Inheritance Flashcards
What is frequency measured between?
0-1
What is gamblers fallacy?
Independent events are not impacted by previous events.
How do you find the probability of two independent events occurring together?
Multiplication rule; multiply the probability of one event by the other event
Who was Gregor Mendel?
(1822 - 1884) was an Austrian monk who experimented with garden peas and developed the foundation of modern genetics
What was Gregor Mendels observation?
Noticed that peas had several traits and always showed only one of a pair, rather than a blend
What was Gregor Mendels experiment?
He crossed plants with different traits to see what the offspring would look like
What did Mendel discover?
That one trait always dominated and masked the other - this is known as dominance
What are traits controlled by ?
Factors known as genes
What are the two versions of a gene called?
Allels
Where does an organism get there allels?
An organism inherits an allele for each trait from each parent (two alleles toral for each trait)
What is the principle of dominance?
One allel masks the presence of the other
When do allels separate?
Meiosis - called the law of segregation
What is the law of segregation?
ALlels separate during meiosis so only one gamete gets one allel
What is the Law of independent assortment?
Allels are passed down independently of one another
What does the law of independent assortment result in?
3:1 ratios or 9:3:3:1 rations seen in hybrid crosses
What is the law of dominance>
Recessive allels are masked by dominant ones
What is true breeding crosses?
Crossing two purebred organisims
What is the parental generation?
True breeding plants
What is a purebred?
A organism that exhibits the same characteristics generation over generation (AA or aa)
What are the offspring of the parental generation called?
First filial (F1 generation)
What does the F1 generation do?
Reproduce and create second filial (F2) generation
What does the term dominant mean?
A allels that masks/covers another recessive allel
What does the term recessive mean?
An allel that is often masked by another dominant allel
What does the term heterozygous/hybrid mean?
Different allels (Aa)
What does the term homozygous/purebred mean?
Sane allele (AA, aa)
What does the term genotype mean?
Combination of alleles
What is a phenotype?
Physical expression of allele
What is a punnet square?
A tool used to show the genetic cross to determine the ratio of expected offspring produced
What is a monohybrid cross?
A cross using one trait between two heterozygous
Aa x Aa
Always results in 3:1 phenotype ratio
What is a testcross?
The unknown individual is crossed with a homozygous recessive individual
The genotype of the unknown parent can be deducted from the appearance of the offspring
What are two triat crosses?
A two-trait cross, or dihybrid cross, examines the inheritance of two different traits simultaneously. It involves two pairs of alleles (e.g., AaBb x AaBb), each controlling a different characteristic.
What are the possible phenotypic ratios for two-trait crosses with different combinations of alleles?
Both parents heterozygous (AaBb x AaBb): Ratio is 9:3:3:1.
One parent heterozygous, one homozygous dominant (AaBb x AABB): Ratio is 3:1 (3 show both dominant traits, 1 shows one dominant and one recessive).
One parent heterozygous, one homozygous recessive (AaBb x aabb): Ratio is 1:1:1:1.
One parent double dominant, one double recessive (AABB x aabb): All offspring show the dominant phenotype (100% AaBb).
Where can allels be present?
On an autosomal chromosome or X-linked (meaning on the sex chromosome)
What happens to y-linked chromosomes?
As there is only one Y chromosome, any Y-lined traits are passed down to son.
What is incomplete dominance?
Mixing of phentypes, occurs when an organisim is heterozygous.
Ex: White rose mixes with white rose
What is codominance?
When both phenotypes are expressed in a heterzygote (dont mix)
Ex: Blood type in Humans
What is ploygenic inheritance?
Occurs when one characteristis is controlled by two or more genes. Often genes are leafe in quantity but small in effect.
What are some examples of polygenic inheritance?
Height, skin colour, eye colour
What gene controlles blood type?
Designated as I and has three allels Ia, Ib, i
What are the four blood type phenotypes?
A (Ia), B (Ib), AB(Ia, Ib), O (ii)
What is the relationship between allels for A, B, i? (Blood)
A & B is codominate and O is recessive
What is a pedigree?
A family tree that shows the genetic traits of the individuals
What can you incur about a trait if two parents who are unaffected produce an affected child?
The trait is recessive and the parents are heterzygous
What is genetic linkage?
Genetic linkage is the tendency of genes located close together on the same chromosome to be inherited together during meiosis because they are less likely to be separated by recombination.
What determines the strength of genetic linkage between two genes?
The physical distance between the genes on the chromosome. The closer they are, the stronger the genetic linkage.
What is recombination frequency?
It is the percentage of offspring in which recombination occurs between two genes, reflecting their physical distance on the chromosome.
What does a recombination frequency of 1% represent?
It represents one map unit or one centimorgan (cM) of genetic distance.
At what recombination frequency are genes considered unlinked?
Genes are considered unlinked if their recombination frequency is 50% or higher, as they assort independently.
How could you tell if two trates are linked?
If the ratio is different from expected
