Biotechnology Bell Ringers September 27 th, What are some differences between plant cells and animal cells? 2. What two resources were used to examine different examples of cells? 3. Bacteria are prokaryotes. What is a prokaryote?

Biotechnology Objectives September 27 th, 2010 (EB04.03) We will explore the structure of DNA We will explore DNA’s relationship to the cell We will Extract DNA from a Strawberry Time permitting, we will go over some Biotechnology current events

Genetics and DNA 1860s, Gregor Mendel discovered that “factors” determine inheritance in pea plants He observed that many traits control these factors

Genetics and DNA 1903, researcher William Sutton made connection between Mendel’s “factors” and chromosomes- microscopic structures in the cell nucleus that carry genetic material

Genetics and DNA The genetic material itself, known as DNA, was discovered by Johann Miescher in Switzerland in 1869

Genetics and DNA Yet, it wasn’t until two researchers, Francis Crick and James Watson, proposed a double-helix structure for the molecule that we began to understand how this material carries the genetic code of life

Early drawing by Watson and Crick of the DNA Double-helix

Genetics and DNA A gene is a unit of information that can be passed on to offspring They are a power influence on physical and mental characteristics They aren’t just found in people, they are found in all living things

Genetics and DNA As powerful as genes are, however, it’s important to remember that environment also helps shape organisms The interactions between a living thing and its environment affect how it will turn out

Domineering Genes With few exceptions, every organism has two of each kind of gene Genes are usually either dominant or recessive

Domineering Genes A dominant gene is expressed in the offspring no matter what gene the other parent contributes A recessive gene is expressed in the offspring only if both parents contribute recessive genes

Domineering Genes BROWN/BROWNBROWN /blue blue/ BROWN blue/blue

Mutations Rule Over billions of years the earth has been around, plants, animals, and other living things have evolved through the changing of genes Genes have been transferred, deleted, and mutated between generations

Mutations Rule Mutation has produced the countless variations of living things we see around us Many mutations are neutral and have no effect at all Some mutations place a living thing at a disadvantage Some mutations, however, give an individual a better chance of survival This makes them more likely to survive to have offspring Over time, this mutant gene will likely become established in the gene pool (the genes of a breeding population

Mutations Rule

Secret Codes DNA holds the secret code to make and maintain proteins (long chains of molecules that help living things grow and function But how does this secret code move from the nucleus to the protein- making factories in the cells?

Secret Codes Rather than move the DNA out of the nucleus, the cell makes a copy of the gene(s) and sends it to the protein assembly site outside the cell nucleus The copy is messenger RNA (ribonucleic Acid)

Secret Codes RNA is a single-stranded copy of a single cell of a single gene It carries codes from the DNA to the protein assembly sites outside the nucleus

Genes Across the Ages In nature, genes generally are transferred between members of the same species Some new studies, however, suggest that genes also move between unrelated organisms For the most part, such “horizontal” gene transfer takes place among bacteria and viruses

Genes Across Ages Today, horizontal gene transfer also can occur through genetic engineering DNA can be transferred via direct injection or by inserting the DNA into bacteria or viruses that carry it into the cells they infect This means that traits determined by single genes can be transferred from one kind of organism to another

Genes Across Ages Characteristics coded for by more than one gene are much harder to transfer, since the contributing genes must all first be identified, found, and isolated Many human diseases are thought to result from interactions of multiple genes