1. AP Biology
Cellular Division
Cell Reproduction

2. Binary Fission DNA replicated Membrane added AP Biology Figure: 11.1
Title:
Prokaryotic cells divide by binary fission
Caption:
1) The circular DNA double helix attaches to the plasma membrane at one point. 2) The DNA replicates and the two DNA double helices attach to the plasma membrane at nearby points. 3) As the cell grows, new plasma membrane is added between the attachment points, pushing them further apart. 4) The plasma membrane grows inward at the middle of the cell. 5) The parent cell has divided into two daughter cells.
Membrane added
Cell Reproduction

3. Functions in Reproduction, Growth, and Repair Unicellular Organisms
Cell Division
Functions in Reproduction, Growth, and Repair
Unicellular Organisms
Reproduction of Entire Organisms
Multicellular Organisms
Growth and Development from the Fertilized Egg
Replacement of Damaged or Dead Cells
Distributes Identical Sets of Chromosomes
Precisely Replicates its DNA
Results in 2 Daughter Cells

4. Binary Fission in Bacterium: Asexual Reproduction by Mitosis
AP Biology
Binary Fission in Bacterium: Asexual Reproduction by Mitosis
Nuclear material
Division plane
Cell wall
Cytoplasm
Figure: 11.1a
Title:
Prokaryotic cells divide by binary fission
Caption:
1) The circular DNA double helix attaches to the plasma membrane at one point. 2) The DNA replicates and the two DNA double helices attach to the plasma membrane at nearby points. 3) As the cell grows, new plasma membrane is added between the attachment points, pushing them further apart. 4) The plasma membrane grows inward at the middle of the cell. 5) The parent cell has divided into two daughter cells.
Cell Reproduction

5. Binary Fission in Paramecium: Asexual Reproduction by Mitosis
AP Biology
Binary Fission in Paramecium: Asexual Reproduction by Mitosis
Figure: 11.3a
Title:
Mitotic cell division in eukaryotes enables asexual reproduction
Caption:
In unicellular microorganisms, such as the protist Tetrahymena, mitotic cell division produces two new, independent organisms.
New individuals
Cell Reproduction

6. Budding Yeast: Asexual Reproduction by Mitosis
AP Biology
Budding Yeast: Asexual Reproduction by Mitosis
Nucleus divides by mitosis.
Bud forms on cell.
Nucleus moves into bud.
Bud separates.
Figure: 11.3b
Title:
Mitotic cell division in eukaryotes enables asexual reproduction
Caption:
Yeast, a unicellular fungus, reproduces by mitotic cell division.
Cell Reproduction

7. Budding Hydra: Asexual Reproduction by Mitosis
AP Biology
Budding Hydra: Asexual Reproduction by Mitosis
Figure: 11.3c
Title:
Mitotic cell division in eukaryotes enables asexual reproduction
Caption:
Hydra, a freshwater relative of jellyfish, grows a miniature replica of itself (a bud) protruding from its side. When fully developed, the bud breaks off and assumes independent life.
Cell Reproduction

8. Growth and Development: Functions of Mitosis
AP Biology
Growth and Development: Functions of Mitosis
Organs
Fertilized egg
(zygote)
Multicell stage
Mitotic cell division &
differ-entiation
Mitotic
cell division
Figure: 11.2
Title:
Mitotic cell division in eukaryotic cells produces cells needed for growth, development, and maintenance and repair
Caption:
Mitotic cell divisions produce the cells that make up the body of an embryo . Mitotic cell divisions continue to allow the embryo to grow, eventually, into an adult. (d) In the adult, mitotic cell divisions maintain tissues such as skin that are made of cells with short life spans.
Tissues
Cell Reproduction

9. The Eukaryotic Cell Cycle
AP Biology
The Eukaryotic Cell Cycle
G0: nondividing
Mitosis
S: Synthesis of DNA; chromosomes duplicated
prophase
G1: Growth
anaphase
metaphase
telophase
cytokinesis
G2: Growth
interphase
cell division
Figure: 11.9
Title:
The eukaryotic cell cycle
Caption:
The eukaryotic cell cycle consists of two major phases, interphase and cell division. Each is divided into subphases.
Cell Reproduction

10. Alternates between mitotic (M) phase and interphase in eukaryotes.
The Cell Cycle
Alternates between mitotic (M) phase and interphase in eukaryotes.
Interphase
~90% of cycle
chromosome replication
cell growth and metabolism
three periods
G1 phase – first growth phase
S phase – synthesis of duplicated DNA
G2 phase – second growth phase

