CELL DIVISION (MEIOSIS) Flashcards by KATRINA DENISE REYES

HUMAN HAS HOW MANY SETS OF HOMOLOGOUS CHROMOSOMES?

23 SETS OF HOMOLOGOUS CHROMOSOMES

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EACH HOMOLOGOUS SET IIS MADE UP OF ?

2 HOMOLOGOUS

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21ST SET ADDITIONAL IS CONSIDERED AS ?

DOWN SYNDROME OR OTHER.

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IN HUMANS THE “___ ___” ARE THE 23RD SET

SEX CHROMOSOMES

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> IS A TYPE OF CELL DIVISION THAT REDUCES THE NUMBER OF CHROMOSOMES IN THE PARENT CELL BY HALF AND PRODUCES FOUR (4) GAMETE CELLS (HAPLOID).
THIS PROCESS IS REQUIRED TO PRODUCE EGG AND SPERM CELLS
IN MOST ORGANISMS, TWO SETS OF CHROMOSOMES (DIPLOAD) ARE REDUCED TO ONE SET (HAPLOID).

MEIOSIS

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WHAT ARE THE DIFFERENCES IN THE NUMBER OF CHROMOSOMES BETWEEN MITOSIS AND MEIOSIS?

START (MITOSIS)        START (MEIOSIS)
>46                             >46
END (MITOSIS            END (MEIOSIS)
>46 >46                      >23   >23
                             >23  >23 >23 >23
DIPLOAD                    HAPLOID

PLODY
>DIPLOAD (2n)
>23 CHROMOSOMES (46)
>HAPLOID (1n)
>SINGLE SETS CHROMOSOMES (23)

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THIS PHASE FOCUS ON THE CELL GROWTH AND REPLICATION.

G1 OR GAP 1 PHASE

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DNA REPLICATION.

S OR SYNTHESIS

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CELL UNDERGOES THE FINAL PREPARATIONS.

G2 OR GAP 2 PHASE

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> A.K.A REDUCTION OR HETEROTYPIC DIVISION
REDUCES THE CHROMOSOMES NUMBER IN THE DAUGHTER CELLS.
HOMOLOGOUS CHROMOSOMES ARE PRESENT AT THE BEGINNING.
A COMPLEX DIVISION AND TAKES MORE TIME.
PRECEDED BY INTERPHASE.

MEIOSIS I

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STAGE OF PROPHASE I

>LEPTOTENE
>ZYGOTENE
>PACHYTHENE
>DIPLOTENE
>DIAKINESIS

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CHROMOSOMES START TO CONDESE AND BECOMES VISIBLE (SISTER CHROMATIDS).

LEPTOTENE

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SYNAPTOMENAL COMPLEX FORM AND MEDIATE SYNAPSIS.

ZYGOTENE

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IT IS A PROCESS BY WHICH REPLICATED HOMOLOGOUS PAIR OR CHROMOSOMES COMES TOGETHER.

SYNAPSIS

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CROSSING OVER OCCUR

PACHYTENE

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HOMOLOGOUS PAIRS REMAIN ATTACHED AT “CHIASMATA”.

DIPLOTENE

NUCLEAR MEMBRANE DISINTEGRATES PRIOP METAPHASE I.

DIAKINESIS

PROPHASE I >SIGNIFICANT EVENTS

> CHROMOSOMES ARE NOW VISIBLE
NUCLEAR MEMBRANE AND NUCLEOLUS COMPLETELY DISINTEGRATED.
SPINDLE FIBERS ARE ATTACHED TO THE TETRADS.
TETRADS START TO MOVE TO THE MEMBRANE.

METAPHASE I >SIGNIFICANT EVENTS

> NUCLEAR MEMBRANE ARE COMPLETELY DISINTEGRATED.
CENTROSOMES ARE NOW ON THE OPPOSIT POLE.
TETRADS OR SISTER CHROMOSOMES ARE ALIGNED TO THE METAPHASE PLATE (OR AT THE EQUATOR OF THE CELL).

