The Cell Cycle• Cells must divide to maintain maximum efficiency.• Mitosis is the process in which somatic (body) cells divide to form a new cell.• Mitosis consists of four phases.• Interphase is the period in between each mitotic cell division.
Reproduction• Asexual Reproduction: A single cell or group of cells each duplicates its genetic material and then splits into two new genetically identical cells. – The offspring are genetically identical• Sexual Reproduction: Genetic material from each of two parents combines, producing offspring that differ genetically from either parent. – Involves the union of sex cells (egg and sperm)
Parent cellDNA replicates Cell division = One cell makes two cells Two daughter cells are genetically identical to each other and to parent cell = clones
The same DNA can appear in two formsChromatin = uncondensed DNA Chromosome = condensed DNA
1 Chromosome1 chromatid per chromosome1 DNA double helix DNA replication1 Chromosome2 chromatids per chromosome2 DNA double helices
Cell division in eukaryotic cells: Cytokinesis = division of the cytoplasm
Interphase• Interphase is made of 3 stages.• The Gap 1 and 2 or G1 and G2 phase is when cells grow and make RNA, proteins, and other macromolecules.• The S or Synthesis phase is when the cell is making DNA.
DNA Replication• During the S phase of the cell cycle, DNA replicates.• A short section of the DNA uncoils.• New nucleotides bond to the open sections of the DNA.• The “new” and “old” sections of DNA separate and now there are 2 DNA strands.
Interphase• ATP is synthesized.• Damaged parts are repaired.• Wastes are excreted.• Proteins are made.• Organelles are formed.• Chromosomes are copied.• Specialized tasks are performed .