2. Why do cells reproduce? Three main reasons: 1.Produce and replace body cells. 2.Produce new organisms that are genetically identical to parent (asexual reproduction) 3.Produce reproductive cells that will be used to create new genetically distinct organisms (sexual reproduction).

3. Review of the cell theory 1.All living things are made of cells. 2.Cells are the basic unit of structure and function of living things. 3. All cells come from pre-existing cells.

4. Then where did the first cell come from?

5. The Earth was formed 4.5 billion years ago. About 3.5 billion years ago, life started here on Earth. Studies of modern volcanic eruptions support, the Earth’s atmosphere was made up of Hydrogen Gas, Methane and Ammonia, with little or no free oxygen. There was also some water. But how did life start?

6. The primordial Earth was a very different place than today, with greater amounts of energy, stronger storms, etc. The oceans were a "soup" of organic compounds that formed by spontaneous processes.

9. Stanley Miller (1953) Miller put methane, ammonia, water vapor and hydrogen in a flask, sealed it off and boiled it. He also shot electricity through it to represent lightning.

11. What was the result? A brown, red sludge appeared on the sides of the flask. In that brown, red sludge were amino acids, the “building blocks of life”.

12. This suggests that life could have arisen from materials and conditions present in early Earth history.

22. The Earth is very different now So all new cells come from pre-existing cells!!!

23. Living things are produced from other living things. Duh!!

24. Mice Recipe (17 th century) 1.Place sweaty underwear and husks of wheat in an open-mouthed jar 2. Wait for about 21 days, during which time it was alleged that the sweat from the underwear would penetrate the husks of wheat, changing them into mice.

26. Spontaneous Generation Due to faulty experiments, some scientists concluded that nonliving things could give rise to living things spontaneously.

27. Redi designed an experiment that tests whether maggots come from non-living meat

28. Redi’s experiment

29. But what about microorganisms?

30. In England, John Needham placed a broth, or “gravy,” into a bottle, heated the bottle to kill anything inside, then sealed it. Days later, he reported the presence of life in the broth and announced that life had been created from nonlife.

31. Spallanzani So Spallanzani did an experiment where he sealed the gravy/broth and then cooked the broth.

32. Perhaps microorganisms entered the broth from the air after the broth was boiled, before it was sealed.

33. The sealed bottle showed no signs of life..

34. Proponents of Spontaneous Generation Spontaneous Generation still occurs, it just needs….air!!!!!!

35. Pasteur (1859) Louis Pasteur, the notable French scientist, accepted the challenge to re- create the Needham’s experiment and leave the system open to air. He designed several bottles with S-curved necks that were oriented downward so gravity would prevent access by airborne foreign materials.

38. He reasoned that the contamination came from life-forms in the air. Pasteur finally convinced the world that even if exposed to air, life did not arise from nonlife.

39. Theory of Biogenesis - All life must come from life.

40. Cellular Division for Growth and Repair

41. All organisms start with a single cell. Then they begin to grow. In adulthood, cells are continuously being renewed and replaced.

46. So organisms must produce new cells in order to get bigger or to heal

47. Let these pasta pieces represent chromosomes

48. What are two things that you noticed? ____________________________________ Humans have 46 chromosomes. If cell division happened as it does in this model, what would be the maximum number of cells a human could have?

49. What are two things that you noticed? 1.The cells get smaller and smaller 2.There are not many cell divisions possible Humans have 46 chromosomes. If cell division happened as it does in this model, what would be the maximum number of cells a human could have? 46

50. In order to divide a cell must do two things: 1. grow 2. make copies of their genetic material

51. The Mitotic Cell Cycle 1.Interphase 2.Prophase 3.Metaphase 4.Anaphase 5.Telophase 6.Cytokinesis

53. Cell Cycle 1.I 2.Picked 3.More 4.Apples 5.Today 6.Cutie

54. The Cell Cycle Put these in order: Cytokinesis, Interphase, Telophase, Prophase, Anaphase, Metaphase

55. Video Clip from S drive

59. Organelles and centrioles (animals) double

62. Spindle Fibers (Microtubules) become visible Nuclear envelope breaks down

66. along the center equator Microtubules attach to centromeres

70. at the centromere, as Spindle Fibers shorten

74. as nuclear envelope reforms spindle fibers break down and disappear

78. Cytokinesis The process by which the cytoplasm divides and one cell becomes two individual cells. The process is different in plants and animals

79. Animals - cell pinches inward Plants - a new cell wall forms between the two new cells

81. Mitosis - nuclear division, number of chromosomes remains the same So the only phases that are part of mitosis are: ________________________________

85. The image above shows groups of boxy cells undergoing various stages of mitosis. The artwork, which was created bye superimposing images on a mass- produced floral fabric, won first prize in Princeton University's 2006 Art of Science competition

87. Mitosis and Cytokinesis http://highered.mcgraw-hill.com/olc/dl/120073/bio14.swf

88. Before we introduce the second type of cell reproduction in eukaryotic cells. Let’s recap. There are two types of eukaryotic cell division: 1. ____________________ 2. ____________________

89. #1

90. CELL DIVISION There are two types of cell division: 1. MITOSIS – my toes & all body cells used for growth and repair 2. ____________________

91. #2 And if you are a male- the testes

92. CELL DIVISION There are two types of cell division: 1. MITOSIS – my toes & all body cells used for growth and repair 2. MEIOSIS- my o’s (and if male- testes) used for reproduction

93. Let’s think back to the different forms DNA can be in

94. Oooo there is chromatin and chromosomes When a cell is not preparing to divide it is relaxed in the form of chromatin. When a cell is preparing to divide it forms into chromosomes.

96. 2 Single stranded chromosomes

97. Each human has _____ chromosomes (or ____ pairs)

98. Each human has 46 chromosomes (or 23 pairs)

99. You have 2 sets of genetic information 1 set you got from _________ And the other set you got from _________

100. You have 2 sets of genetic information 1 set you got from MOM And the other set you got from DAD

101. FERTILIZATION

102. Normal human sperm cell 23 chromosomes Human fertilized egg (zygote) with 46 chromosomes 23 46

105. In diploid cells, each chromosome of a pair has the same basic structure. The two members of each pair are called _______________ or ______________ ________________ homologues homologous chromos omes

106. This is a karyotype (____________________) of a human. Humans have __23____ pairs of homologous chromosomes. Picture of chromosomes

107. In order to make gametes, only __1__ of each pair of homologous chromosmes can be given. The other gamete will the provide the other homologues restoring the diploid number.

108. To make gametes(sex cells), eukaryotic cells divide by __meiosis____________. To remember the stages in order write: IPMATCPMATC 1 1 1112 2 2 22

109. Remember: Sperm and egg cells (gametes)only have half the chromosome number of body cells- haploid (1n) The fertilized egg and all other body cells (somatic cells) have the regular amount of chromosomes- diploid (2n)

110. Interphase -Same as in Mitosis-

111. Organelles and centrioles (animals) double

112. Prophase I Nuclear membrane breaks down Duplicated Homologous chromosomes are attached together at the centromere- called tetrads. ** Crossing over occurs- »DNA from one chromosome can shift over to other chromosome- creating more »variety in gametes

113. Metaphase I Tetrads line up in the middle. Spindle fibers attach at the centromeres.

114. Anaphase I Tetrads are pulled apart, and the duplicated chromosomes go towards opposite poles.

115. Telophase I Nuclear membranes re-form around the duplicated chromosomes.

116. Cytokinesis I Cytoplasm splits resulting in two cells that must divide again.

117. Prophase II- Looks like prophase of mitosis but 2 cells Nuclear membrane breaks down, and duplicated chromosomes are visible.

118. Metaphase II- Looks like metaphase of mitosis but 2 cells Duplicated chromosomes line up in the middle. Spindle fibers attach at the centromeres.

119. Anaphase II- Looks like anaphase of mitosis but 2 cells Sister chromatids are pulled apart- now called single stranded chromosomes.

120. Telophase II- looks like telophase of mitosis but 2 cells Nuclear membranes re-form around the single stranded chromosomes. Each nuclei now has half the genetic information as original cell. Only one of chromosome of each homologous pair.

121. Cytokinesis II Cytoplasm splits, resulting in 4 haploid cells.

126. The meiotic cell cycle differs in Male and Females Animals. Males- spermatogenesis- all 4 cells are viable sperm. Males will produce more sperm than females eggs in their lifetime. Females- oogenesis- only 1 of the 4 cells is a viable egg. Females will produce less eggs than males sperm in their lifetime.