Lesson Title: Cell Cycle
Key Focus: Understanding the steps and phases of the cell cycle, particularly mitosis.
IST-1.B: Describe the events that occur in the cell cycle.
IST-1.C: Explain how mitosis results in the transmission of chromosomes from one generation to the next.
Importance of distinguishing between describing (noting characteristics) and explaining (stating why/how).
G1 Phase: Cell growth, normal function.
S Phase: Synthesis phase where DNA is replicated.
G2 Phase: Final preparations for mitosis.
M Phase: Mitosis and cytokinesis, where cell division occurs.
Prophase: Chromosomes condense.
Metaphase: Chromosomes align at the cell's equator.
Anaphase: Sister chromatids are pulled apart.
Telophase: Nuclear membranes re-form around each set of separated chromosomes.
Essential for organisms to grow, replace damaged cells, and reproduce asexually.
G0 Phase: A quiescent state where most cells reside when they are not actively dividing.
DNA Packaging: Cells organize DNA by wrapping it around histones to form nucleosomes, creating chromatin.
Chromosome Formation: DNA condenses into chromosomes after replication.
Sister Chromatids: Result from DNA replication; held together at the centromere and linked to the mitotic spindle by kinetochores.
Nucleus: Where chromosomes and chromatids are located.
Chromatin: The less packed form of DNA when the cell is not dividing.
Definition: All the genetic information of a cell.
Types:
Prokaryotes: Singular, circular DNA.
Eukaryotes: Multiple linear chromosomes, each species has a specific chromosome number.
Example Counts: Humans (46), Chimps (48), Elephants (56).
Characteristics: Body cells, diploid (2n), divide by mitosis.
Example: Humans have 2n = 46 chromosomes (23 from each parent).
Characteristics: Reproductive cells, haploid (n), divide by meiosis.
Example: Humans have n = 23 chromosomes in gametes.
Interphase: Longest stage (90% of the cell cycle).
G1 Phase: Initial growth and function.
S Phase: DNA replication.
G2 Phase: Preparation for mitosis.
M Phase: Actual division of the cell into two identical daughter cells.
Overall Duration: Approximately 24 hours.
Interphase: Takes 23 hours; Mitosis takes about 1 hour.
Cells may enter a resting state (G0 phase) depending on conditions and needs.
Development: New cells needed for growth.
Repair: Replacing damaged somatic cells and for tissue repair.
Reproduction: Asexual organisms use cell division to propagate their DNA.
Recognizes the significance of interphase and how DNA is configured before undergoing mitosis.
Understanding parts of the cell life cycle: Identify which part is not interphase.
Recognizing phases where cells spend most of their time, particularly in non-dividing cells.