Blog #4 Describe the three types of selection: directional, stabilizing and disruptive and give an example of each in your own words

Directional: A process in Natural Selection where a a single phenotype is favored resulting in the allele frequency to shift in a driection continuously.
e.g. The grey hound was breeded for speed and is now one of the fastest types of dog.

Stabilizing:  The type of selection where genetic diversity is slowly decreased on a particular trait value.
e.g. Human birth weight: babies of low weight lose heat more quickly and get ill from infectious disease more easily, whereas babies of large body weight are more difficult to deliver through the pelvis.

Disruption:  changes in population genetics in which extreme values for a trait are favored over intermediate values.
e.g. The color of a rabbits fur helps it blend in to it's environment. BUT if a different color that doesn't camouflage  the rabbit is introduced into the environment, it will be killed because of it's lack of camouflage.  This is where disruption comes into play. The rabbits that are camouflaged will breed with the rabbits without any camouflage thus creating babies that are camouflaged.

Blog#3 What is microevolution and list the ways it occurs.

Microevolution is a change in gene frequency within a population. It can occur through mutation, selection (artificial and natural) and genetic drift.

Blog#2 Why is a fossil record hard to interpret?

Fossil records are hard to interpret because many of them are jumbled together and not intact. If they were intact, it would be easier to figure out which animal the fossil is.

Blog#1 Why is evolution a theory and not a law?

Evolution is a theory and not a law because the theory lacks in evidence and hard, solid proof to prove it is real.

LAST BLOG OF THE SEMESTER!

My favorite activity this year was definently the karoke project. It was fun being able to express our creativity as well as the review. It forced us to use our brains and really review what was learned.

My least favorite was probably not being given notice of the benchmark. Unfortunently, I was unprepared and was one point away from bombing it.

If I could change one thing, it would be to have more karoke projects. :D

Blog 13 How has DNA profiling changed the way we investigate crimes? What are the two main tests?

DNA profiling has helped change the way we investigate crimes by helping to narrow down the options exponentially.  DNA profiling has created a new form of looking at crimes. All the evidence can be DNA tested and therefore breakdown the possible victims. The two main types of DNA profiling are:

PCR Analysis

Polymerase chain reaction (PCR) is used to make millions of exact copies of DNA from a biological sample. DNA amplification with PCR allows DNA analysis on biological samples as small as a few skin cells. With RFLP, DNA samples would have to be about the size of a quarter. The ability of PCR to amplify such tiny quantities of DNA enables even highly degraded samples to be analyzed. Great care, however, must be taken to prevent contamination with other biological materials during the identifying, collecting, and preserving of a sample.

STR Analysis

Short tandem repeat (STR) technology is used to evaluate specific regions (loci) within nuclear DNA. Variability in STR regions can be used to distinguish one DNA profile from another. The Federal Bureau of Investigation (FBI) uses a standard set of 13 specific STR regions for CODIS. CODIS is a software program that operates local, state, and national databases of DNA profiles from convicted offenders, unsolved crime scene evidence, and missing persons. The odds that two individuals will have the same 13-loci DNA profile is about one in a billion..

Blog #12 PEA PLANTS MENDELS EXPERIMENT!

Mendel’s Pea Experiment
In one experiment, Mendel cross-pollinated smooth yellow pea plants with wrinkly green peas. (The organisms that are used as the original mating in an experiment are called the parental generation and are marked by P in science textbooks). Every single pea in the first generation crop (marked as f1) was as yellow and as round as was the yellow, round parent. Somehow, yellow completely dominated green and round dominated wrinkly.

Mendel learned from this that there are two kinds of traits - dominant and recessive. In this case, the dominant traits are the yellow color and the round shape since they show up at the expense of the green color and the wrinkly shape. He also learned that the inheritance of each trait is determined by "units" or "factors" - now called genes.

Now he went on with his experiment and planted seeds from the all-yellow, all-round crop, achieved from the parent generation, and self-pollinated the grown up plants. The results led to some surprises. Most of the second generation (marked as f2) of peas were yellow and smooth, but some were green or wrinkly. Mendel repeated his experiment many times and the f2 generation consistently had a 3:1 ratio of yellow to green and round to wrinkly. How did Mendel explain his results?
As mentioned above, Mendel postulated that there are dominant and recessive traits in heredity.
In his experiment Mendel marked with capital letters dominant traits and with small letters recessive traits.

Y = dominant yellow color g = recessive green color R = dominant round shape w = recessive wrinkly shape

When the f1 plants breed, each has an equal chance of passing on either Y or g units to each offspring (f2 generation), and the same is with R and w.

In the pollination process the offsprings get one trait unit (gene) from every parent; in the case of color the possible combinations are gY Yg YY gg. Three combinations from the four - gY Yg YY - will give yellow offsprings since all of them possess at least one Y dominant unit. Only one combination from the four - gg - will give green offsprings since it has two recessive units.

Because, in order to show-up, a dominant trait needs only one trait unit from one of the parents, and the recessive one needs two, from both parents, in order to prevail, that is the reason why the ratio between occurrences of dominant traits and recessive traits is 3:1. The same explanation applies to the shape traits.

Mendel came to three important conclusions from these experimental results:

• That the inheritance of each trait is determined by "units" or "factors" (now called genes) that are passed on to descendents unchanged
  
  
• That an individual inherits one such unit from each parent for each trait
  
  
• That a trait may not show up in an individual but can still be passed on to the next generation.
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