ºÝºÝߣ

ºÝºÝߣShare a Scribd company logo

The case of the dividing cell

•Download as PPTX, PDF•
•
A
Aarti Patel

Mitosis and meiosis are two types of cell division. Mitosis produces two identical daughter cells and occurs in eukaryotic cells during growth and repair. Meiosis produces four non-identical sex cells and occurs only in eukaryotic sex cells. During meiosis, the chromosomes are copied and line up in pairs during the first division, and then separately during the second division, resulting in four cells each with half the number of chromosomes. This allows for genetic variation that is important for evolution.

1 of 10
Downloaded 23 times
The Case of the Dividing Cell: Mitosis and Meiosis in the Cellular Court By Garielle Wagnac and Aarti Patel
The case of the dividing cell
Cell Life Cycle A cell goes through six stages during its life cycle: • Interphase- cells start to grow and make proteins and organelles • Prophase- cells make an extra copy of their DNA and join together to make chromosomes, the two parts of the chromosome, the original DNA and the copy, are called chromatids. • Metaphase- the chromosomes line up in the center of the cell • Anaphase- the chromatids are split apart and pulled to opposite sides of the cell by spindle fibers from centrioles • Telaphase- the cell splits into two and a new nuclear membrane is formed
Cell Division in… Prokaryotes • The cell divides using binary fission • The cell makes a copy of it DNA and then divides into two • Each part receives a copy of the DNA Eukaryotes • The cell divides using mitosis or meiosis • During mitosis or meiosis, the chromosomes are copied • They are then separated and the cell divides into two • In meiosis, the two cells repeat this process and divide once again
The case of the dividing cell
Stages of Meiosis • Prophase I: The nuclear membrane dissolves and the mother’s chromosomes pair with the father’s chromosomes. • Metaphase I: The pairs line up in the center of the cell in two rows of 23 chromosomes. • Anaphase I: The pairs of chromosomes are separated and took to opposite ends of the cell by spindle fibers. • Telophase I: The cell divides into two cells each with 23 chromosomes. • Prophase II: The nuclear membrane dissolves again in the two new cells. • Metaphase II: The chromosomes line up in the center of the cells in one line. • Anaphase II: Spindle fibers separate the chromatids. • Telophase II: Both cells divide again and form a total of four cells, each with one set of chromosomes.
• The cell divides once • Chromosomes line up in one line during metaphase • Occurs in all cells except sex cells • The cell divides twice • Chromosomes line up in pairs during metaphase I • Occurs only in sex cells http://ghr.nlm.nih.gov/handbook/illustrations/mitosismeiosis.jpg
Prokaryotes • Prokaryotes undergo binary fission. They do not have mitosis or meiosis. • During binary fission, DNA is copied and then the cell divides into two. Each receives a copy of the DNA. http://www.micro.cornell.edu/cals/micro/research/labs/angert-lab/images/binary_fission.jpg
Crossing Over • During prophase 1 the chromosomes from the mother match up with the chromosomes from the father • The chromosomes pair up with the same chromosome from the opposite cell • A crossover can not occur between two different chromosomes http://kvhs.nbed.nb.ca/gallant/biology/crossing_over.jpg
Evolution and Meiosis • Meiosis evolved around the same time as sexual reproduction • This is important because meiosis allows for unique organisms • Without meiosis, everything would have the same genetic material, thus becoming clones of each other

More Related Content

The case of the dividing cell

  • 1. The Case of the Dividing Cell: Mitosis and Meiosis in the Cellular Court By Garielle Wagnac and Aarti Patel
  • 3. Cell Life Cycle A cell goes through six stages during its life cycle: • Interphase- cells start to grow and make proteins and organelles • Prophase- cells make an extra copy of their DNA and join together to make chromosomes, the two parts of the chromosome, the original DNA and the copy, are called chromatids. • Metaphase- the chromosomes line up in the center of the cell • Anaphase- the chromatids are split apart and pulled to opposite sides of the cell by spindle fibers from centrioles • Telaphase- the cell splits into two and a new nuclear membrane is formed
  • 4. Cell Division in… Prokaryotes • The cell divides using binary fission • The cell makes a copy of it DNA and then divides into two • Each part receives a copy of the DNA Eukaryotes • The cell divides using mitosis or meiosis • During mitosis or meiosis, the chromosomes are copied • They are then separated and the cell divides into two • In meiosis, the two cells repeat this process and divide once again
  • 6. Stages of Meiosis • Prophase I: The nuclear membrane dissolves and the mother’s chromosomes pair with the father’s chromosomes. • Metaphase I: The pairs line up in the center of the cell in two rows of 23 chromosomes. • Anaphase I: The pairs of chromosomes are separated and took to opposite ends of the cell by spindle fibers. • Telophase I: The cell divides into two cells each with 23 chromosomes. • Prophase II: The nuclear membrane dissolves again in the two new cells. • Metaphase II: The chromosomes line up in the center of the cells in one line. • Anaphase II: Spindle fibers separate the chromatids. • Telophase II: Both cells divide again and form a total of four cells, each with one set of chromosomes.
  • 7. • The cell divides once • Chromosomes line up in one line during metaphase • Occurs in all cells except sex cells • The cell divides twice • Chromosomes line up in pairs during metaphase I • Occurs only in sex cells http://ghr.nlm.nih.gov/handbook/illustrations/mitosismeiosis.jpg
  • 8. Prokaryotes • Prokaryotes undergo binary fission. They do not have mitosis or meiosis. • During binary fission, DNA is copied and then the cell divides into two. Each receives a copy of the DNA. http://www.micro.cornell.edu/cals/micro/research/labs/angert-lab/images/binary_fission.jpg
  • 9. Crossing Over • During prophase 1 the chromosomes from the mother match up with the chromosomes from the father • The chromosomes pair up with the same chromosome from the opposite cell • A crossover can not occur between two different chromosomes http://kvhs.nbed.nb.ca/gallant/biology/crossing_over.jpg
  • 10. Evolution and Meiosis • Meiosis evolved around the same time as sexual reproduction • This is important because meiosis allows for unique organisms • Without meiosis, everything would have the same genetic material, thus becoming clones of each other