Chromosomes and Inheritance Flashcards
True breeding
Homozygous dominant; traits do not change from parent to offspring
Monohybrid cross
Cross between true breeding strains that differ by 1 trait
Reciprocal cross
Crossing forward and backwards to determine if trait is affected by sex
Back cross
breeding between parent and offspring to confirm origin of allele
Expected ratio of back cross
1:1
Expected ratio of monohybrid cross
3:1
Expected ratio of dihybrid cross
9:3:3:1
Dihybrid cross
2 seperate traits
Mendel’s 1st law
- law of segregation
- genes consist of paired units, 1 may be dominant over other
- segregate randomly in meiosis
Mendel’s 2nd law
- law of independent assortment
- all possible combinations of alleles are equally likely, alleles assort independently of one another
What sex is homogametic
Female
What sex is heterogametic
Males
Autosome
non-sex chromosome
What separates first in meiosis
homologous pair THEN sister chromatids
What 3 mechanisms contribute to genetic variation
- independent segregation of chromosomes
- random fertilisation of gametes
- recombination
What does 1 map unit represent
1% chance crossing over will take place and seperate linked genes
Types of trait classifications:
- autosomal dominant
- autosomal recessive
- x-linked dominant
- x-linked recessive
- y-linked (father-to-son)
- mitochondrial (mother-to-children)
- codominant
How many individual combinations of chromosomes in humans
7x10^13 / 70 trillion
