It’s The circle of cell life How do cells reproduce and grow?

Why do cells divide? To replace other cells that have been damaged or worn out To allow multicellular organisms to grow For asexual reproduction Because they get too big!

What is MITOSIS? Mitosis is the process by which the nucleus of one cell DIVIDES into two nuclei Therefore, each cell has the same genetic material as the original cell Its like “photocopying” the cell- the two daughter cells are identical

Genetic Information Genetic information is contained in the DNA of the cell DNA is found in the thread-like coils called CHROMATIN when the cell is NOT dividing When the cell is dividing, the chromatin condenses (packs into) chromosomes genes are small sections of chromosomes that contain the information for a specific cell function

The big picture

Human Chromosomes

The cell cycle

The cell spends the most amount of time in interphase- growing Cell Cycle The cell spends the most amount of time in interphase- growing

Cell Cycle- Interphase During INTERPHASE the cell is GROWING and preparing to reproduce The cell’s DNA is being copied (replicated) The DNA is in the form of loosely coiled CHROMATIN

Cell Cycle- Mitosis Remember! Mitosis is the stages of the cell cycle in which the nucleus and cell divides Mitosis is divided into: Prophase Metaphase Anaphase Telophase Cytokenesis

The cell spends a very short amount of time in mitosis- dividing Cell Cycle The cell spends a very short amount of time in mitosis- dividing

The phases of mitosis

Early Prophase Chromosomes are condensed and consist of 2 sister chromatids The nuclear membrane begins to break down Spindle fibers appear

Late Prophase The CENTROMERE joins each pair of sister chromatids to the spindle fiber

Metaphase Chromosomes line up along the middle of the cell

Anaphase Spindle fibers separate sister chromatids and pull them apart Once they have separated they are individual chromosomes

Telophase Spindle fibers disassemble Nuclear envelope reforms The nuclear envelope will become the nuclear membrane

Cytokinesis In animal cells, the new cell membrane pinches off forming two new separate cells In plant cells, new cell membrane pinches off and a cell wall forms The cytoplasm is divided between the two cells