* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Cell Reproduction - wentworth science
Survey
Document related concepts
Endomembrane system wikipedia , lookup
Extracellular matrix wikipedia , lookup
Biochemical switches in the cell cycle wikipedia , lookup
Tissue engineering wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cytokinesis wikipedia , lookup
Cell culture wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Cell growth wikipedia , lookup
Transcript
Cell Reproduction Many Cells from One Many living organisms are multi-cellular. This means that they are made of many cells Humans, for instance, are made of approximately 100 trillion cells But, we all started out as one cell. Where did the other 99,999,999,999,999 cells come from? Body Growth and Repair Bodies make new cells to grow and repair themselves Each cell has the ability to divide into two new cells These new cells, called daughter cells, are identical to the original cell, called a parent cell. These daughter cells can then divide into two more, and so on, and so on. This type of cell division is referred to as mitosis. Mitosis Mitosis: Cell reproduction in which two identical cells are made from one. All body cells in you, for instance, are formed by mitosis “Body cells” refers to all cells that make up most of the body, such as skin, blood, bones and your internal organs. Mitosis occurs at different rates for different tissues Brain cells may last up to 50 years whereas the cells in your stomach lining only last 2 days Introduction to Mitosis Mitosis is sort of like photocopying. You get copies based on the original Mitosis involves the chromosomes, centrioles, nucleus An important step that happens before mitosis is when each chromosomes is doubled. The DNA strands make copies of themselves The two strands are held together at one single point (called a centromere) The stands that are joined are called sister chromatids The centrioles double also Step 1: Sister chromatids start to shorten and thicken Nuclear membrane starts to breakdown Centrioles move away from each other Fibers form between centrioles Step 2: Centrioles move to opposite ends of cell Sister chromatids attach to the fibers Chromatids are pulled toward the center of cell Chromatids are now lined up at center of cell Step 3: Sister chromatids are pulled apart by fibers Sister chromatids are pulled to opposite ends of the cell Step 4: Each end of cell now has a complete set of DNA Fibers disappear Nuclear envelopes re-form around DNA Cell membrane pinches in at both sides to form two new cells After Mitosis The two new daughter cells are genetically identical to the parent cell This means that their chromosomes are identical to the parent cell’s and they both have the same number of chromosomes as the parent cell The new cells are slightly smaller than the parent cell but they will grow Benefits of Mitosis Helps organisms grow Replaces cells that have died or are damaged Plant Cells vs. Animal Cells Plant cells do not have centrioles After mitosis in plant cells, a new cell forms to make the two new cells Meiosis Meiosis is a different type of cell division Meiosis results in the formation of sex cells (sperm and egg cells) The big difference between meiosis and mitosis is that meiosis involves two cell divisions and results in 4 cells. Each with half the number of chromosomes as the original cell Step 1: Sister chromatids shorten and thicken Nuclear membrane breaks down Centrioles move away from each other Matching chromosomes come together to form pairs Step 2: Centrioles move to opposite ends of cell Sister chromatids attach to the fibers Fibers move the two pairs of chromosomes to center of cell Step 3: Fibers move matching chromosomes apart (sister chromatids remain together) Cell membrane pinches together and forms two new cells