1. When bacteria growing well at 30°C are cooled to 20°C, which of the following membrane lipids are they most likely to synthesize, membrane lipids with saturated or unsaturated fatty acids? Explain.

1) Placing phospholipids in water will spontaneously form a spherical structure called a:Group of answer choices lumen ball sphingoid cytoskeleton liposome 2) Saturated fatty acidsGroup of answer choices Have each carbon "saturated" with hydrogen Have each carbon "saturated" with other carbons Have each carbon "saturated" with hydrogen and are solids at room temperature Are solids at room temperature Contain double bonds 3)  In intestinal epithelia, glucose can be taken into cells against its concentration gradient. How can glucose be transported against its concentration gradient without the direct expenditure of ATP in intestinal epithelial cells?Group of answer choices It uses simple diffusion It uses the Glut1 transporter It uses the Glucose ATPase It uses the Glucose/Na+ symporter None of the above. Due to the Second Law of Thermodynamics, molecules cannot be moved against their concentration gradient.

Two different membrane components are shown in the figure below. HO B A CH3 choline head group C glycerol backbone H3C D hydrocarbon tail CH3 CH3 CH3 B- C- D CH₂ 0 CH3 O CH3 C=O C=O CH-CH₂ What are the molecular modules indicated by the letters A-D? Select from the two options provided for each module. Asterol polar head group CH₂ CH₂ O CH3

6. A control phospholipid membrane is isolated in which the phospholipid tails all have an 18-C chain length and are comprised of a 50:50 mixture of saturated and unsaturated tails. In addition, about 25% of the lipids are fluorescently labeled on the head groups. a) Draw a single plot of Fluidity vs. Temperature that contains the expected curves for: Control phospholipid (line- -) Control supplemented with 18-C saturated phospholipids (dashed line - Control supplemented with 16-C chain length (dotted line • • • • • • ) b) Draw a single plot of the Fluorescence Intensity vs. Time that contains the expected curves of a Fluorescence Recovery After Photobleaching (FRAP) using the same samples as in (a) above. The FRAP experiment is conducted at the same temperature for each sample (which is the Tm of the of the control phospholipid).