week 7 mitosis and genetics

7/22/2019 Week 7 Mitosis and Genetics

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Cell ReproductionChapter 9 &10

Biology 114

Developed By Adam F. Sprague

Ocean County College


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OBJECTIVES:

Describe the structure of a chromosome.

Compare prokaryotic chromosomes with

eukaryotic chromosomes. Explain thedifferences between sex chromosomes and

autosomes. Give examples of diploid and

haploid cells.


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CHROMOSOMES

DNA is a long thin

molecule that stores

Genetic Information.The DNA in a human

cell is estimated to

consist of six billion

pairs of nucleotides.
http://rds.yahoo.com/S=96062857/K=DNA/v=2/SID=e/l=II/R=7/SS=i/OID=dd6303a61a4ba0b8/SIG=1ia977hi1/EXP=1131197856/*-http%3A//images.search.yahoo.com/search/images/view?back=http%3A%2F%2Fimages.search.yahoo.com%2Fsearch%2Fimages%3Fp%3DDNA%26sm%3DYahoo%2521%2BSearch%26fr%3DFP-tab-img-t%26toggle%3D1%26cop%3D%26ei%3DUTF-8&h=480&w=435&imgcurl=www.lakemichigancollege.edu%2Fliberal%2Fbio%2Fpics%2FDNA.gif&imgurl=www.lakemichigancollege.edu%2Fliberal%2Fbio%2Fpics%2FDNA.gif&size=52.8kB&name=DNA.gif&rcurl=http%3A%2F%2Fwww.lmc.cc.mi.us%2Fliberal%2Fbio%2Fbio212%2Fgenetic.html&rurl=http%3A%2F%2Fwww.lmc.cc.mi.us%2Fliberal%2Fbio%2Fbio212%2Fgenetic.html&p=DNA&type=gif&no=7&tt=285,519&ei=UTF-8


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CHROMOSOME

STRUCTURE

1. During Cell Division, the DNA (CHROMATIN) in an Eukaryotic Cell's

Nucleus is coiled into very tight compact structures called CHROMOSOMES

2. Chromosomes are Rod Shaped structures made of DNA and Proteins.

3. The Chromosomes of stained Eukaryotic cells undergoing cell division arevisible as darkened structures inside the Nuclear Membrane.

4. The DNA in Eukaryotic cells wraps tightly around Proteins called

HISTONES. They help to maintain the shape of Chromosomes and aid in the

tight packing of DNA.

5. Proteins called NONHISTONEProteins Do Not participate in packing ofDNA, they are involved in Controlling the Activity of Specific Regions of the

DNA.


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CHROMOSOME

STRUCTURE

6. When preparing for Cell Division, Chromosomes form Copies of

themselves, Each half of the Chromosome is called a CHROMATID or

SISTER CHROMATIDS. Chromatids form as the DNA makes copies of

itself before cell division. (Figure 8-2)

7. The constricted area of each Chromatid is called a CENTROMERE. The

Centromere holds the Two Chromatids together until the separate during Cell

Division.

8. Between Cell Division, DNA IS NOT so Tightly Coiled into Chromosomes.

The Less tightly coiled DNA-Protein complex is called CHROMATIN.

9. Chromosomes are simpler in prokaryotes. The DNA of most Prokaryotes

comprises only ONE Chromosome, which is attached to the inside of the Cell

Membrane.

10. Prokaryotic Chromosomes consist of a circular DNA Molecule and

associated Proteins.


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CHROMOSOME NUMBERS

1. EACH HUMAN BODY CELL CONTAINS 46 CHROMOSOMES, (2n)

OR TWO COMPLETE SETS.

2. ANY CELL THAT CONTAINS TWO COMPLETE SETS OF

CHROMOSOMES IS CALLED A DIPLOID CELL. A Diploid Cell iscommonly abbreviated as 2n.

3. THE NUMBER OF CHROMOSOMES IN A DIPLOID CELL IS CALLED

THE DIPLOID NUMBER. EVERY ORGANISM HAS A

CHARACTERISTIC DIPLOID NUMBER (2n).

4. EXAMPLES: FRUIT FLIES - 8, LETTUCE - 14, GOLDFISH 94, ANDHUMANS 46.

5. A CELL WITH ONLY ONE COMPLETE SETOF CHROMOSOMES IS

CALLED A HAPLOID CELL.

A Haploid Cell is abbreviated as 1n.


