ap biology review part 4 animal repro – menstrual cycle ecology - succession ecology –...
TRANSCRIPT
AP Biology Review Part 4
Animal Repro – Menstrual CycleEcology - Succession
Ecology – Biochemical CyclesGenetics - 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 cyclesWater Cycle Carbon Cycle Nitrogen Cycle Phosphorus Cycle
Storage location (reservoir)
Oceans,air (water vapor), groundwater, glaciers
Atmosphere, fossil fuels, peat, durable organic matter (such as cellulose)
Atmosphere and soil Rocks
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 CO2 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 CO2 through respiration and decomposition.
CO2 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
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
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
AP Biology Review Part 4