🏷️ LIMITED TIME OFFER: GET 20% OFF GRADE+ YEARLY SUBSCRIPTION →
Log in
HomeClass Notes1,200,000CA670,000

BIOC 3300 Lecture Notes - Lecture 26: Thymidylate Synthase, Pyrimidine Metabolism, Thymidine Monophosphate

40 views3 pages
coffeeoyster95
4 Apr 2016
School
Dalhousie University
Department
Biochem & Molecular Biology
Course
BIOC 3300
Professor
Mc Leod Roger

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

What are the origins of the pyrimidine ring atoms: what is the difference between cpsi and cpsii in terms of the substrate they use to incorporate the amine group into carbamoyl. Study online at quizlet. com/_1am7sq: what is the. Cpsi is located in the mitochondria and uses ammonia. Cpsii is located in the cytosol and uses glutamine: what is the function of. Reductase (rnr)? deoxygenates the 2" oh to turn the ribose ring into a deoxyribose ring. Atcase (aspartate transcarbamylase) is inhibited by ctp/utp (feedback inhibition) and activated by. Cpsii is inhibited by udp/utp (feedback inhibition) and activated by atp/prpp. Omp decarboxylase is inhibited by ump (product elements of the. Phenoxy radical at tyr122 inhibition: where is the. Pyrimidines: cytidine (although it can be dephosphorylated to dcmp and then deaminated to make dump) active site located in the. Thf is oxidized to dhf in this reaction: how does. Either glutaredoxin or thioredoxin, which get their electrons from nadph: describe how.

Get access

Grade+20% off
$8 USD/m$10 USD/m
Billed $96 USD annually
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
40 Verified Answers
Class+
$8 USD/m
Billed $96 USD annually
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
30 Verified Answers

Related Documents

BIOC 3300
Final Exam
Study Guide
BIOC 3300 Study Guide - Midterm Guide: Pyruvate Dehydrogenase Complex, Glycogen Phosphorylase, Pyruvate Dehydrogenase
coffeeoyster95
BIOC 3300 Lecture Notes - Lecture 8: Acyl Carrier Protein, Acetyl-Coa, Carboxylation
coffeeoyster95
BIOC 3300 Lecture Notes - Lecture 9: Essential Fatty Acid, Carbon 15, Catabolism
coffeeoyster95

Related Questions

B-Oxidation of Trans Fats ljnsaturated fats with trans double bonds are commonly referred to as "trans fats." There has been much discussion about the effects of dietary trans fats on health. In their investigations of the effects of trans fatty acid metabolism on health, Yu and col- Ieagues (2004) showed that a model trans fatty acid was processed differently from its cis isomer. They used three related l8-carbon fatty acids to explore the difference in F oxidation between cis and trans isomers of the same-size fatty acid.

(a) Why did Yu and colleagues need to use CoA deriva- tives rather than the free fatty acids in these experiments?

(b) Why were no lower molecular weight CoA derivatives found in the reaction with stearoyl-CoA?

(c) How many rounds of B oxidation would be required to convert the oleoyl-CoA and the elaidoyl-CoA to cd,s-L5- tetradecenoyl- C oA and trans-A5-tetrade cenoyl- C oA, respectively?

There are two forms of the enzyme acyl-CoA dehydroge- nase (see Fig. l7-8a): long-chain acyl-CoA dehydrogenase (LCAD) and very-long-chain acyl-CoA dehydrogenase (VLCAD). Yu and coworkers measured the kinetic parameters of both enzymes. They used the CoA derivatives of three fatty acids: tetradecanoyl-CoA (C1a-CoA), c'i,s-L5-tetradecenoyl- CoA (cAsC,n-CoA), and trans-L5-tetradecenoyl-CoA (tAsOr4- CoA). The results are shown below. (See Chapter 6 for defini- tions of the kinetic parameters.)

(d) For LCAD, the K^ differs dramatically for the cis and trans substrates. Provide a plausible explanation for this observation in terms of the structures of the substrate mole- cules. (Hint: You may want to refer to Fig. I0-2.)

(e) The kinetic parameters of the two enzymes are rele- vant to the differential processing of these fatty acids only tf the LCAD or VLCAD reaction (or both) is the rate-limiting step in the pathway. What evidence is there to support this assumption?

(f) How do these different kinetic parameters explain the different levels of the CoA derivatives found after incubation of rat liver mitochondria with stearoyl-CoA, oleoyl-CoA, and elaidoyl-CoA (shown in the three-panel figure)?

