1. Mitosis and DNA Learning Targets 1-12

2. The Nucleus The central structure in most eukaryotic cells The central structure in most eukaryotic cells Usually the largest structure in most eukaryotic cells Usually the largest structure in most eukaryotic cells The “boss” of the cell; running all cell functions The “boss” of the cell; running all cell functions Has 2 phospholipid bilayers (2 x 2 = 4 layers) Has 2 phospholipid bilayers (2 x 2 = 4 layers) Layers pierced with holes called nuclear pores Layers pierced with holes called nuclear pores LT 1

3. The Nucleus

4. The Nucleus (cont.) Nuclear envelope – outer membrane that contains genetic material; 2 layers thick; has pores Nuclear Pore – hole in the nuclear membrane where large molecules pass through

5. The Nucleus (cont.) Nucleolus – sphere within the nucleus; where ribosome parts are made Chromatin – unorganized genetic material; the instruction manual to the cell

6. Cell Division Q: How does an organism grow in size? by its cell(s) getting bigger in size? -by its cell(s) getting bigger in size?OR -by making more cells? Q: Why is it that cells are so small? Q: Why are you made of trillions of microscopic cells ? Q: Why aren’t you made of 1-2 giant, oozing cells? LT 2

7. Why So Small? A: In most cases the cells will divide and make more small cells instead of becoming large cells.

8. Why do Cells Divide? 1.Large cells put more demands on the DNA – Think of OLSD. As we get more and more students, could one principal, at one building effectively manage all of them? Not likely, so what do we do…we split. We have three principals at three HS’s. Same goes for the cell. 2.Diffusion is only good over short distances

9. 3. The cell will have difficulty moving nutrients and wastes across the membrane. Area of One Face Total Surfa ce Area Volu me of the Cell Dista nce from the Cent er Weig ht of Cell SA to Volu me Ratio SA to Weig ht Ratio s = 11610.52.162.86 s = 24248112.931.86 s = 3954271.534.621.58 s = 4169664287.11.51.10 Let’s look at our lab data 1.Which best represents the cell’s membrane? Column 2 = Tot. Surface Area= Cell Membrane = Roads 2.Which represents the cell’s contents? Column 3 & 5 = Vol & Wt= Cell Size = City Size

10. Why do Cells Divide? Think of the Columbus/I-71 example? As the city grew faster than the road system, we had traffic jams (more cars trying to come in or go out than the roads could support). How is this like question 4 and 5?

11. Why do Cells Divide? As the cell size increases, the SA-Vol ratio decreases!! This is like Columbus growing but the roads not growing as quickly. If your SA –Vol ratio is not large, then you cannot move materials in or out very well. This like a traffic jam. This means the cell As the cell size increases, the SA-Vol ratio decreases!! This is like Columbus growing but the roads not growing as quickly. If your SA –Vol ratio is not large, then you cannot move materials in or out very well. This like a traffic jam. This means the cell – would starve for lack of food, – or be poisoned by not being able to get rid of wastes fast enough!!

12. Why do Cells Divide? So in order to not overload the DNA, to allow for the fastest diffusion, and to keep the Surface Area to Volume Ratio large, the cell will DIVIDE. So in order to not overload the DNA, to allow for the fastest diffusion, and to keep the Surface Area to Volume Ratio large, the cell will DIVIDE. The parent cell will divide into 2 daughter cells The parent cell will divide into 2 daughter cells The DNA in the parent cell will be copied The DNA in the parent cell will be copied One copy of DNA will go to each new daughter cell One copy of DNA will go to each new daughter cell VIDEO

13. Lab Quiz Time Learning Target 1 1.This structure is responsible for making ribosomes 2.This substance is the master molecule of the cell and in an unorganized form 3.This contains pores by which materials can leave the nucleus 4.This structure is only found in eukaryotic cells a. nuclear envelope b. nucleus c. chromatin d. nucleolus

14. Lab Quiz Time Learning Target 2: 5.Roads : City::________: Cell 6.Total Surface Area : Cell Membrane:: ______ & ______: Cell Size 7.As the cell grows larger and gets more cell content, will it need more or less cell membrane? _______________

