Chapter 10 and 11– Homework
1. Describe the stages of transcription.
A. Begins when RNA polymerase binds to promoter
B. RNA polymerase moves along DNA, adding complimentary ribonucleotides, until the end of the gene is reached C. RNA polymerase can only add to the 3’ end
D. Transcription occurs in the 5’ to 3’ direction
E. An RNA transcript is the end result
F. All three types of RNA are transcribed from DNA
Name 3 classes of RNA and their function.
Ribosomal RNA, which is the site of protein synthesis.
Transfer RNA, which transports the correct amino acids to ribosomes and pairs them up. Messenger RNA, which is the genetic blue print for making proteins. 2. What is the function of RNA polymerase and the promoter? It adds complimentary ribonucleotides and a promoter is the base sequence in the DNA that signals the start of a gene. 3. List 3 ways RNA is modified.
Addition of a 5’ cap, Addition of a 3’ poly A tail, and introns being removed. 4. What is the genetic code? What does it mean to state the genetic code is redundant and practically universal?
Most of the code is the same for all organisms.
5. What is the difference between an anticodon and a codon? A codon is a sequence of three nucleotides that together form a unit of genetic code of DNA or RNA. An anticodon is a sequence of three nucleotides that together form a unit of genetic code in the transfer RNA. 6. Describe the stages of translation. Include initiation, elongation and termination in your explanation.
The initiator tRNA binds to small ribosomal subunits. mRNA passes through, tRNAs deliver amino acids to the ribosomal binding site in the elongation, a stop codon in the mRNA moves onto the ribosomal binding site in termination, proteins called release factors bind to the ribosome, and mRNA and polypeptide are released. 7. Where does transcription occur?
8. Where does translation occur?
9. What happens to newly formed polypeptides?
Some enter the cytoplasm; others enter the ER and move through the cytomembrane system where they are modified. 10. Describe gene mutations and explain how they affect gene function. An extra base added or a base deleted. They affect the way that the entire gene is read and shift the reading frame. Results in many wrong amino acids. 11. What are three types of control mechanism and how does each work? Include activator and repressor in your discussion.
Positive Control System: Activator protein binds to DNA and promotes initiation of transcription and activator protein enhances some activity. Negative Control System: Repressor protein binds to DNA to block transcription; repressors can be removed by inducers; repressor protein inhibits some activity.
12. Describe how the lactose operon functions. What is the operator? The lactose operon will only be turned on when lactose is present and glucose is absent. The operator is the binding site for the repressor. 13. Explain X chromosomes inactivation?
When one X is inactivated in each cell of a female mammal.
14. How do hormones function?
They stimulate or inhibit activity in the target cells.
Chapter 13 and 14
1. Describe the early theories of each person listed below: Hippocrates: All aspects of nature can be traced to their underlying causes Aristotle: Each organism is distinct from all the rest and nature is a continuum or organization George Cuvier: Theory of Catastrophism: Original population destroyed by great catastrophe; repopulated by few survivors; multiple catastrophes Jean-Baptiste Lamarck: Theory of Inheritance of Acquired Characteristics: Environmental pressures and internal desires bring about changes in the individual’s body; offspring inherit these changes Charles Darwin: Theory of Evolution by Natural Selection: A population can change over time when individuals differ in one or more heritable traits that are responsible for differences in the ability to survive and reproduce...
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