Producers Song - Mr. Parr My Role Model

Biome Song - Mr. Parr is da bomb

The Way to Reuse - Plastic Bottles as Light Bulbs!

Allele vs Genotype vs Phenotype - The Breakdown

Often students find it hard to tell the difference between alleles, genotypes, and phenotypes, just because they are so intertwined. Here's a breakdown of how these tricky biology vocab words are related.. 

Alleles are versions of genes, there's tons of alleles and thus genes on our chromosomes. For each gene, whether it be eye color, hair color, or whether we are right handed or left, there are two alleles (sometimes more). The reason there are two is because we get one chromosome from our mom and one from our dad. Those chromosomes carry tons of alleles - each being a different version for a particular gene. So for every chromosome pair (remember humans carry 46 chromosomes, or 23 pairs - these pairs are made up of one chromosome from dad and one from mom) there are two alleles for every gene. 

Those two alleles make your genotypes ( written as Aa or AA or aa) for a particular gene. So you can either be homozygous recessive (written as aa) for a gene, homozygous dominant (written as AA) or heterozygous (written as Aa) meaning you have one dominant allele and one recessive. When you're heterozygous, what's expressed is the dominant allele (A, not a). When you're homozygous dominant or recessive then only the A or the a allele is expressed. Whatever is expressed makes up your phenotype.

It's easier to explain with an example. Lets say you have two alleles (A and a) that you acquired from your mom and dad. From your dad you got an allele for blue eyes, which is recessive (so the allele would be written as "a"). From your mom, you got an allele for brown eyes which is dominant (allele would be "A"). So your genotype then, for eye color  would be Aa - or heterozygous. Your phenotype is what is going to be expressed, which is always the dominant allele with a heterozygous genotype. The dominant allele here is brown eyes, so your phenotype would be brown eyes! Your phenotype is what is physically expressed, it is what's produced from expressing the gene/alleles. It can be eye color, height, hair color, or anything down to different proteins. In general terms, it's what you "see" as a result. 

Chiton's Have Eyes?

Did you know...chitons have evolved to have eyes with lenses made of rock?? 

Check out this article to learn more!

Help Reduce Fisheries Bycatch and Earn Big Bucks!

For those of you who are artistic or imaginative and 18 or older, design a way to reduce fisheries bycatch and earn up to $30,000 for your idea! Check out the 2011 International Smart Gear Competition below. 


http://smartgear.org/

Hardy-Wein - WHAT?

What the heck is Hardy-Weinberg equilibrium?

As Darwin discovered, populations change from generation to generation to adapt to the environment their living in. What we see changing are physical characteristics or traits, however what's actually changing from generation to generation are the genes or alleles (versions of genes) responsible for making those trait we see. 

Thus, when a population evolves, the genetic material present in that population is changing.

A common way scientists measure whether or not a population is evolving is by seeing if that population meets Hardy-Weinberg equilibrium.

If a population meets Hardy-Weinberg equilibrium, then it is considered to NOT be in the process of evolution. (However, know evolution takes years to occur, thus although a population may seem to not be evolving and thus meet Hardy-Weinberg equilibrium, it could actually be in the process - just extremely slowly)   

If Hardy-Weinberg equilibrium is met, it means there are no mechanisms of evolution occurring - No natural selection, No genetic drift, No gene flow, No mutations, and only random mating. These are also the 5 conditions that must be met in order for this equilibrium to happen in a population.   

The way scientists try to find out if a population meets Hardy-Weinberg equilibrium is be using the Hardy-Weinberg equations below. Note that usually ONE gene at a time is looked at to see if it meets this equilibrium, thus there's only 2 alleles (or two versions of that gene, p and q) that are observed.  

p² + 2pq + q² = 1

Where p²stands for the AA (homozygous dominant) genotype

Where 2pq stands for the Aa (heterozygous) genotype

Where q² stands for the aa (homozygous recessive) genotype

Also...

p + q = 1

Used to find the frequency for alleles 

What these equations describe are the frequency of the genotypes for a particular gene, as well as the frequency of alleles for that particular gene in a population. Because frequency is usually written in percent or decimal, and there are only two alleles present for the gene in question (p and q) then they must add up to be 1 (reasoning for the 2nd equation).

Here's an example problem to show you how you might use this equation: 

What are the allele frequencies for a particular gene in a population if the frequency of homozygous recessive individuals in that population is 25%?

