Thursday, October 4, 2007

DNA/RNA

1. What is DNA? DNA is the Blueprint of the Life of Every living organism, which contains it within itself, where as it is the information it needs to build a new organism. This information or blueprint, is stored in the organism's genome. The genome is made up of a material called DNA, which stands for deoxyribonucleic acid. If you look at a 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? There are four bases in every DNA, which are A, T, C and G; where as 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? The two pieces of information were the Phosphate backbone and the double helix.



4. What are the specific base pairs? The specific base pairs are the (adenine-thynine) and (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 the equal size and the sugar-phosphate backbone would be considered smooth.



6. What does the DNA do during cell division? It unzips 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? E. Coli produces 4 million pairs every 20 minutes and it is curled up in a condensed fashion like.



8. How many base pairs does Human DNA have? How long does it take to replicate? How is the DNA packaged in the cell? The human DNA produces 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 is a Blueprint Copy, where as when an organism needs to use the data stored in the genome 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. Like DNA, RNA is an abbreviated term for ribonucleic acid.



2. How are the RNA messages formed? The alphabet in the RNA molecule contains 4 letters, which are, A, U, C, G as previously mentioned. To construct a word in the RNA language, three of these letters are grouped together. The 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, in 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 contains an identical system that reads the RNA, which interprets the different codons and constructs a protein with various combinations of the amino acids, where as the RNA word or codon, corresponds to one single amino acid. The codons and their correlation with the amino acids are constructed in a protein sequence, which is called the genetic code.



1. Describe cell cycle. The cell cycle illustrates the different phases of cell division. The key molecules which control and coordinate the cell division are called “CDK” and “Cyclin”. Chromosomes in a cell nucleus encounters the cell growth to begin, where as the chromosomes are then divided and duplicated. The cell growth continues, where as the cell then reaches proper size.



2. What is nuclear division? The division of the nucleus and its genetic information into more than one cell, deriving from a parent cell, either via-meiosis or mitosis.



3. What is interphase? An interphase is a stage in the cell cycle, where as the cell doubles its cytoplasm and synthesizes DNA. Interphase is the "holding" stage or the stage between two successive cell divisions.



4. Cytokinesis refers to the division of a eukaryotic cell. Cytokinesis usually occurs after a cell has undergone nuclear cell division as part of mitosis or meiosis. However, the amount of cytoplasm and number of organelles and cellular components in each daughter cell is redistributed equally to each daughter cell. The ovum nearly takes all the cytoplasm and organelles, leaving little for the resulting polar bodies encountering to die.



5. Homologous chromosomes is 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. 5 Phases of mitosis. 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 meiosis has only one phase not two.