THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT

“LIKE BEGETS LIKE…MORE OR LESS” ASEXUAL REPRODUCTION VS. SEXUAL REPRODUCTION – ASEXUAL  DEFINITION? – SEXUAL  DEFINITION? HOW DO OFFSPRING OF PARENTS FROM SEXUAL REPRODUCTION COMPARE TO THEIR PARENTS? EACH OTHER? NON-RELATED ORGANISMS? CHROMOSOMES – DEFINITION??

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CELLS ARISE ONLY FROM PRE-EXISTING CELLS THE PERPETUATION (CONTINUATION) OF LIFE, IN ALL ITS ASPECTS RELIES ON THE PRINCIPLES OF CELLULAR REPRODUCTION CELL DIVISION = CELLULAR REPRODUCTION

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CELL DIVISION PLAYS THREE MAJOR ROLES – 1) ?? – 2) ?? – 3) ??

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT PROKARYOTES REPRODUCE BY BINARY FISSION – MOST PROKARYOTES HAVE A SINGLE, CIRCULAR CHROMOSOME – EVEN COPYING A SINGLE CIRCULAR CHROMOSOME CAN BE EXTREMELY DIFFICULT

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT THE LARGE, COMPLEX CHROMOSOMES OF EUKARYOTES DUPLICATE WITH EACH CELL DIVISION

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CHROMOSOMES ARE ONLY VISIBLE DURING ACTIVE CELL DIVISION CHROMOSOME  ?? CHROMATIN  ?? SISTER CHROMATIDS  ?? CENTROMERE  ??

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT THE CELL CYCLE MULTIPLIES CELLS – CELLS DIVIDE TO (OTHER THAN REPRODUCE) GROWTH AND DEVELOPMENT REPLACE LOST/DEAD CELLS – CELL CYCLE AN ORDERLY SEQUENCE OF EVENTS THAT EXTENDS FROM THE TIME A CELL DIVIDES TO FORM 2 DAUGHTER CELLS TO THE TIME THESE DAUGHTER CELLS DIVIDE AGAIN

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT

INTERPHASE  ?? – G1 – S – G2 MITOTIC PHASE (CELL DIVISION)  ?? – MITOSIS – CYTOKINESIS

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CELL DIVISION IS A CONTINUUM OF DYNAMIC CHANGES CELL DIVISION IS A CONTINUUM OF DYNAMIC CHANGES

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT MITOSIS IS BROKEN UP INTO 4 MAIN STAGES – PROPHASE – METAPHASE – ANAPHASE – TELOPHASE

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT SPECIAL STRUCTURES THAT ASSIST MITOSIS – MITOTIC SPINDLE – CENTROSOMES (2 CENTRIOLES) ONLY IN ANIMAL CELLS!!!

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CYTOKINESIS – DIVISION OF THE CELL MEMBRANE TO FORM TWO DISTINCT CELLS – DIFFERS BETWEEN PLANT AND ANIMAL CELLS – WHY??

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CLEAVAGE VS CELL PLATE FORMATION

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT DO YOU THINK IT IS GOOD FOR CELLS TO CONSTANTLY BE DIVIDING? – ANCHORAGE, CELL DENSITY, AND CHEMICAL GROWTH FACTORS IMPACT CELL DIVISION ANCHORAGE  ?? DENSITY-DEPENDENCE  ??

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT GROWTH FACTORS – PROTEIN SECRETED BY A CELL THAT STIMULATES CELL DIVISION IN NEARBY CELLS – IMPACT THE CELL CYCLE CONTROL SYSTEM – THIS PARTICULAR ASPECT OF BIOLOGY IS BEING CLOSELY STUDIED TO BETTER UNDERSTAND CANCER!!

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CANCER – DEFINITION  ?? – TUMOR  ?? – BENIGN VS MALIGNANT – METASTASIS

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT FOUR CATEGORIES OF CANCER – CARCINOMA – SARCOMA – LEUKEMIA – LYMPHOMA TWO MAJOR TYPES OF TREATMENT – CHEMOTHERAPY – RADIATION THERAPY

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT REVIEW – ROLE OF MITOTIC CELL DIVISION 1) 2) 3) – REMEMBER, MITOTIC CELL DIVISION RESULTS IN THE SAME NUMBER AND TYPES OF CHROMOSOMES IN THE DAUGHTER CELLS!!!

