ENDOSYMBIOTIC THEORY Theory that mitochondria and chloroplast were

ENDOSYMBIOTIC THEORY • Theory that mitochondria and chloroplast were once free living prokaryotes that now live symbiotically with eukaryotic cells • Evidence • 2 membranes of chloroplast and mitochondria • Chl. & Mit. each contain their own DNA • Chl. & Mit. each divide on their own in a way similar to prokaryotic division

WATER POTENTIAL

The molar concentration of a sugar solution in an open beaker has been determined to be 0. 3 M. Calculate the solute potential at 27 degrees celsius.

• Solute potential= –i. CRT i= 1 C= 0. 3 R = Pressure constant = 0. 0831 T= 27 +273=300 K Solute concentration= -7. 5 bars

ROLES OF CELL DIVISION - MITOSIS • Reproduction of single celled organisms • Growth • Repair • Cell division must distribute identical genetic material to two daughter cells.

CELL CYCLE - PARTS 1. Interphase - (90% of cycle) - when the cell grows and duplicates the chromosomes. 2. Mitotic Phase (M) - when the chromosomes are split into separate cells.

INTERPHASE - PARTS • G 1 - Cell grows and carries out regular biochemical functions. • S – synthesis (replication) of DNA • G 2 – cell replicates organelles, prepares for division

MITOSIS STEPS • Put the following sequence of events in mitosis in order of beginning to end 1. chromatin condenses into chromosomes 2. the nuclear envelope dissolves 3. chromosomes line up in the middle of the cell 4. sister chromatids separate 5. the nuclear envelope reforms 6. chromosomes uncoil into chromatin

CDK • Protein Kinase (enzyme that adds phosphate to a molecule to energize it). • Amount remains constant during cycle. • Inactive unless bound with cyclin.

CYCLIN • Protein whose concentration builds up over G 1, S and G 2. • When enough cyclin is present, active MPF is formed.

ACTIVE MPF • Triggers Mitosis. • Activates a cyclin-degrading enzyme, which lowers the amount of cyclin in the cell. • Result - no active MPF to trigger another mitosis until the cycle is repeated.