Mendelian Genetics Flashcards
gene
segment of DNA that controls a particular characteristic or trait
allele
different forms/variations of a gene
genotype
genetic makeup of an organism, an organism’s combination alleles
phenotype
the physical expression of an organism’s genes - what you can see
homozygous
2 alleles are the same
heterozygous
2 alleles are different
dominant
an allele that masks a recessive allele;
an allele that expresses itself even in the presence of another allele
recessive
gene is not allowed to express itself when it is covered up or masked by the presence of another gene
hybrid
Mendel’s term for heterozygous
purebred
Mendel’s term for homozygous
Law/Principle of Dominance
in every pair of contrasting traits, one is dominant one is recessive
when two or more alleles exist, some are dominant some are recessive
basically, some alleles are dominant and some are recessive
Law of Segregation
alleles for a gene segregate independently from one another during the formation of gametes
Genotypic Ratios
DD:Dr:rr
Phenotypic Ratio
dominant:recessive
Phenotypic Ratio in a two-factor cross
DD:DR:RD:RR
Law of Independent Assortment
genes that code for different traits are located on different chromosomes and assort independently from one another
alleles for different genes segregate independently of each other during gamete formation/and do not affect the inheritance of each other’s genes
Two-Factor Crosses
crosses that involve two different genes/traits
Mono-hybrid crosses
a cross with two heterozygous parents
phenotypic ratio: 3:1
Di-hybrid crosses
a cross with two heterozygous parents for two characteristics
phenotypic ratio: 9:3:3:1
When will allele pairs be reformed?
during gamete formation when they come together during fertilization
Gene Expression
transcription and translation of genes into proteins
Gregor Mendel observed how many characteristics?
7
