Epithelium & Glands
What is the secretory mechanism for a sebaceous glands and a lactating mammary gland respectively?
Holocrine, Apocrine
How does the cell keep single stranded DNA from forming secondary structures?
Single stranded binding proteins
A researcher studying gene expression isolates mRNA after exposure of a cell culture to insulin-like growth factor. Single strands of DNA are synthesized using the mRNA as template with the help of the enzyme reverse transcriptase. Which of the following would best characterize the DNA strands that are synthesized in this procedure?
They lack intron sequences
What phase of cell division is halted for karyotyping?
Metaphase
Mahir was diagnosed with an atypical form of Osteogenesis imperfecta – a condition associated with mutations of the collagen type 1A1 gene. Diagnostic tests designed to identify all known mutations in the collagen gene were negative. Which of the following diagnostic tools should be used to rule out a novel mutation in Mahir’s collagen 1A1 gene?
Gene sequencing
Biopsy of a breast mass reveals loss of cell differentiation and lack of tissue organization. Which of the following terms best corresponds to this finding?
Dysplasia
What polymerase forms the Ozaki fragments for the lagging strand?
DNA polymerase III
A woman comes into the clinic complaining of arthritis. She also explains to the physician she feels fatigued. The physician notes a butterfly rash, and a fever (38C). She is diagnosed with Systemic Lupus Erythematous. What are her antibodies likely marking for destruction?
Spliceosome
A cell going through mitosis is entering into prophase what are some features to be seen?
Nuclear envelope dissolves, mitotic spindle forms
A man who was diagnosed with lung cancer was given a drug camptothecin. What is likely to happen in replication?
DNA breakage due to coiling
A child was born and showed signs of cyanosis and labored breathing. He was diagnosed with a deficiency in Poly-A-polymerase. What is likely to happen to the mRNA in the newborn?
Destruction from ribonucleases
A 4 y.o child is brought to the doctor due to concerns about the child's eyes. He has leukocoria, glaucoma, and strabismus. After several tests the doctor confirms that this is due to a mutation in the Rb gene. How would this mutation affect the cell cycle?
Decreased inhibition of cells at the G1-S checkpoint
An 8 month-old child was referred to a neurologist displaying symptoms indicating a loss of motor skills and a ‘cherry-red' spot on his retina. The clinician suspected Tay-Sachs disease. Blood tests revealed no detectable B-hexosaminidase A activity. Analysis of genetic material revealed a frameshift mutation in the gene encoding B-hexosaminase A which radically altered all of the subsequent amino acids from that point on. Which of the following mutations was responsible?
Deletion of one nucleotide in an exon
The drug actinomycin D is highly toxic and inhibits DNA synthesis and transcription in both prokaryotes and eukaryotes, and causes DNA damage. Actinomycin D exerts its toxic effects by..
Intercalating with bases in the DNA
Recent investigations in to polyglutamine diseases suggest that aberrant transcriptional regulation might be central to the molecular pathogenesis. Several groups have reports suggesting that defective acetylation of histones as a cause of abnormal transcription. Which of the following is true with respect to the role of histone acetylation and gene transcription?
Deacetylation of histones results in reduced transcriptional activity
A 32-year-old man comes to his physician with itchy, blistering sores on his lower lip that have been present for 1 day. His physician prescribes a medication that is an analogue of deoxyguanosine. What is the likely mechanism of action of the prescribed drug?
Inhibition of viral thymidine kinase - Acyclovir