Origin of Life on Earth.... as we know it

Today's lesson focused on the origin of life. To understand the origin of life we must first understand what life is defined as.

Life -- The property or quality that distinguishes living organisms from dead organisms and inanimate matter, manifested in functions such as metabolism, growth, reproduction, response to stimuli, development (change over a lifetime), reproduction, and regulation (homeostasis).

Now that we have the definition of life down, we may proceed to The Origin of Life, or at least the three main hypotheses:

1. Creationism -- Was life created by a supernatural or divine force (i.e.: God). This hypothesis is untestable. (extra information: In 1925, the Scopes Trial ("Monkey Trial") was publicized due to the teaching of Darwin's theory of Evolution in a Tennessee high school by John Scopes. This broke the doctrine which stated that no information which denied the validity of creationism could be taught in public schools. Scopes was found guilty and paid a $100 fine. This law as repealed in 1967.)

2. Extraterrestrial Origin -- The idea that extraterrestrial objects such as meteorites and comets that struck the earth were the original source of organic materials such as carbon. This hypothesis is testable.

3. Spontaneous Abiotic Origin -- Abiotic: meaning non-living. The idea that life spontaneously arose from non-living materials such as inorganic molecules. This hypothesis is testable.

---- Abiotic Synthesis: In 1920 Oparin and Haldane proposed the reducing atmosphere hypothesis in which life originated in an environment that contained less than 1% oxygen and the majority of the atmosphere contained Carbon dioxide. In 1953, Miller and Urey found a way to test this hypothesis: an apparatus. This apparatus simulated early earth environments of which it was believed life formed from. The experiment resulted in that organic compounds such as amino acids, simple sugars, and nucleotides such as adenine (the building blocks of life) were formed. A diagram of this could be seen below:

Origin of Cells:

One theory suggests that the membrane of the cells were developed from lipid-membrane bubbles in that they were easily split into more bubbles, thus creating more cells. These proto-cells separated the inside from the outside (non-polar membrane). These cells preformed metabolism and reproduced.

3.5-2.0 billion years ago Prokaryotes (comprising the bacteria and cyanobacteria, characterized by the absence of a distinct, membrane-bound nucleus or membrane-bound organelles, and by DNA that is not organized into chromosomes) dominated the majority of life on earth. See diagram of ancient fossilized prokaryotes

Stromatolites: fossilized mats of prokaryotes resemble modern microbial colonies see photo below:

Photosyntheic Bacteria: Cyanobacteria, blue-green algae:
-Oxidized the atmosphere. They made aerobic respiration possible.

Eukaryotes: A single-celled or multi cellular organism whose cells contain a distinct membrane-bound nucleus. Developed by enfolding plasma membranes into and around the center going form an oval to a spherical circular. Provided internal micro-environments. The DNA was protected now in the nucleus.

Endosymbiosis: A mutually beneficial relationship in which one organism lives inside the other. This theory, developed by Lynn Margulis, is supported by structures found in modern cells such as mitochondria and chloroplasts that resemble bacterial structure, have their own DNA as does bacteria, move freely within the cell, and reproduce independently from the cell thus giving the illusion that they are separate organisms.


Evolution of Eukaryotes: Mitochondria and Chloroplasts

Mitochondria - cell engulfed aerobic bacteria but did not digest them. Provided a mutual-beneficial relationship.
Chloroplasts - Cell engulfed photosynthetic bacteria but does not digest them. Provided a mutual-beneficial relationship.

Which came first the RNA or the DNA?
RNA is most likely the first genetic material produced in that it has more functions in a cell. It codes information: self replicating, makes inheritance possible, allows for natural selection and evolution. Enzyme functions: robozymes and replication.

Classifying Life

Five Kindoms:
Monera
Protista
Plantae
Fungi
Animalia

Three Domains ("Super Kingdoms"):
Bacteria
Archaea - (extremophiles-live in extreme enviornments)
Eukarya - Protists, fungi, plants, animals

And heres a few videos for your entertainment:

1942 Fantasia: The Rite of Spring - Part 2: Evolution



This is just a few cartoons put together with evolution parodys. Dilbert, Family Guy, and Simpsons are on it (its the same Simpsons on Kim's post, but the others are pretty good).

-- Shannah

oh and the next sherpa is ............. Maria

Were it all started: The origin of species!!!