ANAPHASE I >SIGNIFICANT EVENTS

> SPINDLE FIBERS PULL APART THE SISTER CHROMOSOMES (OR HOMOLOGOUS CHROMOSOMES).
SISER CHROMATIDS ARE STILL ATTACHED TO THE CENTROMERE.

TELOPHASE I >SIGNIFICANT EVENTS

> SISTER CHROMATIDS ARE NOW ON THE OPPOSITE POLE STARTING TO DECONDENSE.
NUCLEAR MEMBRANE AND NUCLEOLUS REAPPEAR.
FORMATION OF CLEAVAGE FURROW.
SPINDLE FIBERS DISAPPEAR.

MEIOSIS I & CYTOKINESIS >SIGNIFICANT EVENTS

> TWO CYTOPLASM OF THE CELL SPLIT INTO TWO, MAKING TWO NEW CELLS (23n(.
MEIOSIS I PRODUCES DAUGTHER CELLS THAT ARE NOT IDENTICAL.

> THE CYTOPLASM OF THE CELL SPLIT INTO TWO, MAKING TWO NEW CELLS (23n).

CYTOKINESIS I

> A.K.A EQUATIONAL DIVISION
EQUALIZES THE CHROMOSOMES NUMBER OF BOTH PARENT AND DAUGHTER CELLS
INDIVIDUAL CHROMOSOMES ARE PRESENTING IN THE BEGINNING.
LESS SIMPLE AND TAKES LESS TIME.
NO INTERPHASE TAKES PLACE.

MEIOSIS II

PROPHASE II >SIGNIFICANT EVENTS

>DECONDENSED CHROMATIDS IN TELOPHASE I, STARTS TO CONDENSE AGAIN. >A NEW SPINDLE FIBERS FORM. >THE NUCLEAR ENVELOPE DISINTEGRATES.

METAPHASE II >SIGNIFICANT EVENTS

>SISTER CHROMATIDS ALIGNED TO THE METAPHASE PLATE OF THE CELL.

ANAPHASE II

>SPINDLE FIBERS PULL APART THE SISTER CHROMATIDS TOWARDS THE OPPOSITE POLE. >NON-KINETOCHORE SPINDLE FIBERS LENGTHEN THE CELL.

TELOPHASE II >SIGNIFICANT EVENTS

>THE NUCLEAR ENVELOPE REAPPEAR AROUND THE FOUR NUCLEI. >CHROMATIDS START TO CONDENSE. >FORMATION OF CLEAVAGE FURROW.

CYTOKINESIS >SIGNIFICANT EVENTS

>FORMATION OF FOUR (4) HAPLOID DAUGTHER CELLS. | >AT THE CONCLUSION OF MEIOSIS, THESE FOUR HAPLOID DAUGTHER CELLS GO ON TO DEVELOP INTO EITHER SPERM OR EGG CELLS.

SIMILARITIES OF MITOSIS AND MEIOSIS

>THEY ARE BOTH "PRECEDED BY INTERPHASE" (WHICH INCLUDES DNA REPLICATION). >THEY BOTH "DIVIDE" ACCORDING TO A "COMMON PATHWAY" (PROPHASE -> METAPHASE -> ANAPHASE -> TELOPHASE). >THEY BOTH "SPLIT THEIR CELLS VIA "CYTOKINESIS".

DIFFERENCES BETWEEN MITOSIS AND MEIOSIS

``` >DIVISION (MITOSIS AND MEIOSIS) >ONE>TWO >SYNAPSIS (MITOSIS AND MEIOSIS) >NO>YES >CROSSING OVER (MITOSIS AND MEIOSIS) >NO>YES >NUMBER OF DAUGHTER CELLS (MITOSIS AND MEIOSIS) >2 D.C>4D.C (MITOSIS AND MEIOSIS) >POIDY (MITOSIS AND MEIOSIS) >DIPLOID>HAPLOID >USE (MITOSIS AND MEIOSIS) >BODY CELL (SOMATIC CELL)>SEX CELL (GAMETES) >GENETICS (MITOSIS AND MEIOSIS) >IDENTICAL D.C>NON-IDENTICAL D.C ```