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Biology 1001A Lecture Notes - Lecture 9: Dna Repair, Ketone, Thymine

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School
Western University
Department
Biology
Course
Biology 1001A
Professor
Tom Haffie

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Document Summary

Most of your cells most of the time are not even in the cell cycle, they are not replicating. Most of the time they are just doing their task in the body g0. In the cells that produce gametes (primarily in males) Cells replicating to maintain tissues that are getting worn away. In the cork cambium trees grow out comes from marry stem. Single nucleotide polymorphisms (single base pair differences) Copy number variation: we believe we have two copies of all of our genes (one from mom, and one from dad) but we don"t, our genome is very variable in copy number sequences. Venter was different in 300 variants because of mobile elements. The smallest known sequence that can move by itself is called an insertion sequence in bacteria. Codes only for its own mobility transposase enzyme which allows is to move. If two insertion sequences are side by side, they can move the dna between them.

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Summary

please!

Multipotent versus restricted

Morphologically detectable neural crest cells usually are first observed as the cells individualize and delaminate upon emigration from the neural tube, following their epithelial to mesenchymal transition (EMT), in which they convert from a tightly adherent sheet of cells to a dispersed and more individual mesenchymal population. Prior to EMT, however, it is difficult or impossible at most axial levels and in most species to distinguish presumptive neural crest cells from cells that will form dorsal neural tube derivatives. However, there are exceptions, such as a subpopulation of cranial neural crest cells in chick and mouse that appears to be set aside and morphologically distinct at midbrain levels. In addition, some species such as axolotl have a clearly segregated population of neural crest cells that exists as a ridge on the dorsal neural tube.

A long-standing debate in the neural crest literature has been whether neural crest cells are multipotent and/or restricted in their developmental potential. In other words, can a single neural crest precursor form only one type of derivative or are the cells multipotent and able to produce multiple derivatives. Single cell lineage experiments (Bronner-Fraser and Fraser, 1988), in which individual cells within the chick dorsal neural tube are labeled with vital dye, show that some of the labeled clones contribute to multiple differentiated cell types in the periphery, including melanocytes, sympathetic and sensory ganglion cells. Thus, the original precursor was “multipotent” in its developmental potential to form neural crest derivatives. In addition to neural crest derivatives, single dorsal neuroepithelial cell also give rise both to migrating neural crest cells and cells that remain in the dorsal neural tube, such as roof plate cells and dorsal sensory neurons and/or interneurons. This suggests a shared lineage between the neural tube and neural crest, at least at this stage. However, labeling migrating neural crest cells in vivo also produced clones that could contribute to more than one neural crest lineage (Fraser and Bronner-Fraser, 1991), again supporting the idea that some of the migrating population retained multipotency.

Clonogenic culture of neural crest cells cultured shortly after their emigration from the neural tube definitely shows that many early migrating neural crest cells are multipotent in vitro as well (Baroffio et al., 1988, Calloni et al., 2007, Calloni et al., 2009, LeDouarin et al., 2008a, LeDouarin et al., 2008b, Sieber-Blum and Cohen, 1980 and Stemple and Anderson, 1993). Exposure to different growth factors can profoundly influence their lineage decisions (e.g. Lahav et al., 1998). Furthermore, they have a capacity for self-renewal, at least for a few cell divisions (Stemple and Anderson, 1993 and Trentin et al., 2004).

The fact that individual neural crest cells can form multiple derivatives has led to the idea that they have stem cell properties. Stem cells are defined as individual progenitor cells that can generate one or more specialized cell types. A cardinal feature of stem cells is their ability to self-renew, that is, to divide so as to give rise to at least one daughter cell that maintains the multipotent character of its parent. The fact that cloned neural crest cells have a limited ability to self-renew has led to the idea that they are stem-like (progenitors) cells rather than true stem cells. Interestingly, however, neural crest stem cells can be derived from adult tissues (Fernandes et al., 2008 and Shakhova and Sommer, 2010; see Chapter Dupin and Sommer), suggesting that they can remain quiescent for long periods of time or maintain long term self-renewal ability when left in situ.

