DNA Replication/ Protein Synthesis

DNA Replication is the process of replicating a DNA strand in a semi- conservative sense. First the Helicase comes in and unwind the strands by breaking the hydrogen bond. Then the RNA primase adds short sequences of RNA to both strands (the primer). Thirdly the primer allows DNA polymerase III to bind and start replication. Then DNA polymerase III adds nucleotides to each template strand in a 5'→3' direction. These nucleotides are initially deoxyribonucleoside triphosphates but they lose two phosphate groups during the replication process to release energy. One strand is replicated in a continuous manner in the same direction as the replication fork (leading strand. The other strand is replicated in fragments (Okazaki fragments) in the opposite direction (lagging strand). Then the DNA polymerase I removes the RNA primers and replaces them with DNA. Finally, DNA ligase then joins the Okazaki fragments together to form a continuous strand

Protein synthesis is one of the most fundamental biological processes by which individual cells build their specific proteins. Within the process are involved both DNA (deoxyribonucleic acid) and different in their function ribonucleic acids (RNA). The process is initiated in the cell’s nucleus, where specific enzymes unwind the needed section of DNA, which makes the DNA in this region accessible and a RNA copy can be made. This RNA molecule then moves from the nucleus to the cell cytoplasm, where the actual the process of protein synthesis take place.

DNA Structure

Today in class we discussed the DNA structure as shown below and started cutting out a paper model for it. The structure was discovered by James Waston, and we also learned that there are 4 different bases including Adenine (A), Cytosine (C), Thymine (T) and Guanine (G) and we learn that A is complementary with T while C is complementary with G.

Colored flower/ Extra fingers

According to the book Survival of the sickest, the flowers appears to be this way because of an inherited mutation in its cells. Since scientists found that mutations are inherited when they are beneficial or neutral, therefore this mutation most probably increase the chances of its survival, for example a camouflage while at the same time it may also have no effects on the survival of this species. 

As Your Inner Fish mentioned, hands with extra fingers is due to the ZPA (very similar to the sonic hedgehog genes), specifically too much skin concentrated in a ZPA zone. These genes contains the instructions for a body to construct fingers, and most probably there's extra ZPA gene thus causing more fingers to grow from the baby's hand.

Your Inner Fish Chapter 3

Why do we all look different? Scientists try to solve these questions by looking into embryos and messed around with our DNA to see what would  change. Later they discovered the zone of polarizing activity (ZPA), something that instructs cells to produce different things, such as limbs. They named a gene Sonic hedgehog gene, one relating to flying and hypothesized that these genes are capable of making bodies look different. They found a supplier of shark eggs and started performing experiments on shark embryos since they are very distant from humans. And the results matched with the chicken experiments. That was how scientists solved the answer to what makes us look different

Survival of Sickest Chapter 6 review

The Chapter begins with the history of cowpox and how Edward Jenner invented vaccines as he found out that people who caught cowpox were resistant to small pox. Every human starts of from being 1 bacteria and duplicates millions of times to get to our form and shape now. Our DNA consists of 3 billions different nucleotides and every human has 23 chromosomes from each one of their parents, these are called the sex chromosomes adding up to a total of 46. These chromosomes determine our characteristics.

Scientists originally believed that only accidental mutations can possibly cause genetic changes. They thought pandemics followed a trend with sun spots, but they later realized it was because of the antigenic drift that caused our body to be vulnerable. Babara McClintock discovers the "jumping genes" and proposes that genetic changes does not necessarily have to be accidental. She puts an example of how corn's DNA migrates. John Cairns also did an experiment to prove that digestive bacteria can mutate to be not lactose tolerant when only fed lactose. Proving that genetic changes can happen intentionally.

Finally, only 3% of our DNA are used for coding sequences.And scientists found out that the rest are actually a lot of "jumping genes" instead of "junk sequences". Moreover, the Weissmann barrier distinguishes germ cells and somatic cells as changes of somatic cells cannot be passed on.

From Atoms to Traits

1. Explain the significance of Mendel. 

Mendel observed that the pea plants' traits were often similar to those of their parents. Sometimes, however, the pea plants had different traits than their parents. Mendel experimented with thousands of pea plants to understand the process of heredity. Mendel's work formed the foundation of genetics, the scientific study of heredity. Mendel's experiments changed the general
perception of heritable variants from ephemeral
and blendable to discreet entities passed from
parents to offspring, present even though they
are not always visible.

2. Draw the structure of DNA and who discovered this structure. 


James Watson, Francis Crick, Maurice Wilkins


3. Explain each of the five examples of variations that occur to DNA and give an example of each.

Gene copy number - chimpanzees
point mutation - whipped dogs
insertion - pea plants
Inversion - flipping of large segments of DNA within a chromosome
Repitition - repetitions like those that underlie forensic DNA tests


4. What is evo-devo?  A subspecialty ithin
evolutionary biology that has come to be known
as evo-devo Concentrates on studying the effects
of changes in important developmental genes
and the role they play in evolution.
5. Make a connection between human migration and the mutation of lactose intolerance.

Lactose-tolerant population started with a little population then later  the populations have differ-
ent mutations in the key region-a striking ex-
ample of the repeated evolution of a similar trait
by independent changes affecting one gene.

Unit Test 2

Today we took the second unit test, I thought it was slightly harder than the first one that we did because of the enzyme part that I wasn't really sure about and there were some questions that I didn't really understand very well. But overall I am confident that I did okay.