Chapters 19 & 20 Work

Derek Lee

Mr. Hillegas

Ap Biology

Chapters 19 & 20 Work

II.

1.      Sympatric speciation is a speciation model that occurs inside the home range of a species in the absence of a physical barrier by way of polyploidy. This occurs when individuals inherit three or more sets of chromosomes when a somatic cell fails to divide mitotically after its DNA, is duplicated, or nondisjunction occurs at meiosis and results in an unreduced chromosomes number of gametes,  as a result of the incorrect separation by microtubules.

2.      Endosymbiosis & Atmospheric Gases- Endosymbiotic relationships began millions of years ago when certain prokaryotic cells had adapted to the concentration of free oxygen atmospheric concentration of gases and were already engaged in aerobic respiration. The ancestors of eukaryotic cells preyed upon some aerobic bacteria that were parasitized by others, thus beginning endosymbiotic interactions.

3.      Adaptive radiation & Character Displacement- Resource partitioning occurs when at least 2 species overlap, in which the specific individuals that are able to pursue these resources in slightly different ways (partitions), in order to minimize competition, will be the most successful, and those traits will be selected for character displacement. This occurrence creates adaptive zones which are necessary for adaptive radiation, or the burst of divergences from a single lineage that leads to many new species. I.E. Hawaiian honeycreepers.

4.      Proto-cells & Uracil- rRNA components of ribosomes catalyzes protein synthesis whose structure and function of ribosomes have been conserved over time and whose catalytic behavior probably evolved early in Earth history. Coenzymes and metal ions assist most enzymes and certain coenzymes are structurally identical with RNA subunits. Two of RNA’s building blocks cytosine and uracil- proteins may have evolved into the earliest form of proto-cells.

III.

1.      Prezygotic Mechanisms: Stop cross-pollination or cross-breeding, the formation of gametes, or fertilization.

- Mechanical isolation: Individuals can’t mate or pollinate because of physical incompatibilities

-          Temporal Isolation: Individuals of different species reproduce at different times.

-          Behavioral Isolation: Individuals of different species ignore or don’t get the required cues for sex.

-          Ecological isolation: Individuals of different species live in different places and never meet up.

Postzygotic mechanisms: Kill hybrids or make them weak or infertile.

-          Hybrid inviability: Hybrid embryos die early or the new individuals die before they can reproduce.

-          Hybrid sterility: Hybrid individuals can’t make functional gametes.

2. The gradual model of speciation says that species originate by slight morphological changes over long time spans. It shows gradual morphological change as with minute changes In fossil sequences over time. Punctual equilibrium offers a different explanation for patterns of speciation, saying morphological changes are said to evolve in a relatively brief geologic period, within the tens to hundreds of thousand of years when populations are starting to diverge.  This may occur through directional selection, genetic drift, the founder effect, bottlenecks, or some combination of them which favor rapid speciation.

3.   Stanley Miller was the first to test the hypothesis that the simple compounds that now serve as the building blocks of life can form by chemical processes. He put water, methane, hydrogen, and ammonia in a reaction chamber. He kept circulating the mixture and zapping it with sparks to simulate lightning. In less than a week, amino acids and other small organic compounds had formed in the chemical brew.

4. Membranes – Mitochondria have their own cell membranes, just like a prokaryotic cell.

- DNA – Each mitochondrion has its own circular DNA genome, but much smaller. This DNA is passed from a mitochondrion to its offspring and is separate from the host cell’s genome in the nucleus.

Reproduction- Mitochondria multiply by pinching in half – the same process used by bacteria. Every new mitochondrion must be produced from a parent mitochondrion in this way; if a cell’s mitochondria are removed, it can’t build new ones without a “parent” mitochondrion.

Mitochondria resemble tiny bacteria making their livings inside eukaryotic cells. Such is common to other cellular organelles including chloroplasts or tiny factories within plant cells that help convert energy form sunlight into sugars. These organelles have become completely dependent on their host cells. As such these are all evident from endosymbiosis.

5. On Note Card