Mr. T's Science Scene

Life and Life Traits

When looking around the internet you will find many differnt Life Trait lists.  We are using a universal list from the textbook; Biology.  In order to remember the 8 life traits we use GERRDCHM.  The 8 life traits are as follows:

1.  Growth and Development

      All living things will grow and/or develop various body parts or structures.  New Link


2.  Evolution

     Living things will evolve (as a species).  This evolution is driven by genetic mutation and external environmental pressures.  The greater the genetic

     divergence from the parent species the greater the chance of a new species being formed.

3.  Reproduction

    All living things (as a species) reproduce more of their own kind.  Those who can not or do not have offspring are still considered living because, as a

    species, the potential is still there.  There are some exceptions (human made) such as the mule, liger, and brocciflower- all genetic creations by people

    who have NO potential to reproduce.

4.  Response or Reaction

    Living things will react or respond to stimuli (a stimulus is an external force that acts apon the senses or sensory structures). . . . . READ MORE



Biotic, Dead, and Abiotic

From now on we will define life or living things as biotic.  If something is biotic then it has ALL EIGHT LIFE TRAITS.

When something was biotic and looses even one of the eight life traits they are dead.  (Usually they loose a bunch of life traits all at once, however, dead things still possess cells and DNA.

If something was never biotic, is not biotic now, and never will be biotic in the future it is abiotic.  Abiotic things are elements, rocks, metal, plastic, etc.

An organism WILL become abiotic through the process of decomposition.  On the "road of death" a biotic thing dies and is, in general, eaten by scavengers.  Scavengers take apart and use much of the digestible parts of an organism.  After that (and during- really) bacteria and fungus will work to break down whatever is left.  They break down the bones, hair, skin, etc. into the organisms essential elements. So a deer that dies in a field will, eventually, become part of that field in the form of carbon, nitrogen, oxygen, sodium, etc. . . . . READ MORE


Spontaneous Generation and The Cell Theory

Spontaneous Generation was the scientific theory that "lower life forms" (frogs, mice, verman, worms, insects, etc.) came from abiotic things.  For example, mice came from the combination of sweaty clothing and wheat, maggots came from rotting meat, worms came from the dirt, and so on.  

In 1668, Francesco Redi performed an experiment with rotting meat to show that maggots came from flies and not the meat itself.  He put rotting meat in an open mouth container, a totally closed container, and a container that was covered with gauze (so the smell would come out but the flies couldn't get in).  The results were that the flies flew into the open container and landed on the meat, they didn't do anything with the closed container, and they landed on the gauze.  Maggots formed on the open rotting meat and on the gauze- proving that flies laid eggs that turned into maggots! Still, even Redi thought that some things did spontaneous generate from the matter around them.

In 1745, two priests performed nearly the same experiment to prove and disprove Spontaneous Generation . . . . READ MORE


Eukaryotes, Prokaryotes and Cell Organelles

As we move into cell parts it is important to distinguish between two types of cells.  Those two types of cells are:


Eukaryotes- have a nucleus and complicated organelles.

     a.  (you)karyotes. . . You (humans) have eukaryotic cells.

     b.  Have a nucleus and DNA (inside the nucleus)

     c.  Have the following cell parts:  cell membrane, cytoskeleton, cytoplasm, nucleus, mitochondria, ribosomes, endoplasmic reticulum (ER), golgi,

          vacuoles, lysosomes, cell wall (plants), chloroplast (plants)

     d.  All living things EXCEPT bacteria/viruses


Prokaryotes- do NOT have a nucleus and only have a few parts.

      a.  Oldest and most abundant life on the planet!

      b.  Do not have a nucleus but do have floating DNA

      c.  Have the following cell parts:  cell membrane, cytoskeleton, cytoplasm, ribosomes


Cell Parts: Here is a great site to go to Cells Alive . . . . READ MORE


Microscopes

The compound light microscope is the instrument that you will be using to view microscopic things in class.  The compound light microscope is pictured below.  . . . READ MORE



Microscope Measuring and Wet Mount Slides

Measuring with a microscope is pretty easy but you have to know the diameter of the FOV at each power.  Remember, the diameter is the line from one side of a circle to the direct other side- it splits the circle into two equal halves.  The diameter does not have to go across the middle; left to right!  It can cut the circle at any two points as long as the two sides are equal- think of a pizza.

So, at low power the diameter is 4.5 mm, at medium power the diameter is 1.5 mm, and at high power the diameter is .45 mm.  The FOV doesn't really shrink but the higher powers and closer lenses make the FOV appear to be smaller.

Now that you know the different diameters of the FOV, the rest is pretty easy.  When you see something on the microscope you need to measure you simply ESTIMATE how MANY of that "thing" would fit across the diameter (see above).  Then the math is: divide the FOV by the estimated number.

For example, I estimate that five things can fit across the diameter of the FOV at low power.  That means the equation is 4.5mm / 5 = .9 mm. . . . . READ MORE


Mitosis

In order for something to be considered living it must have all eight life traits.  One of those traits is the ability to reproduce. Mitosis is cellular reproduction- that is, mitosis accounts for the making of new cells.  

In multicellular animals this cellular reproduction is used for growth and repair of the larger tissues and body.  For example, without mitosis, you'd be "Johnny the One Celled Boy" since after your mother's egg cell was fertilized by your father's sperm cell, that resulting fertilized, single cell needs to reproduce over and over again to make you- a multicellular organism.  This is the same with all living organisms.  Also, if it were not for mitosis, cuts and breaks would never heal!

