04/13/23 Lecture 5: Higher Cells 1

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Online bioscience course for grades 6-12

Fall 2009

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Class mechanics…

• Attend the online Office Hour on Tuesdays at 3 PM via tokbox-Discuss previous week’s video lecture• Online video lecture e-mailed every Wednesday-view lecture and prepare to discuss the following Tuesday• Comment on video lecture using website discussion board• Online Final Exam given 12/9/2009

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Lecture 5: Higher cells

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Take Homes:

I. Higher cells are very complex, highly compartmentalized and not streamlined…II. The DNA genome of higher cells is packaged in linear chromosomes…III. The genes of higher cells are in pieces IV. Higher cells move in ways mediated via their cytoskeletons…V. Higher cells communicate via small molecules and proteins which regulate their behaviors…

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The basic structure of higher cells (eukaryotes):

plant

animal

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Eukaryotic animal cell structure:

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Tour of an animal cell:

http://www.youtube.com/watch?v=PXbv95P3uhI

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Eukaryotic plant cell structure:

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Tour of a plant cell:

http://www.youtube.com/watch?v=LMVQ-INMSVw

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Compartmentalization of the eukaryotic cell…

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Compartmentalization of the eukaryotic cell nucleus…

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Endocytosis:

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Cell membrane, exocytosis and endocytosis:

http://www.youtube.com/watch?v=K7yku3sa4Y8

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Amoeba Feeds! An example of endocytosis:

http://www.youtube.com/watch?v=W6rnhiMxtKU

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Higher cells also have an internal cytoskeleton:

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Actin and Tubulin proteins in the cytoskeleton in higher cells:

nucleus

nucleus

microtubules(made of tubulin)

microfilaments(made of actin)

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Tagging a gene with GFP:

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The cytoskeleton is dynamic in higher cells:

http://www.youtube.com/watch?v=DA8DvDE_nZo

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The cytoskeleton controls movement inside higher cells:

http://www.youtube.com/watch?v=CDWoOOd_VHo

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DNA in higher cells is packaged in linear chromosomes:

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Higher cell chromosome structure:

http://www.youtube.com/watch?v=OStI5pniHPA

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Take Home I

From their complex membrane structure, their internal cytoskeleton to their chromosomal DNA, higher cells are extremely complex and versatile…

Higher cells are very complex, highly compartmentalized andnot streamlined…

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Genes in higher organisms are in pieces-introns and exons:

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Chromosomes, Chromatids, Chromatin, etc…

http://www.youtube.com/watch?v=s9HPNwXd9fk

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The ends of linear chromosomes (telomeres) cause a problem:

unlike bacterial circular chromosomes, linear chromosomes shorten with each round of DNA replication because of the way DNA polymerase works…

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Telomeres and telomerase:

http://www.youtube.com/watch?v=AJNoTmWsE0s

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Mitosis:

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Mitosis-animation:

http://www.youtube.com/watch?v=VlN7K1-9QB0

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The centriole:

http://en.wikipedia.org/wiki/Centriole

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GFP tagged tubulin-role of microtubules in mitosis:

http://www.youtube.com/watch?v=TBfFJlKMyPA

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The cell cycle:

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Take Home II

Unlike bacterial chromosomes, which are circular, the chromosomes of higher cells are divided-up into collections of single linear DNA molecules…this created unique challenges in replication…and the chromosomes interact with the cytoskeletal microtubules during cell division…cell division is controlled by a clock-like mechanism called the cell cycle…

The DNA genome of higher cells is packaged in linear chromosomes…

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Introns splices from mRNAs, often generating alternative products:

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Gene expression in higher cells…:

http://www.youtube.com/watch?v=bk7PW1FKMTI

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Take Home III

Genes in higher cells are often broken-up into exons and introns, with the introns being spliced-out of RNA before it is translated by the ribosomes…genes in turn are controlled by DNA binding regulatory proteins…

The genes of higher cells are in pieces and are highly regulatedand processed…

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Movement in higher cells-pseudopodia:

http://www.youtube.com/watch?v=7pR7TNzJ_pA

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Role of actin in cell movement via pseudopodia:

http://dictybase.org/Multimedia/motility/motility.htm

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Mechanism behind pseudopodia :

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Movement in higher cells-flagella and cilia:

http://www.youtube.com/watch?v=QGAm6hMysTA

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Structure of higher cell flagellum :

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Take Home IV

Actin, myosin, tubulin and a number of other protein components of the cellular cytoskeleton effect the movement of cells via several different mechanisms…

Higher cells move in ways mediated via their cytoskeletons…

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Higher cell communication I:

http://www.youtube.com/watch?v=QGd5kg9JqoM

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Higher cell communication II:

http://www.youtube.com/watch?v=12QHDoSiEWM

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Take Home V

Small molecules such as cyclic AMP and proteins such as growth factors regulate cellular activities and behaviors through the regulation of genes…

Higher cells communicate via small molecules and proteins which regulate their behaviors…

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Next Week:

Organs, tissues and organisms

How higher cells interact and cooperated to form the tissues and organs of organisms…

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instructorMark E Minie PhD

mark@meminie.com