DNA and RNA

DNA and RNA
1. What is DNA?
- DNA - the Blueprint of Life
Every living organism contains within itself the information it needs to build a new organism. This information, you could think of it as a blueprint of life, is stored in the organism's genome. The genome is made up of a material called DNA, which stands for deoxyribonucleic acid. If you take a really, really close look at the DNA molecule you will see that it looks like an ordinary ladder, although somewhat twisted. The steps that connects the two strands in this ladder are composed of four different molecules of the same type, called nucleotides.
2. What are the 4 bases?
- In DNA they are A, T, C and G; where A stands for adenine, T for thymine, C for cytosine and finally G for guanine.
3. What 2 peices of information did the scientists need to solve the elusive structure of DNA?
- Phosphate backbone, double helix.
4. What are the specific base pairs?
- (adenine,thynine) (guanine,cytosine)
5. How does the pairing rule effect the shape and structure of DNA?
- Each rung of the twisted ladder in the Helix would be of equal size, and the sugar-phosphate backbone would be smooth.
6. What does the DNA do during cell division?
- It is able to unzip into two pairs.
7. How many base pairs does E. Coli have? How long does it take to replicate? How is the DNA packaged in the cell?
- It makes 4 million pairs in once every 20 minutes and it is curled up in a condensed fashion.
8. How many base pairs does Human DNA have? How long does it take to replicate? How is the DNA packaged in the cell?
- It makes 3 billion pairs in about 12 - 24 hours and is packaged into 23 distinct chromosome pairs.

1. What is RNA? How different is it from DNA?
RNA - a Blueprint Copy
-When an organism needs to use the data stored in the genome, e.g. to build components of a new cell, a copy of the required DNA part is made. This copy is called RNA and is almost identical to DNA. Just like DNA, RNA is an abbreviated form of a chemical name which in the case of RNA is ribonucleic acid.
2. How are the RNA messages formed?
- The alphabet in the RNA molecule contains 4 letters, i.e. A, U, C, G as previously mentioned. To construct a word in the RNA language, three of these letters are grouped together. This three-letter word are often referred to as a triplet or a codon. An example of such a codon is ACG. The letters don't have to be of different kinds, so UUU is also a valid codon. These codons are placed after each other in the RNA molecule, to construct a message, a RNA sequence. This message will later be read by the protein producing machinery in the body. The RNA part to the left contains 39 letters and since each codon contains 3 letters, 13 codons are present (39 letters divided by 3 letters equals 13 words or codons.)

3. How are the RNA messages interpreted?
- Every organism has an almost identical system that is able to read the RNA, interpret the different codons and construct a protein with various combinations of the amino acids mentioned previously. In fact every RNA word or codon, corresponds to one single amino acid. These codons and their correlation with the amino acids in a protein sequence is what defines the genetic code.
1. Describe cell cycle.
- The cell cycle illustrates the different phases of division. The key molecules which control and coordinate cell division are called “CDK” and “Cyclin”. Chromosomes in cell nucleus Gap 1 Phase: Cell growth begins Synthesis Phase: Chromosomes divide and duplicate, Cell growth continues Gap 2 Phase: Cell reaches proper size Mitosis Phase: Cell Division.
2. What is nuclear division.
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3. What is interphase.
- A stage in the cell cycle when a cell doubles its cytoplasm and synthesizes DNA. Interphase is the "holding" stage or the stage between two successive cell divisions.
4. Cytokinesis.
- Cytokinesis refers to the division of a eukaryotic cell. Cytokinesis usually occurs after a cell has undergone nuclear division as part of mitosis or meiosis. Except for some special cases, the amount of cytoplasm and number of organelles and cellular components in each daughter cell is redistributed equally to each daughter cell. Notable exceptions include oogenesis, where the ovum nearly takes all the cytoplasm and organelles, leaving little for the resulting polar bodies, which then die.
5. Homologous chromosomes.
- A pair of chromosomes made up of two homologs. Homologous chromosomes have corresponding DNA sequences and come from separate parents; one homolog comes from the mother and the other comes from the father. Homologous chromosomes line up and synapse during meiosis.
6. Phases of mitosis (5 of them).
- Phase 1: Interphase the chromosomes replicate Phase 2: Prophase the nuclear memebrane disintergrates and the spindle is formed. Phase 3:Metaphase the chromosomes line up on the equatorial plate of cell Phase 4: Anaphase the centrioles will separate in animal cells. The chromatids are pulled apart. Phase 5: Telophase cytokinesis occurs (cytoplasm divides) and two new nuclei are formed.
7. Phases of meiosis and how it is different from mitosis.
- meiosis 1: prophase 1, metaphase 1, anaphase 1, and telophase 1
meiosis 2: prophase 2, metaphase 2, anaphase 2, and telophase 2.
It is different from mitosis because mitosis only has one phase not two.
8. Describe the process and purpose of crossing over.