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CHROMOSOME NUMBERS

6.GAMETES, EGGS AND SPERM CONTAIN ONLY ONE COMPLETE

SET. EACH HUMAN SPERM OR EGG (GAMETE) CONTAINS 23

CHROMOSOMES, THE HAPLOID NUMBER (1n) FOR ALL

HUMANS.

7. WHEN AN EGG AND A SPERM OF THE SAME TYPE OF ORGANISM

JOIN TO PRODUCE A NEW INDIVIDUAL, THE PROCESS IS CALLEDFERTILIZATION.

8. THE SINGLE CELL THAT RESULTS FROM FERTILIZATION IS

KNOWN AS A ZYGOTE.THE ZYGOTE CONTAINS TWO COMPLETE

SETS OF CHROMOSOMES, ONE SET FROM EACH GAMETE,

FORMING A DIPLOID CELL. IN MOST MULTICELLULARORGANISMS, THE ZYGOTE IS THE FIRST CELL OF THE NEW

INDIVIDUAL.

9. The Chromosomes in the Zygote exist in PAIRS. For every Chromosome

that was in the egg, there is a matching Chromosome from the sperm.

10. Human and Animal Chromosomes are categorized as eitherSEXCHROMOSOMES or AUTOSOMES.


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CHROMOSOME NUMBERS

11.SEX CHROMOSOMESare Chromosomes that Determine the SEX of an

Organism.

12. In Humans, Sex Chromosomes are either X or Y. Females have TWO X

Chromosomes and Males have an X and Y Chromosome. 13. All the Other Chromosomes in an Organism are called AUTOSOMES.

14. TWO of the 46 Human Chromosomes are Sex Chromosomes, while the

reaming 44 are Autosomes.

15. MATCH SET OF AUTOSOMES IN A DIPLOID CELL ARE CALLED

HOMOLOGOUS PAIRS. BOTH CHROMOSOMES IN A HOMOLOGOUSPAIR CONTAIN INFORMATION THAT CODE THE SAME TRAIT

(GENES). Example Eye Color.


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CELL DIVISION

CELL DIVISION IN PROKARYOTES

1. BINARY FISSIONis the Division of a

Prokaryotic cell INTO TWO Offspring

Cells.

2. Binary Fission consist of THREE

General Stages:


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THREE General Stages

STAGE 1- The Chromosome, which is

attached to the Inside of the Cell

Membrane, makes a COPY of Itself,

Resulting in Two Identical

Chromosomes Attached to the Inside ofthe Inner Cell Membrane.

STAGE 2- The Cell continues to grow

until it reaches approximately TWICE

its Normal Size. Then a CELL WALL

Begins forms between the Two

Chromosomes.

STAGE 3- The Cell SPLITS into

TWO NEW CELLS. Each New Cell

contains on the Identical Chromosomes.


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CELL DIVISION IN

EUKARYOTES

THE PHASES OF

LIFE OF A CELL

ARE CALLED THECELL CYCLE.

THE CELL CYCLE

CONSISTS OF

THREE PHASES:A. INTERPHASE

B. MITOSIS

C. CYTOKINESIS.


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MITOSIS

is a Series of PHASES in Cell Division

during which the NUCLEUS of a Cell

Divides into TWO NUCLEI WITHIDENTICAL GENETIC MATERIAL.

MITOSIS OCCURS ONLY IN

EUKARYOTES.


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INTERPHASE CONSIST OF

THREE PHASES:

A. G1 PHASE- PERIOD OF NORMAL METABOLIC CELLULAR

ACTIVITIES: THE NUMBER OF ORGANELLES AND AMOUNT OF

CYTOPLASM IN A CELL INCREASE. Offspring Cells Grow to Mature

Size.

B. S PHASE- THE GENETIC MATERIAL (DNA) IS DUPLICATED

(COPIED). THE CHROMOSOMES OF THE CELL REPLICATE.

C. G2 PHASE- Structure directly involved with mitosis are formed. The Cell

makes the Organelles and substances it needs for Cell Division. A time during

which the Cell prepares to divide.


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CELL DIVISION INVOLVES TWO

STEPS: CALLED MITOTIC CELL

DIVISION.

A. MITOSIS - FIRST STEP. A SERIES OF

PHASES IN CELL DIVISION DURING WHICH

THE NUCLEUS OF A CELL DIVIDES INTOTWO NUCLEI WITH IDENTICAL GENETIC

MATERIAL.

B. CYTOKINESIS - SECOND STEP. THE

CYTOPLASM OF THE CELL DIVIDES INTOTWO NEW CELLS CALLED DAUGHTER

CELLS.


