_The Plasma Membrane_ Test Study Guide.pdf

_The Plasma Membrane_ Test Study Guide.pdf - The Plasma...

Info icon This preview shows pages 1–3. Sign up to view the full content.

The Plasma Membrane Intro to the Plasma Membrane: -separates the living cell from its surroundings -8 nm thick, controls traffic into and out of the cell -Selectively permeable→ allowing some substances to cross more easily than others -Major macromolecules in membranes are lipids, proteins, and carbohydrates - Made of a bilayer of phospholipids. With polar heads, hydrophilic, and non-polar tails, hydrophobic -The membrane is represented as a fluid mosaic model, a fluid environment with a mosaic of proteins and carbs embedded or attached that serve several functions -Phospholipids are packed together by cohesion and hydrophobic interactions -Fluid Mosaic Model: -Proteins: -In membrane→ Integral Proteins -Not in Membrane→ Peripheral Proteins -Lipids: -Cholesterol→ needed in animal cells from diet and liver -Phospholipids -Carbohydrates: -Glycoprotein→ carb and protein -Glycolipid→ carb and lipid Membrane Movement and Cholesterol: -Most of the lipids and some proteins can drift laterally in the plane of the membrane, but rarely flip-flop from one layer to the other Cholesterol: -wedged between phospholipid molecules in the plasma membrane of animal cells -retains the movement of phospholipids in warm temperatures -maintains the fluidity by preventing tight packing at cold temperatures Cells can Change their Membrane Composition: -Cells can modify the lipid makeup of membranes to compensate for changes in fluidity caused by changing temperatures -Ex: Winter wheat, increases the percentage of unsaturated phospholipids in the autumn
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

-This lets them prevent their membranes from solidifying during winter A Mosaic of Proteins: -Membranes are very complex and dynamic containing many different parts -Proteins decide most of the membrane’s functions -Contain lipids and carbohydrates also -The collection of molecules in the membrane vary from membrane to membrane -All of the structures in the membrane serve various functions like cell recognition proteins The Role of Membrane Carbohydrates in Cell-Cell Recognition: -Cells recognize each other by binding to surface molecules, often carbohydrates, on the plasma membrane -Membrane carbohydrates may be covalently bonded to lipids (forming glycolipids) or more commonly to proteins (forming glycoproteins) -Carbohydrates on the external side of the plasma membrane vary among species, individuals, and even cell types in an individual -Immune System need cell recognition proteins Synthesis and Sidedness of Membranes: -Membranes have distinct inner and outer faces -The asymmetrical distribution of proteins, lipids, and associated carbohydrates in the plasma membrane is determined when the membrane is built by the ER and Golgi apparatus -Carb has to end up on the outside of the cell -Needs to stand on the inside of vesicle in the ER 2 Types of Proteins: -Peripheral Proteins: not embedded in the lipid bilayer, they are loosely bounded to the surface
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern