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Chapter 9: Patterns of Inheritance

Terms in this set (63)

4 types of changes in chromosome structure
deletion, duplication, inversion, translocation
4 types of changes in chromosome structure (pic)
deletion
the loss of a chromosome segment
duplication
the repeat of a chromosome segment
inversion
the reversal of a chromosome segment
translocation
the attachment of a segment to a nonhomologous chromosome. It may be reciprocal
heredity
the transmission of traits from one generation to the next
genetics
the study of heredity
who studied pea plants?
Gregor Mendel
why did Mendel study pea plants?
-short generation times
-produce large numbers of offspring with each mating
-came in many distinguishable varieites (easy to handle and take care of)
what hypothesis did Mendel disprove?
the blending hypothesis
character
a heritable feature that varies amongst individuals in a population (ex: flower color)
trait
each variant of a character (ex: purple v. white)
gene
a 'heritable factor' that each character is controlled by
alleles
a gene's two alternative versions
homozygous
if an individual's alleles for a given gene are the same
heterozygous
if an individual has two different alleles for a gene
dominant
if the two alleles for a given gene differ and one allele masks the expression of the other
recessive
the other allele that is not expressed
homozygous dominant (example)
a pea plant that is YY and will have yellow seeds
heterozygous (example)
a pea plant that is Yy and will have yellow seeds
homozygous recessive (example)
a pea plant that is yy and will have green seeds
genotype
the organism's genetic makeup, depicted as letters (ex: YY, Dd, RrYy, etc.)
phenotype
an organism's physical or expressed traits, depicted as words (ex: yellow seeds, tall, white, etc.)
punnett squares pic
monohybrid cross
mating of parents that differ only by one character
law of segregation
allele pairs segregate (separate) during meiosis so that each gamete carries only one allele for each gene
steps for doing pungent square problems
1. assign letters for the alleles given (ex: brown eyes=B, blue eyes=b)
2. write out the cross (ex: AABB x aaBb)
3. assign possible gametes for each parent (ex: B, D, bD, Ab)
4. construct a punnett square big enough to put the gametes of one parent across the top, and the gametes of the other parent down the side
5. fill in the punnett square, maintaining proper letter order
6. evalate your results and answer the question(s) being asked
rule of multiplication
the way of solving problems by determining the probilitiy of offsprings there will be
testcross
a mating of an individual with an unknown genotype and dominant phenotype with a homozygous recessive individual
dihybrid cross
a mating of parents that differ in two characteristics
what is the ratio observed in the F2 generation of a typical dihybrid cross
9:3:3:1
law of independent assortment
the inheritance of one character has no effect on the inheritance of another
incomplete dominance
a pattern of inheritance where the phenotype of a heterozygote is an intermediate between the two homozygotes (blend)
incomplete dominance (pic)
complete dominance
Mendel's peas showed this pattern of inheritance
complete dominance (pic)
codominance
a pattern of inheritance where two alleles are both expressed (descretely, no blending) in heterozygous individuals
codominance pic
multiple alleles
where there are more than 2 alleles for a gene
antigens
carbohydrates on the surfaces of red blood cells which identify the type of red blood cell
antibodies
present in blood plasma, when a type of blood is anti- something (a different type)
ex: type A blood cells injected into a person with type B blood will cause the person's blood to clump
universal recipient
type AB blood: can receive blood from anyone
universal donor
type O blood: can give blood to anyone
sex-linked genes
genes located on either the X or Y chromosome, usually the X chromosome
why are sex-linked genes normally on the X chromosome?
because it is bigger than the Y chromosome
sex-linked recessive/ x linked recessive types (4)
1. white eyes in fruit flies (mutent) (red eyes are wild-type)
2. hemophilia
3. red-green colorblindness
4. duchenne muscular dystrophy
wild-type
prevailing in nature
hemophilia
lack of protein required for blood clotting (excessive bleeding)
red-green colorblindness
malfunction of light-sensitive cells in eyes
Duchenne muscular dystrophy
progressive weakening of muscles and loss of coordination
carrier
a heterozygous individual (ex: XBXb); only females can be this
pedigree (pic) (but men cannot be carriers)
why are sex-linked recessive traits more common in males than females?
males have only one X, so they will automatically express any X-linked trait. They cannot be carriers. Females can be carriers, therefore an X-linked trait can be hidden
pleiotropy
a pattern of inheritance where one gene influences multiple characters (phenotypes)
ex: sickle-cell disease
sickle-cell disease
-an example of pleiotropy
-caused by a recessive allele, but has a variety of effects: direct effect, other effects
direct effects in sickle-cell disease
red blood cells produce abnormal hemoglobin
other effects in sickle-cell disease
sickle-shaped red blood cells, anemia, fever, weakening, pain
polygenic inheritance
a pattern of inheritance where two or more genes affect a single phenotype
ex: human skin color, height
chromosome theory of inheritance
genes occupy specific location, or loci, on chromosomes. Therefore, it is the behavior of chromosomes during meiosis and fertilization that affect inheritance
linked genes
genes that are on the same chromosome (red hair & freckles)
who worked with fruit flies and and discovered linked genes
Thomas hunt MORGAN
recombination frequency
divide the number of recominants by the number of total offspting
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