Biology

Mutations

All mutations are changes in the DNA of a gene.

Mutations in gametes are passed on to the offspring, but mutations in somatic cells affect only the individual cell. But mutations in both cells cause changes in DNA.

Types of Mutations

1. Gene Rearrangements- change in a gene's position
2. Gene Alterations- changes in the genetic code
3. Transposons- mobile segments of DNA and they move randomly along chromosomes can cause both gene rearrangements and gene alterations
4. Gene Rearrangement- in a new position a gene does not have the same regulatory control and cannot be turned on and off as efficiently or at all
5. Point Mutations- a single nucleotide change
6. Gene Alteration- change in the genetic code usually causes a change in the amino acid sequence
7. Substitution- a different nucleotide takes the place of the original nucleotide

The possible results of substitution:

• a single amino acid is changed which can affect protein folding (shape) & function
• no change is made and the protein functions normally
• creation of an early stop codon shortens proteins

Frameshift

• changes the total number of nucleotides in a gene
• alters the reading frame, so codons are shifted & read in different triplet groups

Possible results of frameshift:

• the amino acid sequence from the point of the mutation on is different resulting in a dysfunctional protein
• stop codons may be found early

Types of Frameshift Mutations

• Insertion- a sizable length of DNA is inserted into a gene
• Deletion- segments of a gene are lost (often during meiosis)

Inversion- a section of DNA that has a reverse base order

Translocation- a section of a chromosome breaks off & attaches to a non-homologous chromosome (often during meiosis) is reciprocal hapens to both new DNA is under the inflence of different promoters- changes gene function, may break in part, so the gene cannot function

World Geography

Mexico

Mexico was originally settled by the native peoples-Mayan, Aztec, etc. Then Cortes came and conquered the Aztec for Spain. Mexico was part of the Spanish Empire for 300 years. The huge draw for them was the natural resources such as gold and silver. In 1821, Mexico finally gained independence. But even afterwards, the land was unequally distributed; the rich owned land and had peasant workers. A new constitution finally redistributed the land to all the people in 1917.

Before the Spanish came, the natives were quite advanced. The Aztec built cities with temples and practiced human sacrifice. The Spanish destroyed the Aztec capital and built Mexico City on top of its ruins. They brought along their language and religion with them, both of which are still dominant in Mexico today. There is a large mestizo population there. Mestizo are people of Spanish and Native heritage.

The two main challenges in their economy is the gap between the rich and the poor and developing an industrial economy from a traditional agricultural one. More and more people move to the cities for economic opportunities. Mexico is big in the oil industry and uses its profits for development. There's also many maquiladoras there as well. Maquiladoras are factories that assemble important materials to make a final product, so it can be exported to the U.S. or some other country. Mexico also takes part in NAFTA (The North American Free Trade Agreement). NAFTA is an important agreement requiring cooperation regarding economic and trade issues in North America.

Today, people are leaving Mexico to find jobs in the United States because of the growing populations and the shortages of jobs. Workers often send money back home to their families to make life easier. And although 85% of school age kids there go to school, there is little higher education available for most people.

World Geography

Central America & the Caribbean Islands

Central America has a history of Mayan culture. The Mayans were known for their temples, which were the tallest structures in the Americas before the 1900s. The Spanish came and conquered their land. But after Mexico gained its independence, so did all the rest of Central America. Central America was one region before it was split into nations.

Christopher Columbus landed on the Caribbean islands in 1492. He thought he'd reached the West Indies. He named the natives of the islands "Indians." The Spanish created sugar plantations and brought slaves over. Eventually, other European nations came and settled on the islands. The sugar was a huge draw. After 100 years (1800-1900) all the islands gained their independence.

Central America is Spanish dominant because they came and conquered the land. The native peoples were oppressed and their homes were taken from them. They were moved to the cities.

The Caribbean islands had many different cultural influences because of the many different nations that settled there. African slavery had a huge impact on their culture. Their religion is Catholicism, Protestant, and African practices and rituals. Their language is Spanish, English, French, and a smattering of Dutch.

Both Central America and the Caribbean islands are pretty poor.

Agriculture is the islands' main export: sugar canes, coffee, bananas, spices, and citrus fruits. Most of the islands are overpopulated, most people live in cities-slums.

Agriculture and mining are the main source of income for Central America. The Panama Canal is used for trade in the region.