Essential+Questions

DNA is a molecule and is found in the nucleus of the cell. It stands for deoxyribonucleic acid, and it is genetic material that caries information about an organisms, directs all the cell's function and is passed from parent to offspring. Chromosomes are composed of DNA. Another type of nucleic acid is RNA (ribonucleic acid). ||< || DNA comes in a spiral shape called a double helix and the shape can be described as twisted ladder or spiral staircase. The four nitrogen bases that make up the rungs of the ladder are cytosine (C), adenine (A), guanine (G), and thymine (T).
 * < **//DNA Essential Question - What is the fact and fiction of the statement “DNA is like a tightly wound rubber band doing the same job as a hard drive in your computer”//** ||<  ||
 * < **1. What is DNA and where is it found?**
 * < **2. What does it look like (its structure) and what is it made from?**

Adenine only bonds with thymine and guanine and cytosine will only bond with each other. There are billions of different arrangements in a DNA strand, therefore there can be various outcomes of proteins.

The sides of the ladder (the brown thing in the picture) are made from phosphate and deoxyribose (sugar). ||< media type="youtube" key="qy8dk5iS1f0" height="315" width="420" http://www.youtube.com/watch?v=qy8dk5iS1f0&feature=player_embedded || DNA copies itself through the cell cycle (mitosis) and meiosis. (See mitosis and meiosis page) (Go to **resources** page and check out the video).
 * < **3. How and why does it copy itself?**

DNA unzips, and becomes two incomplete strands of DNA. Then the nitrogen bases that are floating in the cell that are not part of the DNA strand begin bonding. Because A always bonds with T and G always bonds with C, the two new strands are exactly the same as the original strand.

DNA must copy itself during interphase because exact copies of DNA has to be distributed to two different daughter cells during mitosis, so that the cell can carry out the function's that it must properly as DNA controls the cell. ||< (see resources) media type="youtube" key="z685FFqmrpo" height="315" width="420" http://www.youtube.com/watch?v=z685FFqmrpo&feature=player_embedded || Genes are a section in chromosomes that are made from DNA and contain the information to code for one specific protein. They are made up of a series of the four nitrogen bases (cytosine, adenine, guanine, and thymine) in a row. Genes are found in chromosomes, and chromosomes are found in the nucleus of a cell. ||< || There is genetic diversity due to the fact that the offspring gets both genes from the parents. More chances of variable offspring that will survive in different conditions (diseases) and environments (or environment changes).
 * < **4. What are genes and where are genes found?**
 * < **Cell Cycle, Mitosis and Meiosis Essential Questions - Compare and contrast a photocopier and a muscle cell? Compare and contrast chromosomes and playing cards?** ||<  ||
 * < **1. What are the advantages and disadvantages of both sexual and asexual reproduction?**
 * The advantages of sexual reproduction:**

Mutations may occur, and the process takes longer to produce offspring, compared to asexual reproduction, or, it is not as efficient.
 * The disadvantages of sexual reproduction:**

Absolutely identical cells (clones), regeneration (farmers used this technique to plant more plants), one cell to reproduce (no need to find mate) - much simpler and saves energy, faster reproduction.
 * The advantages of asexual reproduction:**

All clones, no genetic diversity, could cause species or population to go extinct. ||< Sexual:
 * The disadvantages of asexual reproduction:**

Asexual: || 3 organisms that reproduce sexually: cow, horse, frog 3 organisms that reproduce asexually: sea sponge, starfish, sea urchin ||<  || Mitosis is part of the cell cycle, and both of them are forms of cell division. There is no relationship between meiosis and the cell cycle. ||< Cell Cycle: media type="youtube" key="l88IJoM2aK0" height="315" width="420" http://www.youtube.com/watch?v=l88IJoM2aK0&feature=player_embedded
 * < **2. Name 3 organisms that reproduce sexually and 3 that reproduce asexually.**
 * < **3. What is the relationship between the cell cycle, mitosis and meiosis?**

Mitosis:

Meiosis: ||

The cell cycle and meiosis are used for producing more cells. The purpose of the cell cycle is for growth and repair of your body. The purpose of meiosis is to produce sex cells, reduce the number of chromosomes, and have genetic variety. ||  || The cell cycle and meiosis are similar because there is always a parent cell, and they divide to make daughter cells.
 * **4. What are the cell cycle and meiosis**
 * used for?**
 * **5. What is similar about the cell cycle and meiosis?**

Meiosis causes variation in genes because there is random separation of chromosome pairs in Meiosis I, and there is crossing over, which could occur or not occur. || media type="youtube" key="Ba9LXKH2ztU" height="315" width="420" http://www.youtube.com/watch?v=Ba9LXKH2ztU&feature=player_embedded || What is different about the cell cycle and meiosis is that the amount of daughter cells produced from one parent cell are different, 4 for one cell in meiosis (two divisions), and 2 in the cell cycle (one division).
 * **6. What is different about cell cycle and meiosis?**

The cell cycle is used in asexual reproduction and meiosis is used for sexual reproduction.

The number of chromosomes in the cells that go through meiosis are half of the amount always found in cells that go through the cell cycle.

The sex cells are also genetically different from the parent cell, while the cells that go through the cell cycle are genetically identical to the parent cell. ||  ||