Cellular Reproduction Life Structure and Function

Atoms & Molecules make up the components of DNA

Chromosomes are structures in the nucleus that contain hereditary material. Chromosomes consist of large amounts (one molecule) of DNA wrapped around histone proteins, coiled up and condensed in the nucleus

The centromere is the part of the chromosome that links sister chromatids together They serve as a checking point in mitosis to ensure the proper separation of the chromosomes

Homologous chromosomes pair up based on similar size, shape, and genetic information (traits) One chromosome comes from the maternal parent (mom) & the other chromosome is from the paternal parent (dad)

DNA is copied for two main reasons: Cell division (growth, repair, & replacement of cells) 2) Making proteins (proteins regulate cell processes & make cell structures)

Proteins and DNA Some proteins initiate DNA replication (begin DNA copying process) during the cell cycle Other Proteins are in control of gene transcription (how DNA is made into a complimentary strand of RNA) Some proteins assist with the folding of the DNA as it is wrapped up within the chromosome

The cell cycle consists of 3 main stages Interphase (longest stage) Mitosis cytokinesis

Cell Cycle The cycle begins with one diploid cell and ends with two daughter cells (A diploid cell has paired chromosomes one from each parent)

Interphase During this stage of the cell cycle, chromatin, nuclear envelope and nucleolus are clearly visible (In animal cells the centrioles are also visible)

Mitosis (mitotic phase) There are four phases in mitosis…. Prophase Metaphase Anaphase Telophase

Prophase (1st stage of mitosis) The chromosomes condense and become visible in the nucleus of the cell and the spindles begin to form in the cytoplasm

Metaphase (2nd stage of mitosis) Spindle fibers connect to the centrioles that are at opposite poles from each other. The duplicated chromosomes are lined up in the middle along the metaphase plate