Cell Membrane

Julia Castellani
Mind Map by , created about 4 years ago

components and functionality of a cell membrane

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Julia Castellani
Created by Julia Castellani about 4 years ago
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Cell Membrane
1 Functions
1.1 Separates cytoplasm from environment
1.2 controls the traffic of molecules(**selectively permeable**)
1.3 recognized by other cells, hormones, and antibodies
2 Membrane Lipids
2.1 Phospholipids

Annotations:

  • most abundant lipids in membrane
  • amphipathic (hydrophobic & hydrophillic regions)
  • Functions: -form layers on surface of water -determine fluidity at lower temps (varying degrees of unsaturation in tails)
2.2 Glycolipids

Annotations:

  • like phospholipids, but with sugars attached at head
  • Found only on outside layer of plasma membrane
  • Functions: -protect cell surface -act as recognition sites -help cells stick to surfaces
2.3 Cholesterol

Annotations:

  • small, flat, ringed steroid between phospholipid molecules
  • Functions: -decrease membrane fluidity -decrease membrane permeability -make membranes tougher
3 Membrane Proteins
3.1 Functions
3.1.1 Enzymes
3.1.2 Transport
3.1.3 Receptors
3.1.4 Formation of Junctions
3.1.5 Cell-Cell Recognition
3.1.6 Attachment to extracellular matrix
3.2 Properties
3.2.1 Amphipathic
3.2.2 move around in membrane
3.2.3 some protrude on both sides of membrane
3.3 Eg) Globular Proteins ('Potato"), Glycoprotein
4 Membrane Transport
4.1 Passive Trasport
4.1.1 Simple Diffusion (high-low concentration)
4.1.1.1 Non-polar solutes

Annotations:

  • cross easily (eg oxygen, hydrocarbons)
  • smaller molecules cross faster
4.1.1.2 Polar solutes

Annotations:

  • small ones (eg Carbon Dioxide, Water) cross easily
  • larger molecules (eg sugars) won't pass readily
  • Ions pass hardly at all
4.1.2 Facilitated Diffusion (high-low concentration of solute)

Annotations:

  • polar solutes and ions are helped by transport proteins
  • solute is moving across a membrane from high-low concentration
4.1.2.1 carrier proteins

Annotations:

  • bind to a solute and physically move them across membranes
  • very specific
4.1.2.2 channel proteins

Annotations:

  • provide a hydrophilic channel for ions
  • less specific
4.2 Active Transport

Annotations:

  • molecules move against concentration gradient (low-high)
  • Requires transport protein and energy input (eg Sodium / Potassium pump)
4.2.1 Eg) Sodium-Potassium pump

Annotations:

  • -found in plasma membrane
  • same carrier transports sodium and potassium ions across  membrane in opposite directions
  • 3 sodium ions out for every 2 potassium ions in
  • pump is "electrogenic" (produces a change in electrical charge) because it creates a membrane potential
  • uses ATP as energy
4.2.2 Molecules move against concentration gradient
4.2.3 requires transport proteins and energy
4.3 Co-Transport Systems
4.3.1 Ion pump works together with another protein transporter

Annotations:

  • Eg) glucose pump
4.4 Regulated Transport

Annotations:

  • can be PASSIVE or ACTIVE
  • involves the movement of molecules through specialized channels
4.4.1 Voltage Gated Channels

Annotations:

  • -closed when electric potential is high (polarized) -open when potential is low (depolarized)
4.4.2 Ligand Gated Channels

Annotations:

  • -closed when concentration of molecule is low -open when concentration is high
5 Transport of Large Molecules
5.1 Endocytosis
5.1.1 Phagocytosis (uptake of solids)
5.1.2 Pinocytosis (uptake of fluids)
5.1.3 Receptor-mediated endocytosis (specific uptake of proteins)
5.2 Exocytosis
5.2.1 reverse of endocytosis

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