Chapter 14: Foundations of Genetics Flashcards
father of genetics
Gregor medel
things to know about mendel
- Austrian monk
- background as a farmer
- Statistician (strong background in
mathematics) - he counted the
different types of offspring - worked with pea plants Pisum
sativum - He was a plant breeder as well as a
mathematician.
what plants did Mendel use for his experiments?
pea plants Pisum sativum
Why are pea plants a good organism
to use for genetic experiments?
1.Inexpensive
2.Short lifetime
3.many observable traits
4.lots of progeny
5.self-fertilizing
6.can be cross-fertilized
A heritable feature that varies among
individuals (such as flower color) is called a
character
Each variant for a character, such as purple
or white color for flowers, is called a
trait
The particular genes an organism
carries
genotype
An individual’s observable physical
traits
phenotype
When offspring of genetic crosses
(breeding) that inherit two identical
alleles for a trait.
True-Breeding Lineage
what offsprings do True-Breeding Lineage breed?
ones with the same trait as their parents.
When offspring of a genetic cross
inherit a pair of non-identical alleles
for a trait
hybrid offspring
When the two alleles of a pair for a
certain trait are different
heterozygous
the allele that is fully expressed in the phenotype of a heterozygous individual
Dominant allele
the allele that is fully masked in the phenotype of a heterozygous individual
Recessive allele
Both alleles for the same trait are dominant
Homozygous Dominant
what do Homozygous Dominant look like
[AA]
One allele has the dominant form of the gene
and the other has the recessive form.
Heterozygous
what do Heterozygous look like
[Aa]
Both alleles for the same trait are recessive
Homozygous Recessive
what do homozygous recessive look like
[aa]
P
parental generation
F1
first generation of offspring (first
filial)
F2
second generation of offspring
(second filial)
the location for a specific gene on a specific type of chromosome
gene locus
Alleles segregate when?
during gamete production
is a chance event, with a
number of possible outcomes that
could be predicted based on
probability
fertilization
the likelihood that a particular
event will happen.
probability
Helps to visualize the probability
of different outcomes in a genetic
cross.
Punnet Square
Only one trait is followed through
a series of genetic crosses.
Monohybrid Cross
Two traits are followed through a
series of genetic crosses.
Dihybrid Cross
An individual with the dominant phenotype could be what?
either homozygous dominant or heterozygous
To determine the genotype we can carry out a what?
testcross
breeding the mystery individual with a
homozygous recessive individual
testcross
If any offspring display the recessive phenotype, the mystery parent must be what?
heterozygous
occurs when phenotypes
of the heterozygote and dominant homozygote are identical
complete dominance
the phenotype of F1 hybrids is somewhere between the phenotypes of
the two parental varieties
incomplete dominance
two dominant alleles affect the
phenotype in separate, distinguishable ways
codominance,
example of codominance
blood types
This positive and negative in our blood type indicates what?
Rh factor
determines the presence or absence of a protein on the surface of the RBC.
Rh factor
how much of the population is Rh positive?
85%
are called “universal
donors”
O Rh negative
“universal receivers.”
AB Rh postive
what is the definition of Rh factor incompatibility
If you’re Rh-negative and your baby is Rh-positive
(thanks to your husband’s genes), that’s fine….
until your blood mixes with your baby’s blood a
bit during placental separation at birth.
* At that critical point, fetal blood cells can
accidentally combine with your system, and you
make antibodies to fight them which damages fetal red blood cells
Most genes have multiple phenotypic effects, a
property called
pleiotropy
what are pleiotropic alleles responsible for?
multiple symptoms of certain hereditary
diseases, such as cystic fibrosis and sickle-cell
disease
what does wet ear wax code for?
glycine
what does dry ear wax code for?
arginine
a gene at one locus alters the
phenotypic expression of a gene at a second
locus
epistasis
what is an example of epistasis
albinism
are those that vary in the population along a continuum
Quantitative characters
an additive effect of two or more genes on a single phenotype
polygenic inheritance
Quantitative variation usually indicates what?
polygenic inheritance
examples of polygenic inheritance
skin color
and
height
is the phenotypic range
of a genotype influenced by the environment
norm of reaction
Another departure from Mendelian genetics
arises when what?
the phenotype for a character
depends on environment as well as genotype
is a family tree that describes the
interrelationships of parents and children
across generations
pedigree
Inheritance patterns of particular traits can be
traced and described using what
pedigrees
Recessively inherited disorders show up only in what type of alleles?
individuals homozygous
are heterozygous individuals who
carry the recessive allele but are phenotypically
normal;
carriers
most individuals with recessive
disorders are born to what?
carrier parents
is a recessive condition characterized
by a lack of pigmentation in skin and hair
albinism
is the most common lethal genetic disease in the United States, striking one out of every 2,500 people of European descent
Cystic fibrosis
results in defective or absent chloride transport channels in plasma membranes leading to a buildup of chloride ions inside the cell
Cystic fibrosis
symptoms of cystic fibrosis
mucus buildup in some
internal organs and abnormal absorption of
nutrients in the small intestine (pleiotropy)
affects one out of 400 African-Americans
Sickle-cell disease
caused by the substitution of a
single amino acid in the hemoglobin protein in
red blood cells
sickle-cell disease
In what kind of individuals, all hemoglobin is
abnormal (sickle-cell)
homozygous
symptoms of sickle-cell disease are?
physical weakness, pain,
organ damage, and even paralysis (pleiotropy)
In what kind of individuals, are usually healthy but may suffer some symptoms
Heterozygotes
what is the Statistics of AA who has sickle cell trait?
one out of ten African Americans
If a recessive allele that causes a disease is
rare, then the chance of two carriers meeting
and mating is
low
increase the chance of mating between two carriers of the same rare allele
Consanguineous matings
what percent of pakistan people carries out consanguineous marriages?
60 percent of the population
what genetic disorders does this lead to?
Congenital heart disease, blood diseases such
as hemophilia and thalassemia, deafness,
cystic fibrosis, breast cancer and depression.
what kind of alleles that cause a lethal disease
are rare and arise by mutation
Dominant
is a form of dwarfism caused by a rare dominant allele
Achondroplasia
There are now tests that can identify carriers of the alleles for
Tay-Sachs disease, sickle-cell disease,
and the most common form of cystic fibrosis.
