Biology 150 THOUGHT QUESTIONS
These are Thought Questions on our Biology 150 Lecture topics,     which are designed to make you think, They are structured     to help you understand a concept, topic, or paradigm better.        Using your prior knowledge and your comprehension of a topic     you should be able to explain or clarify through multiple avenues     an answer that predicts or expresses insight into a better    understanding of a topic or concept.
You may collaborative with your neighbor and exchange ideas     to come to a conclusion that you believe will support your hypothesis.
There are generally no right nor wrong answers, just a thought process     that can lead to a viable experimentation and a conclusion.
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How did life originate on Earth???
Good luck.
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   The origin of life on earth likely arose by  ABIOGENESIS,  which is the theory
that life evolved from nonliving chemical systems, and is the leading theory
for the origin of life.

  Haldane and Oparin theorized that a "soup" of organic molecules on ancient Earth
was the source of life's building blocks.  Harold Urey and Stanley Miller performed
laboratory experiments to show that simple inorgainic molecules could abiotically
produce organic molecules common to living things.  Simple organic molecules
built complex chemical systems that exhibit the emergent property we describe as Life.
Thus simple chemistry lead to greater and great complexity, and produced what
we know as Life today.
 

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Can you suggest any good strategies to help           control Human Population growth?
some posssible answers

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To fully understand the processes occurring in present-day living cells, we need to consider how they arose in evolution? The most fundamental of all such problems is the expression of hereditary information, which today requires extraordinarily complex machinery and proceeds from DNA to protein through an RNA intermediate. How did this machinery arise?       Which Came first?                                            PROTEINS.....RNA.....DNA

a possible answer?

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Circumstantial evidence indicates that all life on Earth today developed from a shared common ancestor (LUCA), that likely formed via abiogenesis.                                  But what was the first information molecule?       Proteins,      RNA,      or      DNA? Miller and Urey’s experiments provide support of the abiogenesis of proteins. Yet, RNA is an attractive choice for being first because it combines features of proteins and DNA. RNA can catalyze chemical reactions akin to enzymes. In fact maybe the most important biological reaction - the FORMATION of PEPTIDE BONDS in proteins is made by a CATALYTIC RNA MOLECULES - a RIBOZYME.  RNAs can store genetic information like DNA and the GENETIC CODE is an RNA based self-editing coding system. It would seem RNA evolved all the essential methods for storing and expressing genetic information before DNA came onto the scene. Thus RNA may have played a crucial role in the early history of life on Earth - thus an RNA WORLD. However, single-stranded RNA is rather unstable and is easily damaged by enzymes. By essentially doubling the existing RNA molecule, and using deoxyribose sugar instead of ribose, DNA evolved as a much more stable form to pass genetic information with more accuracy.

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Why is life Carbon Based and not Silicon Based?  Both occur in the same group (14  IVa) in the periodic table. The elements of Group 14 have 4 electrons in the valance shell allowing them to form compounds by sharing electrons or lose some and becoming +ion.   Silicon is familiar to us in daily life as (sand = silicon dioxide)  makes up 59% of the Earth's crust and is the main constituent of rocks...                           O=Si=O       vs.      O=C=O              So... why not silicon based life forms?
answer

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Carbon is better than silicon for life processes because it's LIGHTER. The mass of a silicon atom is twice what a carbon atom is (12.01 vs. 28.09 amu).   With C at about 20% of the mass of a human body, you'd weigh much more if we replaced carbon with silicon. That would make you slower, and your ancestors would likely have  been eaten by lighter, lither saber-toothed tigers.                                                       Silicon is also  Larger,  making it less flexible.   Carbon easily forms long, complicated organic molecules. The atoms of silicon aren't as mobile, so they're harder to make into the myriad shapes you would need to support a living body. Carbon chemistry works with little more than C, H, O, and N, some of the most abundant elements in the universe, and they're easy to combine in many different ways. Silicon bases are hard to form because the primary form of silicon on earth, silicon dioxide, is too immensely stable. It's sand, and getting the silicon out of sand involves immense amounts of energy. The primary form of carbon on a lifeless planet, carbon dioxide, is also stable, but not nearly so stable as silicon dioxide.
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An A-T base pair is stabilized by only two hydrogen bonds. Hydrogen-bonding schemes of very similar strengths can also be drawn between other base combinations that normally do not occur in DNA molecules, such as the A-C and the A-G pairs. What would happen if these pairs formed during DNA replication and the inappropriate bases were incorporated? Discuss why this does not often happen.

Answer

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MORPHINE   vs.  ENDORPHIN    Morphine - is an opiate made from opium and heroin, that is used to relieve pain as an opioid analgesic. Morphine and opiates work on the brain by binding to opioid G-protein coupled receptors (GPCRs).    Endorphins - are hormones release by the hypothalmus and pituitary gland in response to pain and/or stress.    In 1975 it was shown that the GPC-Receptors, which bind natural endorphins, have molecular shapes similar enough to structurally mimic, with a complementary shape, so that they can efficiently bind opiates, such as morphine, producing similar analgesic and general feelings of well being, pleasant  effects as natural endorphins.          back

.   .    The two electron micrographs show nuclei of two different cell types. Can you tell from these pictures which of the two cells is transcribing more of its genes? Explain how you arrived at your answer.
answer

.  .      In the electron micrographs, you can detect chromatin regions of two different densities; the densely stained regions correspond to heterochromatin, while less condensed chromatin is more lightly stained. The chromatin in A is mostly in the form of condensed, transcriptionally inactive heterochromatin, whereas most of the chromatin in B is decondensed and therefore potentially transcriptionally active.    The nucleus in A is from a reticulocyte, a red blood cell precursor, which is largely devoted to making a single protein, hemoglobin. The nucleus in B is from a lymphocyte, which is active in transcribing many different genes.     back                        next