Biology: Genetics
Genetics
Scientific study of heredity
Mendel
Born in 1822 in Czechoslovakia
Monk in 1843
Studied at University of Vienna
Monk in 1843
Studied at University of Vienna
Mendel used pea plants to study..
The inheritance of traits
Offspring that result from crosses between parents with different traits
Hybrids
Mendel removed the male parts from the flowers of some plants in order to
make controlled crosses between plants.
The chemical factors that determine traits are called
Genes
Gregor Mendel concluded that traits are
inherited through the passing of factors from parents to offspring.
When Gregor Mendel crossed a tall plant with a short plant, the F1 plants inherited
an allele for tallness from the tall parent and an allele for shortness from the short parent.
The principle of dominance states that
Some traits of dominant and some are recessive
When Gregor Mendel crossed true-breeding tall plants with true-breeding short plants, all the offspring were tall because
the allele for tall plants is dominant.
If a pea plant has a recessive allele for green peas, it will produce
green peas if it does not also have a dominant allele for yellow peas.
A tall plant is crossed with a short plant. If the tall F1 pea plants are allowed to self-pollinate,
some of the offspring will be tall, and some will be short.
In the P generation, a tall plant was crossed with a short plant. Short plants reappeared in the F2 generation because
the allele for shortness and the allele for tallness segregated when the F1 plants produced gametes.
In the P generation, a tall plant was crossed with a short plant. If alleles did not segregate during gamete formation,
all of the F2 plants would be tall.
When you flip a coin, what is the probability that it will come up tails?
1/2
The principles of probability can be used to
predict the traits of the offspring produced by genetic crosses.
Mendel concluded that inheritance is determined by…
Factors passes on from one generation to anotheri
Factors are..
Genes
Each gene has different forms called
Alleles
In the P generation, a tall plant is crossed with a short plant. The probability that an F2 plant will be tall is
75%
Organisms that have two identical alleles for a particular trait are said to be
Homozygous
A Punnett square shows all of the following EXCEPT
The actual result of a genetic cross
If you made a Punnett square showing Gregor Mendel’s cross between true-breeding tall plants and true-breeding short plants, the square would show that the offspring had
a genotype that was different from that of both parents.
Punned square
A diagram used to show probability of certain trait bring passed from one generation to generation another
What principle states that during gamete formation genes for different traits separate without influencing each other’s inheritance?
principle of independent assortment
Homozygous
An organism posses two identical alleles
Heterozygous
Organism posses two different alleles
Genotype
Genetic makeup
Symbolized with letters
Symbolized with letters
Phenotype
Physical appearance of the organisms
Expression of trait in words (tall, yellow, smooth)
Expression of trait in words (tall, yellow, smooth)
How many different allele combinations would be found in the gametes produced by a pea plant whose genotype was RrYY?
2
Situations in which one allele for a gene is not completely dominant over another allele for that gene are called
Incomplete dominance
Incomplete dominance
A situation in which neither allele is dominant
Variation in human skin color is an example of
Polygenic traits
Gregor Mendel’s principles of genetics apply to
All organisms
Why did Thomas Hunt Morgan use fruit flies in his studies?
They produce a large amount of offspring
The number of chromosomes in a gamete is represented by the symbol
N
Multiple allele inheritance
Two or more alleles contribute to the phenotype
Polygenic triat
Traits controlled by two or more genes
Haploid
Only one copy of chromosomes
Gene linkage
Chromosomes assort independently during meiosis
Linked genes are
On the same chromosome
Gene maps are based on
the frequencies of crossing-over between genes.
T or F A trait is a specific characteristic that varies from one individual to another.
True
T or F Gregor Mendel concluded that the tall plants in the P generation passed the factor for tallness to the F1 generation
True
T of F An organism with a dominant allele for a particular form of a trait will sometimes exhibit that trait.
False; always
T or F True-breeding plants that produced axial flowers were crossed with true-breeding plants that produced terminal flowers. The resulting offspring produced terminal flowers because the allele for terminal flowers is recessive.
False; dominant
T or F When alleles segregate from each other, they join
False; they separate
T or F If the alleles for a trait did not segregate during gamete formation, offspring would always show the trait of at least one of the parents
True
T or F Coat color in rabbits is determined by a single gene that has multiple alleles.
True
A cross between two organisms heterozygous for two different genes (AaBb; a dihybrid cross) results in a
9:3:1 ratio