DNA and RNA

1. What is DNA?
DeoxyriboNucleic Acid –any of various nucleic acids that are usually the molecular basis of heredity, are constructed of a double helix held together by hydrogen bonds between purine and pyrimidine bases which project inward from two chains containing alternate links of deoxyribose and phosphate, and that in eukaryotes are localized chiefly in cell nuclei

2. What are the 4 bases?
Adenine (A)

Thymine (T)

Cytosine (C)

Guanine (G)

3. What 2 pieces of information did the scientists need to solve the elusive structure of DNA?
The sugar-phosphate backbone is on the outside and the four different bases are on the inside of the DNA molecule.

4. What are the specific base pairs?
A is together with T and G is together with C.

5. How does the pairing rule affect the shape and structure of DNA?
It is either an adenine and thymine pair that form a two-hydrogen bond together, or a cytosine and guanine pair that form a three-hydrogen bond. The base pairing restricts the structure and shape of the DNA molecule during its cell division process.

6. What does the DNA do during cell division?
During cell division the DNA is copied. It is “unzipped”, spilt, and then copied exactly.

7. How many base pairs does E. Coli have? How long does it take to replicate? How is the DNA packaged in the cell?
There are 4,639,221 base pairs that an E. Coli has and it takes 40 minutes to replicate. A DNA is stored deep inside the genetic makeup of the cell.

8. How many base pairs does Human DNA have? How long does it take to replicate? How is the DNA packaged in the cell?
like a mouse, a human have about more than 3 billion base pair. These pairs take about 12-24 hours to replicate. Like the answer above, the DNA is stored deep inside the genetic makeup of the cell.


1. What is RNA? How different is it from DNA?
RNA or ribonucleic acid are any of various nucleic acids that contain ribose and uracil as structural components and are associated with the control of cellular chemical activities.

“Both DNA and RNA are composed of repeating units of nucleotides. Each

Nucleotide consists of a sugar, a phosphate and a nucleic acid base.

The sugar in DNA is deoxyribose. The sugar in RNA is ribose, the same

as deoxyribose but with one more OH (oxygen-hydrogen atom combination

called a hydroxyl). This is the biggest difference between DNA and RNA.

Another difference is that RNA molecules can have a much greater variety of nucleic acid bases. DNA has mostly just 4 different bases with a few extra occasionally. The difference in these bases (between DNA and RNA) allows RNA molecules to assume a wide variety of shapes and also many different functions. DNA, on the other hand, serves as a set of directions.”----- http://www.newton.dep.anl.gov/askasci/bio99/bio99410.htm

2. How are the RNA messages formed?
To construct a word in the RNA language, three of these letters are grouped together. These three-letter words are often referred to as a triplet or a codon. These codons are placed after each other in the RNA molecule, to construct a message, a RNA sequence. The protein producing machinery in the body will later read this message.

3. How are the RNA messages interpreted?
Ribosomes take in the amino acids, which make up a codon, and attach them together to make up a protein.

1. Describe cell cycle.

2. What is nuclear division?
Nuclear division is the division of the nucleus and genetic information into more than one cell from a parent cell, usually through mitosis or meiosis.

3. What is interphase?
Interphase is the "holding" stage or the stage between two successive cell divisions. It is where chromosomes are uncoiled and functionally active.

4. What is Cytokinesis?
Cytokinesis is the division of the cytoplasm of a cell into two daughter cells.

5. What are Homologous chromosomes?
Pair of chromosomes that contains the same genetic sequence coming from the same parent cell.

6. Phases of mitosis (5 of them).
The 5 phases of mitosis are Prophase, Metaphase, Anaphase, Telophase, and Interphase.

7. Phases of meiosis and how it is different from mitosis.
The phases of the meiosis cycle are Early prophase, Late prophase, Metaphase, Anaphase, Telophase, and II Telophase.

The mitotic metaphase can be distinguished from the metaphase I of meiosis as no pairing of homolog chromosomes occurs in mitosis; this is not necessary, even not suitable for the mitotic process (why?). Further, homolog chromosomes separate during metaphase I of meiosis, whereas during mitosis and metaphase II the separating structures are the chromatides. The difference between the separation in mitosis and metaphase II (meiosis) is that halfing of the number of chromosomes has preceeded meiosis II, in contrast to mitosis. Also the meiotic products are genetically diverse with respect to their parent and among each other. This is not the case in mitosis!

For further info please look in http://www.vcbio.science.ru.nl/en/virtuallessons/cellcycle/mitomeio/.

8. Describe the process and purpose of crossing over.

Crossing-over is the exchange of chromosome segments between homologous pairs ensures that there is a reshuffling of genes and, therefore, genetic diversity among the offspring. Every individual has pairs of chromosomes derived from the mother and the father. Genetic recombination ensures that a recombination of maternal and paternal chromosomes and genes are passed on to the offspring.