University of Phoenix Material
Comparing Cell Cycles
Complete the Cell Cycle charts below. Describe the events in each phase for Cell Cycle A. Compare the steps in mitosis and meiosis for Cell Cycle B.
Cell Cycle A
Phase
Describe the events in each phase
G1 (1st growth stage)
Synthesis of ribosomes, organelles, and other proteins
S (Synthesis)
Synthesis of complete DNA copy in nucleus
Duplication of centrosome
G2 (2nd growth stage)
Rapid cell growth characterized by synthesis of proteins, organelles
Checkpoints:
Kinase-dependent entry into M-phase
DNA-repair mechanisms that halt entry into M phase
Prophase of mitosis
Chromosomes begin to condense
Mitotic spindle forms
Nucleolus disappears, signaling division-competent cells
Nuclear envelope breaks down
Mitotic spindle grows
Metaphase of mitosis
Spindle captures all chromosomes
Chromosomes lined up in cell by mitotic spindle at metaphase plate
Checkpoint:
Are all chromosomes lined up on metaphase plate?
Anaphase of mitosis
Microtubules pull cells apart; specifically, kinetochore microtubules (those connected to a chromosome) pull towards the metaphase poles, while non-kinetochores (microtubules not connected to a chromosome) push poles away
Telophase and ckytokinesis
Cell is “pinched” by the separation of the chromosomes along the metaphase poles, which enables cell to separate
Mitotic spindle is broken down
New nuclei form
Chromosomes lose “condensed” nature and elongate
Cell is cleaved by actin into two different cells
Interphase
Period of normal cell growth and activity
Cells that are either not ready or not needed for replicative purposes spend time in this state
Cell Cycle B
Mitosis
Meiosis
1: Prophase. Nuclear membrane dissolves, chromatin coils chromosomes into compact structures, centrosomes move away from nucleus
1:
Prophase 1. Nuclear membrane dissolves, chromosomes are condensed, centrosomes push apart, homologous chromosomes pair up to...