Chapter 10: Cell Growth and Division 10-1 Cell...

Mitosis Meiosis Genetic Eng (Lang) October 21, 2015

Chapter 10: Cell Growth and Division

10-1 Cell Growth

• All living things are made up of one or more cells, formed by pre-existing cells through the process of cell division.• Organisms grow by producing more cells

• The cells of a small organism are roughly the same size of those of a larger organism


Why do cells divide rather than continue to grow indefinitely?2 reasons:

a) 'DNA overload' - larger cells place more demand on its limited DNA

b) exchanging materials - larger cells have problems moving nutrients and wastes across the cell membrane

• Rate of movement of nutrients in and wastes out of the cell is dependent on cell's surface area.

• Rate of the usage of nutrients and the production of wastes is dependent on the cell's volume.

•As cell size increases, the volume increases at a much faster rate than the surface area.


• Before getting too large, a growing cell divides to form two 'daughter cells'• Before this division, the cell copies off of its DNA and each daughter cell gets a copy

• Cell division is a form of reproduction for some organisms

• Cell division enables the growth and development of organisms, and the renewal and repair of tissues

Cell Division


Life Spans of Various Human Cells

Why do some cells divide extremely rapidly while some divide very infrequently or not at all?


10.2 Cell Division and Mitosis

• Many organisms, particularly unicellualar organisms, reproduce by mitosis• Reproduction by mitosis is asexual• Mitosis is the source of new cells as a particular organism grows and developes

Mitosis: cell division in which the daughter cells recieve the same number of chromosomes as the parent cell.


The Cell CycleThe series of events cells go through as they grow and divide

Consists of four stages:G1 Phase: cell growth

G2 Phase: Preparation for mitosisS Phase: DNA replication

M Phase: Cell Division


Mitosis (Fig. 105)Prophase: centrioles separate to opposite poles,spindle begins to form

Metaphase: each linedup chromosome is attached to a spindle fibre at the centromere

Anaphase: Chromosomeseparation into individual chromatids

Telophase: Chromatidsgather at opposite ends of the cell, two new nuclear envelopes form

Cytokinesis: division of the cytoplasm (along with organelles) between two daughter cells


Part A Circle the best response 1. Which stage of mitosis is pictured in the cell?A) MetaphaseB) AnaphaseC) InterphaseD) Telophase

2. Which of the following is true of mitosis?A) It results in the formation of two haploid daughter cells.B) It results in the formation of two diploid daughter cells.C) It results in two daughter cells that are physically smaller than the parent cell. D) It is considered sexual reproduction.

3. Which answer gives the stages of mitosis in proper chronological order?A) Anaphase, prophase, metaphase, telophaseB) Metaphase, anaphase, telophase, prophaseC) Prophase, metaphase, anaphase, telophaseD) Interphase, prophase, metaphase, anaphase, telophase

4. A cell with 12 chromosomes undergoes mitosis and cell division. How many daughter cells are produced and how many chromosomes does each have?

A) 2 daughter cells, 6 chromosomes eachB) 4 daughter cells, 6 chromosomes eachC) 4 daughter cells, 24 chromosomes eachD) 2 daughter cells, 12 chromosomes each

5. Cell division is completed when which phase is finished:A) mitosisB) cytokinesisC) interphaseD) telophase


Part B Identify the cell cycle stage in which each activity occurs: (I, P, M, A, T, C) 6. Chromosomes become visible7. Cleavage furrow forms8. DNA synthesis occurs9. Nuclear membrane breaks down10. Chromatin reappears

Part C Draw the following:

2n = 6 Telophase 2n = 8 Prophase 2n = 4 Anaphase

Part D State two differences between plant cells and animal cells with respect to the events of mitosis.


Mitosis Animation

http://phschool.com/webcodes10/index.cfm?wcprefix=cbp&wcsuffix=3102&fuseaction=home.gotoWebCode&x=15&y=11

Active Art p. 247

http://www.hybridmedicalanimation.com/work/animation/thestagesofmitosis/

Mitosis 3 D Animation

http://www.youtube.com/watch?v=mx8itzrdV7I

http://www.youtube.com/watch?v=aDAw2Zg4IgEMitosis in a lily cell

http://www.teachersdomain.org/resources/tdc02/sci/life/stru/dnadivide/assets/tdc02_vid_dnadivide/tdc02_vid_dnadivide_56_mov.html

http://www.youtube.com/watch?v=mx8itzrdV7I

http://www.youtube.com/watch?v=aDAw2Zg4IgE


State the Stage of Mitosis 1. Dyads separate into 2 monads. (chromosomes) 2. Asters appear. (star structure that appear around each centriole.) 3. Chromosomes replicate.4. Chromosomes become defined and visible.5. Chromatin in nucleus.6. Dyads line up at equitorial plate.7. Cleavage furrow forms.8. 90% of the cell cycle.9. Centrioles double and move to opposite poles.10. Nuclear membrane reappears.11. Cytokinesis begins.12. Spindle fibres form.13. General cell growth and metabolim.14. Nuclear membrane breaks down.15. Spindle fibres break down.16. Chromatin reforms.17. Single chromatids move to opposite poles.18. 2 nuclei form with 2n chromosome count.19. Cytoplasmic division.20.Cell plate forms in plant cells.

6


103: Regulating the Cell Cycle

• Experiments have shown that controls on cell growth and division can be turned on and off.

• What 'tells' the cells when it is time to divide?

