Animal Cell 2

Animal Cell

the experience

an interactive simulation that will take you on the ride of your life!

please keep your hands and feet inside the vehicle at all times....

get ready...

get set....

go!!!!!!

First, we'll begin with an overview of the cell

Here's what an animal cell looks like......

Each of these animal cells contain organelles, those are the colored objects within the cell. Organelles are specialized parts of the cell that carry out distinct vital processes.

You will be exploring several organelles in detail later in the tour. It is STRONGLY suggested that you purchase a colorful and informative souvenir in the gift shop on your way out! (What a better way to suck up to your AP Biology teacher than get them a beautifully sculptured cell!)

Our first organelle is the nucleus.

F.Y.I

All of those white arrows were pointing to the nucleus!

The nucleus is spherical in shape and the easiest to see organelle of them all. It is typically located near the center of the cell. The nucleus is surrounded by two membranes which are both phospholipid bilayers and form the nuclear envelope. The surface of the membrane is studded with nuclear pores that are blocked by proteins. These selective proteins allow certain molecules to pass through. The center of the nucleus is the nucleolus, which is where constant synthesis of rRNA takes place.

The nucleoli are surrounded by a fibrous, gel-like liquid called nucleoplasm that is similar to cytoplasm in consistency.

Function of the Nucleus:

The nucleus contains the hereditary material (DNA) of the cell. It is the control center of the entire cell, functioning quite similar to the brain that humans possess. It directs cell reproduction and protein synthesis. In eukaryotes, this hereditary material is in the form of several linear spindles and chromosomes.

ITS FUN FACT TIME!!!!!!!!!

Some cells, (not many but a few types of fungi) have more than one nucleus.

Now, onto the next organelle....

Mitochondria

The yellow "beans" with squigglies inside (yeah, they're the mitochondria)

Mitochondria are tube-shaped organelles that are about the same size as modern day bacteria.

They are located throughout the cytoplasm. They contain two membranes, a smooth outer membrane and an inner folded one.

Within the inner-membrane, there are two separate compartments.

The matrix is located inside the membrane and the intermembrane space is, well, space inside the membrane.

Mitochondria are also very valuable because they contain proteins. These specific proteins are in charge of oxidative metabolism, which is the process by which ATP gains its energy storing macromolecules.

Fun Fact!!!!!

According the the endosymbiotic theory, millions of years ago, a bacterium resembling modern-day mitochondria was engulfed by a larger cell. They formed a symbiotic relationship: the mitochondrion provided energy for the larger cell and the larger cell provided a homeostatic environment for the smaller cell. (Aw, they were helping each other out!)

Mitochondria contain their own hereditary information (DNA), which is evidence for the endosymbiotic theory. (How do you like those apples, all you skeptics out there?). Although it contains its own DNA, these organelles are not fully autonomous because the genes for oxidative metabolism are in the nucleus. Thus, mitochondria cannot be cultured without the cell.

More information is avaliable on the endosymbiotic theory at the gift shop near the exit.

Function of Mitochondria:

Proteins synthesized by mitochondriad carry out oxidative metabolism that creates energy for the cell. This process is carried out on the surface of the inner membrane.

During cell reproduction, mitochondria split themselves in two. Each new mitochondrion goes to a different cell.

Now, to the small, busy workers of the cell......

Ribosomes

They are slightly hard to see but...

the tiny blue dots are ribosomes.

Little blue dots on a piece of clipart can't be THAT important can they?

WRONG!!!!

The ribosomes are dense particles of the cell that are found floating through the cytoplasm or attached to the endoplasmic reticulum (we will be going in to further detail on this organelle later in the tour).

Interesting Fact...

The ribosomes on the rough endoplasmic reticulum manufacture the proteins that are exported outside of the cell.

The ribosomes have the very important job of performing protein synthesis.

And what is protein synthesis you ask?

Protein synthesis is when the ribosomes create proteins. Some people assume that since the nucleus encodes the amino acid sequence of each protein, the nucleus also assembles then. Well, you know what assuming does...

They synthesize proteins by utilizing two subunits, they fit together like a glove. These two subunits join to form a functional ribosome. Later, a mRNA floats over the the ribosome and says "Hey, I got a message for you from the nucleus." Then, the ribosome produces whatever protein the mRNA tells it to.

Heres a great site that describes proteins synthesis in detail:

http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120077/micro06.swf::Protein%20Synthesis

the nucleolus manufactures ribosomal subunits

By the way...

rRNA stands for ribsomal RNA and mRNA stands for messenger RNA. Clever, huh?!?

Did You Know......

