Chapter 19 & 20

1. Sympatric speciation & Microtubules

Sympatric speciation is when new species form within one environment without any geographical barriers getting in the way. One way that sympatric speciation can occur is through polyploidy (when an organism inherits three or more sets of every chromosome) and this happens through the nondisjunction of chromosomes during mitosis or meiosis. Nondisjunction is when spindle fibers, which are composed of microtubules, don’t attach correctly to a chromosome which causes the chromosome to defectively separate.

2. Endosymbiosis & Atmospheric Gases

Endosymbiosis is when an organism of one species lives out its life inside another host species, and the interaction benefits one or both of them. Chloroplast and mitochondria were formed through endosymbiosis. Chloroplasts are used for photosynthesis and photosynthesis uses Co2  and produces O2 and O2 is an atmospheric gas.

3. Adaptive Radiation & Character Displacement

Adaptive radiation occurs when many species emerge from one common ancestor and this occurs through character displacement. Character displacement is when only the individuals that have the best traits are able to survive and reproduce and therefore pass on their traits while the weaker individuals die and eventually become completely extinct. In character displacement, the allele frequencies change and this causes evolution.

4. Proto-cells & Uracil

Proto-cells are the transitional forms between simple organic compounds and the first living cells. These cells consist of membrane bound sacs which contain enzymes and systems of metabolism. Protocells are self-replicating meaning that they had DNA and RNA protein systems and in RNA there is uracil, a nucleotide base, which differs from RNA and DNA.

1.Prezygotic and Postzygotic isolation mechanisms:

Prezygotic

- Mechanical Isolation: physical incompatibilities which deter them from mating

- Temporal Isolation: Cannot mate because the timing of reproduction is different

- Behavioral Isolation: Courtship displays are ignored because they are not recognized

- Ecological Isolation: There are geographical separation which prevents them to mate

-Gamete morality: Gametes are incompatible, so no fertilization.

Postzygotic

-Hyprid inviability: Hybrid emboryo die early before they can reproduce

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

2. Compare and Contrast Gradualism and Punctuated Equilibrium:

Gradualism is when speciation occurs slowly through small changes over a long period of time while punctuated equilibrium is when that speciation occurs abruptly through directional selection, genetic drift, bottlenecks, and the founder effect.

3. Miller’s Experiment:

Water, methane, hydrogen, and ammonia are put into a reaction chamber and zapped with sparks which caused simulating lighting striking on earth. Then in a week, amino acids and other organic compounds formed inside the reaction chamber, which led to Miller suggesting that this was what occurred billions of years ago, defining chemical evolution.

4. Endosymbiosis:

- The mitochondria resembles bacteria in size and structure.

- Chloroplasts resembles the cunobacteria

- The amoeba’s were become symbiotic when they were infected by bacteria and led them to rely on bacteria to create an essential enzyme.

5. Cladogram

totals: kangaroo- 5

lamprey -1

rhesus monkey- 6

bullfrog-3

human-7

Snapping turtle-4

tuna-2

Chapter 17 & 18

Connections:

1.       Prophase I & Allele Frequency

The allele frequency is the section of all copies of a gene that consist of a particular gene trait (an allele).  During meiosis in prophase I, the two duplicated chromosomes connect and in this connection, they begin to exchange genetic information at junction points. The process of this crossing over results in genetic variation in genes and many different traits for each offspring. The crossing over and allele frequency are tied together for the crossing over influences the allele frequency between parents.

2.       Analogous structures & Natural Selection

Analogous structures are two structures that perform similar functions by a similar mechanism but evolved separately. Natural selection is the process of favorable traits eventually becoming the normative due to competition or survival of the fittest trait. Hence both of them occur because of the natural results of their surroundings and competition.

3.       Gene pool & Bottleneck

A gene pool is the entire unique group of alleles in a species or population.  Bottle neck is when the size of a population shoots down because of the environmental conditions. Hence, if a bottleneck were to occur, this would affect the gene pool and cause a low reproduction/population rate.

4.       Balance polymorphism & Search Image

Balanced polymorphism can be defined as the number of selective processes by which different alleles and this occurs when natural selection eliminates individuals with detrimental phenotypes from a population.  A search image is the way an animal is able to see its prey only by senses and is necessary for same animals for their everyday habits and eating techniques. That is why balance polymorphism would be needed in order to allow these alleles to work.

Essentials:

1.       Observations made by Darwin

-          All populations by nature increase over time because of their need to reproduce.

-          Populations will be limited because of environmental constraints

-          A group of organisms will compete amongst themselves

-          Species  share a common gene pool with its population

-          Genetic variation is derived from alleles that come from mutations

-          Some traits are more helpful than other trait or alleles because of the environment.

-          Natural selection is the result of the variety of a population due to evolution.

2.       A. First the origin of photosynthetic cells

B.  Then the establishment of crusts of the earth that led to the environment where life can exists.

C. Molecular evolution that began life

D. oxygen in the atmosphere which led to the production of eukaryotic cells

E. Break up of Earth’s supercontinent which led to many different environments

3.       The phrase “individuals don’t evolve, populations do” is what evolution in actuality is because natural selection comes from the DNA changes of individuals and when they mate, their alleles or traits are passed down. That’s why new organisms with different traits are made because of their parents and these usually are based upon the environment and surroundings of the organism. When the child is affected by their parents, then the children mate with each other, the same alleles are passed down, therefore alternating or causing the process of evolution to the population.

4.       p²(AA) + 2pq(Aa) + q²(aa) = 1.0

p and q represent the frequencies of the alleles A and a.

The conditions that are needed are no mutations, the population is indefinitely large, the population is isolated, mating is random, and all individuals survive and produce the same number of offspring.