In single celled organisms, like bacteria and protists, mitosis is used for reproduction (which is still cellular reproduction) call Fission BUT the resulting cells are autonomous (individual and on their own) as they are made. . . . READ MORE


Mitosis and Cancer (LE)

Now that you have the basics of mitosis (Interphase, Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis), we can move on to more specifics about that cell cycle and mitosis.

Mitosis is really a very small part of the cell cycle that includes "getting ready to reproduce" and "splitting".  During interphase, there are no less than three protein checkpoints to make sure the cell and the duplication of the chromosomes goes well.  At some point in the cell's growth a protein called Ras Cyclin will chemically check to see if the cell is big enough, mature enough to move forward with mitosis.  If it is, that means that there is enough cellular material to be split into two cells.  If it is not, the cell will need to grow some more.

If the cell is mature enough then a protein called p53 will check the chromosomes to see that they are undamaged and in good order.  If the chromosomes (DNA) is damaged, another protein will attempt to "fix it".  Usually the issue is a slight change in the A,T, C, G sequence.  If the DNA is severly damaged, the cell may not undergo mitosis and all- it will simply die. . . . READ MORE


Cell Membrane

The cell membrane is composed of phospholipids and proteins.  The phosopholipids form a double layer of lipid (fat) molecules (on the outside and inside of a cell- hydrophyllic) and are connected to phosphate tails in between the two lipid layers (hydrophobic)- like a jelly sandwich where the lipids are the bread and the phosphates are the jelly.  So the layer facing the environment and the layer facing the cytoplasm are exactly the same (hydrophyllic).  The charges on the phospholipids (the lipid heads are positively charged [+] and the tails are negatively charged [-]) keep charged ions from passing through the cell membrane (opposite charges repel!).   In addition, the lipid heads are round and form spaces between them.  These spaces are very small so larger particles and molecules can't get through.  All in all, only small, neutral particles can pass through the cell membrane "at will".  Substances like oxygen and carbon dioxide are able to pass through "at will". . . . READ MORE


Diffusion and Transport

This movement of particles back and forth across the cell membrane may be passive (passive transport; which requires no energy) or active (active transport; which requires energy or ATP.  This transport of particles (atoms and/or molecules) happens because of differences in concentration.  Concentration is defined as "how many particles are in a specific area".  The differences in the concentration of particles forms a concentration gradient (hill) with more particles on one side than the other.  Where the particles are more numerous we have a high concentration (top of the hill).  Where particles are less numerous we have a low concentration (bottom of the hill).  Particles are always moving (Brownian Motion) and trying to come to equilibrium- balance.  This tendancy to try and achieve balance or equilbrium is what drives the particle movement . . . . READ MORE


Cellular Respiration

In order to do ANYTHING with your body (or, for that matter, any living thing's body- including plants) there must be available ATP or energy.  In all plants and animals the process that produces that ATP is cellular respiration.

Cellular Respiration IS NOT breathing.

Breathing is not cellular respiration.  Breathing is an act that few organisms do; those that do breath are mammals, birds, and reptiles.  Breathing is simply the act of getting air (which contains oxygen) into the body.  Everything else has a different way of getting oxygen into the body; fish use gills, amphibians use their skin, plants use stomata.  So, you may be able to "breath" just fine but if your respiration is messed up then you will die.

So, in humans (you!), cellular respiration actually starts outside our body!  Here is how it goes:

A.  The air has oxygen in it and we need that oxygen. . .

B.  so we breath- sucking down air which contains, among other things, oxygen.

C.  Our lungs (specifically our alveoli- thousands of small sacs which make up our lungs) now have a high concentration of oxygen and . . .

D.  our blood, which is pressed right up against our alveloi, has a low concentration of oxygen.

E.  Oxygen, therefore, diffuses, from the lungs (alveoli) into our blood and is taken to the billions of . . . READ MORE


Nutrients

So far we have been talking about sugar and its role in respiration (how the sugar is split in the cytoplasm and so forth and so on until ATP (energy) is made).  Now we will learn about sugar's distant cousins, starch, protein, and fat (lipids).  These are the four main nutrients that you get from food and which your bodies use to build you, make you work, make you grow, etc.  Other nutrients are vitamins and minerals- which help chemical reactions in your body and make up your bones- and water!


Proteins are widely distributed in nature and no living organisms are known without them.  Humans and animals use proteins for the growth and repair of tissues.  The protein-rich foods from animal sources contain complete proteins, which supply all the building blocks (amino acids) necessary in an animal’s diet.  Protein can also be found in a variety of nuts and nut products.  Proteins are used in a wide variety of chemicla and microscopic processes such as enzymes, transfer proteins, and holding DNA together.


As you eat protein (foods or food products from animals) your digestive system breaks down the animal protiens to their amino acids.  Those amino acids are distributed to your cells and "hang out" in your cytoplasm to be used by your ribosomes to make parts of you!  So you really ARE what you EAT!



Carbohydrates are the most abundant food sources of energy.  . . . READ MORE


Nutrient Testing


Fast and Easy Tests

Protein Test:

1.  Place all your samples on a plate or petri dish.  Make sure they do not touch.

2.  Put 1-3 drops of BIURET'S SOLUTION on each sample.  Be careful:  Biuret's is a medium acid which will cause itching on the skin.


Positive Color/Result:  Purple or Lavender

Negative Color/Result:  (Stays the same color- light blue)


Notes:  This can be a hard test to evaluate becuase meat is typically dark and you can't see the color change.  Remember:  all protein products come from animals in one way or another.  You also need to leave the chemicla on for a minute or so. . . . READ MORE