Yu and coworkers measured the substrate specificity of rat liver mitochondrial thioesterase, which hydrolyzes acyl- CoA to CoA and free fatty acid (see Chapter 21). This enzyme was approximately twice as active with C1a-CoA thioesters as with C 1s-CoA thioesters.

(S) Other research has suggested that free fatty acids can paSS through membranes. In their experiments, Yu and colleagues found trans-L5-tetradecenoic acid outside mito- chondria (i.e., in the medium) that had been incubated with elaidoyl-CoA. Describe the pathway that led to this extramito- chondrial trans-L5-tetradecenoic acid. Be sure to indicate where in the cell the various transformations take place, as well as the enzymes that catalyze the transformations.

(h) It is often said in the popular press that "trans fats are not broken down by your cells and instead accumulate in your body." In what sense is this statement correct and in what sense is it an oversimplification?

BIOL 110 Principles of Biology

1.Describe the structure of a plasma membrane.

2.Define an amphipathic molecule and give an example.

3.Explain the difference between integral and peripheral proteins.

4.Describe the fluid-mosaic model of a membrane.

5.Identify and discuss the function of proteins located in the plasma membrane.

6.Explain the difference between glycoproteins and glycolipids.

7.Why can carbon form chemical bonds with so many elements?

8.Explain the meaning of concentration gradient as it pertains to movement of substances into and out of cells.

9.Explain diffusion and osmosis.

10.What molecule is thought to facilitate the movement of water molecules through a plasma membrane?

11.Explain the difference between active and passive transport across the plasma membrane. Provide examples that occur in the human body.

12.Explain the impact to a cell if placed in a hypertonic solution; include a definition of hypertonic solution and why the change occurs.

13.Identify a similarity and difference between facilitated transport and active transport. Do not state that both move substances across the membrane.

14.Explain the sodium-potassium pump and identify the type of membrane protein involved.

15.Identify and explain the process used by cells to secrete substances.

16.Explain the composition of a plant cell wall and how it differs from the cell wall of a prokaryotic cell.

17.Explain the plasmodesmata and identify the kingdom in which they are found.

18.Define energy and identify the two basic forms of energy.

19.Define entropy.

20.Define metabolism.

21.Explain the difference between exergonic and endergonic reactions.

22.What are coupled reactions and what roles can ATP serve in these reactions?

23.Explain the difference between oxidation and reduction reactions.

24.What is energy of activation?

25.What factors affect the speed of enzymatic reactions?

26.What is an electron transport chain?

27.What occurs at the active site of an enzyme?

28.Define enzymatic inhibition.

29.Define chemiosmosis.

30.Define vitamins and identify their function.

1. In addition to identifying the genetic material, the experiments of Avery, MacLeod, and McCarty with different strains of Streptococcus pneumoniae demonstrated that
DNA is a double helix.
DNA may be taken up by bacterial cells and be active.
DNA is present in bacteriophage T2.
eukaryotic cells may be genetically transformed.
DNA binds to the cell wall of the bacterium.
2. In order to show that DNA in cell extracts is responsible for genetic transformation in Streptococcus pneumoniae, important corroborating evidence should indicate that _______ also destroy transforming activity.
temperatures high enough to kill cells
enzymes that hydrolyze proteins
enzymes that hydrolyze DNA
enzymes that hydrolyze polysaccharides
enzymes that hydrolyze RNA
3. Based on what you have learned about the experiments conducted by Griffith and Avery and colleagues with bacteria, which of the following would result in transformation of living R cells?
Pure RNA from S cells
Cell-membrane extracts from S cells
A mixture of pure RNA and protein from S cells
Cell-free extracts from S cells
Pure protein from S cells
4. A-T base pairs in a DNA double helix
form three hydrogen bonds with each other.
are more heat-stable than G-C base pairs.
are of a substantially different length than G-C base pairs.
are not accessible to DNA binding proteins.
are chemically distinct from G-C base pairs.
5. If 23 percent of the bases in a sample of double-stranded DNA are adenine, what percentage of the bases are uracil?
27
50
0
73
23
6. The uniform diameter of the DNA structure provides evidence for
antiparallel DNA strands.
a right-handed helix.
a double-stranded helix.
3′ end phosphorylation.
purine–pyrimidine pairing.
7. If a sequence of one strand of DNA is 5′-TGACTATC-3′, what is the complementary strand?
5′-ACTGATAG-3′
3′-TGACTATC-5′
3′-ACTGATAG-5′
3′-ACTGATAG-3′
5′-TGACTATC-3′
8. What structural aspect of the DNA facilitates dissociation of the two DNA strands for replication?
3′ end phosphorylation
Purine–pyrimidine pairing
Antiparallel DNA strands
Covalent bonds between sugars and phosphate groups
Hydrogen bonding between paired bases
9. If the Meselson–Stahl density gradient experiment had resulted in two bands of DNA molecules after only one round of replication, one containing only 15N and the second only 14N, this result would have indicated that replication was
unidirectional.
dispersive.
conservative.
bidirectional.

