life’s molecules. carbohydrates monosaccharide (glucose) carbohydrates
Post on 15-Jan-2016
237 views
TRANSCRIPT
Life’s Molecules
Carbohydrates
Monosaccharide (Glucose)
Carbohydrates
Polysaccharide (glycogen)
Carbohydrates
Polysaccharides (amylose and cellulose)
Carbohydrates
Lipids
glycerol Three fatty acid tails
Triglyceride
Lipids
Triglycerides are the most common fats in food.
Lipids
Saturated and unsaturated fatty acids
Stearic acid: saturated
Oleic acid: unsaturated
Linoleic acid: polyunsaturated
Lipids
Phospholipid
Lipids
Phospholipids arrange themselves as a bilayer in water. The hydrophilic heads face out, the hydrophobic
tails face inward.
Lipids
Lipids are hydrophobic. Plant leaves are coated withwaxes to keep water inside the plant.
Lipids
One of 20 amino acids (valine). Amino acids vary bythe “R” group they contain.
R group
Carboxyl groupAmino group
Proteins
Amino acids are linked by peptide bondsto form polypeptides
Proteins
A bit of the primary structure (amino acid sequence)of globin.
Proteins
A globin molecule. The arrangement of amino acids in this molecule encourages formation of hydrogen bonds. These bonds cause the molecule to coil helically, giving
rise to its secondary structure (the purple portion).
Protein, Secondary structure
Interactions between R groups at various areas along the spiral cause it to fold and bend. This gives the molecule its tertiary structure (the green portion).
Protein, Tertiary structure
Hemoglobin is an example of the fourth level of protein structure (quaternary structure). In all proteins at this level of organization, two or more polypeptide
chains are joined together. Hemoglobin has four polypeptide chains.
Protein, Quaternary structure
To summarize the four levels of protein structure:
1. Primary structure is the sequence of amino acids in a polypeptide chain.
2. Secondary structure is the coiled or extended shape that the chain assumes owing to hydrogen bonds at short intervals along the chain.
3. Tertiary structure refers to further folding of a coiled chain owing to bend-producing amino acids and interactions among R groups far apart on the chain.
4. Quaternary structure is the linkage of two or more polypeptide chains by hydrogen bonds and other interactions.
Proteins
Nucleic Acids
Nucleotide
Nucleic Acids
DNA: nucleotides bonded by hydrogen bonds
Nucleic Acids
ATP (adenosine triphosphate), the energycurrency of every cell
Nitrogen-containing base
5 carbon sugar
3 phosphate groups
Nucleic Acids
ADP (adenosine diphosphate). When ATP releases itsstored energy, it is converted to ADP + Pi
Nucleic Acids
Enzymes and Reactions
• An enzyme is a protein that accelerates a chemical reaction.
• They may combine, separate or rearrange molecules.• The enzyme and its substrate have a key and lock type
of relationship, one enzyme usually only works with one or two molecules.
Terminology
• - ase• Substrate• Active site• Coenzyme• Metabolic pathway• Metabolism• Activation Energy• Endergonic• Exergonic
Regulation of Enzyme Activity
1. The amount of substrate present regulates the reaction
2. The active site of the enzyme can be blocked by a molecule similar to the substrate. This is called Competitive Inhibition.
3. Allosteric Regulation, the regulation of enzyme activity by means of a molecule binding to a site other than the active site.
- Can decrease or increase enzyme activity.
Lowering the Activation Energy of a Reaction
Lowering the Activation Energy of a Reaction
Electron Carriers transport electrons from one molecule to another.
The
ATP / ADP cycle
Oxidation – Reduction Reactions
OIL RIG
Respiration: Deriving energy from food
C6H12O6 + 6O2 + 36 ADP + 36 Pi -------->
6CO2 + 6H20 + 36ATP
Aerobic respiration
Glucose: the starting point for cellular respiration
Three stages of aerobic respiration
Where does it happen?
Step 1
Glycolysis
Step 1.5
Conversionof Pyruvic
acid to
Acetyl CoA
Step 2
Kreb’s Cycle
Step 3
Electron Transport Cycle
How other foods fit into Cellular respiration
Anaerobic Respiration or Fermentation
• Far less efficient than Cellular Respiration with only
2 ATP generated per Glucose.
• By products are varied : alcohol, lactic acid, acetic acid
Anaerobic respiration or alcoholic fermentation
Anaerobic respiration or lactic acid fermentation
6H2O + 6CO2 ------------> 6O2 + C6H12O6
PhotosynthesisThe process by which certain groups of organisms capture energy from
sunlight and convert this solar energy into chemical energy that is initially stored as a carbohydrate.
sunlight
Two steps in photosynthesis
Photosynthetic terminology
• Leaf, petiole, blade• Epidermis, mesophyll cells, stomata• Chloroplast, vacuole, cell wall• Thylakoids, stroma, granum, inner/outer membrane• Thylakoid membrane, thylakoid compartment• Chlorophyll a, accessory pigments
Light wavelengths absorbed by chlorophylls
Plants reflect green light and absorbs the red and blue light.
Photosystem
• An organized complex of molecules within a thylakoid membrane, that collects solar energy and transforms it into chemical energy.
• Pigment molecules and accessory pigments serve as ‘antennae’ and absorb energy from the sun and pass it onto the reaction center ( a couple of chlorophyll a molecules).– Electrons are moved in two ways
• Physically transferred to the electron acceptor• Metaphorically up the energy hill
The chlorophyll molecules lose electrons to the primary electron acceptor.
This is a redox reaction
• This is the photo of photosynthesis• Photosystem II collects solar energy, its electron moves
to another part of the reaction center, the primary electron acceptor.
• This leaves an energy ‘hole’ which is filled by splitting water into 2 H+ and ½ O2. (Oh, that’s where Oxygen comes from!)
When the energized electrons fall they release energy that is captured as they are transferred through a series of electron transport molecules.
• They then arrive at Photosystem I where they are again boosted by light energy. Again the electrons pass along an electron transport chain and at the end are received by NADP+ where they proceed to the dark reactions.
The light reactions.
Physical movement of electrons
• Started out in the water of the thylakoid compartment.
• Moved into and through the thylakoid membrane• End in stroma, attached to NADPH
• ATP that is produced in the light reactions is used in the dark reactions to produce food.
The Dark Side
• Also called the Calvin Cycle or C3 Cycle.
• This is the synthesis of photosynthesis.
• A process by which CO2 is taken from the atmosphere and joined to a sugar (energized) and stored as a carbohydrate.
• NADPH and ATP are located in the stroma where there Calvin Cycle takes place.
• Fixation, the process where a gas is incorporated into an organic molecule.
• The starting point is RuBP or ribulose biphosphate a type of sugar.– Bring together CO2 and RuBP by enzyme rubisco
– Energize the sugar– Exit of the product– Regeneration of RuBP– Start over
The Calvin CycleThe dark reactions
Summary
• Solar energy is converted to chemical energy in the thylakoids and stored as ATP, NADPH
• Water is required• Oxygen is a byproduct• Stored chemical energy is used in the Calvin
Cycle (in the stroma) to produce a high-energy sugar from CO2 (from the atmosphere, in thru the stromata) and RuBP.
• Dinner is served!
A summary of photosynthesis