12IP Cell Cycle Cancer

Learn: Cell Cycle, Mitosis, and Cancer

Lecture Goals:

• To examine the steps of the cell cycle
• Understand the process that cells divide and how that relates to growth
• Examine the impacts of when this cycle is no longer able to regulate, resulting in cancer growth

Course Competencies: 16. Compare and contrast the biological processes of binary fission, mitosis and meiosis.(IX) 17. Describe the process of DNA replication and its relationship to cell division. (VII, IX)

Day 1

Day 2

Presentation Links

Cell CycleOverview

Interphase

Mitosis

Cancer: When Cell Cycle Breaks

Cell Cycle

Cell Replication and Division

• Cell Cycle is the process of cells growing, performing required metabolic functions, and replicating.
• It has two major phases, each of which have subphases.

Cell Cycle

Cell Replication and Division

• Mitotic Phase
• Cell is activily dividing
• Composed of the subphases mitosis and cytokinesis
• Interphase
• Cell is growing and performing its function
• Composed of growth and DNA synthesis phases

Check your notes

01:00

Define Cell Cycle

Interphase

Cell Function, Growth, DNA Synthesis

• G1: First Gap Phase
• Little change is visible
• Accumulating the material for DNA replication
• S: Synthesis of DNA
• DNA remains in a semi-condensed chromatin form
• S phase creates identical pairs of DNA molecules, called sister chromatids, that are firmly attached at the centromere
• G2: Second Gap Phase

Recall: Nucleic Acids

Homologous Chromosomes VS Sister Chromatids

Interphase

Cell Function, Growth, DNA Synthesis

• G2: Second Gap Phase
• Cell replenishes its energy stores
• Grows larger to prepare to become two cells
• Synthesizes proteins/organelles necessary for chromosome movement (e.g., centrosomes)
• Organelles are duplicated
• Just before mitosis the cytoskeleton is dismantled

Check your notes

• Explain the difference between homologous chromosomes and sister chromotids
• Provide an overview of the three stages of interphase

03:00

Mitosis (also known as Karyokinesis)

• The steps that a eukaryotic cell takes to divide into two identical cells, called daughter cells.
• Phases
• prophase
• prometaphase
• metaphase
• anaphase
• telophase
• Concludes with cytokinesis (the actual splitting of the two cells)

Mitosis (also known as Karyokinesis)

Prophase

• nuclear envelope "disappears" by become small vesicles
• membranous organelles fragment and are moved to edge of cell
• centrosomes begin moving to opposite ends of cell
• microtubules that form the mitotic spindle extend between the centrosomes
• sister chromatids begin to coil more tightly with the aid of condensin proteins (visible under a light microscope).

Mitosis (also known as Karyokinesis)

Prometaphase

• mitotic spindle continues to develop
• chromosomes become even more condensed
• Each sister chromatid develops a protein structure called a kinetochore
• some of the microtubules bind to the kinetochores
• spindle microtubules that do not engage the chromosomes are called polar microtubules. These are used to elongate the cell.

Mitosis (also known as Karyokinesis)

Metaphase

• the spindle causes the sister chromatids to line up at the metaphase plate (middle of the cell)

Mitosis (also known as Karyokinesis)

Anaphase

• The sister chromatids now seperate, forming daughter chromosomes
• The daughter chromosomes are pulled to opposite sides of the cell by the spindle

Mitosis (also known as Karyokinesis)

Telophase

• chromosomes begin to decondense (unravel) into the looser chromatin configuration
• mitotic spindles are depolymerized into tubulin monomers
• used to assemble the cytoskeleton in each daughter cell.
• nuclear envelopes form around the chromosomes and nucleoli appear within the nuclear area.

Cell Division

• During cytokinesis, the cell pinches inward, separating the cell into two daughter cells
• Plant mitosis works slightly differently
• Cell plate forms between the two cells during cytokinesis
• No centromeres involved; spindles attach elsewhere
• Prokaryotes reproduce and divide by binary fission rather than mitosis (less DNA and organelles to split up; no spindles needed)

Mitosis and Cytokinesis

A story to help remember steps (This is NOT a true story)

• prophase
• prometaphase
• metaphase
• anaphase
• telophase

Mitosis and Cytokinesis

Visual of the process

Check your notes

• What the stages of mitosis and cytokinesis are
• Major events that happen at each stage

03:00

Cancer

Unregulated Cell Growth