REPRODUCTION/CELL DIVISION MEIOSIS

IS DIFFERENT FROM MITOSIS BECAUSE IT REQUIRES FERTILIZATIONS OF AN EGG BY A SPERM

PROCESS THAT PRODUCES EGG AND SPERM

MEIOSIS AND FERTILIZATION OF EGG BY A SPERM

GENETICALLY DIFF FROM PARENTS AND FROM ONE ANOTHER

• BECAUSE
• CROSSING OVER
• INDEPENDENT ASSORTMENT OF CHROMO PAIRS
• RANDOM FERTILIZATION

• 46
• 22PAIRS OF MATCHING HOMOLOGOUS CHROMOSOMES CALLED AUTO SOMES
• TWO DIFFERENT SEX CHROMO X & Y

(OTHER ORGANISMS HAVE DIFF #)

CELLS CONTAIN 2 SETS OF CHROMOSOMES>1 FROM MOTHER 1 FROM FATHER

THEIR GAMETES (EGG AND SPERM) ONLY HAVE 1 SET OF CHROMO

SEXUAL LIFE CYCLES INVOLVES ALTERNATION OF DIPLOID AND HAPLOID STAGES

HOMOLOGOUS PAIR OF CHROMO DIPLOID PARENT

• 1. CHROMO DUPLICATE
• 2. HOMOLOGOUS CHROMO SEPERATE
• 3. SISTER CHROMATID SEPERATE

HAPLOID GAMES ARE PRODUCED BY DIPLOID ORGANISM

OCCCURS IN STES OR PHASES MEOSIS I AND II

HOMOLOGOUS CHROMOS SEPERATE

CHROMOSOMES FORM AND DUPLICATE

HOMOLOGOUS CHROMOS PAIR AND EXCHANGE SEGMENTS

SITE OF CROSSING OVER

TETRADS LINE UP

MICROTUBULES ATTACHED TO CHROMOS

PAIRS OF HOMOLOGOUS CHROMOS SPLIT UP

SISTER CHROMATIDS REMAIN ATTACHED

2 HAPLOID CELLS FORM CHROMO ARE STILL DOUBLED

CLEAVAGE

2 HOMOLOGS ARE JOINED TOGETHER BY A COMPLEX OF PROTEINS

• FROMS TETRAD (BUNDLE OF FOUR)
• CONSIST OF 2 HOMOLOGOUS CHROMO WITH 2 SISTER CHROMATIDS

WHEN CHROMOS ARE IN THIS COMPLEX THEY CAN CROSS OVER

INSCREASES GENETIC VARIATING BY MIXING AND MATCHING THE GENES ON THE HOMOLOGS

• WHEN HOMOLOGOUS CHROMOS ARE LINED UP SIDE BY SIDE
• FATHERS AND MOTHERS DNA CAN MIX AND CHANGE PLACES ON THE CHROMOS

IS IN THE TESTIS PHROPHASE I TAKES ABOUT A WEEK

IN THE EGG CELLS PHROPHASE I BEGINS BEFORE BIRTH IN SOME EGGS CONTINUES FOR 50 YEARS/DEPENDING RELEASE IN MONTHLY OVARIAN CYCLE

4 HAPLOID DAUGHTER CELLS ARE FORMED BY PULLING APART THE SISTER CHROMATIDS

SISTER CHROMATIDS SEPERATE

ALLOWS FOR DIVERSITY

• RESULTS FROM
• CROSSING OVER
• INDEPENDENT ASSORTMENT
• RANDOM FERTILIZATION

EGG CELL IS FETILIZED RAMDOMLY BY ONE SPERM LEADING TO GENETIC VARIENT IN ZYGOTE

MATE CHOSEN AT RANDOM

SPERM CELL THAT GETS TO THE EGG THIS IS RANDOM

MEMEBERS OF A CHROMO PAIR FAIL TO SEPERATED DURING ANAPHASE

GAMETES WITH AN INCORRECT NUMBER OF CHROMO ARE PRODUCE

CONDITION WHERE AN INDIVIDUAL HAS AN EXTRA CHROMO 21

• CALLED TRISOMY 21
• CAN HAPPEN IN SEX CHROMOS

AND ORDERLY ARRANGEMENT OF CHROMOSOMES

HOMOLOGOUS CHROMOS ARE MATCHING PAIRS OF CHROMOS

NODISJUNCTIVE PERSON HAS 3 COPIES OF CHROMO