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Provide 2 reasons you think cells might divide?

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Presentation on theme: "Provide 2 reasons you think cells might divide?"— Presentation transcript:

1 Provide 2 reasons you think cells might divide?
Unit 4: Genetics Provide 2 reasons you think cells might divide?

2 Notes: Intro to Chromosomes & the Cell Cycle
EQ: How and why do cells divide?

3 The Cell Cycle: Process in which cells grow, prepare for division, and divides to form two daughter cells. Reasons cells divide: 1. Size (Surface area to volume ratio) 2. Reproduction ( Asexual vs Sexual) 3. Growth & Development (Multicellular) 4. Repair and Replacement of tissue

4 **Reminder** DNA is contained in the nucleus… but, DNA can look different depending on what you are interested in…

5 We are going to focus on…
CHROMOSOMES! This is a chromosome! It contains your genetic information centromere Each side is a sister chromatid. They contain identical information.

6 Sister chromatids are held together by a centromere
Chromosomes: Sister chromatids are held together by a centromere A duplicated chromosome is made of 2 sister chromatids Sister chromatids are IDENTICAL A single sister chromatid can also be referred to as an unduplicated chromosome

7 How many chromosomes does a human have?
46! 23 from your mom 23 from your dad You have 23 pairs of homologous chromosomes

8 These chromosomes are HOMOLOGOUS
Same size Same shape Same type of information Example: A = dimples Dad has dimples a = no dimples Mom does not have dimples

9 Cells constantly need to make new cells
Cells constantly need to make new cells. Each new cell must have identical DNA to the old cell. How is this accomplished in living organisms? THE CELL CYCLE!

10 Cell Cycle & Mitosis Interphase: a period of growth and preparation for division in cell Mitosis: the division of the cell nucleus (eukaryotic cells)

11 1. Fold your paper into 8 boxes

12 2. Cut your paper down the middle horizontal line

13 3. Tape the two strips of paper together where the dashed line is

14 4. Draw the lines and label each section
INTERPHASE MITOSIS (PMAT) CYTO- KINESIS

15 G1 = growth 1 (Interphase)
Cell grows in size Organelles and proteins made

16 S = synthesis(Interphase)
DNA is replicated (“synthesized”) Each chromosome duplicates to make a sister chromatid 2x as much DNA at the end of synthesis

17 G2: growth 2 (Interphase)
Continued cell growth Organelles and molecules needed for division are produced

18 Prophase (Mitosis) Nucleus disappears
Chromosomes condense and become visible Centrioles move to opposite sides of cell Spindle starts to form X X X

19 Metaphase (Mitosis) X X X Chromosomes line up in the middle
Spindle fibers connect centriole to centromere X X X

20 < < < < < < Anaphase (Mitosis)
Sister chromatids separate (break apart) as spindle fibers pull them to opposite sides of cell Chromatids look like “A” < < < < < <

21 Telophase (Mitosis) Chromosomes are at opposite sides of the cell
Nuclear membrane reforms Chromosomes unwind Spindle breaks apart Nucleolus visible in each daughter cell < < < < < <

22 Cytokinesis: Division of the cytoplasm and organelles
Animal: Division of the cytoplasm and organelles and pinching off into 2 IDENTICAL daughter cells. Plant: Cell plate forms and creates a new cell membrane to make 2 IDENTICAL daughter cells

23 Cell Cycle Overview

24 Cell Cycle Follow-Up Questions
Homework!


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