Cell Life Cycle

Cells have two major periods Interphase Cell grows Cell carries on metabolic processes Cell replicates DNA Cell division Cell replicates itself Function is to produce more cells for growth and repair processes

DNA Replication Genetic material duplicated and readies a cell for division into two cells Occurs toward the end of interphase DNA uncoils and each side serves as a template

Events of Cell Division Mitosis Division of the nucleus Results in the formation of two daughter nuclei Cytokinesis Division of the cytoplasm Begins when mitosis is near completion Results in the formation of two daughter cells

Mitosis

Interphase No cell division occurs The cell carries out normal metabolic activity and growth; transcription (DNA to mRNA), translation (mRNA to proteins), organelles duplicate Three stages: G 1 - cell grows and functions normally S - (Synthesis) - DNA is duplicated G 2 - cell resumes growth

Stages of Mitosis “A guy named Pro Met-a girl named Ana, and they Telo- phoned each other.” Prophase Nuclear envelope begins to dissolve Centrioles migrate to the poles Chromatin starts to bundle into chromosomes (two chromatids) The familiar ‘X’ shape

Stages of Mitosis Metaphase Chromosomes align at the center of the cell Special microtubules called spindle fibers attach to the chromosome’s centromeres

Stages of Mitosis Anaphase Spindle fibers shorten and duplicated chromosomes (chromatids) are pulled toward the poles The cell begins to elongate

Telophase Chromosomes uncoil to become chromatin again Nuclear envelope forms around each chromatin mass A cleavage furrow (for cell division) begins to form Stages of Mitosis

Cytokinesis Cytoplasm pinches into two parts Two smaller daughter cells that are genetically identical are the result

Cytokinesis

Protein Synthesis

Making Proteins In addition to replicating itself during cell division, DNA serves as the master blueprint for protein synthesis. List some examples of proteins:

Two Major Phases of Protein Synthesis 1. Transcription 2. Translation

Transcription Involves the transfer of information from the DNA molecule into the complementary base sequence of mRNA

Translation The “language” of the nucleic acids (base sequence) is “translated” into the language of proteins (amino acid sequence).