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Chapter 5 Science
| Question | Answer |
|---|---|
| 3 Stages of The Cell Cycle | Interphase, Mitosis, Cytokenisis |
| In interphase, | the cell grows, replicates the DNA, and prepares to divide. |
| In mitosis, | the nuclear material divides. |
| In cytokinesis, | the cell contents including the two nuclei separate into two daughter cells. |
| Mitosis process: | Mitosis is a process that divides the contents of the cell’s nucleus, the chromosomes. |
| There are four stages of mitosis including: | prophase, metaphase, anaphase, and telophase. |
| Methods of asexual reproduction include | binary fission, budding, fragmentation, vegetative reproduction, and spore formation. |
| One-celled organisms can reproduce by | binary fission and budding. |
| Multicellular organisms reproduce by | fragmentation, vegetative reproduction, and spores. |
| Asexual reproductive methods are natural forms of... | cloning |
| Human-assisted methods of cloning plants include | cuttings and grafts. |
| Human-assisted methods of cloning animals include | reproductive cloning and therapeutic cloning. |
| In reproductive cloning, | new individuals are cloned. |
| In therapeutic cloning, | new organs or tissues are cloned. |
| Why is cell division necessary in unicellular organisms? | Cell division is necessary in unicellular organisms so that these organisms can reproduce themselves in great numbers. |
| Why is cell division necessary in multicellular organisms? | Cell division is necessary in multicellular organisms for growth and to replace worn-out cells. |
| Cells spend much of their time in interphase. What is occuring during this stage? | Life functions. Digestive system cells will be making enzymes, retina cells will be performing chemical reactions so that you are able to see. In addition, the cell is preparing for cell division by duplicating organelles. |
| There are checkpoints in the cell cycle. What events must occur in the cell to prevent each checkpoint protein from sending a message to the nucleus to destroy a cell? | Checkpointpro: (a) Are there enough nutrients in the cell to support growth? (b) Is the DNA damaged? (c) Has the DNA replicated? (d) Have the chromosomes become attached to the spindle fibres? (e) Have the chromosomes moved to the poles in anaphase? |
| What would happen if a cell was unable to make protein to form spindle fibres? | If the cell as unable to make the proteins to form spindle fibres, mitosis could not occur successfully since the chromosomes would not be able to attach. The result would be that the chromosomes would not be equally distributed between cells. |
| What can occur if there is a mutation in a checkpoint protein? | If there is a mutation in a checkpoint protein, the cell may continue to proceed through the cell cycle and the result is that the cell may die or have a mutation. |
| How does binary fission result in bacteria becoming resistant to antibiotics? | Bacteria grow at an exponential rate thrugh binary fission and mutations do occur. If a mutation occurs that allows the bacteria to become resistant to antibiotics, these bacteria will survive and multiply. |
| Design a chart listing the phases of mitosis. | Prophase: The chromosomes become visible, and the spindle fibres appear and chromosomes attach. Metaphase: The spindle fibres pull the Xshaped chromosomes into a single line at the equator. |
| Design a chart listing the phases of mitosis. (2) | Anaphase: The spindle fibres contract and shorten, and the chromatids are pulled to opposite poles of the cell. Telophase: The spindle fibres disappear, and the nuclear membrane forms around each set of chromosomes. |
| Make a sketch to illustrate how mitosis in plant cells differs from mitosis in animal cells. | The daughter plant cells will remain together with a cell plate between them, which will form the cell membrane and cell wall. The animal cells will pinch completely apart. |
| What is the major disadvantage of asexual reproduction? | The major disadvantage of asexual reproduction is that there is very little variation so all the offspring are identical. If conditions change, all of the individuals could die. |
| Give three reasons for human-assisted cloning. | Three reasons for human-assisted cloning are to save an endangered species, to mass produce an organism with a desired trait, or to correct health problems. |
| What is reproductive cloning? | Reproductive cloning is also known as adult DNA cloning, and it is used to duplicate an entire individual that has a desired trait. |
| What are stem cells? | Stem cells are cells that are not yet differentiated to become a specific kind of cell. They have the potential to become many different types of cells. |
| What are two characteristics of asexual reproduction? | Two characteristics of asexual reproduction are that only one parent is required and all of the offspring are genetic clones of the parent. |