Hello everyone. Well the point of todays class and the main point that Ms.Foglia was tying to make was how and why species diverged from each other. There are two ways: Pre-Reproduction and Post-Reproduction.

First and foremost, What is meant by the word species??? that is the question...
Species is a population where the organisms are able to interbreed and produce offspring that will be able to survive and reproduce. The organisms must be reproductively compatible which means they are able to mate with each other.

OK well thats said huh? So whats next... PRE-Reproduction and how it causes species to diverse. WooHoo

There are 6 different barriers that may be obstacles and may prevent mating or inability to fertilize if mating occurs. Here they are:


Geographic Isolation: There is a physical barrier that does not allow the species to inter mate. The species will occur in different areas.

Ecological Isolation: Species occur in the same area but occupy different habitats. This means that the seldom if never meet.

Temporal(Time) Isolation: Species breed during either different times of the day, different seasons, or different years. This means that the species cannot mate.

Behavioral Isolation: Unique behavior patterns isolate species. If an organism doesn't recognize the calls, dances, songs, etc. then they do not mate.

Mechanical Isolation: Morphological differences can prevent successful mating.

Gametic Isolation: The sperm of one species may not be able to fertilize the egg of another species.

POST-Reproduction

The three post-reproduction barriers, which prevent hybrid offspring from developing into survivable fertile adult, are a)reduced hybrid viability b)reduced hybrid fertility c)hybrid breakdown.

Reduced Hybrid Viability- The hybrid would be very fragile. The genes of the different parents will interact and impair the hybrids development.

Reduced Hybrid Fertility- The hybrids will survive and live a full life but they are unable to produce offspring. Probably because the number in chromosomes may differ in the parents and cause the hybrid to have abnormal gametes.

Hybrid Breakdown- hybrids could be fertile and viable in the first generation but when they mate offspring are feeble and sterile.

Well folks thats all there is. See you all in class tomorrow or i should say today cause its already 12:12am.

OH WAIT ONE MORE THING...

HAHAHA Just searching for a cool cartoon and look what i can across. I think you'll all enjoy it.



Hey guys just check out this link i think the banana thing is cute. You'll get it once you see it.
http://evolution.berkeley.edu/evosite/evo101/VC1gReproIsolation.shtml

Evidence of Evolution by Natural Selection

Dear Mrs. Foglia's Favorite Class Ever,

Today we reviewed many parts of evolution! One thing we talked about was the anatomical record which is made of homologous structures. These are when organisms have the same structure that performs different functions. For example we saw the same structure in a human, cat, whale, and bat. Another example we saw was emryological development. We saw how cells for a fish made gills. No humans do not have gills, but we have the same cells that serve for a different purpose in our body.

The opposite of homologous structures are analogous structures. These structures have similar external form, and functions. These structures also have different origin, and internal structure. The best way to explain this would be don't judge a book by it cover. The organisms may look similar on the outside but inside are very different.

Another topic discussed in class to help us understand natural selection was peppered moths. We saw percents of dark vs. light moths. This was an example of industrial melanism. Industrial because it was caused by huge industries. Melanism because the brown color in all animals is called melanin. When pollution was low, and lichen existed on trees light colored moths made up 95% of the population. Instead when factories created soot covered trees, and killed lichen dark moths blended better with their surroundings. Then in the mid 1900s clean air laws went into affect, and as a result light moths made up most of the population. This is an example of natural selection, because depending on successful traits such as color helped moths to have a high survival rate and reproduce. The moths who fit their surroundings best could escape predators.

I found this youtube video on evolution and it is weird to say the least!

The sherpa for tom. will be Kim

Hello period 8 and 9 bio class, its Jaclyn.On Friday September 21st the class reviewed the requirements for what was needed on the Population Genetics Lab. This Lab was suppose to represent populations under different conditions of evolutionary change. The first being in Hardy Weinberg equilibrium, the second being in a selection against homozygous recessive, the third being where the homozygous had an advantage and the fourth was the case with genetic drift. Through case four we see how Genetic Drift proves that Hardy Weinberg Equilibrium is a synthetic theory because we see how genetic drift occurs and causes evolutionary change. For case numbers 1, 2, and 3 we had an original population of 17 individuals with 34 alleles(2 per each individual). For Case number 4 we had 6 individuals and 12 alleles. After each person in the class collected their own information for the lab the class combined information together, and calculated the frequencies of the genotype by using the Hardy Weinberg equation which would be.
p² + 2pq + q² = 1
The data is as follows:

