Intro to Cellular Processes and Enzymes

Heterotrophs (Consumers) Organisms that cannot make their own food They must eat and break down food in order to get energy Can be: 1. Carnivores- eat mostly meat 2. Omnivores- eat meat and plants 3. Herbivores- eat mostly plants

Autotrophs (Producers) Organisms that can make their own food They must take in energy from the sun and take in CO2 molecules (from the atmosphere) Combine to make sugars

Heterotrophs and Autotrophs are connected through Food Webs Autotrophs make the molecules needed for heterotrophs

Harvesting stored energy Energy is stored in macromolecules carbohydrates, fats, proteins Heterotrophs eat these organic molecules  food digest organic molecules to get… raw materials fuels for energy “burning” fuels in a series of step-by-step reactions We eat to take in the fuels to make ATP which will then be used to help us build biomolecules and grow and move and… live! heterotrophs = “fed by others” vs. autotrophs = “self-feeders”

Step-by-step reactions Reactions in cells that are controlled by enzymes Lots of small steps in order to have more control Enzyme A Enzyme B Enzyme C Step 1 Step 2 Step 3 Step 4

What Are Enzymes? Most enzymes are Proteins Act as Catalyst to accelerate a reaction Not permanently changed in the process

Enzymes Are specific for what they will catalyze Are Reusable Names end in –ase -Sucrase -Lactase -Maltase

How do enzymes Work? Enzymes work by weakening bonds which lowers activation energy Activation energy= energy required to start a reaction

Enzymes Without Enzyme With Enzyme Free Energy Progress of the reaction Reactants Products Free energy of activation

Enzyme-Substrate Complex The substance (reactant) an enzyme acts on is the substrate Enzyme Joins Substrate

Active Site A specific region of an enzyme molecule which binds to the substrate. Active Site Enzyme Substrate

“Lock and Key” Model The substrate fits into the active site like a key fits into a lock Only one type of substrate molecule can fit into the active site

Results of Chemical Reactions: A product that the cell needs is made

What Affects Enzyme Activity? Three factors: 1. Environmental Conditions 2. Concentration of Enzymes 3. Enzyme Inhibitors

1. Environmental Conditions 1. Extreme Temperatures are the most dangerous - high temps may unfold the enzyme = won’t work pH (most like near neutral)

2. Concentration of Enzyme The more enzymes are present, the faster the reaction can occur Rate of reaction will eventually level out once all substrate has been used up!

3. Two examples of Enzyme Inhibitors a. Competitive inhibitors: are chemicals that resemble an enzyme’s normal substrate and compete with it for the active site. Enzyme Substrate Competitive inhibitor

Inhibitors b. Noncompetitive inhibitors: Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site. Enzyme Noncompetitive Inhibitor Substrate active site altered