Post on 02-Jan-2016
Heredity & The Environment
Unit 2-3 NotesMr. Hefti – Pulaski Biology
BackgroundGene expression often influenced by an organism’s surroundings
“Epigenetics”
InteractionCertain environmental factors “alter” how genes are read
Examples:TemperaturepHSunlightAir quality
Temperature
Siamese cat: fur on extremities grows in darker
Arctic fox: white coat in winterHimalayan rabbit: cold temperatures cause fur to darken
Reptiles: sex determination
Soil pH
Acidic: spruce trees turn blue
Neutral and basic: spruce trees stay green
Acidic: hydrangea flowers blue
Neutral and basic: hydrangea pink or white
Sunlight
Triggers chlorophyll production
Absence of sunlight – leaves turn yellow
In humans, sunlight triggers the production of melanin
Air quality
Identical twins with family history of respiratory disease raised in places with different air quality not equally likely to suffer ailments
In conclusion…Gene expression depends upon:The genetic code inherited
Environmental influences
Gene expression in an organism can be modified by interactions with the
environment.
Gene expression in an organism can be modified by interactions with the
environment.
Gene expression in an organism can be modified by interactions with the
environment.
Gene expression in an organism can be modified by interactions with the
environment.