Biol 1151 Anatomy and Physiology I

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Biol 1151 Anatomy and Physiology I
Barbara Musolf Office Arts and Science
G-110G E-mail BarbaraMusolf_at_clayton.com Web
site http//a-s.clayton.edu/bmusolf/ Phone
[phone]
Office hours Tuesday 1000 am-1230 pm
130-600 pm And by appointment
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The Cellular Level of Organization

• What is a cell?
• What are the primary components of a cell?
• How do chemicals move in and out of cells?
• What structures are found in a cell?
• How do cells produce proteins?
• How do cells reproduce?

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Cell Theory

• All living organisms are made up of one or more
  cells.
• The cell is the fundamental structural and
  functional unit of an organism.
• All cells have the same basic chemistry.
• All cells arise from pre-existing cells through
  cellular division.
• Cells contain hereditary information that is
  passed down during cell division.
• All cells harness and produce energy through
  biochemical and metabolic processes.

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Main parts of a cell
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Plasma membrane Lipid bilayer
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The structure of membrane phospholipid molecules
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The structure of membrane phospholipid molecules
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Plasma membrane Lipid bilayer

• The distribution of proteins is non-random.
• Membranes are patchy.
• Lipid-lipid interactions
• Lipid-protein interactions
• The membrane varies in thickness.

From Nature, Jan 12, 2006
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Membrane fluidity

• Membrane lipids and proteins easily move
  laterally.
• They shift transversely or flip flop very slowly.
• Fluidity allows interactions to occur among
  proteins.
• Fluidity allows for cell movement, growth, and
  division.
• Fluidity allows for the cell to self-seal if torn
  or punctured.

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Membrane fluidity

• Flex
• Lateral shift
• Transverse diffusion

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Membrane proteins Integral
Ion channel
Transporter
Receptor
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Membrane proteins integral and peripheral
Enzyme
Linker
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Membrane protein Cell identity marker
Major histocompatibility (MHC) proteins are often
made up of glycoproteins and glycolipids. They
are found on blood cells.
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Membrane permeability

• The cell plasma membrane determines which
  substances can enter or leave the cell. The
  membrane can be
• Impermeable
• Freely permeable
• Selectively permeable
• Permeability depends on the membrane and the
  substance that seeks to permeate the membrane.

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Transport in and out of cells

• Kinetic energy transport
• Diffusion
• Osmosis
• Transport through transporter proteins
• Active transport
• Facilitated diffusion
• Transport in vesicles
• Endocytosis
• Receptor mediated endocytosis
• Phagocytosis
• Bulk-phase endocytosis
• Exocytosis
• Transcytosis

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Kinetic energy transport Diffusion

• Diffusion a high concentration of particles in
  solution will move to areas of low concentration.
• Diffusion is affected by
• Steepness of the concentration gradient
• Temperature
• Mass of the substance
• Surface area of membrane
• Diffusion distance

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Types of diffusion

• Through the lipid bilayer
• Through ion channels
• Facilitated diffusion

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Kinetic energy transport Osmosis

• Osmosis occurs
• Through the lipid bilayer
• Through aquaporins

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Kinetic energy transport Osmosis
Hydrostatic pressure is pressure exerted by the
liquid
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Kinetic energy transport Osmosis
Osmotic pressure is pressure exerted by the
impermeable solute
Osmosis test
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Tonicity affects the volume of cells

• In an isotonic solution the cell maintains its
  volume.
• In a hypotonic solution the cell swells in size.
• In a hypertonic solution the cell shrinks

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Tonicity affects the volume of cells
100mOs
200mOs
300mOs
400mOs
500mOs
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Active transport

• Needed for transport of polar or charged solutes.
• Needed to transport solutes against a
  concentration gradient.
• Two types of active transport
• Primary active transport gains energy from
  hydrolysis of ATP.
• Secondary active transport uses energy stored in
  a concentration gradient

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Primary active transportThe sodium-potassium
pump
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Na/K pump
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Secondary active transport Antiporters
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Secondary active transport Symporters
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Transport in vesicles Receptor mediated
endocytosis
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Transport in vesicles Phagocytosis in
macrophages and neutrophils
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Phagocytosis
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Transport in vesicles Bulk phase endocytosis
(pinocytosis)
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Exocytosis

• Occurs more frequently in
• Secretory cells that release digestive enzymes,
  hormones, mucus, or other secretions.
• Neurons that release neurotransmitters.
• Cellular waste is also disposed of by exocytosis.

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Transcytosis

• Transcytosis allows movement of particles through
  a cell (ex endothelial cells lining blood
  vessels)

A New Function for the LH/CG Receptor
Transcytosis of Hormone Across the Endothelial
Barrier in Target Organs Nicolae Ghinea Ph.D. ,
Edwin Milgrom M.D.  Ph.D. INSERM U-135, Hormones,
Gènes, et Reproduction, Hôpital de Bicêtre, Le
Kremlin-Bicêtre, France
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Kinetic energy transport Electrochemical
gradients

• Membrane permeability is selective.
• Different concentrations of chemicals can exist
  between the cytosol and extracellular fluid.
• Different charges buildup between the two sides
  of the membrane.
• The differences in concentration and charge help
  move substances across the membrane.