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MITOSIS

The FOUR Phases of Mitosis are called

PROPHASE, METAPHASE, ANAPHASE,

AND TELOPHASE. (Figure 8-6) THE ACTUALLY PROCESS OF MITOSIS IS

CONTINUOUS.

MITOSIS IS THE PROCESS BY WHICH A

NUCLEUS GIVES RISE TO TWO

IDENTICAL NUCLEI.


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FOUR PHASES OF MITOSIS


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PHASE 1- PROPHASE

1. Chromatin condenses into Chromosomes of TWO Sister Chromatids joined

together by the CENTROMERE, and visible when viewed through a

microscope.

2. THE NUCLEOLUS AND NUCLEAR MEMBRANE DISAPPEAR. 3. TWO Structures called CENTROSOMESappear next to the Disappearing

Nucleus. In Animal Cells, each Centrosome contains a pair of small,

cylindrical bodies called CENTRIOLES. Plant Cells lack Centrioles.

4. In BOTH Animal and Plant Cells, the Centrosomes move toward opposite

poles of the cell. As they Separate, SPINDLE FIBERSmade of microtubulesradiate from the Centrosomes in preparation for Mitosis. The array of Spindle

fibers is called the MITOTIC SPINDLE, whichserves to Equally divides the

Sister Chromatids between the Two Offspring Cells.


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PHASE 2 - METAPHASE

1. The Chromosomes are moved to the

CENTER of the CELL (Equatorial Plane)

by the Kinetochore Fibers attached to theCentromeres.

2. The Two Sister Chromatids of each

Chromosome are attached to KinetochoreFibers radiating from OPPOSITE ENDS OF

THE CELL.


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PHASE 3 - ANAPHASE

The Centromeres of Each Chromosome are

pulled by the Kinetochore Fibers toward the

ends of the cell (OPPOSITE POLES).

2. THE SISTER CHROMATIDS ARE

THUS SEPARATED FROM EACH

OTHER. They are now Considered to beIndividual Chromosomes


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PHASE 4 - TELOPHASE

1. After the Chromosomes reach opposite ends of the Cell, the Spindle Fibers

Disassemble.

2. The Chromosomes return to less tightly coiled Chromatin State.

3. New Nuclear Envelope begins to form around the Chromosomes at each endof the cell.

4. CYTOKINESIS BEGINS.

5. THE PROCESS OF MITOSIS IS NOW COMPLETE. THE CELL

MEMBRANE BEGINS TO PINCH THE CELL IN TWO AS CYTOKINESIS

BEGINS.


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CYTOKINESIS

1. Following the last phase of Mitosis, Cytokinesis COMPLETES the

process of Cell Division.

2. During Cytokinesis, the Cytoplasm of a cell and its ORGANELLES

SEPARATE INTO TWO NEW DAUGHTER CELLS.

3. Cytokinesis proceeds differently in animal and plant cells.

4. CYTOKINESIS OF ANIMAL CELLS:The Cytoplasm Divides when a

GROOVE called the CLEAVAGE FURROWforms through the Middle of

the Parent Cell. The Cleavage Furrow Deepens until the parent cell pinches

into TWO New Identical Cells. The New Cells are Now in INTERPHASE. 5. CYTOKINESIS OF PLANT CELLS: In a Plant Cell, the material for

NEW CELL WALL CALLED THE CELL PLATEAND MEMBRANES

GATHER AND FUSE ALONG THE EQUATOR, OR MIDDLE OF THE

CELL, BETWEEN TWO NUCLEI. Forming TWO New Identical Cells.


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MEIOSIS

Objectives:

List and describe the phases of meiosis.

Compare the end products of mitosis with

those of meiosis.

Explain crossing-over and how it

contributes to the production of unique

individuals.

Summarize the major characteristics of

spermatogenesis and oogenesis.


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MEIOSIS facts 1. Most organisms are capable of COMBINING CHROMOSOMES FROM

TWO PARENTS TO PRODUCE OFFSPRING.

2. WHEN CHROMOSOMES OF TWO PARENTS COMBINE TO

PRODUCE OFFSPRING, THE PROCESS IS KNOWN As SEXUAL

REPRODUCTION.

3. THE CHROMOSOMES THAT COMBINE DURING SEXUAL

REPRODUCTION ARE CONTAINED IN SPECIAL REPRODUCTIVE

CELLS CALLED GAMETES.