Case #1:Hardy Weinberg Equilibrium
Generation# :p2 (AA)- parental=.25 F5=.18
2pq(Aa)- parental=.5 F5=.70
q2(aa)- parental=.25 F5=.12
Frequency of alleles:p(A)-.5 q(a)-.5
p(A)-.53 q(a)-.47

Case #2:Generation# :Homozygous recessive
p2 (AA)- parental=.25 F5=.592pq(Aa)- parental=.5 F5=.41q2(aa)- parental=.25 F5=.0
Frequency of alleles:p(A)-.5 q(a)-.5p(A)-..79 q(a)-.21
Case #3:Generation# :Heterozygous advantagep2 (AA)- parental=.25 F5=.18 F10=.352pq(Aa)- parental=.5 F5=.82 F10=.65q2(aa)- parental=.25 F5=.0 F10=.0
Frequency of alleles:p(A)-parental=.5 q(a)-parental= .5p(A)-F5= .59 q(a)-F5= .41
p(A)-F10=.68 q(a)-F10-.65


Case #3:Generation# :Heterozygous advantagep2
(AA)- parental=.25 F5=.18 F10=.352pq
(Aa)- parental=.5 F5=.82 F10=.65q2(aa)- parental=.25 F5=.0 F10=.0
Frequency of alleles:p(A)-parental=.5 q(a)-parental= .5p(A)-F5= .59 q(a)-F5= .41
p(A)-F10=.68 q(a)-F10-.65

Case #4:Genetic Drift.
Each group had different data.

This lab demonstrated that the Hardy Weinberg theory does not work out, because of five agents that affect evolutionary changes. In Hardy Weinberg equilibrium allele frequencies do not change. Hardy Weinberg populations are non-evolving populations that are not affected by the five agents of evolution including, genetic drift, gene flow, mutation, random mating, and natural selection. We know that this can not occur and that these five agents cause evolutionary changes in nature.

The following is a link to better understand the Hardy Weinberg equilibrium and the five agents of evolution.
http://http://zoology.okstate.edu/zoo_lrc/biol1114/tutorials/Flash/life4e_15-6-OSU.swf

http://http://www.phschool.com/science/biology_place/labbench/lab8/intro.html

Later class!
Tommrows sherpa will be Kerrie Sheldrick.

Measuring Evolution of Populations

Today, in period 8 and 9, we discussed Measuring Evolution of Populations. We discussed that evolution is the change in allele frequencies in a population. Also something we discussed in this lesson was what would cause allele frequencies not to change. Which include, very large population, no migration, no mutation, random mating, and no natural selection. This is only hypothetically speaking, this would be very hard to accomplish in a realistic population.
Hardy-Weinberg equilibrium was a major part of the lesson today. G.H. Hardy was a mathematician and W. Weinberg was a physician.

G.H. Hardy

W. Weinberg

This does not really exist anywhere, it serves as a model. It is a null hypothesis. This is used to measure if forces are acting on a population; measuring evolutionary change. When counting alleles, the frequency of the dominant allele is represented by p. The frequency of the recessive allele is represented by q. The frequencies of the two alleles must add up to 1 (100%). The equation used to represent this is p + q=1. When you are counting individuals, using the Hardy-Weinberg theorem, the frequency of the:
homozygous dominant: p x q = q²
homozygous recessive: q x q = q²
heterozygotes: (p x q) + (p x q) = 2pq
Like the frequencies of the alleles, all individuals add to 1 (100%). The equation used to represent this is p² + 2pq + q² = 1. These equations can only work, hypothetically, if the population is in Hardy-Weinberg equilibrium.

We also discussed sickle celled anemia.

Sickle cell anemia affects 1 out of 400 African Americans. It is an inheritance of a mutation in gene coding for hemoglobin. Low oxygen levels causes red blood cells to sickle, which then can lead to the clogging of blood vessels;capillaries, if two sickle cells stick together. This can be lethal to younger children, but have a less, but serious effect on older generations. The heterozygotes have an advantage in this case, they are free of both malaria and sickle cell anemia.

