Biology Test 4: Photosynthesis Reactants and Products

Photosynthesis Overview

• Reactants: Sunlight, carbon dioxide, and water.
• Products: Glucose and oxygen.
• Reactants contributing to glucose: Carbon dioxide, water, and light energy.

Photosynthesis Chemical Processes

• Carbon dioxide is reduced during photosynthesis.
• Photosynthesis occurs in two stages:
  • Light-Dependent Reactions: Located in thylakoid membranes; utilize light energy to produce ATP and NADPH.
  • Calvin Cycle: Occurs in stroma; converts CO2 and water into organic molecules like glucose.

Light and Pigments

• Chlorophyll reflects/transmits green light, which is least effective for photosynthesis.
• End product of Calvin Cycle: G3P (glyceraldehyde-3-phosphate).
• Seasonal color changes in leaves occur due to chlorophyll degradation and the presence of carotenoids.

Photosystem Outputs

• Photosystem I produces NADPH.

Cellular Energy Dynamics

• Photosynthesis produces food using energy; cellular respiration breaks down food to release energy; they are interconnected via chemiosmosis.

DNA Structure and Function

• Eukaryotic chromosomes are made of DNA and histone proteins.
• Nucleotides are joined together by phosphodiester bonds; complementary bases are connected by hydrogen bonds.
• DNA structure: Double helix, with antiparallel strands.

Telomeres

• Protective structures at chromosome ends, preventing damage and fusion with other chromosomes.

DNA Replication

• DNA synthesis occurs in a 5' to 3' direction, adding nucleotides at the 3' end.
• Prokaryotic replication has one origin and occurs in cytoplasm, while eukaryotic replication has multiple origins and occurs within the nucleus.

Key Enzymes in DNA Replication

• Helicase: Separates parent strands.
• Single-strand binding proteins: Prevent secondary structures from forming.
• Topoisomerase: Prevents overwinding of the double helix.
• Primase: Assembles RNA primer on the template.
• DNA Polymerase (I and III): Adds nucleotides and fills gaps.
• DNA Ligase: Stabilizes two DNA strands post-separation.

Leading vs. Lagging Strand Synthesis

• Leading strand: Synthesized continuously.
• Lagging strand: Synthesized in segments due to discontinuity.

Cell Cycle and Mitosis

• Interphase: DNA is copied.
• Prophase: Chromatin condenses, centrosomes move, nucleoli break down.
• Prometaphase: Nuclear membrane disintegrates.
• Metaphase: Chromosomes align at the center; microtubules attach to kinetochores.
• Anaphase: Sister chromatids move apart toward opposite ends.
• Telophase: Nuclear membranes reform around chromosomes, cell begins to split.

Cytokinesis

• Divides the cell post-mitosis; failure to undergo cytokinesis leads to multinucleated cells.
• Animal cells use cleavage furrows, while plant cells form cell plates which develop into cell walls.

Cell Cycle Checkpoints

• Key checkpoints: G1, S phase, G2, and M phase.
• M phase checkpoint ensures proper attachment of chromosomes to spindle fibers.
• Loss of checkpoint regulation can lead to cancerous cell growth.

This quiz focuses on the essential reactants and products of photosynthesis, a key biological process. Players will understand what contributes to this vital function in plants, including the role of sunlight, carbon dioxide, and water. Test your knowledge on these important concepts related to plant biology.