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT BEFORE WE CAN DISCUSS SEXUAL REPRODUCTION, WE NEED TO UNDERSTAND A BIT MORE ABOUT CHROMOSOMES… ORGANISMS TYPICALLY HAVE TWO GENERIC TYPES OF CELLS – SOMATIC CELLS – SEX CELLS (GAMETES)

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT SOMATIC CELLS CONTAIN HOMOLOGOUS PAIRS OF CHROMOSOMES – HOMOLOGOUS CHROMOSOMES  ??

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT TWO GENERAL TYPES OF CHROMOSOMES – AUTOSOMES – SEX CHROMOSOMES WHAT IS A “LOCUS”?

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT SEX CELLS (GAMETES) TYPICALLY ONLY HAVE A SINGLE SET OF CHROMOSOMES (LACK HOMOLOGOUS PAIRS) – WHY IS THIS IMPORTANT?? (WHAT HAPPENS IN SEXUAL REPRODUCTION??) TERMS RELATED TO CHROMOSOMES NUMBER – DIPLOID – HAPLOID

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT

WHAT IS FERTILIZATION? – DEFINITION WHAT IS A ZYGOTE? – DEFINITION IF YOU ARE FROM THE FUSION OF TWO HAPLOID CELLS, HOW DO YOU CREATE A HAPLOID CELL? CAN YOU USE MITOTIC CELL DIVISION FOR THIS?

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT MEIOSIS – OCCURS ONLY IN REPRODUCTIVE ORGANS; A SPECIAL TYPE OF CELL DIVISION TO GIVE RISE TO SEX CELLS (GAMETES) WITH THE HAPLOID NUMBER OF CHROMOSOMES – REDUCES THE CHROMOSOME NUMBER FROM DIPLOID TO HAPLOID – RESEMBLES MITOSIS, BUT THERE ARE KEY DIFFERENCES

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT MEIOSIS – CELLS UNDERGO TWO CONSECUTIVE DIVISIONS (MEIOSIS I AND MEIOSIS II) – THE DIVISIONS ARE PRECEDED BY ONLY ONE DUPLICATION OF DNA(S PHASE) – FOUR DAUGHTER CELLS RESULT – EACH DAUGHTER CELL IS HAPLOID

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT MEIOSIS I – THE ACTUAL HALVING OF CHROMOSOME NUMBER OCCURS IN THIS STAGE – ALL THE “STUFF” THAT IS DIFFERENT TAKES PLACE IN THIS STAGE – THE GOAL OF MEIOSIS I IS TO SEPARATE THE HOMOLOGOUS CHROMOSOMES

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT

STAGES OF MEIOSIS I – PROPHASE I PROPHASE I – METAPHASE I METAPHASE I – ANAPHASE I ANAPHASE I – TELOPHASE I TELOPHASE I

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT MEIOSIS II – CLOSELY RESEMBLES MITOSIS (BUT IS OCCURING WITH A HAPLOID NUMBER OF CHROMOSOMES) – THE GOAL OF MEIOSIS II IS TO SEPARATE THE SISTER CHROMATIDS

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT

STAGES OF MEIOSIS IIMEIOSIS II – PROPHASE II PROPHASE II – METAPHASE II METAPHASE II – ANAPHASE II ANAPHASE II – TELOPHASE II TELOPHASE II

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT A COMPARISON OF MITOSIS AND MEIOSIS MITOSISMEIOSIS

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT WHAT ADVANTAGE IS THEIR TO UTILIZING SEXUAL REPRODUCTION INSTEAD OF ASEXUAL REPRODUCTION? – POSSIBLE ANSWERS…

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT SEXUAL REPRODUCTION OFFERS AN OPPORTUNITY FOR VARIATION IN GENETIC MAKEUP (TRAITS POSSESSED BY AN ORGANISM) INDEPENDENT ORIENTATION OF CHROMOSOMES, CROSSING OVER, RANDOM FERTILIZATION, AND MUTATION ALL ALLOW FOR VARIATION

