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Bio 252 Midterm
Bio 252
| Question | Answer |
|---|---|
| Where is DNA found? | In the Nucleus |
| What is the DNA structure | Double Helix |
| DNA is held together by what? | Hyrodgen Bonds |
| Why does A pair with T and G with C | The number of H bonds; A-T is two hydrogen Bons G-C is three hydrogen bonds |
| Gene segments code for? | Protiens |
| Most proteins are | Enzymes |
| During Trasncription DNA is read in a sequence of | Nucleotide Bases |
| Character | heritable characteristics |
| Trait | variation in a character |
| Phenotype | physical manifestation of a trait |
| Genotype | combination of alleles |
| Allele | alternate expression of a gene |
| Recessive | allele is not expressed in heterozygote |
| Heterozygous | genotype of two or more different alleles |
| Dominant | allele is always expressed |
| Homozygous | two or more identical alleles |
| Variation | 1. Crossing over 2. Segregation 3. Independent assortment 4. Sex |
| Why to Breed using peas | Grows fast, Breeds true (selfs, Many traits Two character states (alleles for each trait, Manipulate crossings by removing anthers or bagging |
| How come genetics is not considered intermediate | Because during Mendel's experient there were not intermediate colors |
| Principle of Segregation | alleles segregate during gamete formation |
| Product Rule | The probability of 2 events happening is the sum of each event happening. Coin flipping example in text if you flip a coin, there is a 1.0 probability it will land face up. |
| Sum Rule | This applies when there is more than one way to get the same outcome-heads and tails. Add the two probabilites |
| What causes dominance and recessive alleles? | Mutations of genes result in altered function |
| Incomplete dominance | not blending, but one allele doesn’t produce enough protein product to fully mask or counteract the other allele |
| Co Dominance | dominance |
| Epistatis | expression of one allele controls the expression of another allele |
| Polygenic Inheritance | many genes contribute to one trait or character |
| Pleiotropic Inheritance | one gene controls many traits. |
| Ecology | the scientific study of the distribution and abundance of organisms and the interactions that determine distribution and abundance |
| Sex linked traits | traits on one of the sex chromosomes. Recessive traits are usually expressed in males. (X is large, y is small) |
| Linkage | two traits are on the same chromosome |
| Cytoplasmic inheritance | organelle genomes |
| X inactivation | Calico cats. One X chromosome carrying alleles for color in skin cells is inactivated early in development. Heterozygote is called mosaic |
| Gene Flow | movement of organisms or gametes. Important to evolution b/c change in a population depends on the degree of genetic difference between populations (individuals in the same space at the same time reproducing) |
| Directional | trait changes over time |
| Stabilizing selection | trait converges on mean so that extremes at either end eliminated (clutch size, birth wt) |
| Disruptive selection | favors 2 or more genotypes |
| Balancing selection | maintains genetic diversity |
| Frequency dependent selection | rare phenotypes is favored by selection, often observed in Predator-Prey interactions |
| Genetic Drift | random loss of alleles |
| Why and when does genetic drift occur | In small populations because of the Founder affect and the Bottleneck affect |
| Morphological Species | what Mayr recorded in New Guinea |
| Biological species | based on who you mate with, ability to interbreed and produce fertile offspring, groups of interbreeding populations, idea of genetic cohesiveness |
| What are two problems with Biological Species definiation | What about asexually reproducing species? Extinct Organisms-how do we classify? |
| Phylogenetic species | reconstruct evo tree based on morphological characteristics and genetics. When a cluster of populations (individuals in the case of fossils) appear |
| Prezygotic Isolating Mechanisms | prevent formation of a zygote |
| Geographic barriers | lead to habitat isolation (islands, mountain tops etc) |
| Temporal barriers | timing of mating or maturity |
| Behavioral Isolation | –bird songs, ducks |
| Mechanical Isolation | morphological features prevent mating insect reproductive structures highly specialized pollen tube of different plant species cannot grow long enough |
| Gametic isolation | gametes of different species recognize each other pollen grains;stigma recognizes pollen of different species and prevent germinination |
| pollen grains; stigma recognizes pollen of different species and prevent germinination | |
| Hybrid sterility | mules (hybridization b/t horses and donkeys chromosomes can’t pair during meiosis |
| Hybrid inviability | embryo doesn’t develop |
| Hybrid breakdown | changes in chromosome structure lead to unequal crossing over |
| Allopatric speciation | gene flow between 2 populations of a species is blocked this can occur for two reasons; Geographic Barrier or Hybrid Zones |
| Parapatric Speciation | Can occur when populations distributed across discontinuous env conditions (habitats) individuals who mate with individuals from the wrong habitat have lower fitness b/c N.S favors different alleles in different env. |
| Sympatric speciation | populations of a single species in same habitat diverge into 2 species |
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flutiecutie423
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