The sherpa for tomorrow will be Jackie K.

evolution of populations

Hey everyone in period 8&9 AP Biology. Todays lesson was on the Evolution of populations which is covered throughout chapter 21. Today we Learned that natural selection affects populations and changes them over time, and we went into detail on how researchers know populations are changing and what causing the change. A main point of this lesson was that Individuals are selected, populations evolve Natural selection acts on individuals. Individual organisms can not evolve they are selected or not selected to survive and reproduce. Many species have adaptations to specific enviorments to prevent predation, such as pocket mice in desert lava flows, their color helps them blend in with the land to prevent themselves from being easily spotted by a predator.
There must be differences and Variation within a population for evolution to occur. Variation is the raw material for natural selection. Variation can be seen from the size of horses to the color of shells and in many other ways. The organisms with the best survival and reproductive success also know as fitness are those that pass on their traits to future generations. Sexual reproduction is successful because it makes the offspring different from the parents and hopefully passes on the traits of good fitness.
A common question would be What is a selecting force? or even, What force is acting on populations to cause a change? Well the answer can be found as one of the 5 agents of evolutionary change. These agents are Mutation, Gene flow, Non-random mating, Genetic drift, and selection. Mutations create variation. They are a change in DNA which in turn changes traits, which can be phenotypes, which is a form of variation natural selection can act upon. Gene flow is the movement of individual and alleles in and out of a population, basically through migration. Populations intermix rahter then staying isolated which affects their variation, and reduces differences between populations. This is seen in the world today with many new faces in America from countries all over the world and they are reproducing with people of other cultures to create a blending of traits. Non-random mating is mainly sexual selection which in many organisms is females choice, and not everyone has an equal chance to have offspring. Genetic drift is based on chance events. This includes the founder effect in which a small group of a population is seperated, like the finches and evolve form the genetic variation they have, making a rare allele become common. Genetic drift also includes the bottleneck which is a random event usually a disaster, that constricts a populations kills off a large percent of a population leaving a small percentage left to expand. There are many conservation issues today trying to increase variation among populations as much as possible.

and tomorrows sherpa is Mia.

Evidence of Evolution by Natural Selection

Hi everyone. Today we started off by talking about fossil records and made way into the links between species. One of Mrs. Foglia's key points was that changes in the climate and environment can lead to extinction. Some creatures have adaptations acquired through many generations that allow them to survive, others that are not suited for the change would start to die off. We also talked about an interesting piece of information, knowing that all life started in the ocean, some creatures had to be links from sea to land animals.

The tetrapod is a missing link, and it was only discovered last year! But also, if mammals evolved on land, some had to return to the ocean for animals such as whales and dolphins to be sea mammals. Also, Mrs. Foglia showed us homologous structures and analogous structures, and we talked about convergent evolution and parallel evolution. Homologous structures are structured and developed similarly, but serve different functions and look differently externally. They have a common ancestor. Analogous structures are just the reverse, they have similar functions and external form, but the internal structure and development is not the same. There is no common ancestor in this evolutionary relationship. Analogous structures are part of convergent evolution. The idea of convergent evolution is that different creatures evolved in a similar way externally, though internally they are very different. Parallel evolution is when creatures, though separated and not closely related, served same job in their environment. Then, we finished off by talking about vestigial organs. These are structures that basically have no function, such as the appendix in humans, and a pelvis in a whale.



The sherpa for tomorrow will be KellyP.

Sexual Selection

Hey 8th period AP biology class members. Today we discussed many things in continuation on the topic of evolution and natural selection. We started off going over the lion mane slide. The key point Mrs. Foglia was showing with that slide was that animals do not choose a mate because they know that they have better genes, but because they are just attracted to that member of the opposite sex. If it happens to be that the member of the opposite sex has good genes, then it's great, but that is not what animals are actually looking for.

Also during class today we discussed phenotypes and genotypes. Phenotype is the physical appearance, anatomy, while genotype is the genetic make-up of an organism. The genotype controls the phenotype of an organism.

We also discussed how alleles (genotype) determine the color or physical appearance (phenotype) in the power point on straw fish. In the example, two blue alleles means the fish would be blue, two yellow alleles means the fish would be yellow, and one blue allele and one yellow allele means the fish would be green. The powerpoint on the straw fish shows how natural selection is based on the phenotype which changes the frequency of alleles. With the example given during class, the predator ate most of the yellow fish because they did not blend in easily, natural selection, which affected the allele frequency because with the yellow fish gone there are less yellow alleles. Remember, even though the frequency may change, in this case yellow decreased and blue increased, the total remains the same.

Tomorrow's sherpa will be Shana Lunney.

