50 genetic ideas book Flashcards
Lamarck’s theory
Physical changes in organisms during their lifetime (such as greater development of an organ due to increased use) were transmitted to their offspring
What does Lamarck’s theory imply which is wrong?
that all organisms would gradually become complex, and simple organisms disappear.
Lamarck’s giraffe analogy
giraffes began with short necks but as trees grew taller they had to stretch their necks more. Their necks stretching meant the neck developed to become longer and then this trait was passed to their offspring.
Lamarck vs Darwin
Lamarck: changes were CAUSED by the environment (giraffes had longer necks BECAUSE OF tall trees)
Darwin: changes were SELECTED for by the environment (giraffes with longer necks benefited more so they had offspring etc)
Gregor Mendel pea experiment
1856
- seed shape (round/wrinkled)
- stem length
- flower colour (purple/white)
F1: first generation only one trait would remain (ie. crossing long and short stems all offspring would have long stems)
F2: second generation the other trait would reappear (some progeny would have short stems again)
Three laws of inheritance
1) law of dominance
2) law of segregation
3) law of independent assortment
law of dominance
dominant alleles always mask recessive alleles
law of segregation
during the formation of gametes the allele pairs in the diploid cell segregate and then reunite again randomly at fertilisation so that the offspring receive one allele from each parent
law of independent assortment
the alleles of two or more different genes get sorted into gametes independently of each other
the allele that one gamete receives doesn’t influence the allele that another gamete receives
who proved the chromsomal basis of genetic inheritance?
Thomas Hunt Morgan
1910
—how—-fly thing—-
What chromosome mutation made us become human (from chimpanzees)
human chromosome 2 was formed when two smaller chromosomes from chimpanzees fused together