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• Other proteins that aid in the regulation of the cell cycle are grouped into two categories:

Internal Regulators allow the cell cycle to proceed only when certain processes have been completed inside the cell

External Regulators respond to events outside the cell; direct cells to speed up or slow down the cell cyle

• Proteins called cyclins regulate the time of the cell cycle in eukaryotic cells.


Uncontrolled Cell Growth

Cancer cells do not respond to the signals that regulate the growth of most cells

They divide uncontrollably, forming masses called tumors and can spread throughout the body

Many causes: radiation exposure, smoking, viral infections, many unknown

http://www.youtube.com/watch?v=vxeyjEmVtwo

Uncontrolled cell growth

http://www.youtube.com/watch?v=vxeyjEmVtwo

http://www.bing.com/videos/search?q=cancerous+cell+growth+animation&qpvt=cancerous+cell+growth+animation&FORM=VDRE#view=detail&mid=0B79506B3F3C60B48CB90B79506B3F3C60B48CB9


Stem Cell Videos

What does Dr Snyder mean when he says stem cells are "flexible and plastic?"

In this video what evidence convinces you that stem cells can be used to cure spinal cord injury?

Dr Snyder points out that there are ethical concerns, and that there is no single answer that will please everyone. Who do you think should be the ones to decide where to obtain stem cells for medical research?

Seeds of Hope Stem Cell Video

How do Stem Cells work?

http://www.bing.com/videos/search?q=seeds+of+hope+stem+cell+video&qpvt=seeds+of+hope+stem+cell+video+&FORM=VDRE#view=detail&mid=924869E9E31AA70DE9E8924869E9E31AA70DE9E8

https://www.youtube.com/watch?v=cEB8656TCIE


Meiosismechanism of sexual reproduction

• Produce sex cells.

• Results in four haploid daughter cells genetically different from each other and the parent cell

• Before meiosis begins, each chromosome pairs with a homologous counterpart in the cell

http://www.youtube.com/watch?v=UgT5rUQ9EmQ


http://www.youtube.com/watch?v=qCLmR9-YY7o


Crossing Over p.277


MEIOSIS

• THE PROCESS BY WHICH THE SEX CELLS FORM.

Meiosis I

Interphase I• Chromosome (DNA) replication.• General cell metabolism.

Prophase I• Nuclear membrane dissolves.• Centrioles separate and move to opposite poles (after doubling).• Spindle fibers and asters form.• Chromosomes become visible.• Chromosomes come together in HOMOLOGOUS PAIRS (a tetrad).• This action is called SYNAPSIS (grab your partner).

Homologous pairs similar in size shape and gene arrangement. • CROSSING OVER occurs between 2 homologous chromosomes when genetic material is exchanged. See Fig. 1116 p. 277.• chiasmata the site of crossing over.

Metephase I• Homologous chromosomes attach themselves to spindle fibers.• TETRADS line up at random at equitorial plate.

Anaphase I• REDUCTION DIVISION OR SEGREGATION.• Dyads separate and move to opposite poles in the cell. 2n n

Telophase I• Cytokinesis.• Formation of 2 haploid daughter cells that are NOT identical.• In some cell types the nuclear membrane develops, spindle fibers and asters break down, and chromatin is formed.


MEIOSIS II

Interphase II (when necessary) NO DNA replication occurs (chromosomes are already dyads).

Prophase II• Nuclear membrane dissolves.• Spindle fibers form.• Certrioles double, separate and move to opposite poles.

Metaphase II• DYADS line up on equitorial plate.

Anaphase IIChromatids (monads) separate and move to opposite poles (as in mitotic anaphase).

Telophase II• Cytokinesis.• Nuclear membrane develops.• Spindle fibers and asters break down.• 4 haploid daughter cells produced each with unique chromosome configuration because of CROSSING OVER, REDUCTION DIVISION, AND RANDOM ASSORTMENT during metaphase.

** The new gene combinations provide a variety of new traits and therefore new adaptations to the environment that may lead to survival**


Independent Assortment


http://www.sumanasinc.com/webcontent/animations/content/meiosis.html

Meiosis Animation

http://www.youtube.com/watch?v=iCL6d0OwKt8&feature=player_embedded#

Square Dancing

http://www.phschool.com/webcodes10/index.cfm?wcprefix=cbp&wcsuffix=4114&area=view&x=11&y=9

http://www.sumanasinc.com/webcontent/animations/content/meiosis.html

http://www.youtube.com/watch?v=iCL6d0OwKt8&feature=player_embedded#

http://www.phschool.com/webcodes10/index.cfm?wcprefix=cbp&wcsuffix=4114&area=view&x=11&y=9


Gametogenesis

Female uneven cell divisions produce one egg with most of the cytoplasm and three 'polar bodies' which don't participatein reproduction.

Males four equalsized gametes are produced called 'sperm'


The last pair of chromosomes differ in males and females. These are the chromosomes that determine the sex of the organism, called the sex chromosomes.

Females have two xshaped chromosomesMales have one 'x' and one 'y'

Autosomes: nonsex chromosomes


Human Karyotype

Karyotype picture of chromosomes


Abnormal Meiosis p.352Nondisjunction occurs when two homologous pairs move to the same pole during meiosis. Most serious during sex cell formation:

If gamete missing one chromosome joins with normal gamete, resulting zygote will have 45 chromosomes.

Monosomy

If gamete with an extra chromosome joins with normal gamete, resulting zygote will have 47 chromosomes.

Trisomy


Nondisjunction DisordersDown syndrome extra chromosome in chromosome pair number 21.


Nondisjunction of Sex Chromosomes

Chapter 10: Cell Growth and Division 10-1 Cell...

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