keystone review genetics dna. homozygous—both alleles the same heterozygous—each allele...

Keystone Review

GeneticsDNA

• Homozygous—both alleles the same• Heterozygous—each allele different

Types of Inheritance Dominant One trait completely masks/dominants the other trait when it is expressed. Can be homozygous or heterozygous dominant

Types of Inheritance Recessive The recessive trait is seen when there are 2 copies present (homozygous recessive)

• Both traits are equally dominant• Both show up at the same time• Use two different letters• R for red and W for white• RR red• WW white• RW red and white

Types of Inheritance Codominance

CodominanceBlack Feathered

Chicken White

feathered chicken

Checkered feather chicken(my favorite!)

Types of Inheritance--Incomplete Dominance

• Neither trait is dominant. • The traits “blend”

together to make a new color/trait.

• Use letters with slashes• R for red and R’ for white• RR = red• R’R’ = white• RR’ = pink

Types of Inheritance Sex-linked

• The trait is carried on the sex chromosome (x-chromosome) so the inheritance is different for males and females.

• Males inherit one gene from mother on X chromosome and an unaffected Y from father.

• Females inherit an X from their father and an X from their mother

• Trait controlled by 2 or more genes and produces a range of outcomes (examples: skin color, eye color, hair color, height)

Types of Inheritance Polygenic

More than 2 forms of a gene control the trait.

Types of InheritanceMultiple Alleles

• These mutations alter the composition or number of chromosomes in the organism.

• Usually have severe consequences for the organism.

• Usually occur during meiosis

Chromosomal Mutations

• Failure of homologous chromosomes to separate during meiosis I or II

• Results in monosomies and trisomies

Nondisjunction

Translocation

Deletion

Duplication

Point (Gene) MutationsOriginal DNA

THE CAT ATE THE FAT RAT.

Silent Mutation (DNA changes but protein does not)THE CAT ATE THE FAT RAT

Nonsense Mutation (inserts a stop)THE CAT ATE THE.

Missense Mutation (changes the protein)THE CAR ATE THE FAT RAT.

Frameshift Mutation (changes every amino acid after)THE CCA TAT ETH EFA TRA T.THC ATA TET HEF ATR AT.

Frameshift Mutations

DNAProtein Synthesis

Genetic Engineering

DNA REPLICATION

Semi Conservative Replication

Protein SynthesisTranscription Translation

• Information from the DNA (in the nucleus) is copied in the form of messenger RNA.

• Copies only the information for the protein that needs to be made

• The mRNA then leaves the nucleus and travels to the ribosome.

Decodes the information from the mRNA

Occurs in the ribosomeNeeds tRNA and mRNA to

make the protein correctly according to the directions that were specified in the original DNA

Genetic code for each amino acid is the same in ALL organisms.

Codon

Protein

• Genetic engineering – the process of altering the genetic material of cells or organisms to allow them to make new substances or to change their traits.

• Selective breeding – when humans select which organisms to breed to get a desirable trait (example – breed cows to get them to produce the most milk) This method used trail/error and was time consuming. Using genetic engineering we can now accurately get the desired results every time.

Genetic Engineering

Cloning – making a genetically identical copy of an organism

• Gene therapy – attempting to treat a genetic defect in an organism by introducing a new gene for the missing/defective original gene

Medicine:

• Create new medications (ex: human insulin made by bacteria, clotting factors for people with hemophilia)

• Figure out how genes function during development – look for ways things go wrong

• Look for cures for genetic diseases (cystic fibrosis – replace missing gene to help lessen symptoms)

• Continuing to research cures for cancer, AIDS, hemophilia etc

• Create new vaccines

Forensics:

• Identify criminals • Identify human remains• Identify the parents of an individual• Trace human origins

Agriculture:

• increase food supply by making crops more tolerant to environmental conditions

• make plants resistant to herbicides, pests and certain diseases

• improve nutritional value

Keystone

Ecology Review

Levels of Organization

• Ecosystem—biotic & abiotic

• Community—all biotic factors

• Pollution—only one group (species) of organisms

Comparing Biotic and Abiotic FactorsBiotic—all living or once living organismsAbiotic—all non living factors

Food Chain in an Antarctic Ecosystem• A food chain shows ONE possible feeding pathway.• The arrow always goes into the mouth of the eater

Food Web in an Antarctic Ecosystem• A food web shows all possible feeding relationships in a

ecosystem

Energy Transfer Through Trophic Levels• Only 10% of energy from each level is available to be

passed on to the next level. • Most of it gets used or lost as heat. That’s why more

organisms on bottom than top

Energy Pyramid

Symbiosis—close, long term relationship b/w to organisms (at least one benefits

Parasitism, mutualism, commensalism

Parasitism

The parasite benefits while the host is hurt

Mutualism

• Both organisms benefit

Commensalism• One benefits while the other is neither hurt nor

helped

Recycling Matter through the Ecosystem

Water Cycle

• Key processes are– Evaporation– Transpiration– Precipitation

Carbon CyclePhotosynthesis & Respiration are the two main steps

Nitrogen Cycle• Nitrogen fixing bacteria change nitrogen gas into a useable

form for nitrogen for plants (& then animals) • Denitrification puts nitrogen gas back into the atmosphere

Phosphorus Cycle

Phosphorous moves from phosphate deposited in rocks , to the soil, to living organisms and finally to the ocean

Succession—gradual sequential regrowth of a community of a species in a area

Two Types:Primary

Secondary

Primary SuccessionOccurs where the land has not supported any prior life, bare rock, newly formed islands (soil lacks nutrients or any life left behind)

Secondary SuccessionOccurs where soil has previously existed and some life is still left behind.

Ecological Succession at Glacier Bay

• Carrying capacity— number of individuals the environment can sustain

• Limiting factor— any factor the restrains the growth of a population (space, sunlight, food, water, mates)

Carrying Capacity of Reindeer in Pribilof Islands