Transcript
Lecture 1b
Basic ChemistryBiological MoleculesIntroduction to Cells
Basic Chemistry• Atomic theory
• All matter is made of atoms
• Molecules are atoms bonded together
• Not all atoms can bind; depends on their nature
• Types of bonds
• Ionic - electrons ‘donated’, creating charge
• Covalent - electrons shared
• H bonds
Basic Chemistry
• Bonds can be strong or weak
• Chemicals form different shapes and the shape influences the activity of the chemical
• Chemical reactions are the basis for most life processes
Chemical bonds
Ionic bond
Covalent Bond
WATER
• Water has polarity
• Leads to H bonds
Water
• Water is a solvent
• Dissolves ionic substances and other polar nonionic substances
Water
• Cohesion
• Water clings to itself
• Surface tension
• Adhesion
• Water clings to other stuff too
• How it gets in everywhere
Water
• High heat capacity
• T of water rises and falls slowly
• How organisms are able to live in a changing environment
• High heat of vaporization
• Has to be really hot to break H bonds and turn to steam
Water
• Ice is less dense than liquid water
• Allows aquatic organisms to live underneath ice because it is on the surface
Carbon• Because C forms 4 bonds, it is very
versatile
• C chains are the basis of organic molecules (molecules containing C and H)
• Organic molecules are divided into 4 groups: Carbohydrates, Lipids, Proteins, Nucleic Acids
• Most are made up of polymers of different types of monomers
Carbohydrates• Polymers of saccharides (sugars)
• Energy use
• Glucose
• Energy storage
• Starch in plants; glycogen in animals
• Structure
• Cellulose in plants; chitin
Lipids• NOT soluble in water
• Fatty acid tails (usually 3) keep from dissolving
• Fats and oils; primary energy storage
• Fatty acid tails come in three varieties:
• Unsaturated, saturated, and trans
Lipids• Not all lipids are bad!
• Phospholipids
• Have polar heads (water soluble); but non-polar tails (not soluble)
• This makes them arrange themselves in a bilayer
• These create the membranes of cells
Proteins• Important to structure and function
of cells
• Support
• Metabolism
• Transport
• Defense
• Regulation
• Motion
Proteins• Amino acids are the building
blocks of proteins
• There are 20 amino acids- combine in different ways to form thousands of different proteins
• The ‘chain’ of amino acids determines its shape, and therefore its function
Proteins• Function of protein is determined by
its shape
• There are 4 levels of structure:
• Primary: the sequence of aa
• Secondary: alpha helix, pleated sheet- formed by H bonds between aa
• Tertiary: the globular shape
• Quaternary: more than one
Nucleic Acids
• DNA and RNA are the nucleic acids in cells
• Nucleotides are the monomers
• DNA stores genetic info
• RNA takes genetic info to site of protein synthesis
DNA• Each nucleotide in DNA contains one of
4 different bases: adenine, guanine, cytosine, thymine
• G always bonds to C; A always bonds to T in double helix structure
• Very important to replication
• Every 3 bases stands for one amino acid
• So, if you know sequence of gene, you know sequence of protein
RNA
• RNA is single stranded
• The complementary pairs allow information to be passed to RNA from DNA; protein synthesis actually occurs from RNA
Nucleic Acids to Proteins
• Very small changes in a gene can potentially result in very large changes in protein
• Ex. Sickle cell: one aa difference
Cells!
• Why are cells small?
• Surface to volume ratio- gives adequate surface area for exchange of chemicals
• All cells have an outer plasma membrane, which encloses the cytoplasm
Cells
• Two main types of cells: prokaryotic and eukaryotic
• Prokaryotes do not have a membrane bound nucleus, eukaryotes do
• Bacteria are prokaryotes
• Extremely successful, widespread and necessary
Prokaryotic structure
• The membrane is surrounded by cell wall and sometimes capsule
• DNA of bacterium is in a region called the nucleoid
• Ribosomes produce proteins
• Appendages include flagella, fimbriae, and conjugation pilli
Bacteria
• Fun fact: bacteria can smell!
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