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Chapter 14 (Mendel's Scientific Approach (Used Pea plants for his…
Chapter 14
Mendel's Scientific Approach
Used Pea plants for his experiment
There are many varieties
They have high generation times
Carpel: egg-bearing organ
Stamens: pollen producing organs
They were all purple flowers
Planted seeds from pod
Transferred sperm bearing from stamens of a white flower to egg bearing carpel of purple flower
Waited for pollinated carpel to mature into pod
Removed stamens from purple flower
True- breeding:
over generations of self pollination the plants plants had only produced the same kind of variety as the parent plant
Mendel used this approach to ensure results
Character
a heritable trait that varies among individuals
Color
Trait
each variant for a character
Purple or white colors for flowers
Hybridization:
crossing of 2 true-breeding parents
P Generation
:The true breeding parents
F1 Generation:
hybrid offspring of the P Generation
F1 Generation hybrids self pollinating produces:
F2 Generation
Law of Segregation
Mendels results lead him to a certan 3:1 ratio
Mnedel developed a model that tested 7 differnt traints
Alleles
:alternate versions of a gene
each character an organism inherits it gets 2 alleles, 1 from each parent
if 2 alleles at locus differ
dominate allele:
determines the appearance
recessive allele:
no noticeable affect on the appearance
Law of Segregation:
the 2 alleles for a heritable character separate from each other during gamete formation and end up in different gametes
Punnett Square:
diagrammatic device that predicts the allele composition of the offspring , by crossing 2 F1 generations
Genetic Vocabulary
homozygote
: has a pair of identical alleles for a gene encoding a character
Homozygous:
having the same alleles
true breeding
Heterozygote:
has 2 different alleles
heterozygous
not true breeding
Phenotype:
the appearance
Genotype:
the genetic makeup
possible to have the same phenotype but different genotypes
testcross:
breeding an organisms unknown unknown genotype with a homozygous recessive individual to determine the unknown genotype of the offspring
can help determine the phenotype
Law of Independent Assortment
Monohybrids:
the F1 progeny produced by true -breeders
meaning they were heterozygous
monohybrid cross:
cross between 2 heteroygotes
dihybrids:
the F1 individuals heterozygous for 2 characteristics being crossed
dihybrid cross:
help determine the offspring of F1 dihybrids
2 or more genes assort independently , each pair of alleles travels on their own during formation
applies to alleles on separate chromosomes
applies to alleles that are far apart on the same chromosome
Inheritance patterns are complex
degrees of dominance
Complete Dominance:
one allele of a gene took over another, the phenotype is indistinguishable
incomplete dominance:
neither allele is complexity dominant
white flower crosses with a red one and forms a pink flower
Codominance:
2 alleles affect a phenotype in a way that they are both distinguishable
Human MN blood groups
are heterozygous because both molecules are present easily
relationship between dominance and phenotype
the dominate allele can code for certain enzymes
Tay Sachs Disease;
inherited disorder in which having the ability to metabolize certain lipids is not possible due to the lack of the enzyme working properly
must have homozygote genes for enzymes to be inactive
Pleitropy:
having multiple phenotypic effects
responsible for hereditary diseases
cystic fibrosis
sickle cell disease
Epistasis:
the phenotype expression of a gene at one locus that alerts that gene on another locus
two genes interacts
the color for the coat of a lab. Can carry the repressive gene but one controls the phenotype
polygenic inheritance:
additive of effect of 2 or more genes on a phenotype character
quantitative characters:
vary different genes
multi-factorial:
many factors both genetic and environmental collectively influence phenotype
Human Traits and Mendelian patterns
unable to manipulate matting pattern
pedigree:
assembling information about a families traits into a family to see how traits are passed across generations
for allele to take aver a dominate trait must be preset
widows peak
recessive alleles can range for severity
carriers:
parents that carry a certain trait and transfer to offspring
Cystic Fibrosis:
a genetic disorder in which the lungs and pancreas are clogged with large quantities of abnormally thick mucus
contain 2 recessive alleles
Sickle cell
a change in one amino acid in Beta Hemoglobin. Causes the red blood cell to make a crescent shape. The cell can't carry enough oxygen.
1 recessive gene can affect the geneotype
dominate inherited disorders
achondroplasia
: form of human dwarfism caused by a single dominant allele; homozygous
Huntington Disease:
causes progressive deterioration of brain cells. caused by a dominant allele. symptoms do not appear until the age of 30 or so
Testing:
Tay sacs ;
amniocenteses:
diagnostic medical procedure that removes a sample of amniotic fluid by inserting a needle in the amniotic sac. A way to check genetic health & development of a fetus.
Chronic villus sampling:
sampling of placental tissue for microscopic and chemical examination to detect fetal abnormalities
Probability Governs Mendel's Inheritance
Multiplication Rule:
to determine the probability of independent events you must multiply the probability of one event by another
apply to n F1 monohybrid
the offspring will have a 1/4 chance of the specific allele
addition rule:
the probability of any mutually exclusive events occurring can be determined by adding their individual probabilities
adding the individual probabilities together
gives the likelihood of most probabilities
