MEIOSIS AND SEXUAL REPRODUCTION

MEOISIS AND SEXUAL REPRODUCTION

WHAT ARE THE TWO TYPES OF CELL DIVISION?◦MITOTIC CELL DIVISION

CREATE “IDENTICAL” OFFSPRING

ONLY ONE PARENT CELL◦MEIOTIC CELL DIVISION

CREATE SIMILAR, BUT DIFFERENT, OFFSPRING REQUIRES TWO DIFFERENT PARENT CELLS

MEOISIS AND SEXUAL REPRODUCTION

WHY HAVE TWO DIFFERENT FORMS OF CELL DIVISION?◦WHY NOT JUST HAVE EVERY CELL BE

“IDENTICAL” TO EVERY OTHER CELL?IN ORDER TO MAKE “DIFFERENT” CELLS,

GENETIC MATERIAL NEEDS TO BE COMBINED IN DIFFERENT WAYS…HENCE, MEIOTIC CELL DIVISION◦MEOISIS GAMETOGENESIS FERTILIZATION

MEOISIS AND SEXUAL REPRODUCTION

IN ORDER TO UNDERSTAND MEIOTIC CELL DIVISION, WE HAVE TO UNDERSTAND A LITTLE BIT MORE ABOUT THE GENETIC INFORMATION FOUND IN CELLS

MEOISIS AND SEXUAL REPRODUCTION

ALL LIVING THINGS HAVE DNA, THE BLUEPRINTS FOR LIFE, WHICH IS STORED INSIDE THE NUCLEUS IN SOME SET NUMBER OF CHROMOSOMES (THIS # IS DIFFERENT FOR DIFFERENT LIVING THINGS)

MEOISIS AND SEXUAL REPRODUCTION

HOW MANY CHROMOSOMES DO HUMANS HAVE?

MEOISIS AND SEXUAL REPRODUCTION

IN ORDER FOR SEXUAL REPRODUCTION TO OCCUR, TWO PARENT CELLS MUST COMBINE…BUT YOU CAN’T CHANGE THE TOTAL CHROMOSOME NUMBER IN THE CELL

THEREFORE, SOMETHING HAS TO HAPPEN TO KEEP THE SAME CHROMOSOME NUMBER AT ALL TIMES

MEOISIS AND SEXUAL REPRODUCTION

DIPLOID VS HAPLOID CELLS◦MOST BODY (SOMATIC) CELLS

ARE DIPLOID CONTAINING THE FULL AMOUNT

OF DNA◦SEX CELLS (GAMETES) ARE

HAPLOID CONTAINING HALF THE AMOUNT

OF DNA

MEOISIS AND SEXUAL REPRODUCTION

WHY DO YOU NEED HAPLOID CELLS?◦SO WHEN THEY COMBINE, THE CORRECT

CHROMOSOME NUMBER IS RESTOREDWHAT IS THE HAPLOID NUMBER IN

HUMANS?◦23

WHAT DO HAPLOID CELLS LOOK LIKE IN HUMANS?◦SPERM AND EGG

MEOISIS AND SEXUAL REPRODUCTION

HOW DO HAPLOID CELLS GET MADE?◦MEIOTIC CELL DIVISION!!!

MEIOSIS IS ALSO CALLEDREDUCTION-DIVISION

LET’S BREAK DOWNTHE STAGES OF MEIOSIS

MEOISIS AND SEXUAL REPRODUCTION

MITOSIS VS MEIOSIS

MEOISIS AND SEXUAL REPRODUCTION

WHAT’S THE POINT OF MEIOTIC CELL DIVISION?◦TO MAKE CELLS THAT CAN BE COMBINED TO

CREATE NEW GENETIC COMBINATIONS IN OFFSPRING CELLS

WHY BOTHER WITH NEW GENETIC COMBINATIONS?

THE PROCESS OF COMBINING THESE SEX CELLS IS CALLED SEXUAL REPRODUCTION (THE FUSION OF GAMETES)

MEOISIS AND SEXUAL REPRODUCTION

SEXUAL REPRODUCTION◦IN BACTERIA AND PROTISTS

MEOISIS AND SEXUAL REPRODUCTION

SEXUAL REPRODUCTION IN ANIMALS◦ANIMALS POSSES REPRODUCTIVE SYSTEMS

SPECIALIZED STRUCTURES (GONADS) THAT PRODUCE GAMETES◦MALE VS FEMALE◦HERMAPHRODITE◦GAMETOGENESIS

SPERMATOGENESIS OOGENESIS

◦FERTILIZATION INTERNAL VS EXTERNAL

◦PARTHENOGENESIS

MEOISIS AND SEXUAL REPRODUCTION

WHAT HAPPENS WHEN THE SPERM AND EGG FUSE?◦FERTILIZATION◦ANIMAL

(EMBRYONIC)DEVELOPMENT ISNEXT!!