Metabolism • Chemical reactions of life • forming bonds between molecules • dehydration synthesis • synthesis • anabolic reactions • breaking bonds between molecules • hydrolysis • digestion • catabolic reactions That’s why they’re calledanabolic steroids!
enzyme enzyme Examples • dehydration synthesis (synthesis) • hydrolysis (digestion)
Enzymes work by decreasing the potential energy difference between reactant and product
Catalysts • So what’s a cell got to do to reduce activation energy? • get help! … chemical help… ENZYMES Call in the ENZYMES! G
As a result of its involvement in a reaction, an enzyme permanently alters its shape.
Enzymes vocabulary substrate • reactant which binds to enzyme • enzyme-substrate complex: temporary association product • end result of reaction active site • enzyme’s catalytic site; substrate fits into active site active site products substrate enzyme
Properties of enzymes • Reaction specific • each enzyme works with a specific substrate • chemical fit between active site & substrate • H bonds & ionic bonds • Not consumed in reaction • single enzyme molecule can catalyze thousands or more reactions per second • enzymes unaffected by the reaction • Affected by cellular conditions • any condition that affects protein structure • temperature, pH, salinity
If a patient in a hospital was accidentally given an IV full of pure water they would be fine because pure water is neutral so it can’t hurt us.
Managing water balance • Cell survival depends on balancing water uptake & loss freshwater balanced saltwater
Aquaporins 1991 | 2003 • Water moves rapidly into & out of cells • evidence that there were water channels • protein channels allowing flow of water across cell membrane Peter Agre John Hopkins Roderick MacKinnon Rockefeller
Do you understand Osmosis… .05 M .03 M Cell (compared to beaker) hypertonic or hypotonic Beaker (compared to cell) hypertonic or hypotonic Which way does the water flow? in or out of cell
Cellular respiration is only done by heterotrophs because autotrophs can make their own energy.
glucose H2O CO2 N K P … What does it mean to be a plant? ATP • Need to… • collect light energy • transform it into chemical energy • store light energy • in a stable form to be moved around the plant or stored • need to get building block atomsfrom the environment • C,H,O,N,P,K,S,Mg • produce all organic moleculesneeded for growth • carbohydrates, proteins, lipids, nucleic acids
The purpose of fermentation is to produce a small amount of energy when cells don’t have access to oxygen.
pyruvate ethanol + CO2 3C 2C 1C NADH NAD+ recycleNADH Alcohol Fermentation bacteria yeast back to glycolysis • Dead end process • at ~12% ethanol, kills yeast • can’t reverse the reaction Count thecarbons!
O2 pyruvate lactic acid NADH NAD+ 3C 3C recycleNADH animalssome fungi Lactic Acid Fermentation back to glycolysis • Reversible process • once O2 is available, lactate is converted back to pyruvate by the liver Count thecarbons!
Plants use water only as a means of keeping their cells full and holding the plant itself upright.
Chloroplasts transform light energy into chemical energy of ATP • use electron carrier NADPH ETC of Photosynthesis generates O2
The second step of photosynthesis is called the dark reactions because it only happens in the dark.
Light: absorption spectra • Photosynthesis gets energy by absorbing wavelengths of light • chlorophyll a • absorbs best in red & blue wavelengths & least in green • accessory pigments with different structures absorb light of different wavelengths • chlorophyll b, carotenoids, xanthophylls Why areplants green?
stroma ATP thylakoid From Light reactions to Calvin cycle • Calvin cycle • chloroplast stroma • Need products of light reactions to drive synthesis reactions • ATP • NADPH
Diagram how a gamete with 3 chromosomes could be produced with two maternal chromosomes and one paternal chromosome. (there isn’t anything wrong in this statement)
Proteins • Most structurally & functionally diverse group • Function: involved in almost everything • enzymes (pepsin, DNA polymerase) • structure (keratin, collagen) • carriers & transport (hemoglobin, aquaporin) • cell communication • signals(insulin & other hormones) • receptors • defense (antibodies) • movement (actin & myosin) • storage (bean seed proteins)
When the environment changes all species living in it will change to adapt to it.
Homologous structures • Similar structure • Similar development • Different functions • Evidence of close evolutionary relationship • recent common ancestor
Analogous structures • Separate evolution of structures • similar functions • similar external form • different internal structure & development • different origin • no evolutionary relationship Don’t be fooledby their looks! Solving a similar problem with a similar solution
Convergent evolution • Flight evolved in 3 separate animal groups • analogous structures Does this mean they have a recent common ancestor?
Convergent evolution • Fish: aquatic vertebrates • Dolphins: aquatic mammals • similar adaptations to life in the sea • not closely related Those fins & tails & sleek bodies areanalogous structures!
Bird and bat wings can only be described as homologous structures, not as analogous structures.
The strongest evidence supporting the endosymbiotic theory is that mitochondria and bacteria are the same size and have a similar shape.
Plant TISSUES • Dermal • epidermis (“skin” of plant) • single layer of tightly packed cells that covers & protects plant • Ground • bulk of plant tissue • photosynthetic mesophyll, storage • Vascular • transport system in shoots & roots • xylem & phloem
Basic plant anatomy 3 • root • root tip • root hairs • shoot (stem) • nodes • internodes • buds • terminal or apical buds • axillary buds • flower buds & flowers • leaves • mesophyll tissue • veins (vascular bundles)