MEIOSIS AND SEXUAL REPRODUCTION
Dec 29, 2015
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
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!!