The portion of the dna molecule that can vary is its
(a) sugar.
(b) base.
(c) deoxyribose.
(d) ribose.
(e) phosphate

What was dr. willem johan kolff’s first step in using the scientific process to invent the hemodialysis machine? he built the machine and tried it with various patients, collecting data about its effectiveness. when a patient’s kidneys failed, he wondered if it would be possible to perform kidney functions with an external machine. he researched and collected data about numerous patients who exhibited symptoms of kidney failure. he drew conclusions from studies of various symptoms of kidney failure, and drew a design for the ideal external blood-processing machine.

Which statement describes john tuzo wilson’s contribution to the theory of plate tectonics?

The empty trna moves off and picks up another matching amino acid from the cytoplasm in the cell. the anticodon of the trna, with its attached amino acid, pairs to the codon of the mrna, which is attached to a ribosome. this sequence is repeated until the ribosome reaches a stop codon on the mrna, which signals the end of protein synthesis. the ribosome forms a peptide bond between the amino acids, and an amino acid chain begins to form. when a second trna with its specific amino acid pairs to the next codon in sequence, the attached amino acid breaks from the first trna and is bonded to the amino acid of the second trna.