Cell Reproduction

1. CELL DIVISION and DNA Cell Reproduction

2. Differentiation • All the cells in your body have the same DNA • The fertilized egg (zygote) that made you divided many times • Cell differentiation- starting stem cells changed into all the different cell types you have by turning on certain genes in your DNA • Stem cells- the cells in early development that have the potential to become any type of cell • Differentiation Video

3. Cell Differentiation STEM CELL All types of cells stem from these cells early in development of Babies.

4. 3 Types of Cell Division • 1. Binary fission -cell division in prokaryotes • 2. Cell Cycle (with Mitosis) -cell division in eukaryotes • 3. Meiosis—cell division to form sex cells (egg and sperm)

5. Prokaryotes Cell Division • Unicellular so divide by binary fission • Circular DNA • Results in two cells genetically the same • What has to take place before ANY cells divide?

6. Reasons for Eukaryote Cell Division • Cell division in multicellular organisms results in: • Growth • Repair or replacement of somatic (body) cells. • Control of size so nutrients can get in and waste can get out in a timely fashion

7. Reasons for Eukaryote Cell Division • Some cells die quickly and need to be replaced a lot (skin cells) • Some cells never get replaced (nerve cells) • Some organisms can regenerate whole body parts

8. The Cell Cycle • Eukaryotic cells goes through a series of phases throughout their life • The cell cycle-all events between one cell division and the next • It is **ONE REPLICATION & ONE DIVISION • Result? 2 daughter cells genetically exact to the parent cell they came from Interphase

9. The Cell Cycle • 2 basic parts of the cell cycle: -1.Interphase- the longest part of cell cycle composed of G1, S, G2 stages -2.M= Mitosis = Nuclear division Interphase

10. Interphase • G1 phase- 1st step of Interphase in the cell cycle • G1 (G=gap) • Cell going through intense growth using lots of food and energy • DNA at this point is unwound and called chromatin Interphase

11. S phase -2nd step of Interphase in the cell cycle • S=Synthesis phase • All DNA replicated during this phase so new DNA being synthesized cell has double the genetic material • Sister chromatid- one of two identical parts of a replicated chromosome Interphase

12. G2 phase- 3rd step of Interphase in the cell cycle • G=gap • Cell grows some more • Extra organelles are being made Interphase

13. "M" Phase • M phase- part of cell cycle after Interphase (G1, S, and G2) in which nuclear division occurs • M=Mitosis = Nuclear division • MITOSIS IS ONLY THE DIVISION OF THE NUCLEUS DURING THE CELL CYCLE!!! • There are four mitotic steps: • Prophase • Metaphase • Anaphase • Telophase Interphase

14. Prophase of Mitosis • DNA coils up into visible chromosomes • Nuclear envelope disappears • Spindle fiber forms from the centrioles

15. Metaphase of Mitosis • Chromosomes begin to line up at the equator of the cell • Spindle fibers attach to the centromere of each sister chromatid of the chromosome

16. Anaphase of Mitosis • Spindle fibers begin to pull apart sister chromatids. Each is now a chromosome • Spindle breaks down after this

17. Telophase of Mitosis • Each side now has a full set of chromosomes • Nuclear envelope will reform

18. Cytokinesis • “Cytokinesis”—division of cytoplasm at the end of the cell cycle which cleaves the cell in half • Animal cells form a “furrow” • Plant cells form a new cell wall • Formation of two, identical daughter cells

19. Overall Cell Cycle Process • Interphase (G1, S, G2) and Mitosis (Prophase, Metaphase, Anaphase, Telophase) IPMAT • Cell Cycle Animation

20. Regulation of Cell Cycle • Cyclins- Proteins that control cell division • Cancer cells don’t respond to the cyclin signals---uncontrolled growth (tumors) • Benign tumors stay intact • Malignant tumors spread throughout body (metastasize)

21. What is DNA? • DNA (deoxyribonucleic acid)- a nucleic acid which stores genetic traits in the proteins it codes for • All living things contain DNA • DNA is the blueprint for chemical changes which take place in cells • Type of cell which is formed, (muscle, blood, nerve etc) is controlled by DNA • Type of organism which is produced (buttercup, giraffe, herring, human, etc) is controlled by DNA

22. How Much DNA Is In OUR Cells? • Chromosome-strands of DNA coiled tightly • Human cell has 46 (23 pairs) • 23 from Mom • 23 from Dad • Other organisms have different numbers of chromosomes

23. 2 Types of Cells • Somatic cells –all body cells except sex cells • Diploidchromosomes are in pairs • 46=23 pairs for humans • 1 set (23) from mom, 1 set (23) from dad • Gametes - sex cells • Egg & sperm • Haploid no pairs (only 23 single chromosomes total) body cells 46 chromosomes sperm 23 chromosomes egg 23 chromosomes

24. Human Chromosomes • If all body cells contain the same # of chromosomes, why are all cells so different? • Different cells make different proteins due to different “active” segments of DNA • Heart cells make proteins needed for the heart to work properly • Brain cells make proteins needed for the brain to work properly

