Week Twelve : Cell Biology

Mitosis vs Meiosis
Simple, easy way to understand the two processes and the difference between the two. 
I also found the following neat summary online:

	Meiosis	Mitosis
Creates:	Sex cells only: Female egg cells or Male sperm cells	Makes everything other than sex cells
Definition:	A type of cellular reproduction in which the number of chromosomes are reduced by half through the separation of homologous chromosomes in a diploid cell.	A process of asexual reproduction in which the cell divides in two producing a replica, with an equal number of chromosomes in haploid cell
Produces:	four haploid daughter cells	two diploid daughter cells
Steps:	The steps of meiosis are Interphase, Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II and Telophase II.	The steps of mitosis are Interphase, Prophase, Metaphase, Anaphase, Telophase and Cytokinesis
Discovered by:	Oscar Hertwig	Walther Flemming
Type of Reproduction:	Sexual	Asexual
Genetically:	different	identical
Cytokenesis:	Occurs in Telophase I & Telohpase II	Occurs in Telophase
Number of Divisions:	2	1
Pairing of Homologues:	Yes	No
Function:	sexual reproduction	Cellular Reproduction & general growth and repair of the body
Chromosome Number:	Reduced by half	Remains the same
Karyokenesis:	Occurs in Interphase I	Occurs in Interphase
Crossing Over:	Mixing of chromosomes	Does not occur
Centromeres Split:	The centromeres do not separate during anaphase I, but during anaphase II	The centromeres split during Anaphase
Occurrence of Crossing Over:	Yes	No
Occurs in:	Humans, animals, plants, fungi	all organisms
Number of Daughter Cells produced:	4	2

Citric Cycle Animation
A very clear illustration of the entire citric acid cycle.  It's amazing how little cells invisible to the human eye can perform highly-complicated chemical processes to give us energy.
Below is my understanding of the cycle:  
Pyruvate supplies energy to living cells through the citric acid cycle.  Citric acid cycle is a series of chemical reactions using enzymes as catalysts.  The cycle takes place in the mitochondria.  The citric acid cycle is involved in the chemical conversion of carbohydrates, fat and proteins into carbon dioxide and water to generate ATP produced in the cycle. 

Comment on "it is the network of interactions ......not one of its components."
Although totally unrelated, but this made me think of how Chinese herbal formulas work.  TCM herbs are never prescribed individually, but always combined with other herbs to create desired effects.  One toxic herb doesn't make the entire formula toxic.  However, the word "toxic" would make many who are foreign to Chinese medicine skeptical and doubtful of the efficacy of the medicine.  There is a famous Chinese saying, "use toxin to attack toxin".  In a well-thought out formula, toxicity of herbs are reduced to minimum if not totally eliminated and each herb's strength is enhanced through the combination.  So, it's never about what a single herb can do, but the power released when it is combined with other herbs.