AP Biology Review Part 4 Animal Repro – Menstrual Cycle Ecology - Succession Ecology – Biochemical Cycles Genetics - Gene Regulation

AP Biology Review Part 4 Animal Repro and Development –Menstrual Cycle

AP Biology Review Part 4 Animal Repro and Development –Menstrual Cycle

AP Biology Review Part 4 Ecology –Succession = the change in the composition of a species over time. Traditional view: –One community of species is replaced by another predictable community of a different species. –Over time species diversity (number of species in a community) and total biomass increase. –Eventually a constant species composition is arrived at = climax community. –Climax community will persist relatively unchanged until it is destroyed by some catastrophe (such as fire) Things are not always as predictable as once thought.

AP Biology Review Part 4 Ecological succession –Primary succession Occurs in areas where there is no soil formation and there has never been previous life forms, such as volcanic islands or land where glacial retreat has occurred. –Secondary succession Occurs where there has been previous life, but it was completely or partially destroyed by some kind of damaging event. –Fire damage –Floods –Abandoned agricultural fields, deserted lots

AP Biology Review Part 4 Ecology – Biogeochemical Cycles –Flow of essential elements from the environment to living things and back to the environment again. Water (hydrologic) cycle Carbon cycle Nitrogen cycle Phosphorus cycle

AP Biology Review Part 4 Biogeochemical cycles Water CycleCarbon CycleNitrogen CyclePhosphorus Cycle Storage location (reservoir) Oceans,air (water vapor), groundwater, glaciers Atmosphere, fossil fuels, peat, durable organic matter (such as cellulose) Atmosphere and soilRocks How element incorporates into plants and animals (assimilation)) Plants absorb water from soil Animals drink water or eat other organisms (which are mostly water) Plants use CO 2 for photosynthesis Animals consume other animals or plants. Plants absorb Animals eat plants or animals Plants absorb from soil Animals eat plants and animals How element returns to the environment (release) Plants transpire. Animals and plants decompose Plants and animals release CO 2 through respiration and decomposition. CO 2 is released when organic material is burned Denitrifying bacteria Detrivorous bacteria Animals excrete Plant and animal decomposition Animals excrete

AP Biology Review Part 4 Water Cycle

AP Biology Review Part 4 Carbon Cycle

AP Biology Review Part 4 Nitrogen Cycle

AP Biology Review Part 4 Phosphorus Cycle

AP Biology Review Part 4 Regulation of gene expression in bacteria –Operons – sequences of DNA, composed of: Promotor Operator Structural gene Regulatory gene that produces a repressor protein –(not actually part of the operon) –Example; lac operon and try operon in E. coli

AP Biology Review Part 4 Components of an operon –Promotor –Operator –Structural Genes Short sequence of DNA where RNA polymerase first attaches to transcribe gene. Short portion of DNA where repressor binds. When the repressor is on the operator, RNA polymerase can’t bind to the promoter. One to several genes coding for enzymes of a metabolic pathway.

AP Biology Review Part 4

The lac Operon –When glucose is not available to E.coli, it can use lactose instead (if available). –Normally doesn’t make the 3 enzymes needed for lactose metabolism. – If those enzymes are needed, E. coli can immediately start to synthesize them. –Click for animation of “normal” situation – cell doesn’t need enzymes to digest lactose. Enzyme 2: Permease Facilitates lactose entry into cell Enzyme 3: Transacetylase Accessory function in lactose metabolism How do we do it!? Enzyme 1: B–galactosidase Lactose  glucose and galactose

AP Biology Review Part 4 The lac Operon –The 3 genes are next to each other on a chromosome. –They are all controlled by the same operator and same promoter. –Normally, regulator gene makes an active repressor that binds to the operator (which prevents RNA polymerase from binding to the promoter). –When lactose is present –it binds to the repressor, changing the repressor’s shape. –Repressor can no longer bind to operator, so genes are transcribed  enzymes are made. –This is an inducible operon because lactose induces enzyme synthesis. Inducible operons are usually turned off-they are induced to turn on, and are usually associated with metabolic systems that break things down. Repressible operons are usually turned on-they are repressed to turn off, and are usually associated with systems that synthesize things.

AP Biology Review Part 4

The Trp Operon –Operon in E. coli that is usually turned on. –Codes for 5 different enzymes that are part of the anabolic pathways of tryptophan (amino acid) synthesis. –Regulator gene codes for a repressor that normally can’t bind to operator. –What happens if E. coli is grown on a media that already has tryptophan in it? (see next slide) –Click for animation – normal situation – tryptophan needs to be made.

AP Biology Review Part 4 The Trp Operon –If tryptophan is present in media Enzymes aren’t needed, so try operon turned off –Tryptophan (from media) binds to repressor  changes shape of repressor so can now bind with operator. RNA polymerase unable to bind to promoter. –This is an example of a repressible operon and tryptophan is called the co repressor. –Repressable operons usually associated with anabolic pathways.

AP Biology Review Part 4