| Why must the nuclear membrane disintegrate during prophase? | The nuclear membrane must disintegrate during prophase so that the chromosomes are free to attach to the spindle fibers. |
| Explain what might happen if the chromosomes did not seperate correctly during anaphase. | the cell will probably not pass the checkpoints to go through the rest of the cell cycle. The cell will die, or it may go unchecked so that one daughter cell will end up with more chromosomes than the other daughter cell. |
| How do cancer cells spread to a new location? | Cancer cells spread to a new location when they break away and move into the bloodstream, where they may begin to divide and form a new tumor. |
| How do blood vessels help cancer cells to multiply? | The blood vessels branch into the tumor and deliver nutrients to it, which allows it to grow even more rapidly. |
| A laboratory technician is observing some cells under a microscope. What might she look for to determine if any of the cells are cancer cells? | A laboratory technician can identify cancer cells because these cells have a large abnormal nucleus since there are extra chromosomes inside. |
| Only less complex forms of animal life can reproduce by asexual reproduction. Why? | Only less complex forms of life can reproduce asexually because lower forms have only a few types of cells. Higher forms have many types of specialized cells to form complex tissues. |
| Why are there concerns about stem cell research? | There are concerns about stem cell research because some people feel it is wrong to destroy cells that are able to develop into an individual. |
| Growth and Preparation (during interphase) | -Cell increases in size -Cell makes proteins and molecules -Some organelles begin to duplicate |
| Replication (during interphase) | -DNA makes copies of itself -The DNA molecule unwinds (A will pair with T, and G with C) |
| Continued Growth and Preparation (during interphase) | -After replication, cell continues to grow (for cytokinesis) -The chromatin is loosely coiled -Loosely coiled DNA copied into RNA to make proteins for cell division -Mitochondria and chloroplasts are duplicated |
| What happens in Prophase? | -Nucleolus dissolves -Spindle fibers reach for centromeres -Centrioles move toward poles -Nuclear membrane breaks down |
| What happens in Metaphase? | -Chromosomes create line on equator of cell -Poles are at each end |
| What happens in Anaphase? | -Cell elongates -Spindle fibers begin to contract -Sister chromatids separate -Centromeres pulls apart -Chromatids are now chromosomes |
| What happens in Telophase? | -Nuclear membrane appears -Nucleolus appears -Spindle fibers disappear -Complete set of chromosomes -Ready to divide |
| Binary Fission: | Ex) Amoeba, Bacteria Single parent cell replicates its genetic material and divides into two equal parts. |
| Budding | Ex) Hyras, Sponges (animals attached to rock, move very little) Repeated mitosis and cell division that can develop into an identical organism |
| Fragmentation | Ex) Animals, plants (Sea star, Eurasian milfoil) If organism breaks apart as a result of injury, each fragment then develops into a clone of its parent |
| Vegitative Reproduction | Ex) Plants (Potatoes) Plant cells (usually plant stems/roots) divide repeatedly to form structures that will develop into a plant identical to it's parent. Advantage: Farmers Disadvantage: plants very close to each other |
| Spore Formation | Ex) Fungi (bread mold), Puffballs, Mosses, Ferns A spore is a reproductive cell that grows into a new individual by mitosis (rely on water and wind to carry it away from parent) The individual will begin to grow wherever it lands |
| Advantages of Asexual Reproduction | -Large number of offspring produced quickly -Large colonies can form and out-compete other organisms for nutrients and water -Large number of organisms mean that species may survive when con./number of predators change -Energy not required to find m8 |
| Disadvantages of Asexual Reproduction | -When error in clone, a negative mutation can make asexual produced orgs susceptible to disease -Some methods of A.R. produce offspring to close to each other (compete food and space) -Unfavorable conditions (extreme temp) can wipe out entire colonies |
| Reproductive Cloning | Ex) Dolly the sheep (or cow that makes a lot of milk) Produce a genetic duplicate of an existing or previously existing organism with desirable qualities |
| Therapeutic Cloning Stem and Embryonic Stem Cells | *Used to correct health problems Stem cells are cells that can become many different types of cells Embryonic stem cells are better for therapeutic cloning because they can become one of 200 types of body cells |
| How does cytokinesis differ in plant and animal cells? | Animal cell- cell membrane pinches together to divide the cell's cytoplasm and organelles Plant cell- cell plate forms along centre of the cell to divide the cell into two daughter cells |
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