Fig 8 5 Eukaryotic cell cycle INTERPHASE G

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Fig. 8 -5 Eukaryotic cell cycle INTERPHASE G 1 First gap phase -growth -normal

Fig. 8 -5 Eukaryotic cell cycle INTERPHASE G 1 First gap phase -growth -normal cell activities s MIT s si ito o M t Cy ki si e n S (DNA synthesis) -DNA copies (replicates) itself G 2 Second gap phase -growth -cell prepares for mitosis PHA OTIC SE (M) Mitosis = division of the nucleus Cytokinesis = division of the cytoplasm

Nucleic Acids • Large polymers • Made of linked nucleotides • Components of a

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

DNA / RNA structure DNA Sugar Nitrogenous bases Shape RNA

DNA / RNA structure DNA Sugar Nitrogenous bases Shape RNA

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

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

CELLcell CYCLE IN in EUKARYOTIC The cycle eukaryotic. CELLS cells INTERPHASE G 1 First

CELLcell CYCLE IN in EUKARYOTIC The cycle eukaryotic. CELLS cells INTERPHASE G 1 First gap phase -growth -normal cell activities s MIT s si o ito t Cy ki si e n M Fig. 8 -5 S (DNA synthesis) -DNA copies (replicates) itself G 2 Second gap phase -growth -cell prepares for mitosis PHA OTIC SE (M) Mitosis = division of the nucleus Cytokinesis = division of the cytoplasm

Fig. 8 -4 bc What happens to a chromosome during the cell cycle Sister

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

Two strands separate Nucleotides come and pair with their complementary base DNA replication Semi-conservative

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

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

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

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

• DNA Polymerase can only add to the 3’ end of a new

• DNA Polymerase can only add to the 3’ end of a new strand

Fig. 8 -5 CELL CYCLE IN EUKARYOTIC CELLS INTERPHASE G 1 First gap phase

Fig. 8 -5 CELL CYCLE IN EUKARYOTIC CELLS INTERPHASE G 1 First gap phase -growth -normal cell activities s MIT s si ito o M t Cy ki si e n S (DNA synthesis) -DNA copies (replicates) itself G 2 Second gap phase -growth -cell prepares for mitosis PHA OTIC SE (M) Mitosis = division of the nucleus Cytokinesis = division of the cytoplasm

Fig. 8 -4 bc What happens to a chromosome during the cell cycle Sister

Fig. 8 -4 bc What happens to a chromosome during the cell cycle Sister chromatids Single, unreplicated chromosome (G 1) Chromosome is replicated/ sister chromatids (identical copies) attached at centromere Centromere Sister chromatids Replicated chromosome splits, each chromatid going to a separate cell

What’s wrong with this? ?

What’s wrong with this? ?

Fig. 8 -9 a G 1 checkpoint Cells can’t get past unless they get

Fig. 8 -9 a G 1 checkpoint Cells can’t get past unless they get a signal from outside G 0 is a nondividing state Ex: brain, muscle Control system G 1 M S G 2 checkpoint size and DNA checked M checkpoint in metaphase all chromosomes attached to spindle

Fig. 8 -9 b Growth factor -outside “signal” that it’s time to divide. -gets

Fig. 8 -9 b Growth factor -outside “signal” that it’s time to divide. -gets a cell to move past the G 1 checkpoint Plasma membrane Receptor protein Relay proteins G 1 checkpoint Control system G 1 M G 2 S