chapter 8

• Zygote - a fertilized egg that divides by mitosis
• Each mature individual produces sex cells by another form of cell division called meiosis.
• At fertilization, the zygote inherits DNA from both gametes.
• Mitotic cell divisions allow an organism to grow and develop, repair tissues, and regenerate lost body parts.
• Apoptosis - programmed cell death, where the cell is destroyed by the cell itself
• genome - all of the cell's genetic material
• Helicases - enzymes that unwind DNA
• Single-strand binding proteins hold the strands apart.
• Primase - adds a short strand of RNA to each template strand, forming a primer
• DNA Polymerase - enzyme that makes new DNA strands, starting at the RNA primers
• The RNA primers provide 3-prime ends, where DNA polymerase adds the nucleotides.​
• On one strand, DNA polymerase follows helicase as it unzips the DNA. This is the leading strand.
• On the other strand, DNA polymerase adds nucleotides in the opposite direction from helicase movement. This is the lagging strand.​
• Ligases - form covalent bonds between DNA segements
• origins of replication - the region of the DNA molecule that is the starting point for replication
• binary fission - asexual process that replicates DNA and distributes it to two daughter cells, common in prokaryotes, such as bacteria, and some unicellular eukaryotes, such as amoebas
• Prokaryotes have a single circular chromosome.
• Eukaryotic cells divide by mitosis.
• nucleosomes - Naked DNA wraps histone proteins, forming bead-like structures
• Nucleosomes cluster together into chromatin.
• Interphase - the longest phase of the cell cycle, where the cell grows and copies its DNA
• G1 Phase - the cell grows and replicates organelles
• S Phase - DNA replication and synthesis occurs, creating two identical copies of each chromosome
• G2 Phase - cell prepares by synthesizing proteins needed for division
• G0 - only non active stage, a resting state, where most cells are
• mitosis - division of the nucleus
• cytokinesis - division of the cytoplasm into two daughter cells
• Prophase - chromosomes condense, nuclear membrane breaks down, spindle starts to form
• Prometaphase - nuclear envelope dissapears completely, spindle attatches to protein structure on centromere called kinetochores
• Metaphase - chromosomes align at the center of the cell
• Anaphase - sister chromatids are seperated, moved to opposite poles by spindle fibers, cleavage furrow begins to form
• Telophase - nuclear envelope reforms, chromosomes decondense, 2 nuclei form, cleavage furrow is visible
• Mitosis results in two identical daughter cells, maintains genetic stablity, is a highly regulated process, form of asexual reproduction, and is essential for growth, repair, and development.
• Cancer cells lose specialization, are immortal, bypass the cell cycle, and regenerate ends of their chromosomes.
• Cancerous cells divide out of control and form a mass called a tumor.
• Tumors are either benign (contained) or malignant (spreadable).​