11. Interphase (nondividing)
AP Biology
Interphase (nondividing)
Interphase : The chromosomes (blue) are in the thin, extended state and appear as a mass in the center of the cell. The microtubules (red) extend outward from the nucleus to all parts of the cell.
Figure: 11.10
Title:
The cell cycle in a plant cell
Caption:
The eukaryotic cell cycle consists of two major phases, interphase and cell division. Each is divided into subphases.
Cell Reproduction

12. Phases of Mitosis (nuclear division): Prophase
AP Biology
Phases of Mitosis (nuclear division): Prophase
Interphase : The chromosomes (blue) are in the thin, extended state and appear as a mass in the center of the cell. The microtubules (red) extend outward from the nucleus to all parts of the cell.
Late prophase: Chromosomes have condensed and attached to microtubules. Microtubules have reorganized to form the spindle. Chromatid develops a kinetechore.
Figure: 11.10
Title:
The cell cycle in a plant cell
Caption:
The eukaryotic cell cycle consists of two major phases, interphase and cell division. Each is divided into subphases.
Cell Reproduction

13. Chromosome Condensation
AP Biology
Chromosome Condensation
single-stranded chromosome
double helix uncondensed
double-stranded chromosome
double helices still uncondensed
DNA replication
Chromosome condensation
cell
1 double-stranded chromosome
2 double helices now condensed
base pairs
Figure: 11.6
Title:
Chromosome condensation
Caption:
Before cell division begins, the DNA double helix in each chromosome replicates. The two newly made double helices remain associated with each other. When cell division begins, the duplicate chromosomes condense and become visible. At this stage, each duplicated chromosome contains two identical DNA double helices. Each DNA double helix is contained within a sister chromatid. Condensation of the duplicated chromosome requires action of many proteins, including histones.
a chromatid
centromere 
closer look
still closer look
even closer look
Cell Reproduction

14. Human Chromosomes during Mitosis
AP Biology
Human Chromosomes during Mitosis
Figure: 11.UN06a
Title:
Formation of sister chromatids
Caption:
Cell Reproduction

15. These are chromosomes from mitosis
AP Biology
Human Karyotype, Male
These are chromosomes from mitosis
Stained to show regions
Numbered by length
Occur in pairs
Figure: 11.UN06b
Title:
Formation of daughter chromosomes
Caption:
Cell Reproduction

16. Phases of Mitosis (nuclear division): Metaphase
AP Biology
Phases of Mitosis (nuclear division): Metaphase
Interphase : The chromosomes (blue) are in the thin, extended state and appear as a mass in the center of the cell. The microtubules (red) extend outward from the nucleus to all parts of the cell.
Late prophase: Chromosomes have condensed and attached to microtubules. Microtubules have reorganized to form the spindle. Chromatid develops a kinetechore.
Metaphase: The chromosomes have moved along the spindle microtubules to the equator of the cell. Centromeres align on the equator. Entire structure of microtubules is called the spindle.
Figure: 11.10
Title:
The cell cycle in a plant cell
Caption:
The eukaryotic cell cycle consists of two major phases, interphase and cell division. Each is divided into subphases.
Cell Reproduction

17. Separation of Sister Chromatids
In metaphase, sister chromatids are held together at centromere
At end of metaphase, centromere releases sister chromatids
In anaphase, they move to opposite poles

18. Phases of Mitosis: Anaphase & Telophase
Anaphase: Sister chromatids have separated into separate chromosomes. Kineteochore microtubules shorten at kinetochore. Poles move farther apart.
Telophase: Nonkinetochore microtubules elongate cell. The chromosomes have gathered into two clusters, one at the site of each future nucleus.
Next interphase: Chromosomes are relaxing again into their extended state. Spindle fibers are disappearing, and the microtubules of the 2 daughter cells rearrange into the interphase pattern.

19. Mitosis: Prophase - Metaphase
AP Biology
Mitosis: Prophase - Metaphase
Duplicated chromosomes remain elongated
Chromosomes condense and shorten
Nucleolus disappears; Nuclear envelope breaks down
Late Interphase
Early Prophase
Late Prophase
Metaphase
Figure: 11.11a-d
Title:
The cell cycle in an animal cell
Caption:
(a) Late interphase: The chromosomes have been duplicated but remain elongated and relaxed within the nucleus. The centrioles have also been duplicated. (b) Early prophase: The chromosomes condense, shortening and thickening. The centrioles begin to move apart, and the spindle microtubules begin to form between them. (c) Late prophase: The nucleolus disappears; the nuclear envelope breaks down, and the spindle microtubules attach to the kinetochore of each sister chromatid (red spot). (d) Metaphase: Interactions between the kinetochores and the microtubules have lined up the chromosomes at the cell’s equator.
Centrioles have also been duplicated
Centrioles begin to move apart;
Spindle forms
Microtubules attach to kinetochores
Kinetochores align at cell’s equator
Cell Reproduction

