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Thursday, January 28, 2010

Psychology: Studies in the Biological Perspective


Donald Buss   
Jealousy may be biologically based:
Women’s patterns of jealousy may vary through their menstrual cycle: during menstruation, when oestrogen levels are low, women are more sexually jealous, and during ovulation, when oestrogen levels are high, women tend to be more emotionally jealous. When menstruating, women fear that the man will seek out other females to mate with since she is unable to mate at the time, and during ovulation, since she is capable of having a child, she fears the male will develop and emotional attachment to another female and thus jeopardize the security of her child.
---- restaurant experiment


Simon LeVay  
Difference in average size of the third Interstitial Nucleus of the Anterior Hypothalamus (NAH3) between heterosexual and homosexual men: NAH3 in heterosexual men was more than twice the size of that of homosexual men. NAH3 of homosexual men was the same size as that of women.
-Reductionist
-Post mortem study

Use as example of:
--methods: quasi-experiment


Paul Broca  
People suffering from damage in the left frontal lobe of the brain – now called Broca’s area – were unable to understand and make grammatically complex sentences. His patients had problems using speech, but were able to understand it. This condition is now known as Broca’s aphasia.
Case study – Tan (all he could say)

Use as example of:
--

Florins and Lashley  
Disproved Atkinson & Shiffrin’s theory of the multi-store model of memory.
A cat was taught to go through a T-maze. Its brain was then damaged through lesioning, the brain being damaged bit by bit as they tried to damage “enrons” that were in theory responsible for storing memory.
After lesioning, the cat continued to remember the was out of the T-maze, but slower after each lesioning. Proved that memory was not localized.

Use as example of:
--ethical considerations: irreversible damage to the cats (pain, etc)


W. Greenough  
Rats
2 cages: one was a “fun”, the other “boring”
Rat in the fun cage had a larger frontal cortex.

Use as example of:
--neuroplasticity


Fred Gage  
Role of dopamine on parkinsons – alleviates symptoms

Joe Martinez  
Rats in a T-maze

Use as example of:
--basic assumptions: use animals to understand human beings
--key concepts: neurotransmission
--method: experiment


The Phineas Gage case study  
In 1848, at the age of 25, Phineas Gage was trying to blast through a rocky cliff, when an explosion sent a metal pole through his skull. The iron rod entered his left cheek, pierced the base of the skull, went through the front of his brain, and exited through the top of his head. The pole landed a hundred feet away covered in blood and brains. Gage was awake and alert, and was carried, sitting upright, to the local hotel on an ox cart.
Although he had lost vision in his left eye, the vision in his right was perfect. He had no noticeable difficulty with speech or language, and suffered no paralysis. Yet, the balance between his intellectual abilities and emotional control was destroyed, which became apparent as soon as the wounds had healed. He became agitated and irreverent, and induged at times in the grossest profanity which had previously not been his custom. He was impatient and indulgent, and although he could make plans for his future, he could not follow through with them. He was described by the doctor as “a child in his intellectual capacity, but with animal passions of a strong man”. Due to his use of shocking pornographic language women were advised not to stay in his presence for long.
This shows that the brain (frontal lobe) does in fact affect personality and social behaviors. Personality is localized, frontal lobe is important for planning and decision making.

Use as example of:
--


Gorsky  
To investigate the role of hormones on sexual behavior:
Injected female rates with testosterone, the male reproductive hormone.
Rats started mounting other female rats.
As the testosterone levels in the rats increased after the injection, the female rats adopted male behavior – hormones are responsible for gender-based behavior.

Use as example of:
--

Wedekind  
Dirty T-shirt study:
Role of genes related to the immune system (major histocompatability complex – MHC) in mate selection.
MHC genes are codominant – both sets of inherited genes have an effect on the immune system of the child. Thus, the more diverse the MHC genes of the parents, the stronger the immune system of the child. Therefore it would be beneficial, evolutionarily, to be able to recognize individuals with different MHC genes and selecting them as mates.
Recruited a group of 49 women and 44 men who had a wide range of MHC genes.
Each man received a clean T-shirt and was asked to wear it for two nights. They were also supplied with odour-free soap and aftershave and were forbidden to eat spicy food.
When the shirts were returned, each was placed in a cardboard box with a sniffing hole on top. Then women returned at the midpoint of their menstrual cycle, when their sense of smell would be keenest, and were each presented with a different set of 7 boxes. Three of the boxes contained t-shirts from men with similar MHC genes, and one contained an clean t-shirt, as a control. The women were asked to rate each shirt as pleasant or unpleasant.

