Biol 155 Human Physiology

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Biol 155Human Physiology

• Instructor Dr. Robert Harris
• Office 1354 Biological Sciences
• Phone [phone]
• Email harris_at_zoology.ubc.ca

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Course requirements

• Texts Fundamentals of Anatomy and
  Physiology 6th ed. Frederic H. Martini
• Anatomy Physiology Coloring Workbook, 7th
  ed. Elaine Marieb
• Read course synopsis!!! Failure to read it, or
  failure to listen to what I say does not
  constitute an excuse
• Lecture Notes and synopsis are posted at
  http//www.zoology.ubc.ca/biomania/biol153/
• lecture/main01.htm

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Mark Breakdown

• Biol 153 Lecture 60
• Lab 40
• Course Total 100
• The lecture mark is based on
• One mid-term exam in each term 20 (10 each)
• Winter exam 20
• Final exam 20
• Total 60

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Mark Breakdown cont.

• Biol 155
• marks will be based solely on the lecture exams,
  which will be weighted as follows
• One mid-term exam in each term 30 (15
  each)
• Anatomy colouring book 5
• Winter exam 30
• Final exam 35
• Total 100

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Atomic structure and elements

• An element is a substance that retains its
  chemical and physical characteristics even when
  it is broken down into its smallest units.
• The smallest practical unit, for our purposes is
  the atom.

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The chemical characteristics are determined by
the number of protons

• These are the three forms of hydrogen
• All three have one electron
• All three have one proton

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Electron orbits

• Number of electrons generally equals number of
  protons.
• There are specific orbits (or shells), that
  contain a specific maximum number of electrons

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Charged atoms

• Atoms are most stable when there are 8 electrons
  in the outermost shell.
• In order for the outermost shell to be filled,
  atoms will either take in or give off electrons.
  When this happens there is a change in net
  charge.
• Charged atoms (ions) can be electrically
  attracted (opposite charges attract)
• This is known as ionic bonding
• Ionic bonds are fairly weak

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Covalent bonds

• Another way atoms can fill their outer shell is
  to share electrons with another atom
• The electrons orbit around BOTH nuclei
• This is known as a covalent bond
• Covalent bonds are much stronger than ionic bonds

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Molecular dipoles

• When covalent bonds are formed, the electrons may
  not be shared equally between the atoms
• This unequal sharing can result in an uneven
  distribution of electrical charges on the
  molecule
• This is known as a partial charge, or a dipole

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Hydrogen bonding

• Water molecules interact with each other
  electrically
• The partial negative charge around the oxygen is
  attracted to the partial positive charge around
  the hydrogen
• These very weak electrical attractions are called
  hydrogen bonds

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Ions in aqueous solution

• Water molecules can form hydrogen bonds with ions
• Ions in solution have a layer of tightly bound
  water molecules around them
• This layer of water molecules is known as the
  hydration sphere
• Water can form hydrogen bonds with uncharged
  molecules as well (providing there is a partial
  charge)

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• pH is the negative log (the small p) of the
  hydrogen concentration (the large H)
• In pure water, some of the H2O molecules will
  dissociate into H and OH-
• The H concentration in pure water is 0.1 mM, or
  1x10-7 moles/L (hence pH 7)

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Molecular Representations

• There are several ways or representing molecular
  structures
• Here are three representations of glucose
• Linear model
• Structural model
• Space-filling model

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Synthetic and Lytic Reactions

• Smaller organic molecules can be linked together
• Often this involves the production of H2O
• Larger organic molecules can be broken down into
  subunits
• This often consumes H2O, hence the term
  Hydrolysis

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Energetics of chemical reactions

• In order for chemicals to react, they must first
  overcome an energy barrier
• This is known as the activation energy
• Some bonds are easily reorganized, resulting in a
  lower activation energy

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Enzyme catalyzed reactions

• Enzyme has binding sites for the reactants
• The active region will attack the bonds in the
  precursors
• Once bonds have been reorganized, product is
  released

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Polymers in organic systems

• A polymer is a chain made up of repeating
  subunits
• Useful compounds are often stored in the form of
  a polymer
• For example, glycogen is a branched polymer of
  glucose
• Glycogen molecules can have different numbers of
  glucose subunits
• Proteins are also polymers

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Fatty acids and lipids
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Phospholipids in aqueous solutions

• Phospholipids and glycolipids are amphipathic
• Meaning they have a hydrophillic region and a
  hydrophobic region
• When they are in solution, they form micelles

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Structure of Amino Acids

• All amino acids have the same basic structure
• A carboxylic acid side
• An amino group side
• A side group on the central carbon
• The side group is referred to as the R-group

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Primary protein structure
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Secondary protein structure

• The chain of amino acids can form folds and coils
  in different regions, depending on the amino acid
  sequence

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Tertiary protein structure

• The tertiary structure of a protein is the 3D
  shape of a single subunit.
• This is a combination of all the folds, coils and
  sheets.
• This is usually dictated by hydrophobic and
  hydrophilic interactions with water

