Biology Chapter: DNA Replication and Enzymes

DNA Replication

• DNA replication is the process by which DNA makes a copy of itself.
• It's semi-conservative, meaning each new DNA molecule consists of one original strand and one new strand.
• Enzymes play a crucial role in this process, including DNA polymerase, which adds nucleotides to the growing DNA chain.
• Helicase unwinds the DNA double helix, separating the two strands.
• Replication forks are Y-shaped structures that form as DNA unwinds.
• Leading strand is synthesized continuously, lagging strand is synthesized discontinuously in short segments (Okazaki fragments).
• Ligase joins Okazaki fragments.

Enzyme Activity

• Enzymes are biological catalysts that speed up chemical reactions in living organisms.
• They are highly specific, meaning each enzyme catalyzes only one type of reaction.
• Enzyme activity is influenced by factors such as temperature, pH, and substrate concentration.
• Enzymes work by lowering the activation energy required for a reaction to occur.
• Active site is the region on the enzyme where the substrate binds.
• Denaturation is the loss of an enzyme's 3D structure, rendering it inactive.
• Enzyme-substrate complex is formed when the enzyme binds to the substrate.

Stages of Mitosis

• Mitosis is a type of cell division that results in two identical daughter cells.
• It's crucial for growth, repair, and asexual reproduction.
• The stages of mitosis are:
  • Prophase: Chromosomes condense, nuclear envelope breaks down, spindle fibers form.
  • Metaphase: Chromosomes align at the metaphase plate.
  • Anaphase: Sister chromatids separate and move to opposite poles.
  • Telophase: Chromosomes decondense, nuclear envelope reforms, spindle fibers disassemble.
  • Cytokinesis: The cytoplasm divides, resulting in two separate daughter cells.

Stages of Meiosis

• Meiosis is a type of cell division that produces four genetically unique daughter cells.
• It's essential for sexual reproduction, producing gametes (sperm and eggs).
• Meiosis involves two rounds of cell division: meiosis I and meiosis II.
• Meiosis I:
  • Prophase I: Homologous chromosomes pair up and exchange genetic material (crossing over).
  • Metaphase I: Homologous chromosome pairs align at the metaphase plate.
  • Anaphase I: Homologous chromosomes separate and move to opposite poles.
  • Telophase I: Chromosomes arrive at the poles, and the cell divides.
• Meiosis II: Similar to mitosis, but with haploid cells.

Facilitated Diffusion

• Facilitated diffusion is a passive transport mechanism that moves molecules across a cell membrane with the help of membrane proteins.
• It does not require energy input.
• It occurs down the concentration gradient: from a region of higher concentration to a region of lower concentration.
• Channel proteins provide a hydrophilic pathway for specific ions or molecules to cross the membrane.
• Carrier proteins bind to molecules, undergo a conformational change to transport the molecule across the membrane, and release it on the other side.
• Examples include glucose transport and ion channels.

This quiz explores critical concepts of DNA replication and enzyme activity. You'll learn about the mechanisms of DNA copying, the role of enzymes as biological catalysts, and how various factors impact enzyme function. Test your understanding of these fundamental biological processes.