WGU Biochemistry EXAM WITH 100% CORRECT ANSWERS

DNA replication is semiconservative, meaning that each new duplex has one original (parent) strand and one new strand. Because the two parent strands are separated during replication and the base pairing is predictable, each parent strand can serve as a template for the new strand synthesis. DNA replication is ___________, which allows each of the two strands to serve as a _______ for the new strands. b. semiconservative, template Helicase unwinds the double stranded DNA to allow for replication, but this is not a problem for the DNA polymerase. Which of the following enzymes does NOT assist the DNA polymerase on the lagging strand to overcome its two problems? (Recall that the DNA polymerase can only make DNA in the 5'->3' direction, and it must bind a double-stranded nucleotide polymer before it can start making its own DNA polymer.) c. Helicase Nucleotide excision repair is used to repair deletions, insertions, and helix-distorting lesions, such as thymine dimers. Several components of cigarette smoke, including benzopyrene, insert themselves (intercalate) into the DNA and lead to several types of mutations such as frameshift mutations, including both insertions and deletion. Which of the following repair pathways would be used to repair this type of damage? c. Nucleotide Excision Repair Frame shift mutations are a kind of mutations which result from addition of deletion of a nucleotide base resulting in an altered reading frame and ultimately a different protein, than the one the gene originally encoded. Frameshift mutations are genetic changes because they alter the DNA sequence, whereas epigenetic changes do not alter the DNA sequence. Epigenetic changes are modifications to genomic structure (not sequence) that are caused by the external environment. These environmental factors affect the overall chromatin structure to allow more or less "access" to the DNA by gene expression machinery to turn the genes "on" or "off". In other words, epigenetics can alter gene expression without changing the underlying DNA sequences. The changes may or may not be heritable, depending on the location and circumstances. Maternal smoking during pregnancy is hazardous yet common in many places. Many studies have associated prenatal smoking to unhealthy physical and psychological outcomes for the baby. Researchers know that maternal smoking affects are epigenetic in nature. Which of the following events can be considered epigenetic in nature? a. Changes in chromatin structure The genes that produce the A and B antigen proteins can both be expressed independently, and a heterozygote (someone with both genes) will be produce both A and B proteins - neither will dominate the other. The is an example of codominance. Blood type is an example of what type of inheritance? a. Codominance