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT INDEPENDENT ORIENTATION OF CHROMOSOMES

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT INDEPENDENT ORIENTATION – THE ORIENTATION OF THE HOMOLOGOUS PAIRS OF CHROMOSOMES (TETRADS) IN METAPHASE I OF MEIOSIS IS BY RANDOM CHANCE – THE TOTAL NUMBER OF POSSIBLE COMBINATIONS FOR CHROMOSOMES PACKAGED IN INDIVIDUAL GAMETES WILL ALWAYS BE 2 N WHERE N = THE HAPLOID NUMBER OF CHROMOSOMES

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT HOW DOES THIS INDEPENDENT ORIENTATION LEAD TO VARIATION? – HOMOLOGOUS CHROMOSOMES CARRY DIFFERENT VERSIONS OF A TRAIT (GENE) AT THE SAME LOCI; SO…

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CROSSING-OVER FURTHER ENHANCES GENETIC VARIATION – CROSSING-OVER CROSSING-OVER THE EXCHANGE OF CORRESPONDING SEGMENTS BETWEEN TWO HOMOLOGOUS CHROMOSOMES

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CROSSING-OVER – CHIASMA  A PLACE WHERE TWO HOMOLOGOUS (NON-SISTER) CHROMATIDS ARE ATTACHED TO EACH OTHER – CROSSING OVER TAKES PLACE DURING SYNAPSIS AND ADDS TO GENETIC VARIABILITY GENETIC RECOMBINATION – THE PRODUCTION OF GENE COMBINATIONS DIFFERENT FROM THOSE CARRIED BY THE ORIGINAL CHROMOSOMES

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CROSSING-OVER – STEPS IN CROSSING OVER 1.SYNAPSIS OF TETRAD 2.BREAKAGE OF HOMOLOGOUS CHROMATIDS 3.JOINING OF HOMOLOGOUS CHROMATIDS 4.SEPARATATION OF HOMOLOGOUS CHROMOSOMES AT ANAPHASE I 5.SEPARATION OF CHROMATIDS AT ANAPHASE II AND COMPLETION OF MEIOSIS

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT ACCIDENTS DURING MEIOSIS CAN ALTER CHROMOSOME NUMBER

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT ACCIDENTS DURING MEIOSIS CAN ALTER CHROMOSOME NUMBER – NONDISJUNCTION – THE FAILURE OF CHROMOSOMAL PAIRS TO SEPARATE – CAN HAPPEN IN EITHER MEIOSIS I OR MEIOSIS II – MORE SERIOUS IN MEIOSIS I; WHY??

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CHROMOSOMAL ABNORMALITIES – TRISOMY 21 (MOST COMMON – 1 OUT OF 700) COMMON NAME = DOWN’S SYNDROME – MOST INCORRECT CHROMOSOME NUMBERS WILL ABORT

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CHROMOSOMAL ABNORMALITIES Sex chromosomesSyndromeOrigin of Nondisjunction Frequency in Population XXYKlinefelter syndrome (male) Meiosis in egg or sperm formation 1 / 2,000 XYYNone (normal male)Meiosis in sperm formation 1 / 2,000 XXXMetafemaleMeiosis in egg or sperm formation 1 / 1,000 XOTurner syndrome (female)Meiosis in egg or sperm formation 1 / 5,000

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT HOW CAN WE DIAGNOSE CHROMOSOMAL ABNORMAILITES?

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT WE USE KARYOTYPES – KARYOTYPE  AN ORDERLY DISPLAY OF MAGNIFIED IMAGES OF AN INDIVIDUALS CHROMOSOMES

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CHROMOSOMAL ABNORMALITIES – THESE ARE NOT JUST LIMITED TO CHROMOSOME NUMBER – EVEN WHEN THE TOTAL NUMBER OF CHROMOSOMES IS CORRECT, ALTERATIONS IN THE STRUCTURE OF CHROMOSOMES CAN STILL OCCUR/EXIST

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT CHROMOSOMAL ABNORMALITIES – THERE ARE FOUR MAJOR TYPES OF CHANGES THAT CAN OCCUR DELETION DUPLICATION INVERSION TRANSLOCATION

THE CELLULAR BASIS OF REPRODUCTION AND DEVELOPMENT

WE HAVE EXPLAINED HOW CELLS DIVIDE, BUT WE HAVEN’T ADDRESSED WHY CERTAIN TRAITS APPEAR IN OFFSPRING OF SUCCESSIVE GENERATIONS COME BACK TO FIND OUT THE FULL STORY!!!