The Cell Cycle Brought to you by:

Today’s Lesson Is brought to you by the letter C And the numbers 23 and 46

Important Vocabulary Chromatin: Long, tangled strands of DNA found in the cell nucleus during Interphase Chromosomes: Structures that carry the genetic material that is copied and passed from generation to generation of cells. Humans have 23 pairs of chromosomes; 46 total chromosomes Chromatids: Chromosomes duplicate during S phase and are attached by a centromere. The two copies are called chromatids.

Chromatids & Centromere

Vocab. Continued... Centromere: Cell structure that joins the two chromatids. Homologous Chromosomes: Paired chromosomes with genes for the same traits, structure and function. Humans have 23 Homologous Chromosomes. Parent Cell: Original cell in interphase, before division occurs. Daughter Cell: Cells produced from parent cell at the end of the cell cycle.

Cell Cycle Made up of 3 Phases –Interphase –Mitosis –Cytokenesis

Interphase Cell spends 90% of its lifetime in interphase G1 phase: cell grows S phase: DNA (chromosomes) replicate G2 phase: cell prepares to divide

Mitosis Occurs AFTER interphase is finished Consists of 4 phases: –Prophase –Metaphase –Anaphase –Telophase

Prophase Early – chromatin coil up and become chromosomes. Each crhomosomes is made up of 2 identical parts called chromatids joined by a centromere Mid – nuclear envelope begins to disappear Late – nuclear envelope gone and centrioles move towards poles as spindles form.

Metaphase Early – centrioles at poles and spindle fibers attach to centromeres of chromosomes Mid – chromosomes in the process of lining up along the equator of the cell Late – chromosomes lined up along equator of cell.

Anaphase Early – Centromeres split apart as spindles bring chromatid pairs towards opposite poles Mid – chromatids moving closer to opposite poles Late – chromatids at opposite poles

Telophase Early – Nuclear envelope begins to form Late – 2 distinct daughter cells are formed

Can you guess what my favorite phase is? Telly – phase!

Cytokenesis Cytoplasm divides IN PLANTS: cell plate forms between cells, cell membrane forms around each side of cell plate, and cell wall forms around membrane IN ANIMALS: cell membrane pinches off between old and new cell, creating 2 separate cells

Let’s count how many daughter cells come from 1 parent cell! daughter cells!