Presentation on theme: "Donna Huffman Biology Lab Instructor Calhoun Community College"— Presentation transcript:
1 Donna Huffman Biology Lab Instructor Calhoun Community College Diploid to HaploidDonna HuffmanBiology Lab InstructorCalhoun Community College
2 Introduction All living things must reproduce to survive. All body or somatic cells reproduce by mitosis which is simple cellular reproduction.All sex cells must reduce their chromosome number as they divide. This reduction division is called meiosis and changes the chromosome number from Diploid to Haploid.Each offspring resulting from the combination of haploid sex cells will contain the same chromosome number as their parents.
3 The Big Picture Meiosis Mitosis 2N somatic (body) cells sex cells (sperm or egg)2N2N2N = Diploid1N = Haploid1N1N2N2N1N1N1N1N2NDiploid
4 Diploid vs. HaploidDiploid (2N) = Full complement of chromosomes found in any somatic cell of an organismHaploid (1N) = Half the number of chromosomes found in a diploid cell. Sex cells have a haploid number of chromosomes.For example:Human cheek cells have 46 chromosomes. (Diploid)Human sex cells have 23 chromosomes. (Haploid)
5 Meiosis Fertilization male female 2N 2N Diploid sex cell production Haploid1N1N1N1N1N1N1N1N1N1N1N1NspermeggDiploid Zygote2NFertilization
6 Somatic CellsEach somatic cell nucleus contains the 2N or diploid number of chromosomes.Each of these human somatic cheek cells contains 46 chromosomes.Each nucleus has all the information needed for an entire organism.Cheek cell nuclei2N
8 2N 1N Meiosis Meiosis in the male and female divides each diploid cell into 4 haploid sex cells.
9 At what point in Meiosis does the chromosome number change from Diploid to Haploid?2N Prophase Icentromere =1N Anaphase I1N Telophase IIThe homologous pair in Prophase I separates in Anaphase I thus changing the number of the chromosomes from Diploid to Haploid.
10 Female Meiosis: Oogenesis Oogenesis occurs within the ovary as an immature follicle develops into a mature follicle containing an egg.mature follicle with eggimmature follicle
11 Female: Diploid to Haploid OvaryEggEgg producing Follicle2N1N
12 Male Meiosis: Spermatogenesis Spermatogenesis occurs in the testis as cells within the wall of the seminiferous tubule divide from diploid somatic cells into mature haploid sperm.1N2Nseminiferous tubulemature sperm
13 Male: Diploid to Haploid 2N1N10X photomicrographof testis cross sectionSpermTestis
14 Conclusion=2N1N NThe haploid sperm nucleus may unite with the haploid egg nucleusresulting in a diploid zygote, and thus the cycle of life begins again.