8.2 The Cell CycleThe sequence of growth and division of a cell

Interphase

Mitosis

IPMAT

Cell Size Limitations

Materials must be able to pass through the cytoplasm quickly

DNA material must be enough in the nucleus to control cell activities

Volume increases faster than surface area as cell’s size increase

Chromosomes Short, stringy, dark-staining

structures Contains DNA Exist as chromatin (strands of

DNA) Coils, shortens, thickens before

cell division

A. Interphase

G-1- Cell growth occurs S - Chromosomes replicate G-2- More cell growth occurs G-o phase – cells in this phase do

not reproduce, most cells of the human body are in this phase

Animal cell in prophase

Review of terms

Sister chromatids Two halves of the doubled

chromosomes

B. Mitosis Division phase Results in two new cells Chromosome sets are identical to

those of the parent cell

Phases of Mitosis

ProphaseMetaphase Anaphase

TelophaseCytokinesis

Prophase First, longest phase Sister chromatids held together by

centromere Nucleus, nucleolus disappears Centrioles move to opposite ends

of cells Spindle forms

Metaphase Short phase Double chromosomes attach to

spindle fibers at centromere Chromosomes line up at the

equator

Anaphase

Sister chromatids separate Centromeres split apart

Telophase

Reverse of prophase occurs Chromosomes uncoil Spindle breaks down Nucleolus reappears New nuclear membrane forms

around chromosomes Plasma membrane separate the

two nuclei

CytokinesisDivision of the cytoplasm

Plants – cell plate forms across cell’s equator

Animals – plasma membrane pinches along the equator

8.3 Control of Cell CycleDNA- Genetic Blueprint for Cells

Gene- segment of DNA that controls production of a single protein

Cancer- Uncontrolled cell division

Cancer Mistake in cell cycle Uncontrolled cell division Cancerous cells forms tumors

(masses of tissue) Tumors deprive normal cells with

nutrients

Factors that affect cancer Environmental

Cigarette smoke UV radiation Air and water pollution

Genetic Programmed in the genes