Genbio 1 2nd q

• Life processes rely on redox reactions, which involve oxidation and reduction.
• Oxidation involves a loss of electrons, and reduction involves a gain of electrons.
• Oxidation and reduction always occur together; one substance is oxidized while another is reduced.
• Oxidized substances donate electrons (reducing agents), and reduced substances accept electrons (oxidizing agents).
• Electrons carry energy in redox reactions.
• Electron Transport Chains (ETCs), found in membranes, consist of proteins specialized for electron transport.
• Each protein in an ETC is reduced as it accepts an electron and oxidized as it passes the electron to the next in the chain.
• Energy released during electron transfer is used by the cell to drive other chemical reactions.
• ATP is composed of adenine, ribose, and three phosphate groups.
• The alpha phosphate in ATP is directly attached to ribose, and high-energy phosphoanhydride bonds connect beta and gamma phosphates.
• ATP is unstable due to repulsion between negatively charged phosphate groups.
• Cells hydrolyze ATP to release energy for various activities.
• The general equation for photosynthesis is: 6CO2 + 12H2O → C6H12O6 + 6O2 + 6H2O.
• Visible light is essential for photosynthesis, absorbed by pigments like chlorophylls and carotenoids.
• Chlorophyll a actively uses light energy, while chlorophyll b and carotenoids are accessory pigments.
• Photosynthesis in eukaryotic cells occurs in chloroplasts with thylakoids forming stacks called grana.
• Photosystems, clusters of proteins and pigments in thylakoid membranes, play a crucial role in photosynthesis.
• ATP (adenosine triphosphate) consists of adenine, ribose, and three phosphate groups (alpha, beta, and gamma).
• The high-energy phosphoanhydride bonds between phosphate groups make ATP unstable and a rich source of energy.
• Hydrolysis of ATP releases energy: ATP + H2O → ADP + PO43 + Energy.
• Cells use ATP hydrolysis for various energy-requiring activities like growth, division, and active transport.
• ADP can store energy through phosphorylation: ADP + PO4-3 + Energy → ATP + H2O.
• ATP-ADP cycle illustrates how cells utilize ATP for energy and regenerate it from ADP.
• Living systems have coupled reactions where energy-releasing (exergonic) reactions support energy-requiring (endergonic) reactions.
• ATP hydrolysis, releasing energy, is often coupled with reactions requiring energy input.
• Coupling involves using energy released from ATP hydrolysis for phosphorylation or altering a molecule's shape.
• Phosphorylation energizes molecules and facilitates chemical reactions.
• Photosynthesis transforms light energy into chemical energy (glucose) in autotrophs (plants, algae, bacteria).
• General equation: 6CO2 + 12H2O → C6H12O6 + 6O2 + 6H2O.
• Light is absorbed by pigments (chlorophyll a, chlorophyll b, carotenoids) to initiate photosynthesis.
• Photosynthesis occurs in chloroplasts, with thylakoids forming grana where light-dependent reactions take place.
• Light reactions involve photosystem I and II, leading to ATP and NADPH production.
• The Calvin Cycle, occurring in the stroma, involves carbon fixation, PGAL synthesis, and RuBP regeneration.
• The Calvin Cycle uses CO2 to produce PGAL, eventually forming glucose or other important molecules.
• Living organisms convert the chemical energy of food molecules like glucose into ATP through cellular respiration.
• Cellular respiration involves breaking down glucose to release energy, which is stored in ATP.
• There are two types of cellular respiration: aerobic (oxygen-dependent) and anaerobic (oxygen-independent).
• Glycolysis is a universal metabolic pathway occurring in the cytosol.
• In glycolysis, a glucose molecule is broken down into two pyruvic acid molecules.
• During the Energy Investment Stage of glycolysis, phosphate groups from ATP are added to glucose, forming glucose-6-phosphate and fructose-6-phosphate.