25. Nucleotides • Nucleotides- subunits of DNA made of: • 1. Phosphate (PO4) • 2. A ring shaped sugar (deoxyribose) • 3. Nitrogen base

26. Phosphate Group • The phosphate group is the same in each nucleotide • It contains the elements phosphate and oxygen

27. Ring Shaped Sugar • The ring-shaped sugar is the same in all nucleotides of DNA • This sugar in DNA nucleotides is deoxyribose • It is composed mainly of carbon and hydrogen • Later you will see there is another nucleic acid called RNA in which the sugar is ribose

28. Nitrogenous Bases • They are “nitrogenous” because they contain nitrogen • The 4 bases that a DNA nucleotide can have are • Adenine (A) • Thymine (T) • Cytosine (C) • Guanine (G)

29. PO4 adenine deoxyribose Entire Nucleotides • These 3 subunits combine to form 4 possible nucleotides in DNA • For example:

30. PO4 PO4 PO4 PO4 sugar-phosphate backbone bases A Nucleic Acid Strand • When many of these nucleotides monomers are joined together, which creates a nucleic acid molecule called DNA • Sequence and length of the nucleotide chains determine the proteins the DNA codes for • Two types of nucleic acids are found in living organisms • DNA • RNA

31. DNA Structure • DNA usually consists of two strands of nucleotides bonded together, like a ladder • The sugar-phosphate chains are the outside “rails” • The strands are held together by chemical bond “rungs” between the bases • In humans there are approximately 3 billion nucleotides in each strand

32. Strand #1 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 Strand #2

33. Adenine Thymine Guanine Cytosine Chargaff’s Rule • He measured amounts of each base in various organisms and found: • % of adenine (A) = % thymine (T) • % of cytosine (C) = % guanine (G) • Chargaff’s rule told us that A bonds to T and C bonds to G • If 20% of strands is A, what %T? %C?

34. Strand #1 Strand #2 PO4 PO4 thymine adenine PO4 PO4 cytosine guanine PO4 PO4 PO4 PO4 Hydrogen bonds between bases hold two strands together

35. 3D Structure of DNA • Discovered by Watson and Crick • Double helix- 2 strands of nucleotides bonded together and twisted • Discovery of this 3D structure helped us determine the exact function of DNA

36. bases sugar-phosphate chain

37. What is DNA Replication? • Replicate = make “exact” copies • DNA replication- copying one double stranded DNA molecule into two genetically identical copies • All DNA must be replicated before a cell can divide. Why? • Replication Animation

38. The strands separate PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4

39. PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 PO4 Each strand builds up its partner by adding the appropriate nucleotides

40. Enzymes and Replication • Helicase- enzyme that unwinds DNA • DNA polymerase-enzyme that moves along each strand and brings in bases for new strand copy

41. DNA Replication Efficiency • Replication is very fast and accurate, but there can be a mistake made • Mutations-change in DNA • Mutagens- substances that cause mutations • X-rays • Toxins • Drugs • UV light, etc.

42. Mutations • 3 types of mutations that can occur during DNA replication: • Insertions -extra nucleotides • Deletions –missing nucleotides • Substitutions –placement of wrong nucleotides • Can be helpful or harmful mutations. Insertion Deletion Substitution

43. How does DNA code for proteins?

44. A Gene Codes for One Protein • Gene- a segment of DNA that codes for a protein • DNA has 1000’s of genes to make many different types of proteins • Why are proteins important? • Protein - polymer of amino acids aa—aa—aa—aa—aa—aa—aa—aa = protein

45. RNA (Ribonucleic acid) is Involved _____DNA____ vs._____RNA___ Transmits copies of the genetic code to the rest of the cell Single stranded Sugar of RNA nucleotides is ribose A, C, G, U (uracil) NO T! Different forms: mRNA, rRNA, tRNA Found all over cell Stores the genetic code in the nucleus Double stranded Sugar of DNA nucleotides is deoxyribose A, C, G, T “DNA is DNA” Found in nucleus only

46. DNA vs. RNA

47. Part 1 of Protein Synthesis: Transcription • Transcription- copying of DNA triplets to mRNA codons in the nucleus • DNA complementary to mRNA • ATA-CGG-AAT (DNA triplets) transcription in nucleus UAU-GCC-UUA (mRNA codons)

48. Transcription cytoplasm Translation

49. Part 2 of Protein Synthesis: Translation: • Translation- converting mRNA copy to protein which occurs at ribosomes in the cytoplasm • UAU-GCC-UUA (3 mRNA codons) translation by ribosomes a.a.---a.a---a.a. (amino acids of protein) cytoplasm

50. Whole Process ATA-CGG-AAT (DNA triplets) transcription in nucleus UAU-GCC-UUA (3 mRNA codons) translation at ribosomes a.a.-a.a-a.a. (amino acids of protein) tyrosine-alanine-leucine ?????? How do we know what amino acid results? The Codon Chart!!! Protein Synthesis and Pain—What is a Protein?