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Life on earth (biological concepts from the non-science major perspective)

1. When comparing the DNA molecule to a twisted ladder, what do the rungs of the ladder represent?

2. Describe the three major properties of genes that are explained by the structure of DNA?

3. What occurs on the sex chromosomes to determine the sex of a mammal?

4. Describe a difference between meiosis and mitosis?

5. A black guinea pig crossed with an albino guinea pig produces 12 black offspring. When the albino is crossed with a second black one, 7 blacks and 5 albinos are obtained. What is the best explanation for this genetic situation?

6. Many bacteria may be able to respond to environmental stress by increasing the rate at which mutations occur during cell division. How might this be accomplished?

7. Describe one recent advance in biotechnology and its practical application.

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1. When comparing the DNA molecule to a twisted ladder, what do the rungs of the ladder represent?

The rungs represent the hydrogen-bonded bases, or nucleotides, that make up DNA. There are 4 kinds of nucleotides: guanine (G), cytosine (C), thymine (T), and adenine (A). G pairs with C, and T pairs with A.

2. Describe the three major properties of genes that are explained by the structure of DNA?

a) Genes are heritable units-DNA is a very stable molecules as a result of its hydrogen bonding in its helical form and is passed on from mother to daughter cells with each cell division. Because of the base pairing rules, one strand acts as the template during DNA synthesis and preserves the genetic information in a semi-conservative manner.
b) Genes encode information-DNA sequences are arranged so that codons (triplets of bases) encode specific amino acids that make up proteins, which are key effectors in biological processes.
c) Genes vary from species to ...

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