Cellular Reproduction

Chromosomes Contain genetic information – DNA DNA is arranged in segments called genes Determine characteristics, or traits Humans have 46 chromosomes in their cells – 23 from each parent

Chromosomes Exist as chromatin prior to cell division - relaxed form of DNA in the cell’s nucleus

Chromosomes Centromere: at the center of the chromosome where the sister chromatids attach Sister chromatids: Each half of the X, contains identical copies of DNA

HUMAN CHROMOSOMES

3 Main Stages: Interphase Mitosis Cytokinesis The Cell Cycle Cells reproduce by growing and dividing WHY?? Cell division prevents the cell from becoming too large To replace other cells For asexual reproduction To allow multicellular organisms to grow 3 Main Stages: Interphase Mitosis Cytokinesis

The Cell Cycle

Interphase G1: The cell is growing, carrying out normal cell functions, and preparing to replicate DNA. Occurs immediately after the cell divides. S: The cell copies its DNA in preparation for cell division. G2: The cell prepares for the division of its nucleus.

Mitosis Process that divides the nucleus of one cell into two nuclei Purpose is to create two daughter cells with identical genetic information Each daughter cell receives the exact same # and type of chromosomes, it’s like photocopying the cell!

Prophase Beginning phase, the longest phase Chromatin tightens, or coils, into chromosomes In this phase the chromosomes are shaped like an X Nuclear envelope disappears Centrioles migrate to poles Spindle fibers form

Metaphase Changing phase, one of the shortest stages Chromosomes are pulled to center of cell and lined up Ensures there are accurate copies of the chromosomes

Anaphase Anew phase The spindle fibers pull the sister chromatids apart into two identical chromosomes The chromosomes are pulled to opposite ends of the cell

Telophase Ending phase Chromosomes reach the poles of the cell and begin to unwind Two new nuclear membranes begin to form Nuclei reappear

It’s not over yet!

Cytokinesis Towards the end of mitosis, the cell undergoes cytokinesis This divides the cytoplasm The cytoplasm is pinched (the furrow) Creates two new cells

Animal Cell - Mitosis Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

Plant Cell - Mitosis Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

Chromosomes

The Cell Cycle

I Pray More At The Church! The Cell Cycle Interphase Prophase Metaphase Anaphase Telophase Cytokinesis I Pray More At The Church!

Cell Cycle Regulation The cell cycle has built-in checkpoints that monitor the cycle and can stop it if something goes wrong.

Abnormal Cell Cycle CANCER: the uncontrolled growth and division of cells Cancer cell can kill an organism by crowding out normal cells, resulting in the loss of tissue function

Cancer Interphase: 120 minutes Prophase: 60 minutes The cancer cell cycle is much faster than the normal cell cycle: Chicken stomach cells Interphase: 120 minutes Prophase: 60 minutes Metaphase: 10 minutes Anaphase: 3 minutes Telophase: 12 minutes Interphase: 16 minutes Prophase: 15 minutes Metaphase: 2 minutes Anaphase: 1 minute Telophase: 3 minutes

Causes The changes that occur in the regulation of cell growth and division of cancer cells are due to mutations. Inherited Carcinogens Radiation

Apoptosis Programmed cell death Cells going through this apoptosis actually shrink and shrivel in a controlled process

Cell Death

Stem Cells Unspecialized cells that can develop into specialized cells when under the right conditions