?

Back 187

1
dATP+H20<->dADP+Pi (-7.3kcal/mole)

2
dATP+DNA<->DNA-dAMP+PPi (0)

3
PPi+H2O<->2Pi

Front 188

What is the DNA polymerase III?

Back 188

Both strands of parental DNA bind to alpha subunits of DNA polymerase III

Moving in 3'->5' direction on both templates, the polymerase places the next bases on the active sites

Fast (2000/sec)
Processive (thousands at a time)
Big (~900 kD)

Front 189

Can a DNA polymerase III start a chain?

Back 189

NO

Requires enzyme primase

Front 190

What is sequence of starting a chain?

Back 190

Enzyme primase uses the template to synthesize a primer (5 base RNA using NTPs, not dNTPs)

DNA Polymerase III uses dNTPs to add DNA to RNA primer

Front 191

What is DNA polymerase I?

Back 191

Removes RNA primer and replaces it with DNA

Does not attach it to the original DNA segment though...still has gap requiring DNA ligase

Front 192

What does the DNA ligase do?

Back 192

Connects DNA fragments

Front 193

The lagging strand contains short segments called:

Back 193

Okazaki's fragments

Front 194

The leading and lagging strands have new DNA replicated in what direction?

Back 194

The DNA is built in a 5'->3' only

==>
Both are in 5'-3' direction

Front 195

What does helicase do?

Back 195

Unwinds the double helix DNA

Front 196

What does the primase do?

Back 196

synthesizes RNA primers

Front 197

What does ssb do?

Back 197

stabilizes DNA single strand regions