Natural Selection

Hey period 8 AP Biology, today in class we went over many forms of selection and their effects on an environment. Certain species need to develop adaptations in order to survive in their surroundings. As seen in the "Effects of Selection" slide on our powerpoint, there are three main types of driving changes in a population. Directional Selection basically means that there are two extremes within the species. As an example, larger horses and smaller horses. If the larger horses are the only variation of the species that will survive then this will be the dominant gene passed on throughout generations. In Stabilizing Selection, the two extremes cannot survive and that variation which is in the middle will carry on. When field mice of dark color, light color and medium tan all live in a field, when the field turns to a tanner color the middle variation will be the only one to survive. In Stabilizing Selection it is favorable to obtain the middle gene. Disruptive Selection has two extremes which both benefit from their environment. Birds with smaller beaks can fit into tiny holes in trees and gets smaller insect. Although, birds with larger beaks can break open larger seeds. If you are anywhere in the middle, you lose both of these abilities and cannot survive.
In Sexual Selection, there are certain aspects of an organism's civilization that are plainly luck of the draw. If you are a male, by obtaining these desired characteristics such as blue feet, large maines or size you are able to survive and hopefully reproduce more efficiently while passing on these traits to your offspring. There is no point to survival for these organisms if they do not sucessfully reproduce and pass on the trait to as many offspring as possible.

Evolution is "So overwhelmingly established that is has become irrational to call it a theory."
-Ernst Mayr

I found this pictures on google describing the change in whales which I thought was pretty crazy.




Also this link has a lot of terms and concepts concerning adaption, genes and selection.


http://www.wsu.edu/~rquinlan/basics.htm

I'm not really sure how to finish this off but if anyone needs help uploading pictures or videos email me and you can ask me for help there.

Darwin & Evolution

Today we learned about natural and artificial selection. For hundreds of thousands of years the theory of the gods creating all life on earth had been accepted and people were not as bold as to question this belief until circa 1800's. Contrary to this belief we have fossil records showing creatures that are very similar to present creatures. Also existing are archeopterix which show the link between reptiles and birds.
Here is a link that i found of a recent journal further explaining this subject: Transitional Forms

Charles Darwin came across fossils of extinct armadillos however he found that the living armadillos on the same continent (South America) were very similar and this helped prove his theory of natural selection and that creatures cannot adapt over a lifetime but through reproduction (however he did not come up with the theory of DNA and genes). He concluded that those armadillos who were not born with the favorable trait did not survive and eventually this favorable trait became normal and only this type of armadillo would survive. He found the same situation with the Mylodon (giant ground sloth) and the Modern sloth.

Another scientist who had ideas about evolution was LaMarck. LaMarck understood that adaptations took place, but was a little off in his theory. LaMarck believed that organisms adapted over their lifetime, like in this cartoon that I found.

Evolution by Natural Selection

The lesson for Monday September 10th covered chapter 22 "The Evidence for Evolution". Today's lesson went over the concept of evolution by natural selection. People often believed and were lead to believe that all life was made by the creator in perfection and was unchanging. There is evidence all around the earth such as the fossil record which gives evidence that the world is always changing. Charles Darwin was a naturalist in the 1800s who traveled on the Beagle to observe the world around him. He did not come up with the idea of evolution. Evolution had been understood by people before him like the Egyptians since evolution means change over time. Darwin came up with evolution by natural selection.

A portrait of Charles Darwin:


Natural selection by definition is the differential reproduction of genotypes; caused by factors in the environment which leads to evolutionary change. This means that certain traits are selected in a species that are advantageous and help them to survive, depending on their environment, and are passed on to future offspring. Darwin's most famous supporting evidence is the finches in the Galapagos Islands. There he observed that there were different types of endemic birds with similar phenotypes. Later he found out that all the birds were finches. All the finches came from a common ancestor but they had adaptations which helped them to survive in the environment. All had different shaped beaks which were best for their survival. The variation in beaks within the same species enabled some to obtain food successfully in the different environments.

Adaptive radiation is where different species originate from a similar ancestor and they inherit different successful adaptations to fulfill their niches. A niche is the position of a species or population in the ecosystem. Organisms cannot choose the traits they want, they cannot adapt but have adaptations.

Lamarck was a naturalist who believed that organisms could adapt and change during their lifetime and pass those useful traits onto future offspring. Darwin and Lamarck were both observers of the world who had great ideas about how the world worked but evidence now shows that natural selection is more accurate and that organisms cannot choose their own genes and that genes are picked at random when an organism is created.

