WGU D115 Exam D115 Advanced Pathophysiology Comprehensive Answer Guide & Study Reference OA Exam Prep Units 2 through 7 ()

Module 1: Genetic Influence on Patient Outcomes Q: What are genes composed of and where are they located? A: Genes are composed of DNA (deoxyribonucleic acid) — segments of DNA that encode proteins. They are located on chromosomes inside the nucleus of cells. Q: What are the four nitrogenous bases that make up DNA? A: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). A pairs with T; G pairs with C. In RNA, Uracil (U) replaces Thymine. HIGH YIELD: A-T and G-C base pairing is a common exam question. Remember: in RNA, T → U. Q: How are new strands of DNA formed? A: Through DNA replication: the double helix unwinds, and each strand serves as a template. DNA polymerase adds complementary nucleotides (A→T, G→C) forming two identical daughter strands. Q: How is transcription regulated? A: Transcription (DNA→mRNA) is regulated by promoter regions, transcription factors, enhancers/silencers, and epigenetic modifications (methylation, histone modification) that control whether a gene is expressed or silenced. Q: How many pairs of chromosomes do humans have? A: Humans have 46 chromosomes total — 23 pairs. 22 pairs are autosomes; 1 pair are sex chromosomes (XX = female, XY = male). Q: Most common chromosome abnormalities? A: Trisomy 21 (Down syndrome), Monosomy X (Turner syndrome — 45,X), Trisomy XXY (Klinefelter syndrome — 47,XXY), deletions, duplications, and translocations. Q: How is gender determined genetically? A: The SRY gene on the Y chromosome triggers male development. XX = female; XY = male. Individuals with no Y chromosome develop as female by default. Q: What are multifactorial diseases? Name examples. A: Diseases caused by the interaction of multiple genes AND environmental factors. Examples: type 2 diabetes, hypertension, coronary artery disease, cleft palate, neural tube defects, schizophrenia. Q: How do monozygotic and dizygotic twins differ genetically? A: Monozygotic (identical) twins share 100% of DNA — from one fertilized egg. Dizygotic (fraternal) twins share ~50% of DNA — from two separate eggs fertilized by two sperm. Q: Which chromosome is affected in Down syndrome? Clinical features?