Membranes are a fluid mosaic of phospholipids and proteins Membrane - - PowerPoint PPT Presentation

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Aug 18, 2022 230 likes •433 views

Membranes are a fluid mosaic of phospholipids and proteins Membrane proteins have specific functions Membranes form spontaneously, a critical step in the origin of life Passive transport is diffusion across a membrane with no energy

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Membranes are a fluid mosaic of phospholipids and proteins

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Membrane proteins have specific functions

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Membranes form spontaneously, a critical step in the origin of life

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Passive transport is diffusion across a membrane with no energy investment

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Osmosis is the diffusion of water across a membrane

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Water balance between cells and its surroundings is crucial to organisms

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Transport proteins may facilitate diffusion across membranes

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Cells expend energy in the active transport of a solute against its concentration gradient

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Exocytosis and endocytosis transport large molecules across membranes

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Cells transform energy as they perform work

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Two laws govern energy transformations

First law of thermodynamics: Energy can be

transferred and transformed, but it cannot be created or destroyed.

Second law of thermodynamics: Energy

conversions increase the Entropy of the universe.

Entropy: A measure of disorder

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Chemical reactions either release or store energy

Exergonic reaction Endergonic reaction

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ATP shuttles chemical energy and drives cellular work

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ATP powers cellular work Phosphorylation

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Enzymes speed up the cell’s chemical reactions by lowering energy barriers

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A specific enzyme catalyzes each cellular reaction

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