15. Lab Quiz Time 8.According to our data, as the cell size increased, did the Total Surface Area to Volume ratio, get larger, smaller, or stay the same? ____________ 9.Which cell (s=1, s=2, s=3, or s-4) had the best total surface area to volume ratio? __________ 10.Based on your response to questions #9, what does this mean for the cell? Would it be better to have an organism made of many small cells or one large cell? ______________; because _______________________________________

16. Lab Quiz Time 11. Besides the factor keeping cells small discussed in the lab, what other 2 factors keep cells small? a. ______________________________ b. ______________________________

17. Answers 1.D 2.C 3.A 4.B 5.Cell Membrane 6.Volume and Weight (1/2 pt each) 7.More 8.SMALLER !!! (that’s a problem) 9.s-=1; the ratio was 6:1, this means there are plenty of roads for the city or cell membrane for the cell size 10.Many small cells BECAUSE the Tot. Surface Area to Volume ratio is HIGHEST/BIGGEST. (1/2 pt per part) 11. a. DNA overload b. Diffusion is not good over long distances (1/2 pt each)

18. Parts and Structure of DNA DNA Recall that inside the nucleus is the genetic material, DNA. master molecule of the cell running all cell functions DNA is the master molecule of the cell and is responsible for running all cell functions. Deoxyribonucleic Acid DNA stands for Deoxyribonucleic Acid So how is the structure of DNA related to its functions? LT 4

19. Parts and Structure of DNA Gene- a segment of the DNA molecule that produces a particular protein and gives a particular trait. Exeye colorGey Gene Bey2 gene Ex: We have two genes for eye color:the Gey Gene and the Bey2 geneJobs: carry on them the information 1.Will carry on them the information to be passed from one generation to the next determine your traits 2.Use this information to determine your traits copied 3.Be easily copied to be sure all the info gets to the next generation

20. Parts and Structure of DNA The Facts: Long molecule nucleotides Made up of parts called nucleotides 3 parts to a nucleotide There are 3 parts to a nucleotide 1.Sugar 1.Sugar (deoxyribose) 2.Phosphate group 3.Nitrogen base LT 5

21. Parts and Structure of DNA 4 kinds of nitrogen bases 2 categories There are 4 kinds of nitrogen bases, divided into 2 categories Adenine(T) Adenine (A) and Thymine (T) (G) Cytosine Guanine (G)and Cytosine (C)

22. Parts and Structure of DNA of two strands It is made up of two strands bound together in the middle backbone phosphate group deoxyribose sugar The backbone is made up of the phosphate group and deoxyribose sugar middle nitrogen bases The middle is made up of the nitrogen bases (A, T, C, and G) complementary One strand is said to be complementary to the other strand; thus if you know the base pairs of one strand you can determine the other strand using Chargaff’s base pairing rules. ANTI- PARELLEL Also the strands are ANTI- PARELLEL or run opposite directions of one another LT 4 & 5

23. DNA Models You will make… 1 strand Each strand will be 4 nucleotides long (any order you desire) Side A ONLY Side A ONLY - Tape your 4-nucleotide strand to the 4-nucleotide strands of your table mates. Therefore your table should have a strand of 12-16 nucleotides (12 if three people at your table, 16 if 4 people at your table) Side B-DO NOT tape ANY nucleotides together Side B-DO NOT tape ANY nucleotides together Sides A and B Sides A and B – Table A join at the the Table B directly across from you. Side B people, make your nucleotides base pair according to Chargaff’s Rule to match Side A’s strand. Once you are satisfied with the base-pairing, be sure the strands are complementary and anti-parallel. Side B- tape your nucleotides both horizontally AND vertically together to finish the double helix. Sugars will be WHITE PhosphatesBLACK Bases Red – CytosineRed Green – GuanineGreen Blue – AdenineBlue Yellow – ThymineYellow LT 4 & 5

24. Human Genome Project Genome – the total genetic content of an organism; your DNA; your 3 billion nucleotides and their A, T, C, and G’s. Human Genome Project: A Study of Genomics The largest science project in the world’s history Aimed at knowing the entire nucleotide sequence of human DNA 13 year international effort led by the US and Britain; October 1990- April 2003 Cost $3 billion dollars (funny that is how many nucleotides there are) Published a book called ENCODE (ENCyclopedia Of DNA Elements) in 2012 that described two kinds of DNA – Coding DNA – Non-Coding DNA – Goal now…find the function of all 3 billion nucleotides

25. Human Genome Project Hypotheses: (NOPE)  Since humans are so complex, we must need or make 100,000+ proteins (NOPE) (YES, or maybe more)  Since genes make proteins, we must make 100,000 proteins (YES, or maybe more) (NOPE, NOPE, NOPE)…say what??  Most DNA will code for proteins (NOPE, NOPE, NOPE)…say what??

