exam 3; chapter 5-7. bio156

What are chemical reactions? What are their starting and ending materials called?

• Rearrange atoms

• Start = reactants

• End = products

What are (bio)chemical pathways? What are the sum of all reactions in an organism called?

• Series of reactions = pathway

• All reactions = metabolism

Which reactions release energy? take-in energy? What is reaction spontaneity? What is the relationship between the energy states of the products and reactants in each of these reactions?

• Exergonic = releases energy

• Endergonic = needs energy

• Spontaneous = happens on its own

• Exergonic: products = lower energy

• Endergonic: products = higher energy

What is entropy? What is enthalpy?

• Entropy = disorder

• Enthalpy = heat energy

What are catalysts? What do they do, energetically?

• Speed up reactions

• Lower activation energy

What are enzymes? What are the molecules they bind called? Where do they bind? What is enzyme specificity? How are they ‘optimized’? How are they rendered inoperative? Why? What is allosteric regulation? Activators? Repressors? What kinds of inhibition are there?

• Protein catalysts

• Substrate = what binds

• Active site = binding spot

• Specificity = fits only certain molecules

• Work best at right temp & pH

• Denature = lose shape → stop working

Regulation:

• Allosteric = binds somewhere else

• Activator = speeds up

• Inhibitor = slows down

What is ATP? What structural features does it have? Where is its energy ‘stored’?

• Cell energy molecule

• Energy in phosphate bonds

What is light composed of? What is meant by light’s wavelength? What is the wavelength of visible light? UV light? Infrared? How are wavelength and energy related?

• Energy waves

• Shorter wavelength = more energy

• Visible: 400–700 nm

• UV = shorter

• Infrared = longer

What happens when a molecule absorbs light? What wavelengths does chlorophyll and carotenoids absorb?

• Light excites electrons

• Chlorophyll: blue/red

• Carotenoids: blue/green

How do humans see different wavelengths? How is the human interpretation of color related to

• See reflected light

• Color = what’s reflected

• Not everyone sees same

Light reactions of photosynthesis? Where does this take place? How is light captured? How are antennae chlorophyll molecules different than reaction center/special pair chlorophyll? What are the products of the electron transport chain? What are the major protein complexes? In what order does an electron move through the chain? How is a H+ gradient established? What is the role of water?

• Location: thylakoid

• Use light → excite electrons

Order:

• PSII → ETC → PSI

Products:

• ATP, NADPH, O₂

• Water → gives electrons

What is ATP synthase? How does it create ATP? Where do you find it?

• Makes ATP using H⁺ gradient

What is the Calvin cycle? What is the major enzyme involved? What is an unfortunate feature of this enzyme? How do various organisms compensate for this? What inorganic molecule is ‘fixed’ in the Calvin cycle? What energy molecules are used in this process? What carbon molecule is the product?

• Location: stroma

• Uses CO₂

• Enzyme: Rubisco (can mess up → photorespiration)

• Uses ATP & NADPH

• Makes G3P (sugar)

What are redox reactions? What are the oxidized and reduced forms of cellular electron carrier molecules (e.g. NAD+/NADH)?

• Oxidation = lose e⁻

• Reduction = gain e⁻

• NAD⁺ → NADH

Where do glycolysis, pyruvate oxidation, Krebs cycle, and the electron transport chain occur?

• Glycolysis: cytoplasm

• Krebs: mitochondria

• ETC: inner membrane

Glycolysis: What are the names and carbon counts of the reactants and products? Which high energy molecules are produced? Why are only two net ATP produced?

• Glucose → 2 pyruvate

• Makes:

  • 2 ATP (net)

  • 2 NADH

The presence/absence of what molecule determines the fate of pyruvate in the cell? What happens to pyruvate in each instance?

• With O₂ → respiration

• No O₂ → fermentation

What are the product/reactants of Acetyl-CoA synthesis?

• Pyruvate → Acetyl-CoA + CO₂ + NADH

What are the products/reactants of the Kreb’s cycle?

• Makes:

  • 2 ATP

  • 6 NADH

  • 2 FADH₂

  • CO₂

What is the total resulting number of high energy molecules from the oxidation of 1 glucose molecule?

• ~30–32 ATP

What is the electron transport chain? Reactants? Products? What complexes are in the chain? What is their ‘purpose’; what do they do with an electron’s energy? Where do the electrons ultimately end up?

• Uses electrons → pump H⁺

• Makes lots of ATP

• Final acceptor = O₂ → water

---

What are the products/reactants of ethanol fermentation? Lactic acid fermentation?

• Ethanol: ethanol + CO₂

• Lactic: lactate

• Purpose: make NAD⁺

10. How are proteins broken down to enter metabolism? Lipids and fats?

• Proteins → amino acids

• Fats → glycerol + fatty acids