The winners of the Nobel Prize for Chemistry in 2009 each won $1.4 million for discovering how the ribosome works using X-ray cyrstallography? Now you know.

Moving right along, our next organelle goes by the name of Golgi apparatus!!

Golgi apparatus

It has a cool name and looks like ham from the deli, but what does it actually do?

The cis face is the recieving end (like your mouth).

The trans face is the discharging end (sorta like your butt).

The Golgi apparatus is usually located near the Rough ER. It is composed of Golgi bodies. Together, the Golgi bodies collect proteins and lipids in transport vesicles produced by the ribosomes on the rough and smooth ER (from the cis face), modify the proteins so they are useful for the cell, and ship them out to where ever they need to be in the cell (through the trans face). They are discharged in secretory vesicles through endocytosis. This whole process is very similar to how a post office operates because the Golgi labels and packages these secretory vesicles for their final destination.

There are two common modifications that take place in the Golgi:

• Glycoprotein: when proteins are bonded to sugars to form a more complex molecule
• Glycolipid: when lipids are bonded to sugars

Knoweledge for Your Noggin:

The Golgi apparatus was named after an Italian physician, because he was the first person to actually pay attention to the organelle. So, if you want to become famous someday, discover something no one really cares about and wait for it to become popular. Then, your name will be widespread!!!

Next, we will take a look at the cytoskeleton. Without it, all of our cells would be big piles of mush. Gross!!! *sounds of gagging in the corner*

or this....

The cytoskeleton is found all throughout the cytoplasm and helps keep the organelles where they are supposed to be. It also functions as a structural device because it helps keep the shape of the cell. Like it was mentioned earlier, cells would be a big messy goop of nastiness if it weren't for the cytoskeleton.

The cytoskeleton is NOT made of bones, like the skeletons in humans. Instead, it is composed of three different kinds of fibers. These fibers are constantly breaking, reforming, and changing shape.

new fibers are formed by a process called polymerization-

identical protein subunits attract to each other to form long chains

fibers dissassemble by the same process, with bonds breaking beginning with the first subunit

The first type of fiber is called actin filament. It's function is to "move" the cell. Cells move by "squirming" and this squirming is made possible by the actin filament. It is also what allows cell to reprduce because if cells weren't getting pinched and reproducing, cells would cease to exist today. So, pretty much, these fibers are essential.

Second on our list of important fibers are the microtubules. These hollow tubes assist the cell by moving things that need to be moved within the cell itself. The protofilaments are lined up around a central core, giving this fiber its characteristic tube shape.

And last but definitly not least, there are the intermediate filaments. Their essential function is holding up the structure of the cell. These tough, fibrous proteins are arranged in a quilt-like overlapping pattern. Some examples of intermediate filaments are vimentin (most common type), keratin, neuroifilaments.

And now it is time for the ENDOPLASMIC RETICULUM!!!!!

also known simply as the ER (specify smooth or rough).

The endoplasmic reticulum helps organize the cell by dividing it into separate compartments or rooms. It is composed of a thin protein sheath and weaves all throughout the cell. It is the largest internal membrane of the cell. The two largest compartments are called the cisternal space, which is within the ER, and the cytosol, which is outside the ER. Another way to think of the ER is as walls in a house, so each organelle can operate, but the walls are not completely shut so the organelle can interact with other visiting organelles.

The ER is also divided into two sub divisions.

The rough ER gets its name because the areas of the ER that are heavily involved with protein synthesis are densely covered with ribosomes. Under a microscope, this give the ER a "rough" appearance. The proteins that are synthesized on the surface are sent to the lysosomes or embedded into the membrane. This external face synthesizes cholesterol and phospholipids. These proteins that are exported have distinct amino acid sequences called signal sequences. Some of these proteins pass through to the cis face of the Golgi apparatus in vesicles. The proteins are bonded to a sugar group in the cisternal group.

The smooth ER, on the other hand, has few ribosomes, but more enzymes. The enzymes in the smooth ER catalyze a variety of carbohydrates and lipids. Smooth ER is plentiful in organs that carry out intensive lipid synthesis such as the brain and intestines. It is also abundant in the liver where it filters and detoxifies the blood of alchohol and other toxins.

All of the information presented today may seem to be overwhelming, but do not fret! As we come to an end of this magnificent tour, there are several brochures that will describe the information presented today in a more thorough manner.

Now to some particularly interesting organelles...