The presence of some multipotent neural crest precursors cannot, however, rule out the possibility that other precursors may be more restricted in their developmental potential. In fact, experiments in zebrafish suggested that neural crest cells contribute to different sets of derivatives accordingly to their migration order (Raible and Eisen, 1994). However, if the leader cell was ablated, the next cell in line took up the fate that would have been filled by the ablated cell (Raible and Eisen, 1996). Similarly, early migrating neural crest cells normally exhibit a broader range of derivatives than later migrating cells; however, when the early population is ablated and replaced by late migrating cells, the late migrating cells assume a broader developmental potential than that prescribed by their normal fate (Baker et al., 1997). This raises a very important issue: that developmental potential is greater than or equal to a cell's normal fate. Only by challenging the cell by putting it into a new environment can one test for restriction of cell fate. This is best exemplified by experiments in which the potential of neural crest populations was challenged by performing heterotopic transplants between different axial levels (LeDouarin and Teillet, 1974), such as exchanging cranial and trunk, or vagal and trunk populations. The results demonstrate a combination of flexibility in cell fate and some axial level-autonomous characteristics. For example, cranial neural crest cells normally make cartilage and bone of the face whereas trunk neural crest cells do not. Transplantation of cranial neural folds to the trunk results in production of many normal trunk derivatives, as well as the formation of ectopic cartilage nodules (Le Lievre et al., 1980 and LeDouarin and Teillet, 1974). Conversely, transplantation of trunk neural folds to the head results in contributions to cranial neurons and glia of cranial ganglia, but not to cartilage, although some connective tissues and pericytes derive from this graft (Nakamura and Ayer-le Lievre, 1982). This reveals some flexibility in fate, but a more limited ability to form skeletal derivatives (LeDouarin et al., 2004). However, trunk neural crest cells can form cartilage in vitro under appropriate culture conditions (Calloni et al., 2007 and McGonnell and Graham, 2002). Because challenging prospective neural crest fate is a difficult experiment, it is much easier to prove multipotency than restricted cell fate, leaving the question of whether or not there are lineage-restricted neural crest precursors still open to debate (see Krispin et al., 2010).

1. Anemia is the general term for conditions that result in theblood not being able to carry enough oxygen to the tissues in thebody. This can be due to a person's inability to produce enoughnormal hemoglobin molecules and/or red blood cells.

Which type of anemia is due to a decrease in red blood cellproduction because of a vitamin B12 deficiency?

Select one:

a. sickle cell anemia

b. pernicious anemia

c. iron-deficiency anemia

2. Which is the most common blood type in the US?

Select one:

a. A

b. B

c. AB

d. O

3. Which of the following is found in plasma?

Select one or more:

a. vitamins

b. red blood cells

c. hormones

d. platelets

e. all of the above

4. Cells that can differentiate into any of the formed elements(red blood cells, white blood cells, platelets) are celled Answercells

5. Eosinophils and monocytes are involved in allergicreactions.

Select one:

True

False

6. Hemoglobin is the molecule that floats around in blood andcarries oxygen molecules to the tissues in your body.

True or false: Oxygen binds to the iron in the hemoglobinmolecule.

Select one:

True

False

7. Hemolytic disease of the newborn can happen during a woman'sfirst pregnancy where the mother is Rh- and the fetus is Rh+.

Select one:

True

False

8. Leukemia is cancer of the white blood cell. It is the resultof an abnormal white blood cell multiplying uncontrollably. Why isit so letal? Because it takes over the red bone marrow and doesn'tallow normal red blood cells, white blood cells and platelets toform.

True or false:

Without enough red blood cells, you can't bring oxygen to thetissues in your body.

Without enough platelets, you won't be able to form clots, forinstance, to stop you from bleeding when you get a cut.

Without enough normal white blood cells, you cannot fightinfections properly.

Select one:

True

False

9. The neutrophil is the first white blood cell to arrive at thesite of an infection.

Select one:

True

False

10. Blood clots serve to stop a person from bleeding, forinstance, when they get a cut (a blood vessel is broken open). Whena blood clot forms in an unbroken blood vessel, it is called anembolus; when the embolus breaks free from the wall of that bloodvessel, it is called a thrombus.

Select one:

True

False

1. Diseases are those abnormal conditionsin which the bodys defensive cells fail to make the self versus thenonself distinction correctly, and attack the body's owntissues.
A. Cancerous
B. Septic
C. Autoimmune
D. Nondiscrete

2. Which of the following determinesgenetic sex (male or female) in mammals?
A. the acrosome of the sperm
B. the temperature of the developing fetus
C. the SRY gene on the Y chromosome
D. the genetic makeup of the parents
E. the Y chromosome contained in the egg

3. Which of the following regardingantigens is true?
A. Antigens can only be recognized by their specificity.
B. An antigen is a molecule which promotes a general immuneresponse.
C. A large antigen is likely to have many different epitopes, eachof which can stimulate a distinct immune response.
D. The most effective antigen are small simple amino acidcomplexes.
E. Bacteria do not contain antigens.

