Mandelian genetics Flashcards
What is genetics
science that deals with heredity and variation
Whats Heredity
Passing of traits from one generation to the next
Traits are either
Inherited or acquired traits
What is the difference in inherited and acquired traits
Inherited traits: passed on from family
(ex. hair type/colour, skin colour, facial features)
Acquired traits: Traits that develop after birth and are not passed on but develop from environment
What are Alleles
> example
> types
Alleles is a version of a gene , one from each parent
> Ex. gene is height, alleles are wether tall or short ( type of alleles inherited from parents)
> Dominant , big letter and recessive, small letter
(ex, T for tall, t for short)
What is homozygous
> example
2 copies of the same Allele , same so no dominant or recessive one
> Ex. TT or tt
What is heterozygous
> example
> which is dominant
Two different alleles for 1 gene
> Ex. Tt
> big T always wins and is more dominant, not inbetween if Tt but tall
What is a genotype
> example
genetic makeup of a individual , two alleles
> ex. TT or Tt or tt
Whats a phenotype
> example
What is seen, expression of a genotype/gene
> ex. short or tall, blue eyes or brown
Who is Gregor Mandel and what did he do
Austrian monk that worked with peas to develop the mandel laws and find out about genetics
(Father of genetics)
Mandel’s Laws
1- Law of doninance
2- Law of Segregation
3- Law of independent assortment
1- Traits are controlled by a pair of factors (alleles) and one factor can be dominant over the other, recessive
2- All individuals have two copies of a gene, these copies segregate during gamete formation and each gamete(sperm/egg) receives one copy of each gene
3- Two alleles for one gene segregate(assort) independently of the alleles for other genes during gamete formation ( one gene for eye colour wouldn’t have effect or tall short gene, happen independently)
Monohybrid Cross expiriment , variables and outcome : genotype and phenotype with purple (P) and white (p) flowrrs
> F1
> F2
1 trait cross: P- purple (d) and p - white (r)
> P generation ( parental) , purple x white flowers
> F1 generation, first mix and dominant wins over so all flowers are purple,
(PP x pp = Pp) first generation all Pp ( genotype) and display as purple (phenotype) bc thats dominant
> F2 generation, second mix (PpxPp= Pp, pp and PP) 3 genotypes but 2 types of phenotype, 3:1 ratio purple: white , 3 display as purple and 1 as white
What are Punnett squares
square diagram used to predict genotype of a particular cross
Mandel’s law of dominance
traits ate controlled by a pair of factors (alleles) and one factor can mask the other (sominant and recessive
Mandel’s law of segregation
All individuals have two copiez of a gene. paired allels separate during gamete formation (meiosis) and each recives one copy
Mandel’s Law of independent assortment
Two allels for one gene segragate (assort) independently of other genes during gamete formation (proven wrong)
Whats a test cross
to determine an unknown dominant genotype cross with a known one: homozygous recessive, helps us determine if unknown is homo or heterozygous
What are the patterns of inheritance in monohybrid crosses
Multiple alleles , Incomplete dominance , co dominance
Whats the pattern of inheritance: multiple alleles in monohybrid crosses
When genes have more than two forms
capital letters with subscript letters used
ex. allels a qnd b for blood dominant over o but even to eachother
What is incomplete dominance in monohybrid crosses:
When two allels are equally dominant and when they interact they form a new phenotype which expresses a combination of traits
ex. Red + White = Pink
What is co dominance in monohybrid crosses
When both parent allels get expressed as a combination of both
no new phenotype just both of the parent phenotypes
What are dihybrid crosses
cross involving two indapendent traits present in alternate forms
indapendent traits are found on different chromosomes
phenotypic ratio:
if parents heterozygous for both traits you get 9:3:3:1 phenotypic ratio
Polygenic inheritance is
trait controlled by 2 or more genes, can have multiple alleles and show incomplete or co dominance and can be affected by environment