4. IN MOST ORGANISMS, GAMETES CAN BE EITHER EGG OR

SPERM.

5. EGGS are larger than sperm and contain a lot of Cytoplasm. An egg is

nonmotile.

6. SPERM Cellscontain very little Cytoplasm, have Flagella, that helps them

swim to the nonmotile egg.

7. The Chromosomes of Two Gametes are added together when they join. The

number of Chromosomes in the offspring DOES NOT DOUBLE WITH

EACH GENERATION, BUT REMAINS THE SAME BECAUSE OF

MEIOSIS.

M i i f t


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Meiosis facts 8. MEIOSISIS THE WAY MANY ORGANISMS PRODUCE GAMETES THROUGH

A TYPE OF CELL REPRODUCTION.

9. MEIOSIS IS A TYPE OF NUCLEAR DIVISIONIN WHICH THE

CHROMOSOME NUMBER IS HALVED. LIKE MITOSIS, MEIOSIS ISFOLLOWED BY CYTOKINESIS.

10. IN HUMANS SPECIALIZED REPRODUCTIVE CELLS WITH 46

CHROMOSOMES (2n) (DIPLOID CELL) UNDERGO MEIOSIS AND

CYTOKINESIS TO GIVE RISE TO EGG OR SPERM THAT HAVE ONLY 23

CHROMOSOMES (1N) (HAPLOID CELL) EACH.

11. MEIOSIS ONLY OCCURS IN EUKARYOTIC CELLS IN PHASES SIMILAR TOTHE PHASES OF MITOSIS.

12. MEIOSIS IS DIFFERENT FROM MITOSIS IN SOME VERY IMPORTANT

WAYS.

A. The process of meiosis results in the production of Daughter Cells that have HALF

THE NUMBER OF CHROMOSOMES OF THE PARENT CELL (HAPLOID CELL). B. Daughter Cell produced by meiosis ARE NOT ALL ALIKE. THE DAUGHTER

CELLS MAY HAVE DIFFERENT CHROMOSOMES FROM EACH OTHER.

C. The NUMBER OF CELLS PRODUCED BY MEIOSIS IS DIFFERENT.

(1) Mitosis - One Parent Cell PRODUCES TWO DIPLOID DAUGHTER CELLS.

(2) Meiosis - One Parent Cell PRODUCES FOUR HAPLOID DAUGHTER CELLS.


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STAGES OF MEIOSIS

THE PROCESS OF MEIOSIS SEPARATES THE PAIRS OF

CHROMOSOMES IN A DIPLOID CELL TO FORM HAPLOID CELLS.

2. ONE PARENT CELL DIVIDES TWICETO PRODUCE FOUR

HAPLOID DAUGHTER CELLS.

3. DURING MEIOSIS, THE NUMBER OF CHROMOSOMES IN EACH

CELL IS REDUCED FROM DIPLOID TO HAPLOID BY SEPARATING

HOMOLOGOUS PAIRS OF CHROMOSOMES.

4. MEIOSIS PROCEEDS IN TWO MAIN STAGES:


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A. MEIOSIS I HOMOLOGOUS PAIRS ARE

SEPARATED.


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B. MEIOSIS II THE SISTER CHROMATIDS

OF EACH CHROMOSOME ARE

SEPARATED.


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MEIOSIS I

1. AT THE START OF MEIOSIS I EACH

CHROMOSOME CONSIST OF TWO STRANDS OF

SISTER CHROMATIDS CONNECTED AT THE

CENTROMERE.

2. HOMOLOGOUS PAIRS OF CHROMOSOMES

COME TOGETHER BEFORE MEIOSIS BEGINS, AN

EVENT THAT DOES NOT OCCUR IN MITOSIS. THIS

EVENT IS CALLED SYNAPSIS.

3. Each Pair of Homologous Chromosomes is called a

TETRAD.


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PROPHASE I. 1. Chromosomes become thick and

visible, the chromosomes of eachhomologous pair are tangled together.

2. Portions of Chromatids may Break

Off and attach to Adjacent Chromatids

on the homologous Chromosome - a

process calledCROSSING-OVER.

(Figure 8-10)

3. Crossing-Over results in Genetic

Recombination by producing a New

Mixture of Genetic Material.

4. Each pair consists of FOUR

CHROMATIDS, BECAUSE EACHCHROMOSOME IN THE PAIR HAD

REPLICATED BEFORE MEIOSIS

BEGAN.

5. The Nucleoli and the Nuclear

Envelope disappear and the spindle

fibers form.

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