1 / 30
Télécharger la présentation

Cell Division Process: Understanding DNA, RNA, and Protein Synthesis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cell Division

  2. Cell Division • process by which cells reproduce themselves • Includes: - nuclear division -cytoplasmic division • Two types: - somatic cell division - reproductive cell division

  3. Transcription • process by which genetic information encoded in DNA is copied onto a strand of RNA • when strands divide, one strand (the sense strand) acts as the template for mRNA synthesis • the other strand is called the antisense strand

  4. What is DNA? • composed of building blocks called nucleotides • double strand of nucleotides • ladder-like molecule • coiled into a spiral • double helix

  5. DNA Replication • DNA helix uncoils • gradually separates into two nucleotide chains • template for next strand • each nucleotide joins in a complementary sequence

  6. Nucleotide Structure • Composed of: - nitrogenous base - pentose monosaccharide - phosphate groups

  7. Nucleotide Structure (cont.) • nitrogenous base - purines (adenine and guanine) - pyrimidines (cytosine, thymine, and uracil

  8. DNA • DNA bases: - adenine (A) - guanine (G) - cytosine (C) - thymine (T) • adenine (A) bonds with thymine(T) • guanine (G) bonds with cytosine (C)

  9. RNA • RNA bases: - adenine (A) - guanine (G) - cytosine (C) - uracil (U)

  10. Messenger RNA • carries genetic information from DNA to cytosol where it serves as template for protein synthesis

  11. Translation • process by which nucleotide sequence on a strand of mRNA is used as a template for protein synthesis • generates a corresponding amino acid sequence in a polypeptide chain • three consecutive nucleotides are called a codon, which specifies one amino acid

  12. Somatic Cell Division • results in an increase in number of cells in body (growth, repair) • Cell life cycle has two major periods: - interphase (resting stage) - mitotic phase (cell division reproduction occurs)

  13. Interphase • series of activities before reproduction • between divisions • each chromosome makes copy of self • two identical chromosomes • chromatids are united by centromere • metabolic activities continue • longest phase of the cell cycle • very active

  14. Cell Division • Process includes: - mitosis nuclear division formation of two daughter nuclei - cytokinesis division of cytoplasm begins once mitosis is nearly complete

  15. Stages of Mitosis • prophase • metaphase • anaphase • telophase

  16. Prophase (pro = before) • chromosomes become visible as chromatids • nucleolus disappears • mitotic spindle appears

  17. Prophase (cont.) • chromatin threads coil and shorten into chromosomes - double stranded (chromatids) • each chromatid is held together by small median body called a centromere • centrosome and its centrioles each move to opposite sides of cell

  18. Prophase (cont.) • mitotic spindle between centrioles (responsible for attachment and movement of chromosomes) • end of stage - nuclear membrane and nucleoli have broken down and disappeared • chromosomes are randomly attached to centromeres by spindle fibers

  19. Prophase Prophase 2 Prophase 1

  20. Metaphase (meta = after) • short • chromosome pairs line up on the metaphase plate (exact midpoint or center of the mitotic spindle) • straight line of chromosomes

  21. Metaphase

  22. Anaphase (ana=upward) • centromeres divide and separate • identical chromosomes move to opposite poles with centromeres

  23. Anaphase

  24. Telophase (telo = far or end) • begins as soon as chromosomal movement stops • chromosomes at poles uncoil • resume chromatin form (threadlike) • nuclear membrane forms around each chromatin mass • nucleoli reappear • mitotic spindle disappears

  25. Telophase

  26. Cytokinesis(kinesis = motion) • division of cytoplasm and organelles • occurs in late anaphase • furrow develops and progresses inward dividing cell into two separate portions of cytoplasm

  27. Conclusion • two daughter cells genetically identical to the original mother cell • each cell diploid in number

  28. Meiosis • cell division • restricted to sex cell (gametes) production • involves two successive nuclear divisions • results in daughter cells with haploid (1/2) number of chromosomes

  29. Haploid • one half the normal number of chromosomes (23 in humans) Diploid • number of chromosomes characteristically found in somatic cells of an organism (46 in humans)

More Related