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Biology 3338A Lecture Notes - Lecture 3: Somatic Cell, Central Dogma Of Molecular Biology, Zygote

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coffeemoose574
9 Jul 2016
School
Western University
Department
Biology
Course
Biology 3338A
Professor
Sashko Damjanovski

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Document Summary

Also how do those cells in the embryo know what to become. His idea was that in the cell there are determinants. There is something called the germplasm and in it there is a limited number of determinants. As cells divide, they get a certain type of determinants. Some cells get muscle determinants and form muscle. Other cells get both blood and neural determinats and divide, so some cells get blood and some get the other. But, keep in mind that gonads (sperm and nuclei) need alll these determinants to be able to pass them to the next generation. So there had to be something special called germ cells that had everything (you can"t divide everything). As the cells divide, how in the end will the germ cells be able to maintain all the determinants??? (a problem with the theory). Extra note: as cells were dividing they will have unique determinants.

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Related Questions


Class 6: Viruses (and Cells, continued)


Making connections: viruses and microbes Match the cell biology concept (on page 1) with an important application of that concept (on page 2). Then answer the follow-up questions at the bottom of page 2.


Cell Biology concepts
1. Bacteria that cannot construct new cell wall material become fragile and break down.
2. During influenza infection, the viral enzyme neuraminidase is required to release new viruses from the host cell in which they were made. Once released, the new viruses can infect many additional cells.
3. Thermus aquaticus is a bacterium found in hot springs and can live at temperatures up to ~80°C (175°F). It has adapted so that its enzymes are most functional at the elevated temperatures, compared with many organisms’ enzymes that function best ~37°C (98°F).
4. Until the isolation and investigation of retroviruses, scientists thought that RNA could be copied from DNA, but DNA could not be copied from RNA. Research on this class of viruses led to an update to this “Central Dogma” of biology.
5. Some bacteria have adapted, so that the enzymes involved in making cell wall materials have a slightly different shape and can no longer be bound by certain drugs.
6. Rhizobia are bacteria that colonize the roots of certain plants (legumes, including beans and peas). The host plant benefits from the prokaryotes’ ability to “fix” nitrogen, converting N2 from the atmosphere into a form that is usable by the plant.
7. Many species of bacteria contain the enzyme cellulase. More than 10 billion such bacteria and other symbiotic microbes may be found in a single milliliter of material from inside the digestive system of ruminant mammals.
8. Fungi, including those that cause athlete’s foot, use ergosterol to maintain healthy membranes. Animal cells do not make ergosterol, they use a similar lipid – cholesterol.
9. During retrovirus infection, a DNA copy is made of the virus’s RNA genome. A cut is made in the host cell’s DNA and the DNA copy of the viral genome is pasted into the host chromosome by a viral enzyme called integrase.
10. Prokaryotic cells contain smaller ribosomes (“70S” ribosomes) than eukaryotic cells (“80S” ribosomes). Both types of ribosomes synthesize proteins, but the macromolecules they use to do it are somewhat different.



2
Applications
_______ Oseltamivir, also called Tamiflu, binds and inhibits the viral protein neuraminidase.
_______ Clotrimazole is a drug that is used to treat certain infections. It interferes with synthesis of ergosterol, a lipid involved in phospholipid membranes.
_______ Penicillin is a drug that interferes with synthesis of peptidoglycans (these are biological molecules that are part protein and part carbohydrate) that are present in certain cell walls.
_______ HIV is often treated with several drugs that inhibit different parts of the viral replicative cycle. Raltegravir is an example of a drug that interferes with the integration of viral genes into the host cell’s chromosome.
_______ Cows, like other vertebrates, lack the ability to breakdown cellulose. Yet they are able to live on a diet of grass and other vegetation high in cellulose.
_______ Enzymes isolated from extremophiles have been very useful in laboratory research. For example, Taq polymerase facilitates PCR, a revolutionary technique for production of DNAs of particular sequences, which requires cycling reactions through high temperatures.
_______ Plants and animals require nitrogen to make biological macromolecules, however they’re unable to convert atmospheric nitrogen (N2) into a biologically useful form.
_______ Azithromycin is a drug that binds to 70S ribosomes and blocks synthesis of any new proteins.
_______ Methicillin-Resistant Staphylococcus aureus (MRSA) can cause life-threatening infections of the skin and bloodstream. One of the reasons MRSA infections are so serious is that they are resistant to treatment by many antibiotics, including methicillin and penicillin.
_______ The enzyme reverse transcriptase, isolated from retroviruses, is an important tool in molecular biology research. Scientists interested in learning what genes are turned on in particular cells use it to make DNA copies of RNAs they are studying (The DNA copies are useful because they are more stable).


