Presentation is loading. Please wait.

Presentation is loading. Please wait.

Cell Divisions Mitosis and Meiosis. Mitosis Division of the nucleus of all cells except sex cells Produces 2 daughter cells each with the same amount.

Similar presentations


Presentation on theme: "Cell Divisions Mitosis and Meiosis. Mitosis Division of the nucleus of all cells except sex cells Produces 2 daughter cells each with the same amount."— Presentation transcript:

1 Cell Divisions Mitosis and Meiosis

2 Mitosis Division of the nucleus of all cells except sex cells Produces 2 daughter cells each with the same amount and type of genetic material as the parent cell

3 Synthesis Also called Interphase of the cell cycle Not technically part of Mitosis DNA is replicated (copied) to make an exact copy of itself Each “new” strand is 1/2 of the “old” strand and 1/2 of newly formed strand

4 Prophase 1st stage of Mitosis Nuclear membrane begins to weaken

5 Prophase Centrioles (Protein structures) form and move to the poles of the nucleus

6 Metaphase Chromosomes line up in the middle Spindle fibers extend from the centrioles to the centromeres

7 Anaphase Spindle fibers shorten Chromosomes are pulled apart at the centromere Chromatids move to the opposite sides

8 Telophase Nuclear membranes begin to reform Spindle fibers are gone Centrioles begin to disassemble Cleavage forms –Cleavage - an indentation in tissue

9 Cytokinesis Nuclear membrane complete New cell membrane forms at cleavage Exact copy of the original cell

10 Cell Division for Sex Cells

11 Meiosis Division of the nucleus of sex cells Produces 4 daughter cells each with the 1/2 amount and type of genetic material as the parent cell

12 Meiosis The first 1/2 is identical to Mitosis Before the 2nd 1/2 the DNA is NOT replicated

13 Prophase 1 of Meiosis Nuclear membrane begins to dissolve Centrioles begin to form and move to the poles

14 Metaphase 1 of Meiosis Chromosomes line up in the middle Spindle fibers extend from the centrioles to the centromeres

15 Anaphase 1 of Meiosis Spindle fibers shorten Chromosomes are pulled apart at the centromere Chromatids move to the opposite sides

16 Telophase 1 of Meiosis Nuclear membranes begin to reform Spindle fibers are gone Centrioles begin to disassemble Cleavage forms

17 Cytokinesis 1 of Meiosis Nuclear membrane complete New cell membrane forms at cleavage Exact copy of the original cell

18 Metaphase 2 of Meiosis Single copy of the chromosomes line up in the middle Spindle fibers extend from the centrioles to the centromeres

19 Anaphase 2 of Meiosis Spindle fibers shorten Single Chromosome is pulled apart at the centromere Chromatids move to the opposite sides

20 Telophase 2 of Meiosis Nuclear membranes begin to reform Spindle fibers are gone Centrioles begin to disassemble Cleavage forms on 4 new cells

21 Cytokinesis 2 of Meiosis Nuclear membranes complete New cell membranes form at cleavage 4 cells each with 1/2 the genetic information of the parent cell

22 Mutations

23 Mutation: –Any change in the sequence (order) of the DNA 3 main types –Insertion –Deletion –Substitution

24 Results of Mutations Benign - not good/not bad –This type of mutation leads to variations of traits Different hair color, skin color, etc Helpful –This type of mutation is beneficial to the organism Harmful –This type of mutation interferes with normal protein production and often leads to illness or death

25 Variation A change in a trait which is caused by a change in the DNA

26 Insertion Mutation If the DNA were a sentence like: My sister is Betty Insertion would add 1 or more letters to the sentence: My sisters is Betty Bad grammar, but the sentence still makes sense

27 Deletion Mutation Using the same sentence: My sister is Betty Deletion mutation removes one or more letters My sister is Btty This can still makes sense, but changes the meaning of the sentence which in a cell could change the protein

28 Problems with Insertion and Deletion Mutations Once the message is carried out of the nucleus by RNA (we have not talked about this) all messages are read in 3 base segments Adding or removing 1 base causes these segments to be completely changed

29 Insertion and Deletion Continued Using our sentence the 3 base sequences would look like this: MYS IST ERI SBE TTY Insertion would cause this: MYS IST ERS ISB ETT Y Deletion would cause this: MYS IST ERI BTT Y

30 Substitution Mutation Still using the same sentence: My sister is pretty Substitution changes one or more letters My mister is pretty

31


Download ppt "Cell Divisions Mitosis and Meiosis. Mitosis Division of the nucleus of all cells except sex cells Produces 2 daughter cells each with the same amount."

Similar presentations


Ads by Google