20. Mitosis Anaphase - Cytokinesis
AP Biology
Mitosis Anaphase - Cytokinesis
Free spindle fibers push poles apart
One set of chromosomes; Begin unwinding
Cytoplasm divided along equator
Figure: 11.11e-I
Title:
The cell cycle in an animal cell
Caption:
(e) Anaphase: Chromatids separate at the centromere, becoming independent chromosomes that move toward the opposite poles of the cell. The free spindle microtubules slide past one another, pushing the poles farther apart. (f) Telophase: One complete set of chromosomes reaches each pole. The chromosomes relax into their extended state, the spindle microtubules begin to disappear, and the nuclear envelopes begin to re-form. (g) Cytokinesis: At the end of telophase, the cytoplasm is divided along the equator of the parent cell, with each daughter cell receiving one nucleus and about half the original cytoplasm. (h) Interphase of daughter cells: The daughter cells enter interphase. The spindle microtubules disappear, the nuclear envelope re-forms, the chromosomes finish extending, and the nucleolus reappears.
Next Interphase
Anaphase
Telophase
Cytokinesis
Each daughter gets 1 nucleus & half of cytoplasm
Spindle disappears; Nucleolus reappears
Chromatids become independent chromosomes
Nuclear envelope re-forms
Cell Reproduction

21. Cytokinesis of a Ciliated Cell
AP Biology
Cytokinesis of a Ciliated Cell
Daughter Cells
Figure: 11.12b
Title:
Cytokinesis in an animal cell
Caption:
Cytokinesis has almost separated the two daughter cells.
Cleavage Furrow
Cell Reproduction

22. Cytokinesis in Plants Vesicles fuse to form cell wall and membranes
AP Biology
Cytokinesis in Plants
Vesicles fuse to form cell wall and membranes
Complete separation of daughter cells
Figure: 11.13
Title:
Cytokinesis in a plant cell
Caption:
Carbohydrate-filled vesicles produced by the Golgi complex congregate at the equator of the cell, forming the cell plate. The membranes of the vesicles will fuse to form the two plasma membranes separating the daughter cells; their carbohydrate contents form part of the cell wall.
Cell Reproduction

23. Mitosis, Meiosis, and the Sexual Cycle
AP Biology
Mitosis, Meiosis, and the Sexual Cycle
Figure: 11.5
Title:
Mitotic and meiotic cell division in humans
Caption:
Mitotic cell divisions maintain and repair the bodies of adults. Within ovaries, meiotic cell division produces eggs; within testes, meiotic cell division produces sperm. Fusion of an egg and a sperm produce a fertilized egg that undergoes hundreds of mitotic cell divisions to produce a baby that can grow by additional mitotic cell divisions into an adult, completing the life cycle.
Cell Reproduction

24. Meiosis I Prophase I Metaphase I Anaphase I Telophase I
AP Biology
Meiosis I
Homologous chromosomes exchange DNA & align on equator
Homologous chromosomes move to opposite poles
Homologous chromosomes pair and cross over
Figure: 11.14a-d
Title:
The details of meiotic cell division
Caption:
In meiotic cell division (meiosis and cytokinesis), the homologous chromosomes of a diploid cell are separated, producing four haploid daughter cells. Each daughter cell contains one member of each pair of parental homologous chromosomes. In these diagrams, two pairs of homologous chromosomes are shown, large and small. The yellow chromosomes are from one parent (for example, the father), and the violet chromosomes are from the other parent. (a) Prophase I. Duplicated chromosomes condense. Homologous chromosomes pair up and chiasmata occur as chromatids of homologues exchange parts. The nuclear envelope disintegrates, and spindle microtubules form. (b) Metaphase I. Paired homologous chromosomes line up along the equator of the cell. One homologue of each pair faces each pole of the cell and attaches to spindle microtubules via its kinetochore (red). (c) Anaphase I. Homologues separate, one member of each pair going to each pole of the cell. Sister chromatids do not separate. (d) Telophase I. Spindle microtubules disappear. Two clusters of chromosomes have formed, each containing one member of each pair of homologues. The daughter nuclei are therefore haploid. Cytokinesis commonly occurs at this stage. There is little or no interphase between meiosis I and meiosis II.
Prophase I
Metaphase I
Anaphase I
Telophase I
Cell Reproduction