4. All of the following are defensemechanism employed by vertebrates except

A. negative test, as in, not findingself-markers.

B. change in chromosomal composition

C. positive test to recognize presence ofnonself-markers

D. specific antibodies.

E. skin and mucous membranes asbarriers.

5. The immune system depends on thefunction of ______, which include several types of phagocytic cellsand two kinds of lymphocytes.

A. platelets

B. leukocytes

C. target cells

D. erythrocytes

6. In comparing the kidneys of marine andfreshwater fish, which of the following is not true?

A. Freshwater fish fluids have a greaterosmotic concentration.

B. Marine fish excrete many of the divalentcations through the anus.

C. The flow of the filtrate is faster inmarine fish.

D. The urine is less concentrated infreshwater fish.

E. Marine fish drink greater quantities ofwater.

7. The kidneys of which one of thefollowing are so highly efficient that it never has to drink waterand can obtain all of its water from its food?

A. desert lizard

B. camel

C. pocket moue Perognathus

D. kangaroo rat

E. gerbil

8. Select the incorrect statement regardingthe temperature of the immune system.

A. Interleukin-1 is a pyrogen, which cancause the neurons in the hypothalamus to raise the body'stemperature, producing a fever.

B. Fevers cause the liver and spleen tostore sodium and potassium which bacteria need for their growth andmetabolism.

C. Fevers above 105 ° F can be fatal.

D. Fever contributes to the body's defensesby stimulating phagocytosis.

E. When macrophages encounter invadingcells, they release interleukin-1, which is carried to the brain bythe circulatory system.

9. Which of the following is not amechanism to prevent polyspermy?

A. change in membrane otential of egg

B. vitelline envelopes lift off surface ofegg

C. sperm nuclei degraded inside eggallowing one to fuse

D. cortical granule enzymes remove spermreceptors from egg

E. altering composition of exterior eggcoat

10. Which of the following cells have anincorrect function?

A. neutrophil---important antigenpresenting cell

B. eosinophil---important to theelimination of parasites

C. mast cell---releases histamine

D. macrophage---phagocytic cell

E. monocyte---precursor of macrophage

11. Which part of the antibody moleculedetermines its role in the immune response?

A. disulfide chains

B. the entire molecule

C. the stem of the Y

D. the heavy chains

E. two arms of the Y

12. Select the incorrectly matchedimmunoglobin (Ig)subclass and a fact about it.

A. IgG---found in the plasma and secretedin secondary response

B. IgM---first secreted during primaryresponse

C. IgE----promotes the release ofhistamine

D. IgA----found in saliva and mother’smilk

E. IgD----serve as receptors on thesurfaces of T cells

13. _______ are the source ofantibody-producing cells.

A. B cells

B. Plasma cells

C. Monocytes

D. Macrophages

E. T cells

14. Select the incorrect statementregarding the inflammatory response.

A. The alarm signals can be histamines orprostaglandins.

B. The inflammation response is a localizedspecific response to infection or injury.

C. Neutrophils spill chemical in the areaof injury or infection that kills bacteria, tissues, andthemselves.

D. Tissue can exhibit edema from thedilation of the blood vessels in the area of injury orinfection.

E. If a cell is injured or infected, itreleases chemical alarm signals that promote dilation of bloodvessels at the injury site.

15. Reproduction in reptiles compares toreproduction in birds in that

A. both newly hatched birds and reptilesrequire parental care.

B. the eggs of both birds and reptiles haveprotective shells.

C. birds are oviparous, reptiles areovoviviparous.

D. both exhibit external fertilization.

E. male or female reptiles reproduceasexually; birds do not.

16. ______diseases are those abnormalconditions in which the body’s defensive cells fail to make theself versus the nonself distinction correctly, and attack thebody’s own tissues.

A. Cancerous

B. Septic

C. Autoimmune

D. Nondiscrete

17. Most marine invertebrates areosmoconformers. This means that

A. the osmolality of their body fluids isequal to that of the osmoregulators who inhabit the sameenvironments.

B. the osmolality of their body fluidsfluctuates between being hypertonic to hyportonic depending on theseason and the tides.

C. the osmolality of their body fluids isnot the same as their seawater environment

D. the osmolality of their body fluids isthe same as their seawater environment and that their bodiescontain the same solutes as their surroundings

E. the osmolality of their body fluids isthe same as their seawater environment

18. Which of the following determinesgenetic (male or female) in mammals?

A. the acrosome of the sperm

B. the temperature of the developingfetus

C. the SRY gene on the Y chromosome

D. the genetic makeup of the parents

E. the Y chromosome contained in theegg





If you can please explain why and how yougot the answer. 5 star rating for correct answers only, I have theanswer sheet, and just want to double check.