Just as humans go through a life cycle, cells go through a cell cycle. grow reproduce marriage puberty

The cell cycle: Chromosomes Divide Grow DNA Replication Daughter cells

Cell Cycle Series of events cells go through as they grow, replicate their DNA, form chromosomes, and divide into two daughter cells. G R C D D

It is considered a cycle because each daughter cell starts the process over after division is complete. D D

Cell cycle diagram in SG: Each section of the diagram represents a different event in the cell’s life Circular diagram = cycle

GROWTH DNA LOOSENS CYTOPLASM DIVIDES NUCLEUS DIVIDES DNA REPLICATION CHROMOSOMES FORM

The cell cycle is divided into 2 main parts. GROWTH DNA LOOSENS CYTOPLASM DIVIDES NUCLEUS DIVIDES DNA REPLICATION CHROMOSOMES FORM

This part of the cell cycle is all about division… GROWTH DNA LOOSENS CYTOPLASM DIVIDES NUCLEUS DIVIDES DNA REPLICATION CHROMOSOMES FORM

…and this part of the cell cycle is all about preparing for division. GROWTH DNA LOOSENS CYTOPLASM DIVIDES NUCLEUS DIVIDES DNA REPLICATION CHROMOSOMES FORM

INTERPHASE M PHASE M = MITOSIS INTER = BETWEEN GROWTH DNA LOOSENS CYTOPLASM DIVIDES INTERPHASE M PHASE NUCLEUS DIVIDES DNA REPLICATION CHROMOSOMES FORM

Interphase Part of the cell cycle when the cell prepares for division. GROWTH DNA LOOSENS CYTOPLASM DIVIDES INTERPHASE M PHASE NUCLEUS DIVIDES DNA REPLICATION CHROMOSOMES FORM Part of the cell cycle when the cell prepares for division. C C P D

M Phase NEW PAGE IN NOTES GROWTH DNA LOOSENS CYTOPLASM DIVIDES INTERPHASE M PHASE NUCLEUS DIVIDES DNA REPLICATION CHROMOSOMES FORM Part of the cell cycle when the cell divides (first the nucleus, then the cytoplasm.) C C D N C

Interphase is longer than M phase. GROWTH DNA LOOSENS CYTOPLASM DIVIDES INTERPHASE M PHASE NUCLEUS DIVIDES DNA REPLICATION CHROMOSOMES FORM

This is because DNA replication occurs during interphase This is because DNA replication occurs during interphase. Remember, the DNA molecule is extremely long, so it takes a long time to replicate… R

…and it must be replicated without making any mistakes.

How can you tell if a cell is in M phase or interphase?

Identifying Cells in the Cell Cycle Interphase (preparing) Chromosomes M phase (dividing)

Since M phase cells are in the process of dividing, they have visible chromosomes. GROWTH DNA LOOSENS CYTOPLASM DIVIDES INTERPHASE M PHASE NUCLEUS DIVIDES DNA REPLICATION CHROMOSOMES FORM

M phase cells: X X X X

Identifying Cells in the Cell Cycle Interphase (preparing) Chromosomes Fully-formed M phase (dividing)

Since interphase cells are not ready to divide, they do not contain chromosomes. GROWTH DNA LOOSENS CYTOPLASM DIVIDES INTERPHASE M PHASE NUCLEUS DIVIDES DNA REPLICATION CHROMOSOMES FORM

Interphase cells:

Identifying Cells in the Cell Cycle Fully-formed chromosomes No chromosomes Interphase (preparing) Fully-formed chromosomes M phase (dividing)

You’ll notice that most of these cells are in interphase, since interphase takes longer than M phase. L

Interphase is divided into 3 parts. GROWTH DNA LOOSENS G1 CYTOPLASM DIVIDES INTERPHASE M PHASE NUCLEUS DIVIDES S DNA REPLICATION G2 CHROMOSOMES FORM

During G1, the cell grows and makes new organelles.

INTERPHASE M PHASE G1 S G2 GROWTH DNA LOOSENS CYTOPLASM DIVIDES NUCLEUS DIVIDES S DNA REPLICATION G2 CHROMOSOMES FORM

During S phase, the DNA is replicated by enzymes.

INTERPHASE M PHASE G1 S G2 GROWTH DNA LOOSENS CYTOPLASM DIVIDES NUCLEUS DIVIDES S DNA REPLICATION G2 CHROMOSOMES FORM

What happens during G2? DNA MOLECULE REPLICATED DNA

During G2, the cell checks for any errors made during DNA replication and fixes them before chromosomes form. E R C

INTERPHASE M PHASE G1 S G2 GROWTH DNA LOOSENS CYTOPLASM DIVIDES NUCLEUS DIVIDES S DNA REPLICATION G2 CHROMOSOMES FORM CHECK FOR ERRORS

How can you tell if a cell is in G1, S, or G2 of interphase?

Identifying Cells in the Cell Cycle Fully-formed chromosomes No chromosomes G1 S Interphase (preparing) End of G2 Fully-formed chromosomes M phase (dividing)

What would G1 cells look like? GROWTH DNA LOOSENS G1 CYTOPLASM DIVIDES INTERPHASE M PHASE NUCLEUS DIVIDES S DNA REPLICATION G2 CHROMOSOMES FORM CHECK FOR ERRORS

Identifying Cells in the Cell Cycle Fully-formed chromosomes No chromosomes G1 Small (just divided) S Interphase (preparing) End of G2 Fully-formed chromosomes M phase (dividing)

G1 cells:

What would S phase cells look like? GROWTH DNA LOOSENS G1 CYTOPLASM DIVIDES INTERPHASE M PHASE NUCLEUS DIVIDES S DNA REPLICATION G2 CHROMOSOMES FORM CHECK FOR ERRORS

Identifying Cells in the Cell Cycle Fully-formed chromosomes No chromosomes G1 Small (just divided) S Fully-grown Interphase End of G2 Fully-formed chromosomes M phase

S phase cells:

What would cells at the end of G2 look like? GROWTH DNA LOOSENS G1 CYTOPLASM DIVIDES INTERPHASE M PHASE NUCLEUS DIVIDES S DNA REPLICATION G2 CHROMOSOMES FORM CHECK FOR ERRORS

Identifying Cells in the Cell Cycle Fully-formed chromosomes No chromosomes G1 Small (just divided) Fully-grown Interphase S End of G2 DNA starting to condense Fully-formed chromosomes M phase

End of G2 cells:

Which cells are in interphase? Why? No chromosomes A B C D

Which cell is in M phase? Why? Fully-formed chromosomes A B C D

Which cell is in S phase? Why? Fully-grown A B C D

Which cell is in at the end of G2? Why? DNA is starting to condense A B C D

Which cell is in G1? Why? Small (just divided) A B C D