26. Human Genome Project Coding DNA = 1.5% of the total DNA molecule only 1.5% proteins Therefore only 1.5% of DNA actually makes proteins 21,000 genes +100,000 proteins This 1.5% accounts for 21,000 genes and make the +100,000 proteins we have discontinuous EXONS DNA is discontinuous meaning the Coding DNA is mixed in with the Non- Coding DNA; these coding “chunks” are called EXONS ALTERNATIVE SPLICING And the exons can be arranged in various configurations so we get the +100,000 proteins – ALTERNATIVE SPLICING

27. Non-Coding DNA = 98.5% of DNA molecule Therefore this 98.5% does NOT make proteins Gives 13,500 genes 28.5% of the 98.5% is made up of the INTRONS(what is cut out between exons) 50% of the 98.5%was called “Junk DNA” but is now thought to be critical in “turning on” and “turning off” genes The last 20% of the 98.5% is still unknown to us at this time.

29. Prokaryotic v. Eukaryotic Cell Division PROKARYOTESBOTHEUKARYOTES Single, circular molecule of DNA No nuclei DNA unconfined within cell membrane Grow rapidly DNA copies throughout the cell cycle DNA replication stops briefly when cell divides No mitotic spindles Have DNA Replicate the DNA before cell division DNA is in the nucleus Divide at varying rates Rates are controlled by growth factors Has periods of growth and rest More complex than prokaryotic cells Have programmed cell death

30. How Do Cells Divide? Recall that when cells get too big, the DNA is copied to be placed into each new cell, then the cell divides. DNA In prokaryotes: A simpler division process A form of ASEXUAL reproduction (cell produced is genetically identical to the parent cell) binary fission Called binary fission (copy DNA & split cell in 2) In eukaryotes: More complex division process A form of ASEXUAL reproduction 3 Stages of Division Interphase Mitosis Cytokinesis Replaces cells and grows the organism LT 6

31. How Do Cells Divide? Copying and moving efficient. Copying and moving the DNA into the daughter cells needs to be efficient. condense the long DNA So cells will condense the long DNA molecule into structures called CHROMOSOMES – condensed, organized DNA on which genetic information is carried from the parent cell to the daughter cells. LT 6

32. How Do Cells Divide? Chromosomes: DNA Made up of DNA Only visible at certain points in the cell’s life two identical halves called sister chromatids Made up of two identical halves called sister chromatids centromere Sister chromatids are joined at the centromere LT 6

33. How Do Cells Divide? has its own number of chromosomes Each species has its own number of chromosomes that are in each of their cells. DIPLOID NUMBER This is called the DIPLOID NUMBER Common Name Genus and Species Diploid # of Chromosomes BuffaloBison bison60 Cat Felis catus38 CattleBos taurus, B. indicus 60 DogCanis familiaris78 PigSus scrofa38 HumanHomo sapiens46 LT 6

34. How Do Cells Divide? 3 Stages There are 3 Stages to Cell Division This is called the… Cell Cycle-a series of events that cells go through as they grow and divide 1. Interphase Growth phase Longest portion of the cell cycle 2. Mitosis nucleus Division of the nucleusShortest phase of the cell cycle 3. Cytokinesis cytoplasm Division of the cytoplasm LT 7

35. How Do Cells Divide? Interphase is the first stage of Cell Division. cell is not dividing GROWING! BUT…the cell is not dividing here. It is GROWING! 3 Phases : 1.G 1 -cell grows (increase in size, new proteins and organelles) 2.S-chromosomes are copied to make 2 DNA molecules 3.G 2 -shortest phase; molecules and organelles for cell division are produced LT 7

