Cell Growth and Division Chapter 10

By the time you finish reading this sentence, 50 million of your cells will have died and been replaced by others. Some are lost through 'wear and tear’, some just reach the end of their life, and others deliberately self-destruct.

A. Importance of Cell Growth and Division Allows for an organism’s growth Replaces damaged cells Allows cells to maintain the proper surface area-to-volume ratio

WHY CAN’T A CELL JUST KEEP GETTING BIGGER? HOWEVER>>>>The larger a cell becomes, the more demands it places on it’s DNA. It also has more trouble moving nutrients and wastes across the cell membrane.

Allows cells to maintain the proper surface area-to-volume ratio 1. Cells cannot simply grow by increasing in size. Cells of adults and children of a species are the same size.

The Cell membrane determines the surface area of the cell. The volume of a cell is determined by the amount of cytoplasm present with all its contents. As a cell’s size increases, its volume increases much faster than its surface area.        The cell overcomes these problems through the process of cell division.

Ratio of Surface Area to Volume    As the size of a cell increases, its volume increases faster than the surface area. The decrease in the cell’s ratio of surface area to volume makes it more difficult for the cell to move needed materials in and waste products out quickly enough for the cell to survive.

Find surface area

Find surface area

Find surface area

Find surface area

Find Volume

Find Volume

Find Volume

Find Volume

Find Ratio

Find Ratio

Find Ratio

Find Ratio

How do little elephants grow up to be BIG elephants?

Why do animals shed their skin?

Cell Division! More next time! Quiz over Ch 10.1 Cell Growth Next Time

Regulating Cell Division (Cell Cycle) Cells stop growing when they come in contact with each other-such as when a wound is healing

a. Internal Cyclins-usually controls cell division events inside the cell like the beginning and end of cell cycle stages. Cyclins-proteins within the cell that regulate the timing of eukaryotic cell division b. External Cyclins -for events outside the cell. These usually speed up or slow down the cell cycle and heal wounds.

CANCER Occurs when cells do not respond to normal signals that regulate growth *Most cancer cells have defect in the p53 gene

Malignant Tumor-invasive uncontrolled growth of cells Skin Cancer Benign Tumor-a tumor that only grows in one place. Noninvasive and usually treatable

Cell Division! Ch 10.2

Cell Reproduction Prokaryotes Bacteria Eukaryotes Plants & animals

Prokaryotes Lack a nucleus Have a single chromosome Reproduce asexually by binary fission Include bacteria

Steps in Binary Fission Cells increase their cell mass slightly DNA & cell components are replicated Each cell divides into 2 daughter cells

Binary Fission of Bacterial Cell

E. Coli Dividing by Binary Fission

Eukaryotes Contain a nucleus & membrane bound organelles Asexually reproduce cells by mitosis

Vocabulary Mitosis = division of the cell nucleus and its contents Cytokinesis = the division of cell cytoplasm into two identical daughter cells Chromatin = the combination of DNA and histone proteins Chromosome-main organelle involved in Cell Cycle Diploid = Two copies of each chromosome, one paternal, one maternal

Chromosomes in the Larger Scheme

Chromosome Structure 1 – Chromatid-because each has an identical half they are “sister” chromatids 2 – Centromere 3 – Short arm 4 – Long arm

Chromosomes Made from DNA Formed from chromatin Genetic material directs activities determines characteristics Formed from chromatin Uncoiled DNA 4/16/2017

From: http://www.rothamsted.bbsrc.ac.uk/ Chromosomes (cont.) Each chromosome (at this point) is made up of 2 identical chromatids Joined strands of identical duplicated genetic material Joined at centromere Chromatids separate and each cell has identical information Formed in S phase of cell cycle 4/16/2017 From: http://www.rothamsted.bbsrc.ac.uk/ notebook/courses/guide/chromo.htm

From: http://www.accessexcellence.org/RC/VL/GG/nucleosome.html 4/16/2017

4/16/2017

Sets of chromosomes Each human somatic (body) cell 23 pairs of chromosomes (46 total) Homologous chromosomes Each pair is called homologous Similar in size, shape and genetic content Not identical! One from each parent 4/16/2017

4/16/2017

Cell Cycle Interphase Mitosis - Division of the nucleus G1 - growth and normal cell activity G0 – never divides again S - Synthesis of DNA DNA replication G2 - Growth for division, organelles double Mitosis - Division of the nucleus Cytokinesis - Division of the cytoplasm (cell) 4/16/2017

