Natural Selection and Evolution

video at khan academy.

There are always variations present in a population. Perhaps a very small % are different, but if the environment changes (sooty, antibiotics, immunity) then the dominant variations will die out, leaving room for the less frequent variations to grow and reproduce (as there is no need to compete for resources).

case peppered moths.

case antibiotics kills bacteria, but if you keep taking them you might help natural selection and create a new strain of bacteria.

Intelligent Design

"intelligent design" is the belief system / theory that god created species and species did not evolve, and that god is the designer.

intelligent design at khan academy

non scientific.

Cellular Respiration

C6H12O6 (glucose) + 6O2 -> 6CO2 + 6H2O + energy

energy is produced, some heat and around 38 ATPs.

Glycolysis is the breakdown of glucose. There is a 2 x 3 carbon chains. This requires 2 ATP, produces 4 ATP, so net gain is 2 ATP.

It is anaerobic reaction because it doesn't need oxygen (as opposed to aerobic).

The Kreb's cycle will produce another 2 ATP.

The the electron transfer chain will produce 34 ATP.

Introduction to cellular respiration at Khan Academy.

Oxidation states

We can add oxidation states for each atom in the above equation, assuming that the order io increasing electronegativity of the atoms is H, C, O.

C60H121+O62- (glucose) + 6O2 -> 6C4+O22- + 6H21+O2- + energy

Splitting the above equation per atom we can see

H oxidation state remains at 12

C6 -> 6C4+ + 24e- (electrons).

C oxidation state changes from 0 to 24

C has lost electrons and has been oxidised.

O62- -> 6O22- + 6O2- - 24e- (electrons).

O oxidation state changes from -12 to -36

Oxidation and reduction in cellular respiration at Khan Academy.


Uses 2 ATPs to break up the 6 chain glucose into 2 molecules of P-C-C-C (PGAL). The ATPs are changed into ADPs.

C-C-C-C-C-C (glucose) + 2ATP -> 2P-C-C-C + 2ADP.

The next group of reactions happens twice.

P-C-C-C + NAD+ + P + 2ADP -> NADH + 2ATP + C-C-C (pyruvate)

Pyruvate is created. NAD+ has been reduced to NADH.

In the end this process has produced 2 ATP and 2 NADH.

This is occurs in the cytosol

Glycolysis at Khan Academy.

Krebs / citric acid cycle

NADH and FADH2 is produced here.

Krebs / citric acid cycle at Khan Academy.

Electron transport chain

NADH -> NAD+ + H+ +2e-

Electrons are moving to a lower energy state, H+ is being moved from the matrix into the outer compartment of mitochondira. The protons want to move back into the matrix, as they do, ATP synthase will created ATP from ADP.

Electron transport chain at Khan Academy.

Oxidative phosphorylation and chemiosmosis at Khan Academy.


These replicate in the host via reverse transcription.

RNA Virus

Virus' genetic material is stored as RNA, and can be translated into protein, or RNA replication.

Examples are influenza.


Caused by Plasmodium parasite carried by mosquito.

Malaria - Life Cycle of Plasmodium [HD Animation] at


A pathogen is anything that causes a disease, such as a virus, bacteria, prion or parasite. They can be described as pathogenic.


Section of DNA that codes for a protein. Genes belong at a locus (position) on a chromosome.


A specific version or variant of a gene.

Alleles and genes at Khan Academy.


Observable traits


A genotype describes the versions of alleles in an organism for a particular gene. In humans (diploid) one allele comes from the father and one from mother. If the alleles are different, then the genotype is heterozygous, if they are the same then the genotype is homozygous.

Introduction to heredity at Khan Academy.


A type of signalling protein.


To parameterize is to train a method or algorithm with data.