What Darwin Never Knew
how many genes are in the human genome? how does this compare to other organisms?
-23,000 genes in the human genome -this is the same number of genes found in a chicken, but less than found in corn -humans thought we would have more than any other organism
what do Hox genes do? How do they explain how a fish obtained legs?
-activate switches -they are crucial to the development of an organism's shape, and is a universal controller of fin and limb development (how an arm can become a fin & vice versa)
why was the discovery of the fossil Tiktaalik significant for the study of evolution? also, describe the features that made this organism significant
-explains how fins became limbs -transitional body form: fish-like but still had an arm-like fin -4 limbed -flat head and upward eyes, suggesting rising above water
how do we know that whales and manatees evolved from 4-legged land creatures that "lost" their legs and move "back" to the sea?
-flippers have all the same bones as arms do (even fingers) -vestiges have pelvises
what makes human hands so unique?
-genes that turn genes off or on -the thumb
list 3 things that Darwin never knew
-how evolution takes place -what happens to make things change -dna -the facts/data to prove that apes and humans share a common ancestor
humans have a jaw muscle mutation that apes do not have. how has the jaw muscle mutation been an evolutionary advantage for humans?
-humans now have a fraction of the force apes have in their jaw due to the size of the muscle -evolutionary advantage = the human brain doesn't have a limitation on how much it can grow (until about age 30)
use an example to explain what variation means
-not every individual is the same/looks the same
describe 2 of the animals of the Galapagos Islands and what is unusual about them
-penguins = live in warm water -iguanas = swim and dive in the sea significance: species change
how was Darwin's view of nature different from the standard view of nature from Victorian times?
-people in the Victorian times though God created ALL animals; whereas Darwin believed all species are connected on a family tree (common ancestor), which then made other animals -Victorian: lambs lay with lions -- Darwin: competition, death, savageness
what did Darwin hypothesize about the origins of life from his study of embryos?
-snakes came from animals with legs -whales had teeth -humans had tiny slits on the neck, like gills +hypothesized a common ancestor in animals, the tree of life
what evidence did Darwin have that species change?
-the different shell shapes/characteristics of the tortoises depending on which island they're from -variation of beaks in finches depending on which island they're from
why is it said that mutations are neither good nor bad?
-they can cause minutiae changes or big changes -can either be advantageous to improve survival or deadly; dependent upon condition they live in
how do finches end up with different beak shapes when they all have the same DNA sequence in their beak genes?
-timing and intensity of the gene -how much and when you turn the gene off
How did Darwin's view of nature tie into his idea of natural selection?
competition and adaptations resulted in survival of the fittest
what did Darwin discover in Argentina?
fossils of giant, extinct mammals -meant that one species came from another/ancestry
explain how camouflage coloration arose in the Rock pocket mouse
mice living on dark rocks (due to a volcanic eruption) turned dark, mice living on light rocks stayed light
why do some fruit flies have wing spots and other do not?
one species uses the gene and the other doesn't; switches can turn the gene on or off
when researchers compared the gene that controls brain size development between humans and chimps, what did they discover?
the genes controlling brain size development were extremely different in normal humans and chimps
why do the finches' beak shapes differ?
their beaks are tools to help them survive; beaks are best suited for their food source
what do switches do?
turn genes on or off