When you have completed the matching activity, answer these follow-up questions:
• What types of infections can be treated with the following drugs?
o Penicillin
o Clotrimazole
o Azithromycin
o Tamiflu
o Raltegravir
• Why are these drugs (above) safe for you to take? That is, why don’t they kill your cells?
• Cancer cells are your own human cells that have become deregulated so that they divide and pile up in an uncontrolled way. Many chemotherapy drugs treat cancer by interfering with cell division and other cell processes.
o Why are there so many more side effects for individuals undergoing chemotherapy than for individuals taking antibiotics?

1.

__________ are fairly small organelles that provide a safe place within the cell to carry out certain biochemical reactions that generate harmful, highly reactive oxygen species. These chemicals are both generated and broken down in the same location.

Lysosomes
Endosomes
Peroxisomes

Nucleosomes

2.

Biologists cannot possibly study all living species. Instead, they try to understand cell behavior by studying a select subset of them. Which of the following characteristics are useful in an organism chosen for use as a model in laboratory studies?

rapid rate of reproduction
all of the above
ability to grow under controlled conditions

amenability to genetic manipulation

3.

By definition, prokaryotic cells do not possess __________.

ribosomes.
a nucleus.
membrane bilayers.

replication machinery.

4.

Cell biologists employ targeted fluorescent dyes or modified fluorescent proteins in both standard fluorescence microscopy and confocal microscopy to observe specific details in the cell. Even though fluorescence permits better visualization, the resolving power is essentially the same as that of a standard light microscope because the resolving power of a microscope is limited by the __________ of light.

intensity
absorption
wavelength

filtering

5.

Choose the phrase that best completes this sentence: Microtubules ____________ and are required to pull duplicated chromosomes to opposite poles of dividing cells.

generate contractile forces
can rapidly reorganize
are found in especially large numbers in muscle cells

are intermediate in thickness

6.

Despite the differences between eukaryotic and prokaryotic cells, prokaryotes have proteins that are distantly related to eukaryotic actin filaments and microtubules. What is likely to be the most ancient function of the cytoskeleton?

cell division
cell motility
vesicle transport

membrane support

7.

DNA and RNA are different types of nucleic acid polymer. Which of the following is true of DNA but not true of RNA?

It contains thymine.
It has 5'-to-3' directionality.
It is single-stranded.

It contains uracil.

8.

Double covalent bonds are both shorter and stronger than single covalent bonds, but they also limit the geometry of the molecule because they ____________________.

prevent additional bonds from being formed with the bonded atoms.
limit the rotation of the bonded atoms.
create a new arrangement of electron shells.

change the reactivity of the bonded atoms.

9.

Drosophila melanogaster is a/an __________. This type of animal is the most abundant of all animal species, making it an appropriate choice as an experimental model.

mammal
amphibian
bird

insect

10.

If the isotope 32S has 16 protons and 16 neutrons, how many protons, neutrons, and electrons will the isotope 35S have, respectively?

16, 19, 17
16, 19, 15
16, 19, 16

16, 20, 15

11.

Living systems are incredibly diverse in size, shape, environment, and behavior. It is estimated that there are between 10 million and 100 million different species. Despite this wide variety of organisms, it remains difficult to define what it means to say something is alive. Which of the following can be described as the smallest living unit?

cell
organelle
protein

DNA

12.

