PSYCH211 Chapter Notes - Chapter 2: Quantitative Trait Locus, Meiosis, Germline Mutation

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
 directly observable characteristics
  the complex blend of genetic information that determines our
species and inuences all out unique characteristics
At the moment of conception, is when we get the hereditary makeup of the
individual
Genetic foundation
 rod like structures that store and transmit genetic
information
 

One is inherited from each parent
The genetic code
 !"#chromosomes are made up of this substance
  segment of DNA along the length of the chromosome
 $

 %: unique feature of DNA that it can duplicate itself into another cell
with the same number of chromosomes and genetic information
oGenes do this by sending information through the cytoplasm, which
proteins trigger chemical reactions throughout the body and then they
make up the characteristics of what de#ne our body
oThe wide range of proteins is what makes our genetic makeup very
complex
oBiological events are the result of both genetic and nongenetic forces
The sex cells
  sex cells the sperm and ovum
 % the cell division in which halves the number of chromosomes
normally present in cells
 & when sperm and ovum unite at conception
Meiosis ensures that constant quantity of genetic material is copied from one
generation to the next
 ' chromosomes next to each other break at one or more
points along their length and exchange segments, so that genes from one are
replaced by genes from another
 ()'
oGenetic variation produces adaptive responses so that the o&spring
will vary in phenotype which can increase the change that at least
some members of a species will cope with the every-changing
environment and survive
In the male there are 4 sperm that are produced
In the female only 1 ovum is produced and the rest degenerates
oFemales are born with all of their ova present and can only give birth
for a couple of decades
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Boy or girl?
 #non sex chromosomes which are the 22 matching pairs of
chromosomes
 (* 23rd pair of chromosomes
o%+,
o-+,
X is large and Y is short and carries little genetic material
Multiple births
 -+./most common type of multiple births,
resulting from the release and fertilization of 2 ova
Genetically, they are no more alike than siblings
Older maternal age, fertility drugs, and in vitro fertilization are major causes
of the rise in fraternal twins
 0.+/a zygote that has started to develop
starts to duplicate and separates into 2 clusters of cells that develop into 2
individuals
o12
Premature babies often develop later than the normal person
Patterns of genetic inheritance:
 #+++2 forms of each gene that occur at the same place on the
chromosomes one from the mother and one from the father
 / both alleles are the same
 / alleles are di&erent and the relationships between the alleles
determine the phenotype
!'
 !'only 1 allele a&ects the child’s
characteristics
Dominant is the one that always shows and recessive is the one that has no
e&ect
Heterozygous individuals with just 1 recessive allele can pass that trait to
their children because they are  of the trait
Many disabilities and diseases are the result of recessive alleles
oE.g. PKU which the doesn’t allow the break down the protein
phenylalanine so its leads to toxic levels and then causes retardation
In dominant-recessive inheritance, if we know the genetic makeup of the
parents, you can determine the percentages of the likeliness to have a
certain trait
 %.3 enhance or dilute the e&ects of other genes
Dominant diseases and disorders are rare because they usually die before
they can reproduce so their heredity ends there
o4.is one of the few dominant disorder diseases
0."(
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0+.
 0+.a pattern of inheritance in which both alleles are
expressed in the phenotype, resulting in a combined traits, or one that is
intermediate between the two
 (2+++ is an example
oOccurs when a child inherits 2 recessive alleles
oCommon in black Africans because of malaria
+2.
 52.harmful allele is carried on the X chromosome
oMales are more likely to exhibit the disorder because their sex
chromosomes do not match
oIn females any recessive allele on one X chromosome has a good
chance of being repressed by a dominant allele o the other X
Many sex di&erences reveal that the male is at a disadvantage
oRates of miscarriage, infant and childhood deaths and mental
retardation is higher for boys
oNature compensates for this because there are more boys born
In many industrialized countries, the male birth has declined because of a
rise in stressful living conditions resulting in spontaneous abortions of male
fetuses
X linked disease Description Mode of
inheritance
Treatment
Duchene muscular
dystrophy
Degenerative
muscle disease
abnormal gait and
loss of ability to
walk in 7-13
Recessive None, death from
respiratory
infection usually
occurs
Diabetes insipidus Insu=cient
production of the
hormone
vasopressin results
in excessive thirst
and urination.
Dehydration can
cause serous
nervous damage
recessive Hormone
replacement

 alleles are imprinted or chemically marked in such a
way that one pair member (either the mother or father) is activated,
regardless of makeup
oImprinting is often temporary and erased in the next generation
Imprinting helps us understand certain genetic patterns
oE.g. children are more likely to develop diabetes if their father rather
than the mother su&ers from it
oAsthma is more common in mothers who also have it
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