Wk 4, Looking Ahead to Wk 5

Frog Dissection Recap

You did it - you made it through frog dissection!! I was very pleased with lab this week.  There was some great dissecting skill, lots of discoveries and learning, and no one vomited or fainted.  It would have been nice if one of our specimen were a male, but we managed to get 8 our to 8 female frogs.  

2nd Hour at work

T shows off her mad scalpel skills (beautiful heart specimen!)

I hope that in examining the frogs you have a better understanding of your own anatomy.  Of course you aren't a frog, but on the grand scale of life you are so very close in structure to a frog (much more so than to a bacteria).

And speaking of bacteria, we are spending week five covering the two prokaryotic domains, Archaea and Bacteria.

Archaea and Bacteria

We read last week about classification, or putting organisms into different groups (taxa) with similar organisms.  The most inclusive taxon (single of taxa) is the Domain.  All life is classified into one of three domains - Archaea, Bacteria, or Eukarya.  Eukarya includes the four Kingdoms Protista, Fungi, Plantae, and Anamalia.  We will cover these kingdoms in the next several weeks...

...but for this week we will focus on domains Archaea and Bacteria.  Bacteria and Archaea both are prokaryotes: single-celled organisms lacking true nuclei and other membrane-enclosed organelles. Bacteria and archaea, however, differ in cell wall characteristics and membrane lipid composition. They also differ in RNA polymerase structure and, therefore, protein synthesis.

Archaea are the oldest, evolutionarily, and came into existence at a time the earth was still young - about 3.5 billion years ago.  The conditions on earth at that time were much more extreme - excessive UV radiation, extremes of temperature, very high concentrations of salt, extremes of pH, no atmospheric oxygen, and loads of atmospheric carbon monoxide, carbon dioxide, methane, and ammonia.  Today, archaea are still found in these extreme environments where they persist on earth, places like hydrothermal vents on the sea floor, high altitude ice sheets, permafrost, hot springs, and the Dead Sea.  We call organisms which live in these extreme environments extremophiles. Note, not all members of Archaea are extremophiles, and there are also extremophiles in domains Eukarya and Bacteria.

Bacteria arose about 3 billion years ago, and they are everywhere.  There are more bacteria in one person's mouth than there are people on the earth!  In fact, there are so many bacteria in the average human body that if we could isolate them all they would weight about 4 pounds.  If you think that is amazing, here's a link with more amazing bacteria facts. Many types of bacteria cause disease in humans, but many other types of bacteria live symbiotically or commensally in or on use. Bacteria are found not just in and on humans, but in and on places all over the earth.

Readings and Other Resources

5

RSO Ch. 29 Domains Bacteria & Archaea

LOE this week Read either CK12 BC or CK12 LSC

CK12 BC 7.1-7.7

CK12 LSC 5.1-5.7

Domains and Kingdoms of life - transition, Ricochet Science covers Bacteria and Archaea (and Eukarya, but we will cover Eukarya in the next several weeks) Bacteria: The Good, the Bad, and the Kind of Gross - transition, Amoeba Sisters talk about bacteria and anti biotics Microbe Evolution and Classification both - excellent animation on the topic, with the bonus of reviewing some things we've already covered this year.  *You have to click on the link in the right hand column found under Microbiology=> Scientific Animations, and then choose Microbe Evolution and Classification (lower right of the 4 animations that come up).  It moves fast, but if you click on the box in the upper left corner of the animation it will stop - you can use this as a kind of pause button in order to finish reading before the animation moves on. Antibiotic-Resistant Superbugs - both, It's Okay to Be Smart, gives some relevancy to studying Bacteria The Three Domains of Life - scholar, Bozeman Science covers al three domains and what characteristics distinguish each Old & Odd: Archaea, Bacteria &Protists - scholar, Crash Course covers Bacteria and Archaea (and Protista, even though we will cover it next week)

Don't forget to:

• do the readings and watch the videos
• keep building your vocabulary list
• hand in Respiratory-Cardiovascual lab (if you haven't already)
• email me pictures of your petri dishes (if you haven't already)

See you Thursday!