Lecture 25-Mendel's Law Of Inneritance Flashcards
What plant did Mendel experiment on and why?
- Green Pea
- Grows fast and in large numbers
- is Bigamous (m& and f parts in same flower)
- Easy to cross pollinate
What law did Mendel propose and what was his hypothesis?
The Law of inheritance
Traits are carried on discrete particles/units/factors which retain their identity during their transmission.
How many traits did Mendel select for his green pea, and what type did he use for breeding?
7 traits, each with a pair of contrasting phenotypes
Pure breeds
What does homozygous mean?
A pure breed, where the phenotype expressed is the same generation after generation. Eg; VV
What is a monohybrid cross
A cross between 2 plants carrying pure contrasting phenotypes (one dominant the other recessive) of a single trait, the result of which is a mixed genotype with the dominant phenotype being expressed
What laws were extrapolated from the findings of the Monohybrid cross?
- Law of (complete) dominance
- Law of segregation - of the pair of genotypes (no linkage)
- Traits are determined by a pair of factor (Genes/Alleles/Chromosomes)
What ratio of dominant phenotype to recessive phenotype is obtained from the crossing of 2 monohybrid plants?
3:1 (Dominant: recessive)
What is the name of a factor that expresses in hybrid condition?
Dominant Allele Vice versa
What is the ratio of hybrid genotype: deisease genotype: dominant phenotype In a monohybrid cross?
2:1:1
For a test cross, what will the phenotype of the controlled plant be?
Recessive phenotype
What are unit factors?
Alleles or genes Located on the chromosomes (23 pairs in total; 22 pairs Autosomal & 1 sex chromosome pair)
Define Gene and Allele
Gene is a functional part of of Chromosome or DNA that encodes RNA or protein, producing a phenotype Allele is an alternative copy or variant, of a gene. Both forms are at the same locus
How many genes approx are in the human genome and what percentage is that from total genome?
25,000-30,000 genes Less than 2% of the genome
What is Euchromatin and Heterochromatin?
Euchromatin is the functional part of the human genome Heterochromatin is the non functional part
What is gene locus?
The location of a gene on the chromosome Most of the genes are in fixed positions Some are mobile AKA Transposones Transposition is a rare phenomenon which causes abrupt change in the phenotype