Using the Hardy-Weinberg Equation, p² + 2pq + q² = 1, we know the frequency of homozygous recessive genotypes are q² 

Thus, q² = .25 --> square root of both sides --> q = .5

If you know q, you can now find the other allele, p by using p+q=1

Thus, p+.5=1 --> subtracting .5 from 1 --> p=.5

Therefore the two allele frequencys are .5 or 50%!

Check out how far this Leatherback Sea Turtle has traveled!

TOPP or Tagging of Pacific Predators tags various animals within the Pacific Ocean with satellite tags, some of whom are critically endangered, to study different characteristics of their lifestyle like their migratory patterns, what habitats they use, or for sea turtles, nesting sites.  This turtle here is a Leatherback, the world's most endangered sea turtle, who was tagged by TOPP researchers and followed. Check out the other animals TOPP tags and follows at: http://www.topp.org/

Get This Widget!TOPP.org

Darwin's Theory of Evolution - Simplified

When it comes to learning about evolution in class, your teacher may tell you A LOT about Charles Darwin, maybe even a little too much...

Although your teacher may quiz you on some random facts about Darwin's life, for instance what was the name of the ship he sailed on (FYI she was called the Beagle), here are the fundamental principles of Darwin's Theory of Evolution you should know:

~ All life is related and we all descended from one common ancestor. 

~ Organisms have evolved from this ancestor through a process called Natural Selection. 

~ Natural Selection refers to the ability of some organisms to outcompete others within a specific environment due to their "possession" of a particular trait. 

~ Because the organisms with a particular trait survived, they produce more offspring than those without. The organisms that survived and reproduced are said to have adapted to the environment their living in. 

Natural Selection leads to adaptation to a specific environment by "selecting" organisms with specific traits suitable for a particular environment 

~ In order for Natural Selection to occur, these 3 conditions must be met:

  1) There must be genetic variation in a population (genetic variation creates different physical traits) 

  2) The variation must be heritable (can be passed on to the offspring)

  3) There must be differential reproductive success ( those with specific traits favored by the environment produce more offspring than those without the favorable trait) 

Lastly it's important to know that Natural Selection is NOT the only form of evolutionary change. 4 other mechanisms can also drive evolution. These are...

~ 1) Genetic Drift: causes traits within a population to change randomly.

   2) Gene Flow: causes traits to enter or leave a population due to organisms entering or leaving a population (emigration and immigration) 

   3) Mutation: modifies traits within a population by introducing new alleles (an allele is a version of a gene --> remember that each "trait" is produced from a specific gene in our DNA)

   4) Non-random mating.  

Hope this helps!

Perfect valentine to give while studying evolution! 

Tutor Review

Check out the awesome tutoring review I received from one of my students on my tutoring website at universitytutor.com! Nice!


Sarah's UniversityTutor.com Profile

Great Place to Visit for a Spectacular View of the Pacific

Montana De Oro is a beautiful California State Park located 6 miles southwest of Morro Bay.  - very close to San Luis Obispo and Cal Poly where I went to college.  

ATP

What is ATP? Why is it considered energy? I thought we ate FOOD for energy?


ATP stands for Adenosine Triphosphate. Here's what the chemical structure looks like..

ATP generally consists of 3 negatively charged phosphate groups, an adenine (a purine nitrogenous base, just like in your DNA) and a ribose (a type of sugar monomer). 


ATP carries a special form of energy within the 3 phosphate groups called potential energy. Because each phosphate is negatively charged, and negative charges repel each other, energy is stored within the bonds of these 3 phosphates. Think of what might happen when a phosphate group is broken off. Do you think it would be a favorable reaction? Of course it would be! Those negative phosphate groups do NOT like being grouped together, thus if one phosphate is broken off, making Adenosine Diphosphate (ADP), the negative charges left can spread out more, repelling each other less. 


When a phosphate group is broken off ATP, making ADP, about 7.3 kilocalories (kcal) of energy per mole of ATP is released. What is this energy used for? Pretty much for all cellular functions! For instance, ATP can be used to move molecules, pump ions, even help a cell in moving itself. Imagine a sperm cell, that flagella needs a LOT of ATP in order to continue to whip back and forth. 


