Genetics-Cell Cycle Questions

1. What is DNA?

· Deoxyribonucleic acid (DNA) is a very important molecule found in all living cells.

2. What are the 4 bases?

· A, T, C, & G. Adenine, Thymine, Cytosine, and Guanine.

3. What 2 pieces of information did the scientists need to solve the elusive structure of DNA?

• base-pair interactions
• Genetic engineering

4. What are the specific base pairs?

• Adenine (A) forms a base pair with thymine (T), as does guanine (G) with cytosine (C) in DNA. In RNA, thymine is replaced by uracil (U).

5. How does the pairing rule effect the shape and structure of DNA?

· The sequence of the pairings forms a code which holds genetic information. When the code is paired, each rung in the helix would become equal in length, and the sugar-phosphate backbone will smoothen.

6. What does the DNA do during cell division?

• Cells stop dividing because the telomeres (protective bits of DNA on the end of a chromosome) become shorter with each division and eventually can no longer protect the chromosome.

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 has around 4 or more million base pairs. They can replicate in millions in minutes and billions a day. E. Coli is package tightly to a cell in 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?

· About 3 billion pairs in about a half to a full day. It is packaged in 23 distinct chromosome pairs that’s “Spiral” shaped.

1. What is RNA? How different is it from DNA?

· Ribo-Nucleic Acid is the copy of the DNA. It has a single filament and the thymine found in DNA is replaced in RNA with uracil.

2. How are the RNA messages formed?

· Messenger RNA (mRNA) is single-stranded. Its sequence of nucleotides is called "sense" because it results in a gene product (protein). Normally, its unpaired nucleotides are "read" by transfer RNA anticodons as the ribosome proceeds to translate the message.

3. How are the RNA messages interpreted?

· Codons, in groups of three nucleotides.

1. Describe cell cycle.

• Cell’s chromosomes are divided between the two daughter cells, and cytokinesis, in which the cell's cytoplasm divides forming distinct cells. From here, the cells continue to divide by two in a repeated process.

2. What is nuclear division.

· When the nucleus divides and engage with subphases

3. What is interphase?

· Interphase is the "holding" stage or the stage between two successive cell divisions.

4. Cytokinesis?

· Is the process whereby the cytoplasm of a single cell is divided to spawn two daughter cells.

5. Homologous chromosomes?

· a pair of chromosomes containing the same linear gene sequences, each derived from one parent. The chromosomes tend to pair or synapse during meiosis. They have the same genes, in the same location, but the genes have different versions (not like in sister chromatics that are exact replicas)

6. Phases of mitosis (5 of them)?

· -Interphase, Prophase, Metaphase, Anaphase, and Telophase

7. Phases of meiosis and how it is different from mitosis?

• Prophase I , Metaphase I, Anaphase I, Telophase I, Prophase II , Metaphase II, Anaphase II, and Telophase II. Meiosis may start out the same as with mitosis, but then they eventually split once again after the first cytokinesis to form more chromosome 8.

8. Describe the process and purpose of crossing over?

· - Each parent cell has pairs of homologous chromosomes, one homolog from the father and one from the mother. In meiosis, the maternal and paternal chromosomes can be shuffled into the daughter cells in many different combinations. This ensures genetic variation in sexually reproducing organisms. Further genetic variation comes from crossing over, which may occur during prophase I of meiosis.