AP Biology (HW 17) (1)

AP Biology (HW 17) (1) - Homework#17 Chapter 17(due Friday...

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Homework #17 : Chapter 17 (due Friday 111216) Amit Patel P3 12/15/11 #19 Gene to Proteins Objectives The Connection Between Genes and Proteins 1. Explain why dwarf peas have shorter stems than tall varieties. Dwarf peas are shorter stemmed than other varieties since their bodies lack growth hormones, called gibberellins, that stimulate stem elongation. -have growth hormones -gibberellins stimulate elongation 2. Explain the reasoning that led Archibald Garrod to first suggest that genes dictate phenotypes through enzymes. Garrod suggested that a hereditary condition, alkaptonuria produced black urine through a the lack of alkapton enzymes. Scientists conducted research decades later that supported his hypothesis that genes dictate the production of an enzyme. -Archibald Garrod -British physician (1909) - genes dictated phenotypes through enzymes -Alkaptonuria 3. Describe Beadle and Tatum’s experiments with Neurospora and explain the contribution they made to our understanding of how genes control metabolism. Beadle and Tatum bombarded Neorospora with x-rays, then looked for mutants differing in nutritional needs from wild-type models. Mutants could not feed but can survive on a complete growth medium, so they concluded that their genes could be mutated and changed to regulate their own metabolism. -Beadle & Tatum worked with Neurospora -experiments prove genes control metabolism 4. Distinguish between the “one gene–one enzyme” hypothesis and the “one gene–one polypeptide” hypothesis and explain why the original hypothesis was changed.
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They can be distinguished by simply recognizing the fact that DNA codes for all proteins, including those that aren’t enzymes. -Beadle and Tatums -support one-gene-one enzyme -changed “one-gene-one polypeptide” 5. Explain how RNA differs from DNA. DNA and RNA differ in the arrangement and types nitrogenous bases and sugars. DNA is deoxyribonucleic acid and thus its ribose sugars lack an oxygen while RNA is simply ribonucleic acid. Additionally, RNA contains uracil as a nitrogenous base, in place of thymine that is present in DNA. -RNA (ribonucleic acid) -DNA (deoxyribonucleic acid) -DNA: thymine -RNA: uracil 6. Briefly explain how information flows from gene to protein. The flow of information starts at transcription where DNA is used as a template to create a specific RNA molecule that codes for a protein when it reaches a ribosome. Translation is where protein synthesis occurs under the directions of the messenger RNA. -from transcription -mRNA (messenger) -translation -to the ribosomes 7. Distinguish between transcription and translation. Transcription is the synthesis of RNA under the direction of DNA translation is the RNA’s use to make a polypeptide. -transcription
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AP Biology (HW 17) (1) - Homework#17 Chapter 17(due Friday...

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