--Basic assumption: behavior is determined by evolution
 

Tiffany Field    
Tough therapy: newborn babies (premies)
Newborns had a daily 40 min long massage
Gained more weight


Demasio on memory  
Neurons


Wednesday, January 27, 2010

Chemistry:10.3 Alkenes

10.3.1 Describe, using equations, the reactions of alkenes with hydrogen and halogens.

Addition Reaction:











Unsaturated hydrocarbon; break double bond; each carbon on either side of the broken double bond gains a hydrogen/halogen (hydrocarbon becomes saturated).


10.3.2 Describe, using equations, the reactions of symmetrical alkenes with hydrogen halides and water.












10.3.3 Distinguish between alkanes and alkenes using bromine water.
Bromine is red liquid; yellow/orange color in solution.
When added to an alkene the product is colorless.

10.3.4 Outline the polymerization of alkenes.
Ethene can undergo addition reations with itself to form a chain of carbon atoms (under certain conditions.)

->








Thus,








10.3.5 Outline the economic importance of the reactions of alkenes.
Hydration: ethene is formed during the cracking of oil. Although ethanol can be formed from the fermentation of starch and sugars, much industrial ethanol is formed from the addition of steam to ethene.
Hydrogenation: margarine is made from the addition of hydrogen to unsaturated vegetable oils. Hydrogenation reduces the number of double bonds in the polyunsaturated vegetable oils present in the margarine, which causes it to become solid at room temperature.

Chemistry: 10.2 Alkanes

10.2.1 Explain the low reactivity of alkanes in term of bond enthalpies and bond polarities.
Alkanes tend to be unreactive because of the relatively strong C-C and C-H bonds and because they have low polarity. They only readily undergo combustion reactions with oxygen, and substitution reactions with halogens when in ultraviolet light.

10.2.2 Describe, using equations, the complete and incomplete combustion of alkanes.
Hydrocarbon: contains only carbon and hydrogen atoms.
Complete: produces CO2 and water; some heat to initiate the reaction, plenty of oxygen
Incomplete: produces CO and water; some heat to initiate the reaction, insufficient O2 (oxygen is the limiting reagent)
General equation for the combustion of any hydrocarbon:



10.2.
3 Describe, using equations, the reactions of methane and ethane with chlorine and bromine.
Alkanes can react with chlorine or other halogens in the presence of ultrviolet light. This forms hydrogen chloride and a substituted alkane. For instance, methane can react with chlorine to form chloromethane and ethane can reaction with bromine to form bromoethane.











10.2.4 Explain the reactions of methane and ethane with chlorine and bromine in terms of a free radical mechanism.

Heterolytic fission: both of the shared electrons go to one of the atoms, resulting in a positive and negative ion.

Homolytic fission:
each of the two atoms that form the bond keeps one of the shared electrons, resulting in two free radicals.


Initiation: The bond between two halogen atoms is weaker than that of C-H and C-C in methane, and can break homolytically when UV light is present.


Propagation: As the free radicals each contain an unpaired electron they are highly reactive. When the chlorine free radicals come into contact with a methane molecule they each combine with a hydrogen to produce hydrogen chloride and a methyl radical. This methyl free radical is also highly reactive and so reacts with a chlorine molecule to form the product and regenerate another chlorine radical. This enables a chain reaction to occur as the process can repeat itself.


Termination: occurs when two radicals react together

Tuesday, January 26, 2010

Biology: 2.1 Cell Division

Outline the stages of the cell cycle, including interphase (G1, S, G2), mitosis, and cytokinesis.
Interphase
  • G1: growth; DNA transcription; protein synthesis
  • S: DNA replication
  • G2: preparation for division
Mitosis: the process by which the cell divides to form two genetically identical nuclei.
Cytokinesis: the process of dividing the cytoplasm to form two cells.

State that tumors (cancers) are the result of uncontrolled cell division and that these can occur in any organ or tissue.

State that interphase is an active period in the life of a cell when many metabolic reactions occur, including protein synthesis, DNA replication and an increase in the number of mitochondria and/or chloroplasts.


Describe the events that occur in the four phases of mitosis (prophase, metaphase, anaphase and telophase).

Prophase:
  • Spindle microtubules are growing.
  • Chromosomes are becoming shorter and fatter by supercoiling.
  • Each chromosome consists of two identical chromatids formed by DNA replication in interphase and held together by a centromere.
  • Spindle microtubules extend from each pole to the equator.
Metaphase:
  • The nuclear membrane has broken down and chromosomes have moved to the equator.
  • Spindle microtubules from both poles attach to each centromere, on opposite sides.
Anaphase:
  • The centromeres have divided and the chromatids have become chromosomes.
  • Spindle microtubules pull the genetically identical chromosomes to opposite poles.
Telophase:
  • All chromosomes have reached the poles and nuclear membranes form around them.
  • Spindle microtubules break down.

Explain how mitosis produces two genetically identical nuclei.

State that growth, embryonic development, tissue repair and asexual reproduction involve mitosis.