But if we use ATP for energy, why is it said that we eat food for energy? We need food in order to make ATP. Glucose, a sugar monomer, is the most favorable molecule to make ATP in a cell. ATP is made from glucose in a process called cellular respiration. However, if glucose is not available (perhaps you haven't eaten any carbohydrates in awhile) then other major molecules from food can be used to make ATP as well - like lipids (fats) or if your body is desperate, proteins. 

Cellular Respiration and Photosynthesis - The BIG Picture

Most likely on your finals your teachers will ask you to compare photosynthesis and cellular respiration. How DO they compare??

First write out their chemical formulas:

Cellular Respiration: C6H12O6 (glucose)+6O2 --> 6H20+6CO2+ATP

We breath in Oxygen and break down glucose (a sugar monomer) to provide our cells with energy in the form of ATP while breathing out Carbon Dioxide as a byproduct 

Photosynthesis: 6CO2+6H20+Sunlight --> C6H1206(glucose)+6O2

Plants take in Carbon Dioxide and use sunlight to convert six of them into a glucose molecule, giving off oxygen as a byproduct  

Do you see how the reactants (the left side of the equation) of one formula is pretty close to the products (the right side of the equation) of the other formula?  

Cellular Respiration and Photosynthesis are opposite chemical reactions! 

Now lets compare these two in several contexts.. 

In terms of the atmosphere...

- Photosynthesis INCREASES Oxygen concentration and DECREASES Carbon Dioxide concentration

- Cellular Respiration DECREASES Oxygen concentration and INCREASES Carbon Dioxide concentration 

In terms of an Anabolic or Catabolic reaction..

(An Anabolic reaction is a chemical reactions that BUILDS UP a molecule, where as a Catabolic reaction is a chemical reaction that BREAKS DOWN a molecule)

- Photosynthesis is a Anabolic reaction (builds a glucose molecule)

- Cellular Respiration is a Catabolic reaction (breaks down a glucose molecule to make ATP)

In terms of an Endothermic or Exothermic reaction..

(An Endothermic reaction requires energy to occur, where as an Exothermic reaction gives off energy)

-Photosynthesis is an Endothermic reaction as it requires energy from sunlight to occur

-Cellular Respiration is an Exothermic reaction as the product is ATP (energy)

By writing the chemical formula for both these reactions at the top of your paper, the answer for these questions will be right there! Keep referring back to them to look and see what molecules remain on the "reactants" side and the "products" side. 

Now here's a question for ya..

Ancient earth had very low levels of Oxygen in the atmosphere but very high levels of Carbon Dioxide. How do you think Oxygen concentration increased so lifeforms like humans could live on earth??

It's That Time of Year Again..

FINALS WEEK!

For all of you that have a biology final coming up, good luck! If you need extra help studying I'm here as well. 

Here's a breakdown of major topics you'll most likely be quizzed on for your biology finals..

- Cells and their organelles (What do plant cells have that animal cells do not?)

- Macromolecules: Proteins, Carbohydrates (sugars), Nucleic Acids, Lipids

- DNA: Structure, function, how it replicates

- Meiosis vs Mitosis

- Genetics: Who is Gregor Mendel? How do you make a punnet square and what does it tell you?

- How proteins are made: Transcription and Translation

- Evolution: Darwin who? 

- Photosynthesis vs Cellular Respiration 

- Plants and the Human body  

Carbon Fixation

What's one of the main concepts of photosynthesis? Carbon fixation!


Carbon fixation is when atmospheric Carbon in the form of Carbon Dioxide is converted into the tissues of plants in the form of glucose (through photosynthesis) and stored as either starch or cellulose. Carbon fixation "fixes" atmospheric Carbon into a more useful biological form.


If it weren't for photosynthesis and Carbon fixation, a lot of the Carbon on earth would be stuck in the atmosphere!


Now here's a question for ya...


If plants take in Carbon in the form of Carbon Dioxide and convert it to glucose, how is Carbon then released back out into the atmosphere??  

SPONCH?

Need a quick and easy way of remembering the most common elements in living organisms? 

Remember the word : SPONCH - S(Sulfur) P(Phosphorus) O(Oxygen) N(Nitrogen) C(Carbon) H(Hydrogen)

Better yet, SPONCH also tells ya which elements are the most common by reading it backwards (beginning with Hydrogen as most common, next to Carbon and so on)