semiconservative.
10. The nucleoside analogue acyclovir, which is used to treat herpes simplex virus (HSV) infections, lacks a 3′ hydroxyl group (–OH). Predict what will happen if the host cell DNA polymerase incorporates a molecule of acyclovir into an elongating strand of HSV DNA.
The replication complex will no longer bind to origins of replication.
The DNA polymerase will only incorporate acyclovir molecules.
Acyclovir will bind single-strand binding proteins.
DNA polymerase will not be able to link a successive nucleotide.
Acyclovir will block the activity of the DNA helicase.
11. Which of the following does not demonstrate the stability of the DNA double helix?
Single-strand binding proteins are required to keep the strands apart.
Paired bases form hydrogen bonds.
High temperatures are required to denature it.
DNA synthesis requires energy.
DNA helicases require ATP.
12. What effect would a primase inhibitor have on DNA replication?
DNA polymerase would not be able to add bases to the DNA.
Primase would be blocked from joining the DNA replication complex.
Primase would not be able to provide primers for DNA polymerases.
DNA polymerase would not be able to use DNA as a template.
There would be no effect on DNA replication.
13. To replicate their DNA in a timely manner, most eukaryotic chromosomes
normally have uncoiled DNA.
have multiple origins of replication.
contain linear molecules of single-stranded DNA.
have two replication forks that move in the same direction.
are composed entirely of DNA.
14. Which statement about DNA replication is false?
Okazaki fragments are synthesized as parts of the leading strand.
Error rates for DNA replication are reduced by proofreading of the DNA polymerase.
The sliding clamp increases the rate of DNA synthesis.
Replication forks represent areas of active DNA synthesis on the chromosomes.
Ligases and polymerases function in the vicinity of replication forks.
15. In many eukaryotes, there are repetitive sequences called telomeres at the ends of chromosomes. After successive rounds of DNA replication, the _______ strand becomes shorter. In some cells, an enzyme called _______ repairs the shortened strand.
leading; telomerase
lagging; telomerase
lagging; DNA polymerase I
leading; DNA polymerase I
leading; replicase
16. A researcher studies normal human fibroblast cells. They can be maintained in culture but die off after about 30 cell generations. Unexpectedly, a colony of cells continues to survive and divide past 30 generations. Which scenario is most likely true for these cells?
DNA polymerase is constantly active.
Primase is able to extend the telomeres.
The mismatch repair system is extra efficient.
The telomerase gene is being expressed.
The cells do not need the ends of their chromosomes.
17. If DNA polymerase III introduces an incorrect nucleotide, what is the first corrective action made by the DNA repair system?
The replication complex excises the incorrect nucleotide.
The excision repair proteins remove the incorrect nucleotide.
The mismatch repair system scans for base-pairing mismatches.
There is no correction, because nucleotide errors by DNA polymerases are not repaired.
DNA ligase connects the correct nucleotide.
18. Choose the correct order of the following four events in the excision repair of DNA:
(1) Base-paired DNA is made complementary to the template.
(2) Damaged bases are recognized.
(3) DNA ligase seals the new strand to existing DNA.
(4) Part of a single strand is excised.
1, 2, 3, 4
2, 1, 3, 4
3, 4, 2, 1
2, 4, 1, 3
4, 2, 3, 1
19. Six complete cycles of PCR should result in a _______-fold increase in the amount of DNA.
64
32
12
128
6
20. When double-stranded DNA is heated to temperatures above 90°C, it denatures. Denaturation is a process that
breaks covalent bonds.
hydrolyzes DNA.
separates double-stranded DNA into two single strands.
causes new hydrogen bonds to form.
irreversibly destroys the double helical structure.