Macromolecules in the cell can often interact transiently as a result of noncovalent interactions. These weak interactions also produce stable, highly specific interactions between molecules. Which of the factors below is the most significant in determining whether the interaction will be transient or stable?

the concentration of each molecule
the size of each molecule
surface complementarity between molecules

the rate of synthesis

13.

Many of the mechanisms that cells use for maintenance and reproduction were first studied at the molecular level in bacteria. Which bacterial species had a central role in advancing the field of molecular biology?

E. coli
S. pombe
C. elegans

D. melanogaster

14.

Many types of cells have stores of lipids in their cytoplasm, usually seen as fat droplets. What is the lipid most commonly found in these droplets?

cholesterol
isoprene
triacylglycerol

palmitic acid

15.

Mitochondria contain their own genome, are able to duplicate, and actually divide on a different time line from the rest of the cell. Nevertheless, mitochondria cannot function for long when isolated from the cell because they are __________________.

anaerobes.
viruses.
parasites.

endosymbionts.

16.

Mitochondria perform cellular respiration, a process that uses oxygen, generates carbon dioxide, and produces chemical energy for the cell. Which answer below indicates a correct pairing of material “burned” and the form of energy produced during cellular respiration?

fat, protein
sugar, fat
sugar, ATP
fat, ADP

17.

Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei. Which one of these molecules contains polar bonds?

propane
methane
molecular oxygen
water

First of all I am not endorsing Intelligent Design (Wikipedialink); I'm asking this because I (someone who does not have abackground in biology, organic chemistry, or philosophy) got into aconversation with someone who does endorse it, and I'm trying tosee his point of view as far as rationality can allow. Second ofall, I apologize for any vagueness; Intelligent Design isn't wellenough defined as a theory for me to help that. I also apologize ifthis is rehashing content already plentiful on the Internet, butfor my purposes I can't simply depend on the likes of Wikipedia orTalk Origins, so what I'm looking for here instead is to take theopposite approach and see, based on your informed minds, if therecould possibly be any reasonable likelihood of an ideal ID theorybeing adopted.

I'm looking for the most favorable consideration for what IDmight be if it were best developed as a viable hypothesis or theoryto get an idea of how far such a discussion is worth taking. Anunbiased, informed Devil's advocate, if you will.

My cursory investigation of what Stephen Meyers (video link) andMichael Behe (video link) say (correct me if I'm wrong) seems to bethat either the first cell was likely designed intelligentlyjudging by the complex code of DNA and that evolution took coursefrom there, or that the first cells were made and many instances ofevolution were from some kind of intelligently guided mutations aswas needed to make "irreducibly complex" cells or body functions(whether the guidance stops after the Cambrian or continued even tothe point of making different types of new bacteria and differenttypes of apes/humans or whether every single mutation and adaptiveability is being guided, I'm not sure if they're at any consensus,and that's why I don't know if I should stop my question atabiogenesis or include evolution). The person I spoke with alsobrought up some specific claims (everything looks designed, DNA hasordered, complex information, blood clotting is irreduciblycomplex, ID can and has make predictions like decades ago that"Junk DNA" wasn't junk) that I don't need you to debunk (I haveGoogle).

But if there could be any possible support or truth to any ofthe above, I would appreciate knowing about that. (Again, Devil'sadvocate so I can be informed and understand where the points comefrom.) Reading an ID book alone, it would be in places hard to knowwhere they differ from actual scientific conclusions. After all,when someone who seems to know what they're talking about and canexplain something in technical detail says that something isimpossible or extremely unlikely, it's hard for me to know why theywould be wrong (are they ignoring other possibilities?misrepresenting facts? are they really right and just getting thecold shoulder from an atheistic scientific community because itimplies a deity?). So I focus on mainstream sources, even if theydon't bother entertaining ID and leave me ignorant of its possiblevirtues. And thus I'm hoping someone from this informed communitymight enlighten me to what those possible virtues might be.