Transgenic bacteria can be used to make human insulin. Explain how bacteria can produce a human protein.

Insulin is a complex protein molecule produced by the pancreas in all vertebrates. It is a hormone that regulates carbohydrate metabolism. Inability to produce insulin results in diabetes mellitus. Diabetes is treated by injections of insulin. Given the law of definite proportion, would you expect there to be any differences in chemical activity between human insulin extracted from pancreatic tissue and human insulin produced by genetically engineered bacteria? Why or why not?

What is the advantage of using transgenic bacteria to produce human proteins?

What is a gene knockout? Is an animal or plant with a gene knockout a heterozygote or homozygote? What might you conclude if a gene knockout does not have a phenotypic effect?

What effect can movement of transposons have on gene expression?

Fish and other organisms that live in the arctic express an antifreeze protein that prevents subzero temperatures from damaging their cells. Scientists have generated transgenic strawberries and tomatoes that express the fish antifreeze protein. However, neither crop has been commercialized. a. Explain the steps involved in generating the transgenic crop plants. What enables these plants to make a fish protein? b. The reason neither crop is on the market is that the antifreeze protein did not produce the desired effect: protection of the fruits from damage in a freeze. Provide a possible hypothesis panning why the fish antifreeze protein might not work in plants.

Which disorder can be diagnosed definitively only at autopsy by the presence of large numbers of amyloid plaques and neurofibrillary tangles?
a. vascular neurocognitive disorder
b. neurocognitive disorder due to Alzheimer’s disease
c. delirium
d. neurocognitive disorder due to Parkinson’s disease

The Drosophila gene Sex lethal (Sxl) is very deserving of its name. Certain alleles have no effect on XY animals, but cause XX animals to die early in development. Other alleles have no effect on XX animals, but XY animals with these alleles die early in development. Thus, some Sxl alleles are lethal to females, while others are lethal to males. a. Would you expect a null mutation in Sxl to cause lethality in males or in females? What about a constitutively active Sxl mutation? b. Why do Sxl alleles of either type cause lethality in a specific sex? The gene transformer (tra) gets its name from “sexual transformation,” since some tra alleles can change XX animals into sterile males, while other tra alleles can change XY animals into normal-appearing females. c. Which of these sex transformations would be caused by null alleles of tra and which would be caused by constituitively active alleles of tra? d. XX animals carrying particular alleles of tra develop as males, but they are sterile. Why? e. In contrast with Sxl, null tra mutations do not cause lethality either in XX or in XY animals. However, the Sxl protein regulates the production of the Tra protein. Why then do all tra mutant animals survive? f. Predict the consequences of null mutations in tra-2 on XX and XY animals. g. XY males carrying loss-of-function mutations in the fruitless (fru) gene display aberrant courtship behavior. Would you predict that either XX or XY animals with wild-type alleles of fru but loss-of-function mutations of tra would also court abnormally?

The Drosophila gene Sex lethal (Sxl) is deserving of its name. Certain alleles have no effect on XY animals, but cause XX animals to die early in development. Other alleles have no effect on XX animals, but cause XY animals to die early in development. Thus, some Sxl alleles are lethal to females, while others are lethal to males. a. would you expect a null mutation in Sxl to cause lethality in males or in females? What about a constitutively active Sxl mutation? b. Why do Sxl alleles of either type cause lethality in a specific sex? The gene transformer (tra) gets its name from "sexual transformation," as some tra alleles can change XX animals into morphological males, while other tra alleles can change XY animals into morphological females. c. Which of these sex transformations would be caused by null alleles of tra and which would be caused by constitutively active alleles of tra? d. In contrast with Sxl, null tra mutations do not cause lethality either in XXX or in XY animals. However, the Sxl protein regulates the production of the Tra protein. Why then do all tra mutant animals survive? e. Predict the consequences of null mutations in tra-2 on XX and XY animals. (Recall that tra-2 encodes a protein, expressed in both sexes, that is required for Tra function.) f. XY males carrying loss-of- function mutations in the fruitless (fru) gene display aberrant courtship behavior. Would you predict that either XX or XY animals with wild-type alleles of fru but loss-of-function mutations of tra would also court abnormally?

Which of the following events is unlikely to be associated with cancer? a. mutations of a cellular proto-oncogene in a normal diploid cell b. chromosomal translocations with breakpoints near a cellular proto-oncogene c. deletion of a cellular proto-oncogene d. mitotic nondisjunction in a cell carrying a deletion of a tumor-suppressor gene e. incorporation of a cellular oncogene into a retrovirus chromosome

Molecules outside and inside the cell regulate the cell cycle, making it start or stop. a. What is an example of an external molecule? b. What is an example of a molecule inside the cell that is involved in cell cycle regulation?

Identical twins are technically clones of each other but can differ in both appearance and behavior. How is it possible that two people with the same genome could be different?

Some fruits and vegetables are the result of crossing different species. A tangelo, for example, results from crossing a tangerine with a grapefruit. How are the genetic engineering processes of making transgenic organisms similar to and different from crossbreeding?.

A plant can send out a runner that will sprout a new plant that is a clone of the "parent." Single-celled organisms divide in two, forming two clones. How is the cloning of an animal similar to and different from the cloning that happens in nature?