Unit 3 Biology: Concept 1 and 2

What is metabolism?

all of the chemical reactions within each cell of an organism

What does metabolism do?

provide energy for life’s processes and creates key molecules

What are chemical reactions?

the breaking and forming of bonds between different substances during chemical changes

What do reactions do with energy?

they either absorb it or release it

What does breaking a bond require?

energy to be absorbed

What does forming a bond require?

energy to be released

Is energy lost in a system?

no due to the law of conservation of energy, it just changes forms (may be released as heat, light, etc)

What is catabolic?

the breaking down of larger molecules into simpler compounds causing a release in energy

What can catabolic reactions be classified as because they release energy?

exergonic

What is anabolic?

the building of larger molecules from smaller ones, requiring the consumption of energy

What can anabolic reactions be classified as because they consume energy?

endergonic

What do all reactions need to happen?

energy

What is activation energy?

the amount of energy needed to make a chemical reaction start

What are reactants/substrates?

substances that are changed during a chemical reaction

What are products?

substances that are made by a chemical reaction

What are the two types of reactions?

endothermic and exothermic

What is an endothermic reaction?

absorbs energy in the form of heat or light (example: photosynthesis)

What is an exothermic reaction?

releases energy in the form of heat or light (example: cellular respiration)

What is the equation for photosynthesis?

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Why is photosynthesis an endothermic reaction?

light energy is stored as chemical energy in sugar

What is the equation for cellular respiration?

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Why is cellular respiration an exothermic reaction?

chemical energy in sugar is converted to chemical energy released as ATP

What controls metabolic reactions?

enzymes

What are enzymes?

mostly proteins that speed up biochemical reactions by lowering activation energy

What are enzymes called?

catalysts because they speed up reactions

What are catalysts?

substances that speed up reactions without being permanently altered

How do enzymes work?

they are very specialized molecules that bind to reactants (aka substrates) and help to break or form bonds releasing a newly created product

Are enzymes used up in reactions?

no, they aren’t changed and can be used over and over again

What are enzymes critical for?

the regulation of life’s processes in all organisms

What is the structure of an enzyme?

they have an active site (the part of the enzyme where the substrate binds) that fits only one substrate

After the substrate connects to an enzyme what occurs?

the bind tights producing an induced fit

What can enzymes do to produce two products?

break bonds in a substrate

What is denaturation?

an enzyme’s active site gets deformed and loses its specific shape resulting in a loss of biological activity

What are some causes of denaturation?

changes in environment like extreme changes in pH, temperature, ion strength, and solubility

Can some enzymes be “renatured?”

yes, they can return to their original shape, but not always

What are 5 ways to change the rate of a chemical reaction?

1. temperature

2. pH

3. substrate concentration

4. catalysts

5. competitive inhibitors

How does temperature change the rate of a chemical reaction?

increasing temperature increases the rate of reaction as molecules are moving faster and colliding more with each other; if the temperature gets outside a certain range, it can cause an enzyme to denaturate

How does pH change the rate of a chemical reaction?

most enzymes only work at very specific pH so if the pH changes it can affect the speed of reaction (outside of a certain pH range, enzymes denature)

How does substrate concentration change the rate of a chemical reaction?

the higher the amount of substrate, the faster the reaction due to more particle collisions

How do catalysts change the rate of a chemical reaction?

like enzymes speed up reactions by lowering activation energy for the reaction to start; there are co-enzymes that also help speed up reactions

How do competitive inhibitors change the rate of a chemical reaction?

they slow down reactions by competing with substrates for the active site on the enzyme

What does ATP stand for?

adenosine triphosphate

What does our body need to run our cells?

energy

Do our bodies directly use food for energy?

no, you can only use the energy in the food you eat stored in its chemical bonds

How do our bodies convert energy into a form it can directly use?

it breaks bonds and forms new ones

What happens once energy is converted into a more usable form?

ATP carries it to be used for cell functions

What is ATP?

an energy carrying molecule that carries/stores energy for cell functions; it is the main energy currency for the cell

What is the structure of ATP?

a nitrogen base (adenine), sugar ring (ribose), and 3 phosphate groups held together with high energy bonds, and it isn’t a stable molecule meaning it is easy to break the bond between the 2nd and 3rd phosphate

What does ADP stand for?

adenosine diphosphate

When is energy released during the ATP-ADP cycle?

when a phosphate group is removed (and added to another molecule)

When does ADP become ATP?

when a phosphate group is added

Where is the most energy stored in ATP?

in the bond between the last two phosphates

What is recycled in the ATP-ADP cycle?

ADP

What kind of process is the ATP-ADP cycle?

chemiosmotic

What is chemiosmosis?

the movement of ions down a concentration gradient

What is used to add the third phosphate to ADP to make ATP using energy from the food we eat?

ATP synthase

When ATP is broken down is energy for the cell to use (and becomes ADP and a phosphate) released or taken in?

released

Is the breaking down of ATP endothermic or exothermic?

exothermic (because more energy is given off than required)

What do cells need to do to make ATP?

they must join together ADP and a phosphate using energy from food

Is the formation of ATP exothermic or endothermic?

endothermic (because energy is taken in)

What is the most common carbon based molecule broken down for ATP?

carbohydrates (can get around 36 ATP from 1 glucose molecule and stores around 4 cal/g of energy)

What is broken down after carbs for energy?

lipids/fats (store 9 cal/g of energy)

What is least likely to be broken down for energy?

proteins (store 4 cal/g of energy)