Explain the roles of XIST and TSIX during X-inactivation in females
What will be an ideal response?
Both XIST and TSIX are long noncoding RNAs (lncRNA). XIST is expressed from the X-chromosome to be inactivated. The XIST lncRNA will repress the genes on the inactivated X-chromosomes. The TSIX is expressed from the X-chromosome that is to remain active. When TSIX is expressed, its lncRNA will repress the XIST.
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Atria differ from ventricles in that they
a. are larger. b. have thicker walls with more muscle. c. receive blood from veins. d. have a higher blood pressure. e. empty through semilunar valves.
Trisomy 21, or Down syndrome, occurs when there is a normal diploid chromosomal complement but one (extra) chromosome 21. Although fertility is reduced in both sexes, females have higher fertility than males. Van Dyke et al
(1995; Down Syndrome Research and Practice 3[2]:65—69 ) summarize data involving children born of Down syndrome individuals. Given the fact that conceptuses with 48 chromosomes (four chromosome 21's) are not likely to survive early development, what percentage of surviving offspring would be expected to have Down syndrome if both parents have Down syndrome? A) One-half of the surviving offspring would be expected to have Down syndrome. B) All the children would be expected to have Down syndrome. C) One-third of the surviving offspring would be expected to have Down syndrome. D) None of the surviving offspring would be expected to have Down syndrome. E) Two-thirds of the surviving offspring would be expected to have Down syndrome.
Gigantism is caused by hypersecretion of ________ hormone during childhood and adolescence
Fill in the blank(s) with correct word
What is the name of the deep layer of skin that consists of connective tissue, with nerves and blood vessels running through it?
A. Dermis B. Epidermis C. Hypodermis D. Nervous tissue E. Epithelial tissue