Question

NEED HELP BY TONIGHT PLEASE!!!

Please help me, I am deeply confused in this class and trying so hard to understand. Please give detailed answers. I know some of these might be confusing but your help will really help me learn. The teacher requires very very detailed answers and he gives nearly no (and I mean literally nearly zero) partial credit so I'm dying here. Thank you sooooooo much, you have no idea.

Also, I am nearly leaglly blind and I am dyslexic so if you could please write clear it would help so much. I just want to learn like everyone else. SUPER SUPER THANK YOU

For part Question 1 you dont have to use the webiste!

4. You are a member of an expedition to study bacteria X that is found living in Antarctica. In the middle of your studies of this bacteria, a colleague of yours discovers that the same species of bacteria living in the soil in Cambridge. To begin your investigation into the similarities and differences of these two bacterial populations, you decide to look at the composition of lipids in the plasma membrane of bacteria X for both samples derived from Antarctica and Cambridge. (5 pts total) a) What differences in composition do you expect to observe and why? [2 ptl You can use Activity 6.2 (www.Life11e.com/ac6.2) to help model this question. b) Why is it mpotant for cells to maintain membrane fluidity? [1 ptl c) You further observe that the membrane composition of this bacteria X that is found living in Cambridge is more similar to that of the inner membrane of the mitochondria within human cells than the outer membranes of the mitochondria. Why do you think this is the case? [1 ptl d) Moreover, why might mitochondria and other organelles maintain different lipid membrane compositions compared to one another and compared to the plasma membrane? [1 pt]

Answer 1

(a) The Antarctica environment is characterized by extreme climatic conditions with freezing temperatures, low water activity and limited nutrient resources. The bacteria residing in such regions have adapted by developing mechanisms to alter membrane fluidity and functionality. These bacteria harbor higher proportion of unsaturated fatty acids by the formation of close array of acyl chains in the membrane. Also, reduction in the acyl chain length and synthesis of branched chain fatty acids is another way to maintain optimum fluidity in the membraneof bacteria residing in lower temperature regions.

When the composition of the plasma membrane was investigated, it was observed that the bacteria residing in Antarctica displayed greater proportion of unsaturated fatty acids in comparison to the same species residing in Cambridge. This is due to the fact that at lower temepartures, the membrane fluidity declines. In order to counter and adapt to the extreme environmental conditions, alteration in the ratio of unsaturated to saturated fatty acids occurs to maintain membrane fluidity.

The physical state of the membrane and fluidity directly regulates the activity of the membrane-bound proteins and signal-transduction events which are vital for membrane functions.

(b) Importance of membrane fluidity

Membrane fluidity is defined as the viscosity in the lipid bilayer of the membrane which affects the rotation and diffusion of ions, proteins and other biomolecules and directly affects teh fucntions of these. The fluidity and membarne deviations are involved in multiple vital cellular functions like cell growth, division, differentiation, solute transport as well as signal transduction. Slight alterations in fluidity may lead to abberations in the normal functioning.

(c) The inner mitochondrial membrane contains high fraction of proteins indicating the abundance of protein complexes for functional electron transport chain and oxidative phosphorylation.

In case of bacteria as well, the essential features of electron transport chain and phosphorylation events for the generation of ATP occurs on the plasma membrane, thus, imparting similarity between the bacterial membrane and inner mitochondrial membrane in human cells.

(d) Lipids are amphipathic molecules composed of two hydrophobic fatty acid chains linked to phosphate-containing hydrophilic head groups. It constitutes about 50% of the membranous mass and proportion varies depending on the type of the membrane. These differences in the lipid proportion and presence of various types of lipid molecules with different modifications play pivotal role in the proper functioning of the membrane types.