Chapter 1.2

Gene

Is a unit of hereditary

A portion of a chromosome

Chromosomes (strand of genes)

Come in pairs except for x and y

DNA

Comprises a gene

Serves as a template for the synthesis of RNA

RNA

Serves as a template for the synthesis of protein molecules (protein part of the

body or enzymes

Homozygous

Two identical genes in a chromosome (DD, rr)

Sex-linked

Genes are located on the sex chromosome

Are usually on the x

(A) (B) (C)

Sex-limited

Are generally on autosomal

Are mainly active in one sex

Triggered by sex hormones

Heredity and environment

To determine contributions of heredity monozygotic (identical) twins and

dizygotic (fraternal)

Multiplier effect

genes can influences your behavior which can influences how other people treat

you thereby reinforcing the behavior

environmental modification

example PKU is a hereditary disease in which the person cannot metabolize

phylnlkaline which can lead to mental retardation if the baby is put on a diet that

restricts phynlakline then this will not occur.

If we speak of a gene for alcoholism we should not imagine that the gene itself

causes alcoholism rather it produces a protein that under certain circumstances

increases the probability of alcoholism.

Chapter 1.2

If you have genes that make you better looking then people will be attracted to

you and may alter your behavior.

Evolution

Offspring resemble their parents

Mutation introduce a new heritable trait that could be harmful or helpful

Certain individuals reproduce more successfully than others

a gene that is associated with reproductive success will become more prevalent

controlled breeding for a certain trait (dogs, plants) is called artificial selection

Misunderstandings

Lamarkain evolution

o The use or disuse of some structure or behavior will increase or decrease

that feature

o Example Lamark would think that the little toe was getting smaller

because it was not being used when in fact it would be getting smaller

only if those with smaller little toes had an advantage over those with

larger little toes and reproduced and passed on the smaller little toe gene

more successfully.

Humans have stopped evolving

o Some theorize that we have stopped evolving because we can keep people

alive by artificial means

o Humans are still evolving because evolution depends on reproductive

success not life span

Evolution means improvement

o What is fit for one generation may be a disadvantage in the next if the

environment changes

Does evolution benefit the individual or the species

o Neither it benefits a certain gene that is pasted along

Evolutionary psychology

Looks at how behaviors (social) evolved by examining why natural selection

would have favored genes that produced those behaviors

Altruistic behavior (evolutionary psych)

May not be selfless and may benefit the actor

Group selection theory (controversial)

Altruistic groups survive better than non cooperative groups

No way to weed out cheaters and that gene would get passed on even if it was

only one lying member of the altruistic group

Reciprocal altruism

Individuals help those that they think will return the favor

Require good sensory organs, memory and memory for faces to ensure that you

do not help someone who has a history of not returning favors

o Maybe why altruism is most common in humans

Kin selection

You will protect your offspring who share your genes and by extension relative

who share your genes