36. How Do Cells Divide? Cells in Interphase LT 7

37. How Do Cells Divide? mostInterphase Cells spend most of the cell cycle in Interphase Skin Cells 22 – Ex: Skin Cells divide about one time a day, but are in Interphase for 22 of the 24hrs. Nerve cells for decades – Ex: Nerve cells may stay in Interphase for decades (think of paralysis!) In Interphase… Chromatin – The DNA is in the form of Chromatin intact – The nuclear envelope is intact copying – DNA is copying LT 7

38. How Does DNA Copy? Q: So how do we actually copy DNA? A: IT’S A TEMPLATE!! A: Each strand has all the info needed to copy it; IT’S A TEMPLATE!! LT 8

39. How Does DNA Copy? LT 8 base pairing The idea that each strand of DNA is a template is based on base pairing A’s pair withT’s C’spair withG’s this strand is to this strand COMPLIMENTARY In ProkaryotesIn Eukaryotes Replication begins at 1 pt and goes in both100’s of pts and goes directionsboth directions

40. How Does DNA Copy? replication fork The location where the DNA molecule starts to copy is called the replication fork one – In prokaryotes, one replication fork 100’s – In eukaryotes, 100’s of replication forks LT 8

41. How Does DNA Copy? bonds must be cut between the base pairs hydrogen bonds To begin replication the bonds must be cut between the base pairs. These are weak hydrogen bonds done by enzymes – The “unzipping” and later “re-zipping” of the base pairs is done by enzymes. – Helicase- “unzips” the base pairs – DNA Polymerase- “re-zips – DNA Polymerase- “re-zips” the base pairs LT 8

42. How Does DNA Copy? Steps to DNA Replication: 1.At the replication fork, helicase “unzips” the DNA molecule. 2.The DNA molecule begins to separate into two strands (the parent strands or templates). 3.Free nucleotides from within the nucleus match up with the parent strand according to the base pairing rules. 4.DNA polymerase bonds the free nucleotides to the parent strands. 5.More of the molecule is unzipped. 6.More free nucleotides pair up and are bonded until both strands have been copied completely. LT 8

43. How Does DNA Copy? Results: IDENTICAL Two new IDENTICAL strands of DNA ½ is the parent strand and ½ is new; called SEMI-CONSERVATIVE For each new molecule formed ½ is the parent strand and ½ is new; called SEMI-CONSERVATIVE LT 8

44. One strand of DNA will go to one daughter cell, the other will go to the other daughter cell. Both daughter cells will have identical DNA ….. Unless there are mistakes…. mutations

45. antiparallel Remember that DNA is antiparallel

46. only move one direction 5’ to 3’ end of parent strand DNA polymerase can only move one direction on the DNA (blue arrow) OR from the 5’ to 3’ end of parent strand

47. newDNA strand 5’ end and moving towards its 3’ end BUT…the new DNA strand can form only by beginning with its 5’ end and moving towards its 3’ end

48. Leading Strand – the new strand can grow in one continuous strand This is easy on one side of the DNA, called the Leading Strand – the new strand can grow in one continuous strand as the enzyme moves up the DNA

49. the DNA must build in the opposite direction of the enzyme – (lagging strand) But the other side presents problems - the DNA must build in the opposite direction of the enzyme – building down the strand. (lagging strand)

50. segments, called Okazaki fragments Therefore, on the lagging strand side, the DNA builds in segments, called Okazaki fragments, which are later joined together (enzymes again!!)

51. Other enzymes follow to join the fragments together

52. It may seem like a lot of enzymes have been mentioned, although only two have been named. There are over 30 enzymes involved in DNA replication!!

53. Cell Division-MITOSIS Recall that there are 3 parts to the cell cycle 1.Interphase –when the cell is growing and DNA is copying 2.Mitosis-when the NUCLEUS and its contents are split 3.Cytokinesis-when the CELL AND CYTOPLASM ARE split Biologists divide Mitosis into 4 phases 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase LT 9

54. Cell Division-MITOSIS PROPHASE first phase The first phase of mitosis Longest phase of mitosis Chromatin CHROMOSOMES Chromatin form of DNA becomes  CHROMOSOMES Centrioles Centrioles separate and move toward the ends/poles of the cell (plant cells do not have these) Nucleolus disappears Nucleolus disappears Nuclear envelope breaks down Nuclear envelope breaks down Chromosomes Centrioles Nuclear Envelope