In conclusion, Darwin did not propose evolution but evolution by natural selection. He supported his idea with experiments like that with the finches from the Galapagos Islands. Natural Selection would fall under Evolution in the eight themes of biology.

I found these cartoons online. These show that organisms cannot adapt and choose traits they desire but it is a long process where organisms have adaptations.






This diagram shows the difference between LaMarck's theory and Darwin's using giraffes (click to see larger version):



To read more about Charles Darwin's Origin of Species or his journal and diary while on the Beagle go to this site: http://darwin-online.org.uk/

How to Blog Safely

Blogging is a very public activity. Anything that is posted on the Internet stays there. FOREVER! Deleting a post simply removes it from the blog it was posted to. Copies of the post may exist scattered all over the Internet. That is why we need to be careful and follow some simple, clear, safety rules.

FIRST RULE:
To protect your privacy, you need to set up your account using ONLY your first name. This means that many of you need to go in and change your profile. If you have the same first name as another classmate, then let's add only your last initial to your first name, like KimF.

SECOND RULE:
We do not use pictures of ourselves in our profiles. If you really want a graphic image associated with your posting use an avatar -- a picture of something that represents you but IS NOT of you.

Other teachers who have blogged with their classes have come up with a list of guidelines for student bloggers.

One of them, Bud Hunt, has these suggestions, among others:

1. Students using blogs are expected to treat blogspaces as classroom spaces. Speech that is inappropriate for class is not appropriate for our blog. While we encourage you to engage in debate and conversation with other bloggers, we also expect that you will conduct yourself in a manner reflective of a representative of this school.


2. Never EVER EVER give out or record personal information on our blog. Our blog exists as a public space on the Internet. Don’t share anything that you don’t want the world to know. For your safety, be careful what you say, too. Don’t give out your phone number or home address. This is particularly important to remember if you have a personal online journal or blog elsewhere.


3. Again, your blog is a public space. And if you put it on the Internet, odds are really good that it will stay on the Internet. Always. That means ten years from now when you are looking for a job, it might be possible for an employer to discover some really hateful and immature things you said when you were younger and more prone to foolish things. Be sure that anything you write you are proud of. It can come back to haunt you if you don’t.


4. Never link to something you haven’t read. While it isn’t your job to police the Internet, when you link to something, you should make sure it is something that you really want to be associated with. If a link contains material that might be creepy or make some people uncomfortable, you should probably try a different source.

Look over the guidelines and add any ones you'd like to suggest in the comments section below this post. I think Bud's suggestions are excellent -- clear and easy to follow. We'll be using these from now on as the basis for how we will create our blogs.

You've got to pay attention to the list of "What Not To Do"!

Regards,

KBF

Cycle 2 Sherpa Guide List

This is the list of possible Sherpa Guides for Cycle 1 of blogging. Pick our next Sherpa from this list. If a classmate has served as a Sherpa Guide then their name will be crossed off. Choose one of the names that hasn't been crossed off.

updated Nov. 20, 2007
Jaclyn
Jesse
KellyP
KellyS
Kerrie
Kimberly
Kristyn
Marc
Maria
Mia
Nicole
Saad
Seung
Shana
Shannah
Tom

Welcome to Our Virtual Classroom

We started blogging this summer, but now we are going to take it to the next level. This will be your blog for AP Biology (Period 8 & 9) for the whole year. Let me make that clear -- this isn't MY blog; this is OUR blog. This blog is what you'll make of it. I'll prod a bit to get you started, but you can then take it as far as you want, to make it a helpful learning environment for all of you.

Since I strongly believe that you don't really learn something until you have to teach it to someone else, we will use this blog for students to teach students. Each day a student in class will be assigned to be the class sherpa -- our guide who will show us the clear path up the mountain of knowledge. I will appoint the first sherpa, but after that... today's sherpa will pass their baton on to the next sherpa of their choosing. This will serve as 50% of your participation mark for the quarter.

What will the sherpa do here?

1. Summarize the day's lesson.
2. Highlight the important points of the lesson -- especially highlighting concepts exemplifying the 8 themes of biology (more about these later).
3. Highlight any unanswered questions left after the class.
4. Help clarify any points of confusion left after class.
5. Point us to resources that help learn today's lesson -- like animations, videos, diagrams, photos, other teacher's Web sites that illustrate concepts we've been learning.