Download Mitosis and Cytokinesis

Chapter 6
Chromosomes and Cell Reproduction
Section 1: Chromosomes
Section 2: The Cell Cycle
Section 3: Mitosis and Cytokinesis
Section 1
Chromosomes
Objectives:
•Identify four examples of cell division in eukaryotes
and one example in prokaryotes.
•Differentiate between a gene, a DNA molecule, a
chromosome, and a chromatid.
•Differentiate between homologous chromosomes,
autosomes, and sex chromosomes.
•Compare haploid and diploid cells.
•Predict how changes in chromosome number or
structure can affect development.
Section 1
Chromosomes
Formation of New Cells by Cell Division
•Function of Cell Division Cell division allows
organisms to reproduce asexually, grow, replace
worn-out or damaged tissue, and form gametes.
•Prokaryotic Cell Reproduction Bacteria
reproduce asexually by binary fission, a process that
produces identical offspring.
•Eukaryotic Cell Reproduction Before eukaryotic
cell division, DNA coils tightly around proteins and
forms chromosomes. At cell division, each
chromosome consists of two chromatids attached at
the centromere.
Section 1
Chromosomes
How Chromosome Number and
Structure Affect Development
•Sets of Chromosomes Each organism has a
characteristic number of chromosomes. Human
somatic cells are diploid, with 23 pairs (46 in total)
of homologous chromosomes. Human gametes are
haploid, with 23 chromosomes.
•Sex Chromosomes Sex chromosomes carry
information that determines an organism’s sex.
Section 1
Chromosomes
How Chromosome Number and
Structure Affect Development continued
•Change in Chromosome Number Changes in
chromosome number can cause abnormal
development. Karyotypes are used to examine an
individual’s chromosomes and identify possible
abnormalities in chromosome number.
•Change in Chromosome Structure Changes in
chromosome structure, called mutations, can also
cause abnormal development.
Section 2
The Cell Cycle
Objectives:
•Identify the major events that characterize each of
the five phases of the cell cycle.
•Describe how the cell cycle is controlled in
eukaryotic cells.
•Relate the role of the cell cycle to the onset of
cancer.
Section 2
The Cell Cycle
The Life of a Eukaryotic Cell
•The Cell Cycle The life of a eukaryotic cell—the
cell cycle—includes interphase, mitosis, and
cytokinesis.
•Interphase Interphase consists of 3 phases:
growth, DNA synthesis (replication) , and
preparation for cell division. A cell spends 90
percent of its time in interphase.
•Mitosis and Cytokinesis A cell about to divide
enters the mitosis (nuclear division) and cytokinesis
(cytoplasm division) phases of the cell cycle.
Section 2
The Cell Cycle
Control of the Cell Cycle
•Cell Checkpoints The cell cycle is carefully
controlled through three main checkpoints.: cell
growth (G1) checkpoint, DNA synthesis (G2)
checkpoint, and mitosis checkpoint.
•When Control is Lost: Cancer Failure of control
of cellular growth and division can result in cancer.
Section 3
Mitosis and Cytokinesis
Objectives:
•Describe the structure and function of the spindle
during mitosis.
•Summarize the events of the four stages of mitosis.
•Differentiate cytokinesis in animal and plant cells.
Section 3
Mitosis and Cytokinesis
Chromatid Separation in Mitosis
•Forming the Spindle The spindle is made up of
centrioles and microtubule fibers.
•Separation of Chromatids by Attaching
Spindle Fibers During mitosis, spindle fibers drag
the chromatids to opposite poles of the cell. This
leads to two nuclei that each contain a set of the
original cell’s chromosomes.
Section 3
Mitosis and Cytokinesis
Mitosis and Cytokinesis
•Function of Mitosis and Cytokinesis The end result
of mitosis and cytokinesis is two genetically identical
cells.
•Mitosis Mitosis consists of four stages: prophase,
metaphase, anaphase, and telophase.
•Cytokinesis Cytokinesis in animal cells occurs when
a belt of protein threads pinches the cell membrane in
half. Cytokinesis in plant cells occurs when vesicles
from the Golgi apparatus fuse to form a cell plate.