Eukaryotic cell cycle INTERPHASE G1 S (DNA synthesis) First gap phase Fig. 8-5 Eukaryotic cell cycle INTERPHASE G1 S (DNA synthesis) First gap phase -growth -normal cell activities -DNA copies (replicates) itself G2 Second gap phase -growth -cell prepares for mitosis Cytokinesis Mitosis MITOTIC PHASE (M) Mitosis = division of the nucleus Cytokinesis = division of the cytoplasm

Nucleic Acids 2 General types Large polymers Made of linked nucleotides Components of a nucleotide? A nucleotide consists of a 5-carbon sugar, phosphate group, nitrogenous base 2 General types

DNA / RNA structure DNA RNA Sugar Nitrogenous bases Shape

DNA is anti-parallel One strand is “flipped” in relation to the other

CELL CYCLE IN EUKARYOTIC CELLS Fig. 8-5 CELL CYCLE IN EUKARYOTIC CELLS INTERPHASE G1 S (DNA synthesis) First gap phase -growth -normal cell activities -DNA copies (replicates) itself G2 Second gap phase -growth -cell prepares for mitosis Cytokinesis Mitosis MITOTIC PHASE (M) Mitosis = division of the nucleus Cytokinesis = division of the cytoplasm

Semi-conservative replication The new strand consists of one old DNA and one new DNA strand Two strands separate Nucleotides come and pair with their complementary base DNA replication Semi-conservative replication

DNA replication starts at an origin of replication (many in eukaryotes) forming replication bubbles

Enzymes involved in replication Helicase  unwinds the double helix DNA polymerase  builds the new DNA strand DNA ligase “glues” DNA fragments together

What happens to a chromosome during the cell cycle Fig. 8-4bc What happens to a chromosome during the cell cycle Sister chromatids Chromosome is replicated/ sister chromatids (identical copies) attached at centromere Sister chromatids Centromere Replicated chromosome splits, each chromatid going to a separate cell