The Cell Cycle Cell Growth Cell Division AP

The Cell Cycle: Cell Growth, Cell Division AP Biology

Biology is the only subject in which multiplication is the same thing as division… AP Biology

Where it all began… § You started as a cell smaller than a period at the end of a sentence…. AP Biology

Getting from there to here… § Cell division u continuity of life = reproduction of cells § growth § repair & renew § Cell cycle u AP Biology 2 genetically identical daughter cells are produced from a parent cell

Getting the right stuff § What is passed to daughter cells? u exact copy of genetic material = DNA § this division step = mitosis u assortment of organelles & cytoplasm § this division step = cytokinesis chromosomes (stained orange) in kangaroo rat epithelial cell AP Biology

Copying DNA § Dividing cell duplicates DNA separates each copy to opposite ends of cell u splits into 2 daughter cells u § separates 2 copies so each daughter cell has complete identical copy § error rate = ~1 per 100 million bases w 3 billion base pairs mammalian genome w ~30 errors per cell cycle n mutations n AP Biology

A bit about DNA § DNA is organized in chromosomes double helix DNA molecule u associated proteins = histone proteins u DNA-protein complex = chromatin u § organized into long thin fiber AP Biology

Copying DNA with care… § After DNA duplication chromatin condenses u u AP Biology coiling & folding to make a smaller package from DNA to chromatin to highly condensed mitotic chromosome

Chromosome § Duplicated chromosome consists of 2 sister chromatids narrow at their centromeres u contain identical copies of the chromosome’s DNA u AP Biology

Cell cycle § Cell has a “life cycle” cell is formed from a mitotic division cell grows & matures to divide again G 1, S, G 2, M epithelial cells, blood cells, stem cells AP Biology cell grows & matures to never divide again liver cells G 0 brain nerve cells

Cell Division cycle § Phases of a dividing cell’s life u Interphase (growth) § cell grows/new organelles are produced § replicates chromosomes § proteins are produced that prepare the cell for mitosis u mitotic phase (cell division) § cell separates & divides chromosomes w mitosis § cell divides cytoplasm & organelles w cytokinesis AP Biology

Control of Cell Cycle AP Biology

Interphase § 90% of cell life cycle u cell doing its “everyday job” § produce RNA, synthesize proteins u AP Biology prepares for duplication if triggered

Interphase § Divided into 3 phases: u G 1 = 1 st Gap § cell doing its “everyday job” § cell grows u S = DNA Synthesis § copies chromosomes u G 2 = 2 nd Gap § prepares for division § cell grows § produces organelles, proteins, membranes AP Biology

Interphase G 2 § Nucleus well-defined chromosome duplication complete u DNA loosely packed in long chromatin fibers u § Prepares for mitosis u AP Biology produces proteins & organelles

Mitosis § copying cell’s DNA & dividing it § between 2 daughter nuclei Mitosis is divided into 4 phases prophase u metaphase u anaphase u telophase u AP Biology

Overview AP Biology

Prophase § Chromatin (DNA) condenses u visible as chromosomes § chromatids fibers extend from the centromeres Centrioles move to opposite poles of cell Fibers (microtubules) cross cell to form mitotic spindle u § § u actin, myosin § Nucleolus disappears § Nuclear membrane breaks down AP Biology

Prometaphase § Proteins attach to centromeres u creating kinetochores § Microtubules attach at kinetochores u connect centromeres to centrioles § Chromosomes begin moving AP Biology

Kinetochore § Each chromatid has own kinetochore proteins u AP Biology microtubules attach to kinetochore proteins

Metaphase § Spindle fibers align chromosomes along the middle of cell meta = middle u metaphase plate u helps to ensure chromosomes separate properly u § so each new nucleus receives only 1 copy of each chromosome AP Biology

AP Biology

Anaphase § Sister chromatids separate at kinetochores move to opposite poles u pulled at centromeres u pulled by motor proteins “walking”along microtubules u § increased production of ATP by mitochondria § Poles move farther apart u AP Biology polar microtubules lengthen

Separation of chromatids § In anaphase, proteins holding together sister chromatids are inactivated u separate to become individual chromosomes 1 chromosome AP Biology 2 chromatids 2 chromosomes

Chromosome movement § Kinetochores use motor proteins that “walk” chromosome along attached microtubule u AP Biology microtubule shortens by dismantling at kinetochore (chromosome) end

Telophase § Chromosomes arrive at opposite poles daughter nuclei form u nucleoli from u chromosomes disperse u § no longer visible under light microscope § Spindle fibers disperse § Cytokinesis begins u AP Biology cell division

Cytokinesis § Animals cleavage furrow forms u ring of actin microfilaments forms around equator of cell u § myosin proteins u tightens to form a cleavage furrow, which splits the cell in two § like tightening a draw string AP Biology

Cytokinesis in Animals AP Biology (play Cells Alive movie here)

Mitosis in whitefish blastula AP Biology

Mitosis in animal cells AP Biology

Cytokinesis in Plants § Plants u vesicles move to equator line up & fuse to form 2 membranes = cell plate § derived from Golgi u AP Biology new cell wall is laid down between membranes § new cell wall fuses with existing cell wall

Cytokinesis in plant cell AP Biology

Mitosis in plant cell AP Biology

onion root tip AP Biology