Title: The Continuity of Life: How Cells Reproduce Chapter 10
1The Continuity of Life How Cells Reproduce
Chapter 10
2Cell division is required for growth and
development
- Cell division is the process by which one cell
gives rise to two or more daughter cells. - Prokaryotic cells divide by binary fission.
- Eukaryotic cells divide by mitotic cell division.
- Reproductive cells (ex. ova/sperm) are produced
by meiotic cell division. - All cells go through a cell cycle during their
reproduction. - After cells reproduce they either differentiate
into specific cell types or they continue to
divide.
3Mitotic cell division is required for asexual
reproduction
Single celled organisms are able to reproduce
asexually. This occurs when a life form
reproduces 2 genetically identical offspring. In
other words, an organism clones itself.
a) Paramecium, cell division produces two new,
independent organisms.
b) Yeast, a unicellular fungus, reproduces by
cell division.
Fig. 10-1
c) Hydra, a freshwater relative of the sea
anemone, grows a bud on its side. When fully
developed, the bud breaks off and assumes
independent life.
a) Paramecium, cell division produces two new,
independent organisms.
4What occurs during prokaryotic binary fission
(cell division)?
- The prokaryotic cell
- cycle has a long period
- of cell growth followed
- by a rapid cell division.
- This process usually occurs very rapidly.
- E. coli can reproduce every 20 minutes!!!
Fig. 10-2
5The process of binary fission
Step 1 the circular DNA double helix is
attached to the plasma membrane at one point.
Fig. 10-2
6The process of binary fission
Step 2 The DNA replicates and the two DNA double
helices attach to the plasma membrane at nearby
points.
Fig. 10-2
7The process of binary fission
Step 3 New plasma membrane is added between the
attachment points, pushing them further apart.
Fig. 10-2
8The process of binary fission
Step 4 The plasma membrane grows inward at the
middle of the cell.
Fig. 10-2
9The process of binary fission
Step 5 The parent cell divides into two
daughter cells.
Fig. 10-2
10The life cycles of eukaryotic organisms include
both mitotic and meiotic cell division
Fig. 10-4
11What occurs during the eukaryotic cell cycle?
- The eukaryotic cell cycle is divided into 2
major phases Interphase and Mitotic division. - There are two types of division in eukaryotic
cells mitotic cell division and meiotic cell
division.
12The eukaryotic cell cycle
- Interphase the period of time during which the
cell grows, replicates its DNA and prepares for
division. - 2. Mitotic division - the period of time when the
cell undergoes nuclear division.
Fig. 10-3
13DNA is organized into chromosomes in eukaryotic
cells.
- Eukaryotic chromosomes consist of DNA bound to
proteins. - Remember that a single chromosome contains many
genes.
14How does DNA in eukaryotic cells organize during
the cell cycle?
- Chromosomes replicate themselves during the DNA
synthesis phase of the cell cycle. - Chromosomes then condense during the mitotic
phase of the cell cycle. - Sister chromatids are duplicated chromosomes
joined at the centromere.
Fig. 10-5
15How does mitotic cell division produce
genetically identical daughter cells?
- Step 1 Mitotically active cells first grow in
the first part of interphase. - Step 2 Cells then duplicate their DNA.
- Step 3 Cells continue to grow and the new DNA is
checked for duplication errors. - Step 4 Cells enter the mitotic phase which is
made up of 4 parts.
Fig. 10-3
16How do chromosomes change during the mitotic cell
cycle?
Interphase Chromosomes (blue) are thin and
appear as a mass in the center of the cell. The
spindle microtubules (red) extend outward from
the nucleus to all parts of the cell.
Fig. 10-7
17How do chromosomes change during the mitotic cell
cycle?
Prophase The chromosomes (blue) have condensed
and are attached to the spindle microtubules
(red).
Fig. 10-7
18How do chromosomes change during the mitotic cell
cycle?
Metaphase The chromosomes have moved to the
equator of the cell.
Fig. 10-7
19How do chromosomes change during the mitotic cell
cycle?
Anaphase Sister chromatids have separated, and
each set moves toward each pole.
Fig. 10-7
20How do chromosomes change during the mitotic cell
cycle?
Telophase The chromosomes have gathered into
two clusters at either end of the cell. Each
cluster of chromosomes is the site of a future
nucleus. Cytokinesis occurs after the
chromosomes have been separated and are located
at opposite poles of the cell.
Fig. 10-7
21How do chromosomes change during the mitotic cell
cycle?
Resumption of interphase The chromosomes are
relaxing again into a loose state. The spindle
microtubules are disappearing, and the cellular
microtubules of the two new daughter cells are
rearranging into the interphase pattern.
Fig. 10-7
22Cytokinesis in a plant cell
Carbohydrate-filled vesicles bud off the
Golgi complex and move to the equator of the
cell.
Fig. 10-10
23Cytokinesis in a plant cell
The carbohydrate-filled vesicles bud off
the Golgi complex and move to the equator of
the cell.
Fig. 10-10
24Cytokinesis in a plant cell
Vesicles fuse to form a new cell wall (red)
and plasma membrane (yellow) between daughter
cells.
Fig. 10-10
25Cytokinesis in a plant cell
Fig. 10-10
Complete separation of daughter cells.
26How does meiotic cell division produce haploid
cells?
- Meiosis produces four haploid daughter nuclei
following cell divisions that occur at the end of
Meiosis I and Meiosis II (2 cell divisions in
total!)
27Fig. 10-11
28Fig. 10-11
29What are the differences between Mitosis and
Meiosis?
Fig. 10-13
30How does meiotic cell division and sexual
reproduction produce genetic variability?
- Shuffling of homologous chromosomes creates new
- combinations of chromosomes.
See Table 10-1
31How does meiotic cell division and sexual
reproduction produce genetic variability?
- The process of crossing over during Prophase I
creates chromosomes with new combinations of
genetic material. - The fusion of gametes at fertilization creates
genetically variable offspring.
32Vocabulary ListKnow the following terms
Cell division Daughter cells Binary fission Cell
cycle Differentiate Binary fission Mitosis Meiosis
Mitotic cell division Meiotic cell
division Chromosomes Centromere Chiasmata Crossing
over
Interphase Prophase Metaphase Anaphase Telophase C
ytokinesis Meiosis I Meiosis II