Lecture 32 Flashcards
Benefits of a diploid genome
greater flexibility in gene expression levels
having a backup good copy or a mutated gene
variation in DNA sequences that may allow selection under changing pressures on species
Cons of diploid genome
more DNA= more possibilities of random mutations
detrimental mutations may be passed onto the next generation instead of selected against
reproduction of complex organisms requires fusion of haploid cells (gametes)
Meiosis is the basis
of genetic variety
Sexual reproduction allows
mixing of parental genes to try new combinations against pressures of natural selection
Steps of meiosis
Meiosis I
Prophase I
Metaphase I
Anaphase I
Telophase I
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telophase II
Product of Meiosis II
4 daughter cells
Recombination dramatically raises what
genetic diversity
What allows crossing over to occur in the recombination in meiosis
tight proximity of tetrad chromatids
Do Alleles independently sort as mendel proposed?
No, groups of genes are “linked” and inherited in chunks as haplotype block
What are the chromosomes that you get from mom and dad
one of each, short and long, from mom and dad (so 4)
Meiosis I provides what
the opportunity for recombination (crossing-over) of homologous chromosomes
Meiosis II does what
separates and passes sister chromatids into gamete cells
Genetic variation from combining parental genomes happens from
natural genetic variations (polymorphisms) and mutations
Traits passed down can be
dominant, recessive, and multi-gene origin
