12: Membranes and Membrane Proteins
- Page ID
- 154163
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- 12.1: Basic Concepts in Membranes
- The orderly movement of compounds through cell membranes is critical for the cell to be able to 1) get food for energy; 2) export materials; 3) maintain osmotic balance; 4) create gradients for secondary transport; 5) provide electromotive force for nerve signaling; and 6) store energy in electrochemical gradients for ATP production (oxidative phosphorylation or photosynthesis). In some cases, energy is required to move the substances (active transport).
- 12.2: Membrane Bilayer and Monolayer Assemblies - Structures and Dynamics
- Fatty acids can be saturated (contain no double bonds in the acyl chain), or unsaturated (with either one -monounsaturated - or multiple - polyunsaturated - double bond(s)).
- 12.3: Working with Lipids
- This page covers the formation and analysis of liposomes and lipids, highlighting the significance of lipid composition on membrane properties and their applications in drug delivery, including mRNA vaccines. It details preparation methods like organic solvent and detergent dispersion, as well as lipidomics techniques such as gas chromatography and mass spectrometry for precise lipid characterization.
- 12.4: Transport in Membranes
- It is essential for cells to be able to uptake nutrients. This function along with movement of ions and other substances is provided by proteins/protein complexes that are highly specific for the compounds they move. Selective movement of ions by membrane proteins and the ions’ extremely low permeability across the lipid bilayer are important for helping to maintain the osmotic balance of the cell and also for providing for the most important mechanism for it to make ATP - the process of oxidat
- 12.6: Membranes and Membrane Proteins
- One easily understandable function of membrane bilayers is to separate the inside and outside of the cell or intracellular organelles. Yet as we mentioned before, such barriers can not be so rigid and impenetrable that they prevent movement of materials across the membrane. Let's turn our attention to proteins that associate with the membrane and confer added functionalities to it.
- 12.7: Diffusion Across a Membrane - Passive and Facilitated Diffusion
- This page collectively addresses membrane transport and diffusion, focusing on mechanisms such as passive diffusion, facilitated diffusion, and active transport. It elaborates on Fick’s First Law, permeability coefficients, and the complexities of solute movement across membranes, including the influence of concentration and electric potential on ion diffusion.
- 12.8: Diffusion Across a Membrane - Channels
- This page covers key concepts of ion channels in biochemistry, detailing their structure, function, and gating mechanisms critical for neuronal signaling. It discusses pentameric ligand-gated ion channels (pLGICs), inhalational anesthetics' effects, and the mechanisms behind voltage-gated sodium channels (NaV) and potassium channels (Kv). The significance of ion selectivity, gating dynamics, and the role of neurotoxins is highlighted.
- 12.9: Diffusion Across a Membrane - Pores
- This page explores the mechanisms, structures, and functions of various membrane proteins and pore-forming complexes involved in cellular transport. Key focuses include pore-forming proteins (PFPs), ion channels like VDAC1 and aquaporins, as well as mechanosensitive channels and the nuclear pore complex (NPC). These structures are essential for ion and molecule transport, cellular communication, and responses to mechanical stimuli.
- 12.10: Active Transport
- This page provides an overview of active and passive transport mechanisms in biochemistry, emphasizing energy-driven processes like ATP hydrolysis in active transport. It categorizes transporters, including uniporters and symporters, and details the Major Facilitator Superfamily and membrane ATPases, with specific examples like LeuT and P-type ATPases.