Chapter 5 Review Powerpoint Science 9 Mitosis
Why do some cells divide more often than others? Do red blood cells or stomach cells divide more often? • Cells that get more wear and tear divide more often. • Stomach cells divide every 2 days, but red blood cells divide ever 120 days.
Why is it important for cells to divide? • To produce new cells that replace old cells that die or mutate so that the whole organism is not hurt. • To produce new organisms through asexual reproduction
If you start with one cell, how many cells do you have at the end of one cell cycle? • Two
What is the original cell called? What are the two new cells called? • Parent cell • Daughter cells
What are the three main stages of the cell cycle? • Interphase • Mitosis • Citokinesis
Describe the three stages of interphase. • 1) Growth and preparation of the cell by gathering nutrients and making proteins and molecules needed for mitosis. • 2) DNA is replicated: An enzyme splits the DNA strand down the center, then new bases pair with the original DNA to make two DNA molecules. • 3) Growth and preparation again to duplicate organelles and prepare for mitosis
Why is DNA replication during interphase so important? • DNA needs to replicate so there is a copy of each DNA strand in the two daughter cells.
Explain the difference between chromatin and chromosomes. In which parts of the cell cycles are each of them found? • Chromatin is loosely coiled DNA in interphase and cytokinesis • Chromosomes are tightly coiled, X-shaped DNA strands during mitosis
What are the four stages of mitosis? Draw and label a diagram for each stage.
What happens to the organelles during the cell cycle? • Organelles are duplicated during interphase so that one of each organelle is in each daughter cell.
What happens during the last stage of the cell cycle? • Cytokinesis: The cell splits to make two daughter cells. • In animal cells the cell membrane pinches together. • In plant cells a cell wall and membrane form along the center to split the cells.
Why is it useful for DNA to be loosely coiled during interphase but tightly coiled during mitosis? • In interphase the DNA is loosely coiled so it is easier to replicate the DNA • In mitosis the DNA is tightly coiled to make it easier for it to be moved around the cell
What are the checkpoints of the cell cycle? Why are they important? • Check if the cell has enough nutrients and has grown • Check if the DNA has been replicated • Check that the DNA is not damaged • These are important to regulate the cell cycle and make sure that no cells pass on mutations or replicate constantly without stopping.
What can happen when the checkpoints in a cell aren’t regulated? • The cells can pass on mutations and start dividing uncontrollably. This can lead to cancer.
What is asexual reproduction? • Reproduction that requires only one parent to produce offspring that are genetic copies of the parent
What is binary fission? • A single-celled organism replicates using mitosis to get two daughter cells.
What is budding? • An organism has certain cells repeatedly undergo the cell cycle to grow a new organism from the parent cell. The daughter cell can detach and go to another environment.
What is fragmentation? • An organism breaks apart then each fragment grows into an identical daughter cell
What is vegetative reproduction? What is grafting? • Vegetative reproduction: specialized plant cells divide repeatedly to grow a new organism from the parent. • Grafting: Humans join the parts of different plants together. • They do this to grow more crops and help a plant grow by joining it to another.
What is spore formation? • Spores (individual reproductive cells) are made by the parent and can be carried by the wind to a new location. An offspring identical to the parent grows from each spore.
What are three advantages and disadvantages to asexual reproduction? • Advantages: • Fast – can make many offspring quickly because you only need one parent cell • Requires less energy for the organism • If many are made they can compete against other species for the territory or area. • Disadvantages: • Genetic copies – mutations are passed down and can harm many of the offspring • Can compete for food and space • Entire colonies can be wiped out by bad conditions because there is no genetic diversity
What is a clone? • A clone is a genetic copy of an organism.
What is the difference between reproductive cloning and therapeutic cloning? • Reproductive cloning duplicates the whole organism, but therapeutic cloning only duplicates a desired part using stem cells.
What are advantages and disadvantages of therapeutic cloning? • Advantages: Used to correct health problems by growing tissues and organisms to replace damaged ones. • Do not need to clone the whole organism for one tissue or organ • Disadvantages: Need to use specific types of cells (stem cells)
What are advantages and disadvantages of reproductive cloning? • Advantages: gives you a duplicate of a desired organism • Disadvantages: only 10% of clones survive • Need to grow the organism to be an adult – takes time