55. Cell Division-MITOSIS METAPHASE “Meta” = Middle second phase The second phase of mitosis Often the shortest phase Centrioles Centrioles are at the poles Sister chromatids line up in the middle of the cell Sister chromatids line up in the middle of the cell Spindle fibers centromeres Spindle fibers that come from the centrioles attach to the centromeres of the sisters Nuclear envelope is gone Sister Chromatids Centrioles Spindle Fibers

56. Cell Division-MITOSIS ANAPHASE “Ana” = Away Third phase Third phase of mitosis Spindle fibers centromere, Spindle fibers attached at the centromere, pull the sister chromatids apart Spindle fibers pull the sister chromatids apart (now individual chromosomes) poles Chromosomes go to the poles of the cell Ends when chromosomes stop moving LT 9 Spindle fibers Sister Chromatids

57. Cell Division-MITOSIS TELOPHASE Fourth and final phase Fourth and final phase of mitosis relax Chromosomes start to relax back into chromatin Nuclear envelope starts to reform Nuclear envelope starts to reform around chromosomes Spindle fibers break apart Nucleolus reforms Nucleolus reforms

58. Cell Division-CYTOKINESIS two nuclei Now each cell has two nuclei divide the cytoplasm Now the cell needs to divide the cytoplasm same time as telophase This is usually happening at the same time as telophase Animals cleavage furrow Animals-cell membrane pinches in so cytoplasm is separated into two parts with its own nucleus and organelles-called the cleavage furrow Plants-cell plate Plants-a cell plate forms between the two new nuclei and gradually separates the cell

59. Old Dead DNA Dudes & Dudettes Recall that DNA found in the nucleus is the molecule responsible for all cell functions. But how do we know this? This took some time for scientists to determine. The question was is the genetic material PROTEIN or a NUCLEIC ACID (like DNA)?? LT 3

60. Old Dead DNA Dudes & Dudettes Frederick Griffith (1928) -studied the pneumonia bacteria -found there were two kinds; S-strain R-strain S-strain (smooth) and R-strain (rough) -Both strains injected into mice 1. S-strain = mice died of pneumonia 2. R-strain = mice lived 3. Heat-killed S-strain = mice lived 4. Heat-killed S-strain + R-strain = mice DIED!!! Somehow the deadly “factor” from the S-strain had “TRANSFORMED” the R-strain and made the combo deadly!! – called the TRANSFORMATION FACTOR -also because the S-strain was heated, and heat denatures proteins, Griffith’s work suggested the “transforming factor” might be DNA and not proteins.

61. Old Dead DNA Dudes & Dudettes Oswald Avery (1944) -Re-did Griffith’s work -found only the DNA of the S-Strain transformed the R-strain -met with much skepticism because scientists did not know much about the structure and function of DNA

62. Old Dead DNA Dudes & Dudettes Hershey & Chase (1952) -studied viruses that infect bacteria because viruses are very simple; a little DNA or RNA and a protein coat-called BACTERIOPHAGES Experiment: -took the protein of a T 2 bacteriophage, marked it, and injected it into E. coli -took the DNA of the T 2 bacteriophage, marked it with another tag, and injected it into E. coli found the bacteriophage DNA, not the protein, was found in the E. coli cells -let both E. coli cultures divide and found the bacteriophage DNA, not the protein, was found in the E. coli cells Therefore, DNA is the genetic material!

63. Old Dead DNA Dudes & Dudettes Erwin Chargaff (1947) -the structure of DNA is many units called nucleotides -nucleotides have one of four nitrogen bases; A = adenine, T = thymine, C = cytosine, G = guanine -the amount of the A, T, C, and G’s are not equal to one another and are different by species BUT…the amount of A = T and C = G -BUT…the amount of A = T and C = G Called the Chargaff Rules

64. Old Dead DNA Dudes & Dudettes Watson & Crick (1953) -DNA now widely accepted as genetic material -wanted to understand the structure of DNA -looked at x-ray crystallography images taken by (and taken from  ) Rosalind Franklin. discovered that the structures was a DOUBLE HELIX (a twisted ladder) - discovered that the structures was a DOUBLE HELIX (a twisted ladder) -structure was two strands with sugars and phosphates on the outside and Chargaff’s nitrogen bases (A =T and C = G) on the inside -won the Nobel Prize for their work -Rosalind Franklin was NOT included!! We now recognize her massive contribution to this discover.