Biology 107 (Dr. Harrington) Problem set 2

Biology 107 B2 - Problem set 2

Question 1 (exam) Woese divided life into three domains: Archaea, _____ , and _____.

A. Bacteria ... Eukarya
B. Plants ... Animals
C. Prokaryotes ... Eukaryotes
D. Monera ... Fungi
E. Ewoks ... Wookies

Question 2 (thinking) How could you determine experimentally if the Archaean Methanobrevibacter oralis is a cause of dental root disease and not just a consequence?

Question 3 (thinking) Recall that the hemoglobin protein is made of two α-Globin and two β-Globin polypeptides. The human β-Globin is 146 amino acids long. The gorilla version is also 146 aa long and there is only a single aa difference. There are 8 differences between the human and rhesus monkey β-Globins, 27 differences between the human and mouse β-Globins, and 67 differences between the human and the frog β-Globins. Make a diagram showing the evolutionary relationships between these five species.

Question 4 (exam) Arabidopsis thaliana, a small well-studied plant, responds to cool temperatures by synthesizing FAD8 proteins. FAD8 is a fatty acid desaturase enzyme which converts C-C bonds in free fatty acids into C=C bonds. Why is this enzyme made when the plants are in cold environments?

Question 5 (exam) A human red blood cell would _____ if placed in tap water because this is a/an _____ environment.

A. swell ... isotonic
B. shrivel ... hypotonic
C. swell ... hypotonic
D. shrivel ... hypertonic
E. swell ... hypertonic

Question 6 (exam) Muscle cells consume molecular oxygen (O₂) as they synthesize ATP.

a) How does the oxygen enter the cell? Why is this mechanism used in this situation?

b) An oxygen molecule has just entered a muscle cell. What, if anything, prevents it from leaving the cell?

Question 7 (organization) Make a table of the seven methods by which molecules enter or leave a cell. Use the following headings:

(a) Method (for example: "passive diffusion through the phospholipid bilayer")

(b) Examples ("molecules transported by this method include oxygen, carbon dioxide, and water)

(c) Situation ("these molecules are transported by this method because they are small and uncharged and can thus pass through the hydrophobic interior of the membrane, no energy is required because they are moving down their concentration gradient")

(d) Diagram