25. Meiosis II Similar to Mitosis Four Haploid Cells Prophase II
AP Biology
Meiosis II
Similar to Mitosis
Figure: 11.14e-I
Title:
The details of meiotic cell division
Caption:
In meiotic cell division (meiosis and cytokinesis), the homologous chromosomes of a diploid cell are separated, producing four haploid daughter cells. Each daughter cell contains one member of each pair of parental homologous chromosomes. In these diagrams, two pairs of homologous chromosomes are shown, large and small. The yellow chromosomes are from one parent (for example, the father), and the violet chromosomes are from the other parent. (e) Prophase II. If chromosomes have relaxed after telophase I, they recondense. Spindle microtubules re-form and attach to the sister chromatids. (f) Metaphase II. Chromosomes line up along the equator, with sister chromatids of each chromosome attached to spindle microtubules that lead to opposite poles. (g) Anaphase II. Chromatids separate into independent daughter chromosomes, one former chromatid moving toward each pole. (h) Telophase II. Chromosomes finish moving to opposite poles. Nuclear envelopes re-form, and the chromosomes become extended again (not shown here). (i) Four haploid cells. Cytokinesis results in four haploid cells, each containing one member of each pair of homologous chromosomes (shown here in condensed state).
Four Haploid Cells
Prophase II
Metaphase II
Anaphase II
Telophase II
Cell Reproduction

26. Protein strands zip together Recombination enzymes snip and rejoin DNA
AP Biology
Crossing Over
Homologues pair up
Protein strands zip together
Recombination enzymes snip and rejoin DNA
Homologs separate with new gene combinations
Figure: 11.15
Title:
The mechanism of crossing over
Caption:
1) Homologous chromosomes pair up side by side. 2) One end of each chromosome binds to the nuclear envelope. Protein strands “zip” homologous chromosomes together. 3) Homologous chromosomes are fully joined by protein strands. 4) Recombination enzymes bind to the chromosomes. Recombination enzymes snip chromatids apart and reattach the chromatids. Chiasmata are formed when one end of a chromatid of a paternal chromosome (yellow) is attached to the other end of a chromatid of a maternal chromosome (violet). 5) The protein strands and recombination enzymes leave as the chromosomes condense. The chiasmata remain as locations where homologous chromosomes are twisted around each other, helping to hold homologues together.
Cell Reproduction

27. Meiosis vs. Mitosis: Comparison of Spindles
AP Biology
Meiosis vs. Mitosis: Comparison of Spindles
Meiosis: Duplicated chromosomes with one kinetochore; Paired homologues go to opposite poles.
Figure: 11.16
Title:
A comparison of the spindles formed during mitosis and meiosis I
Caption:
(a) In mitosis, homologous chromosomes are not paired. The kinetochores of sister chromatids are attached to kinetochore microtubules that lead to opposite poles. When the sister chromatids separate during anaphase, the newly independent daughter chromosomes move to opposite poles of the cell. (b) In meiosis I, homologous chromosomes are paired. Both kinetochores of the sister chromatids of a single chromosome are attached to kinetochore microtubules that lead to the same pole. During anaphase I, sister chromatids of each chromosome remain together, moving to the same pole, but homologous chromosomes separate and move to opposite poles.
Mitosis: Duplicated chromosomes with two kinetochores; Unpaired homologs split between sister chromatids, which go to opposite poles.
Cell Reproduction

28. Meiosis vs. Mitosis: Comparison of Stages
AP Biology
Meiosis vs. Mitosis: Comparison of Stages
Figure: 1.1
Title:
A comparison of mitotic and meiotic cell divisions in animal cells
Caption:
In these diagrams, comparable phases are aligned. In both mitosis and meiosis, chromosomes are replicated during interphase. Meiosis I, with the pairing of homologous chromosomes, formation of chiasmata, exchange of chromosome parts, and separation of homologues to form haploid daughter nuclei, has no counterpart in mitosis. Meiosis II, however, is similar to mitosis.
Cell Reproduction

29. Metaphase Alignment Scenarios
AP Biology
Metaphase Alignment Scenarios
Figure: 11.UN16
Title:
Shuffling of homologues in anaphase I and genetic variability
Caption:
Three pairs of homologous chromosomes will produce eight possible sets of chromosomes in anaphase I.
Cell Reproduction

30. The end