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Tertiary and Quaternary protein structure

• The quaternary structure of a protein is the
  interactions between the different subunits
• If a protein is only composed of a single
  subunit, there is no quaternary structure

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DNA and RNA structure
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Adenosine triphosphate (ATP)

• Adenosine backbone
• Three phosphate groups attached in a chain
• Last two have high energy bonds

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Characteristics of a lipid bilayer

• At normal temperatures, a lipid bilayer is
  liquid.
• This means that the phospho- and glycolipids
  which make it up can move freely, within the
  bilayer.
• Because of the hydrophobic layer in the centre,
  a bilayer is impermeable to water.
• Because of the hydrophilic and hydrophobic
  interactions, a bilayer is structurally quite
  strong.

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Membrane fluidity
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Membrane proteins
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Diffusion
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Effect of osmotic concentration on cells

• Cell membranes are semipermeable, and thus
  subject to osmotic forces.
• Animal cell membranes are flexible, and allow for
  inflation and deflation depending on the movement
  of water

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Transport of solutes through cell membranes

• Cell membranes are made up of phospholipids
  arranged in a bilayer.
• The centre of the bilayer is hydrophobic, which
  means that hydrophilic molecules cant penetrate.
• Hydrophobic and lipid-soluble molecules can
  penetrate cell membranes.
• In order for hydrophilic molecules to be taken
  up, a transport mechanism is needed.
• These transport mechanisms are integral membrane
  proteins.

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Ion channels

• Ions are fairly small molecules.
• Specialized proteins in the membrane form aqueous
  pores, which allow ions through.
• The driving force is the chemical gradient
• These pores can be quite selective.
• Most of these pores are regulated
• Example CFTR

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Facilitated diffusion

• Molecules that are slightly larger need more help
  in getting into or out of cells.
• Rather than a pore, molecules are actually bound
  to carrier protein, which translocates molecule.
• Driving force is still the chemical gradient

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Active transport

• In order to move ions against a concentration
  gradient, energy must be used.
• Energy is supplied by the hydrolysis of the
  terminal high-energy bond of ATP.
• Example Na-K-ATPase

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Active secondary transport

• ATPases only pump ions, nothing bigger.
• Larger molecules are transported by coupling them
  to movement of an ion down its concentration
  gradient.
• Ions can also be transported in this way.
• Example Na-coupled glucose uptake.

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Membrane transport and cycling

• Molecules can bind to cell surface receptors and
  then be internalized.
• This same mechanism can be used to recycle
  membrane.

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Phagocytosis

• Phagocytosis also involves membrane invagination.
• This process does not involve clathrin.
• Pseudopods extend around a particle, forming a
  phagosome.
• Phagosome will fuse with a lysosome, containing
  digestive enzymes.
• There are smaller transport mechanisms in the
  wall of the secondary lysosome.

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Cellular organelles

• Most intracellular organelles are membrane-bound.
• Since membranes are barriers to diffusion of
  aqueous solutes, they allow for partitioning of
  cellular components
• Such partitioning allows for the generation of
  gradients and/or the segregation of specific
  compounds inside the cell, a process that is
  essential for life.

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Endoplasmic reticulum

• The endoplasmic reticulum consists of a series of
  interconnected membrane-bound tubes and lamina
  that are all continuous.
• It is essential in the production of membrane
  proteins.
• It also serves as a Ca2 storage organelle.

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Ribosomes

• Ribosomes are enzymes made up of two subunits.
• Ribosomes are the enzyme that synthesize
  proteins, based on an mRNA template
• Some ribosomes are attached to the ER and some a
  free in the cytoplasm.

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Translation
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Golgi apparatus

• The Golgi apparatus is a contiguous system of
  lamellae and cisternae.
• It is responsible for post-translation
  modifications of proteins, formation of secretory
  vesicles and membrane formation and trafficking.

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Membrane flow

• Transport vesicles bud off the ER and are
  transported to the forming face of the Golgi.
• Membrane-bound proteins and secretory proteins
  then move through the Golgi, where they are
  modified, usually by glycosylation.
• The proteins and membranes are then packaged into
  specific vesicles, which are targeted.

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Mitochondria

• Mitochondria actually have two membranes,
  separated by a small space.
• Mitochondria also have their own DNA.
• Mitochondria are essential for oxidative
  phosphorylation.

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Nucleus

• Nucleus also has two membranes.
• Nucleus protects the DNA and maintains a specific
  environment for the DNA.
• Nuclear pores allow for transport into and out of
  nucleus.

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Library tutorial

• http//toby.library.ubc.ca/ereserve/er-coursepage.
  cfm?id1416
• For the Biol 153 students Lee Ann Bryant
  (from the library) will be here at the end of
  the lecture to give a short talk about the
  library assignment.

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Cell cycle
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DNA condensation
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