Author: Anonymous

Researchers discovered a mutant form of the TYR gene with a deletion of a single guanine nucleotide in the beginning of the coding sequence. Which of the following best predicts the phenotype of an individual who is homozygous for this TYR mutation?

Which of the following adult structures is a derivative of the endoderm?  

Which of the following claims about the TYR, TRP2, and TRP1 mammalian genes is most likely to be accurate?

Use the following information to answer the next FOUR questions. In mammals, the dark color of skin, hair, and eyes is due to a pigment called melanin. Melanin is produced by specialized skin cells called melanocytes. The melanin is then transferred to other skin cells called keratinocytes. Melanocytes synthesize melanin in a multistep metabolic pathway (Figure 1). The amount of melanin produced is dependent on the amount of the enzymes TYR, TRP2, and TRP1 present inside melanocytes. Figure 1. Melanin synthesis pathway The peptide hormone -melanocyte stimulating hormone () activates a signal transduction pathway leading to the activation of MITF. MITF is a transcription factor that increases the expression of the TYR, TRP2, and TRP1 genes (Figure 2). Figure 2. Activation of melanin synthesis genes in melanocytes Some mammals increase melanin production in response to ultraviolet (UV) radiation. The UV radiation causes damage to DNA in keratinocytes, which activates the p53 protein. p53 increases the expression of the POMC gene. The POMC protein is then cleaved to produce  . The keratinocytes secrete  , which signals nearby melanocytes. The increased melanin absorbs UV radiation, reducing further DNA damage. Figure 3. Production of   in keratinocytes in response to UV radiation

Using the pattern of STRs (Short Tandem Repeats) from a crime scene, what can you conclude?

Both liver cells and lens cells have the genes for making the proteins albumin and crystalline. However, only liver cells express the blood protein albumin and only lens cells express crystalline, the main protein in the lens of the eye. Both of these genes have enhancer sequences associated with them. The claim that gene regulation results in differential gene expression and influences cellular products (albumin or crystalline) is best supported by evidence in which of the following statements?

Explain how kidney cells in one individual with two identical SLC alleles could produce SLC protein products with nonidentical amino acid sequences. (1) Explain why the channel labeled C in Figure 1 does not require ATP to move Ca2+ ions from Region I into the kidney cell. (EC 1)  

The mRNA transcribed from the DNA would read

All of the following made the separation of these DNA fragments possible EXCEPT

Plates that have only ampicillin-resistant bacteria growing include which of the following?