Flagella

and

Cilia

Flagella are used for cell locomotion

eukaryotic flagella are completely different than prokaryotic flagella

except of course the function of this organelle.

these flagella consist of nine pairs of microtubules that surround two central microtubules

This is called 9+2 structure

Those microtubules are made of dynein, which is a motion protein

The flagella in eukaryotes undulate (like a wave), contrasted from the rotating motion found in prokaryotes.

each flagellum originates inside of the cell in a region called the basal body

No, no, I know what you're thinking..

Not the plant that makes the delicious sauce pesto which is spelled BASIL, this area of the cell is called the BASAL body.

Nowadays, most eukaryotes do not possess flagella, but that 9+2 arrangement can still be found in another similar structure called cilia.

Cilia are shorter projections from the cell that are more numerous than flagella.

they have the same basal body structure as flagella

cilia are suited for many more tasks than just propelling the cell through water. In fact, the hairs in your nose are actually cilia that function as sensory structures

With that being said, do not think you are free to get up and leave yet! We still have one more pit stop to make. Our final destination will be at the lysosomes.

lysosomes function as the pick-up crew, the janitors, or the custodial staff (political correctness), that clean up after the party is done..

Lysosomes function as the cells digestive system. It cleans out the cell by digesting lipids, carbohydrates, and nucleic acids. It gets rid of the old and non-functional biproducts to make room for the new and useful ones. As a matter of fact, lysosomes can replace the tissue of an entire mitochondrion in less than ten days. Lysosomes are able to be compared to the "cleaning ladies" of the cell. Not that organelles have a gender, but they both do the same types of jobs.

There are different types of lysosomes.

Digestive lysosomes have low pH levels due to the high levels of protons in possesses in its interior. They pump protons into their interior to maintain this pH level.

Primary lysosomes are acidic are are considered inactive. They are capable of becoming active, and when they do, they are then called secondary lysosomes.

lysosomes arise from the Golgi apparatus

Another important function of the lysosomes is thier assistance after a cell performs phagocytosis.

For those less knoweledgable in the area of cell biology, phagocytosis is when one cells "engulfs" another. In a way, the cells act similarly to Packman. But, the lysosomes are so valuable during this process because they are the ones that help dispose of and recyclethe parts of the engulfed cell that are unbeneficial for the "monster cell". This process is carried out by white blood cells when it engulfs a foreign body, and the lysosomes in the cell break that material down.

For all you visual learners out there, here's an animation to help you SEE how lysosomes actually work.

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__lysosomes.html

And as sad as it may seem, all good things must come to an end. And with that, I hope this presentation has been the nucleus of your day.

2009. (2009, October 7). The nobel prize in chemistry 2009 - Press release. Nobelprize.org. Retrieved December 1, 2009, from http://nobelprize.org/nobel_prizes/chemistry/laureates/2009/press.html

Animation: lysosomes. (n.d.). Lysosomes. Retrieved December 2, 2009, from http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__lysosomes.html

AP biology course online. (n.d.). Staff website. Retrieved November 23, 2009, from http://www.nkellogg.com/apbiology.htm

Anissimov, M. (n.d.). What is a ribosome?. Clear answers for common questions. Retrieved December 1, 2009, from http://www.wisegeek.com/what-is-a-ribosome.htm ]

Cell nucleus. (n.d.). Bio-Medicine - latest biology and medical news/technology. Retrieved December 1, 2009, from http://www.bio-medicine.org/biology-definition/Cell_nucleus/

Golgi apparatus. (n.d.). Camilla Golgi. Retrieved November 27, 2009, from media-2.web.britannica.com/eb-media/52/116252-004-9615DB80.jpg

Guzé, C. (n.d.). Eukaryotic cells- Biology 102 course - CarolGuze.com. Carol's classroom - CarolGuze.com. Retrieved November 23, 2009, from http://www.carolguze.com/text/102-7-eukaryoticcells.shtml

Heins, G. (n.d.). A typical animal cell - learning activity. Wisc-online - online learning object repository. Retrieved November 27, 2009, from http://www.wisc-online.com/objects/index_tj.asp?objid=AP11403

Raven, P., Johnson, G., Losos, J., & Singer, S. (2005). Biology. Boston: Mcgraw-Hill Higher Education.

ScienceProfOnline -cell cytoskeleton. (n.d.). ScienceProfOnline. Retrieved December 1, 2009, from http://scienceprofonline.googlepages.com/cellbiologyhelp5

The cytoplasm and its associated structures. (n.d.). Carmel Clay Schools. Retrieved December 1, 2009, from http://www.ccs.k12.in.us/chsBS/kons/kons/eukaryotic%20cell/cytoplasm_and_its_associated_str.htm

(folded)

(smooth)

cell

cilia