Cell Cycle Stages in growth & division G1 Phase S Phase G2 Phase M Phase Cytokinesis

Growth for division Organelles double Growth & normal cell activity G0 DNA replication 4/16/2017

Length of cell cycle Ranges from 20 minutes to 20 hours Some cells divide constantly and others never divide Muscle cells Red Blood cells Skin cells Bone cells Nerve cells 4/16/2017

G1 Phase First growth stage Cell increases in size Cell prepares to copy its DNA

Synthesis (S) Phase Copying of all of DNA’s instructions Chromosomes duplicated

G2 Phase Time between DNA synthesis & mitosis Cell continues growing Needed proteins produced

Mitosis A process in which eukaryotic cells form two identical nuclei. Significance of the process of mitosis Mitosis A process in which eukaryotic cells form two identical nuclei. Each cell receives a complete set of chromosomes division of the nucleus Cytokinesis division of the cytoplasm 2 independent cells (genetically identical) Different in plant and animals 4/16/2017

M Phase Cell growth & protein production stop Cell’s energy used to make 2 daughter cells Called mitosis or karyokinesis (nuclear division)

Life Cycle of a Cell Mitosis is a cycle with no beginning or end.

Interphase – Resting Stage Cells carrying on normal activities Chromosomes aren’t visible Cell metabolism is occurring Occurs before mitosis

Interphase

D. Stages of Mitosis Prophase Metaphase Anaphase Telophase

Major Events in Mitosis

Cells Undergoing Mitosis

Steps in Prophase DNA coils tightly & becomes visible as chromosomes Nuclear membrane disappears Nuceolus disappears Centrioles migrate to poles Spindle fibers begin to form and the chromosomes attach

Eukaryotic Chromosome Spindles attach here

Prophase Plant Cell Animal Cell Spindle fibers Centrioles Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Steps in Metaphase Spindle fibers from centrioles attach to each chromosome Cell preparing to separate its chromosomes Cell aligns its chromosomes in the middle of the cell

Metaphase

Metaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Steps in Anaphase Cell chromosomes are separated Spindle fibers shorten so chromosomes pulled to ends of cell

Mitotic Spindle

Anaphase

Anaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Steps in Telophase Separation of chromosomes completed Cell Plate forms (plants) Cleavage furrow forms(animals) Nucleus & nucleolus reform Chromosomes uncoil

Telophase        Plant             Animal

Telophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Cytokinesis Occurs after chromosomes separate Forms two, identical daughter cells

Cytokinesis Cell Plate Forming in Plant Cells

Animal Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

Plant Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

4/16/2017 From: http://www.kumc.edu/instruction/medicine/anatomy/histoweb/cytology/large/Cyt001.JPG

4/16/2017 http://virtual.yosemite.cc.ca.us/randerson/Lynn's%20Bioslides/45.jpg

4/16/2017 http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20101/Bio%20101%20Laboratory/ Mitosis/Photographs/whitefish_mitosis_prophase_metaphase_anaphaseX400.jpg

4/16/2017 http://faculty.clintoncc.suny.edu/faculty/michael.gregory/ files/Bio%20101/Bio%20101%20Laboratory/Mitosis /Photographs/whitefish_mitosis_telophaseX400.jpg http://faculty.clintoncc.suny.edu/faculty/michael.gregory/ files/Bio%20101/Bio%20101%20Laboratory/ Mitosis/Photographs/whitefish_mitosis_anaphaseX400.jpg 4/16/2017

Quiz Next time!

Regulating Cell Division (Cell Cycle) Cells stop growing when they come in contact with each other-such as when a wound is healing

a. Internal Cyclins-usually controls cell division events inside the cell like the beginning and end of cell cycle stages. Cyclins-proteins within the cell that regulate the timing of eukaryotic cell division b. External Cyclins -for events outside the cell. These usually speed up or slow down the cell cycle and heal wounds.

Malignant Tumor-invasive uncontrolled growth of cells Skin Cancer Benign Tumor-a tumor that only grows in one place. Noninvasive and usually treatable

CANCER Occurs when cells do not respond to normal signals that regulate growth *Most cancer cells have defect in the p53 gene

Make a little book Page one – Title Page two – interphase including G1, S, G2 Page three – prophase Page four – metaphase Page five – anaphase Page six – telephase Page seven – cytokinesis Page eight – the end

Test information Cell Cycle Mitosis completed Chromosomes Mitosis Order S phase Cancer Interphase Mitosis completed What does each cell have? Chromosomes Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis 4/16/2017