BIO CHAPTER 8 - Review Questions
What four functions are performed by nucleic acids?
-1) store information 2) direct the synthesis of proteins 3) chemically change (mutate) genetic characteristics that are transmitted to future generations; and 4) replicate prior to reproduction by directing the manufacture of copies of itself.
What are the three differences between DNA and RNA?
-the difference between DNA and RNA is their sugar. DNA uses a deoxyribose sugar while RNA uses a ribose sugar. An additional difference is that RNA uses the nitrogenous bases (U) instead of the nitrogenous base thymine (T) that is found in DNA.
What is a gene?
A gene must be able to make copies of itself; mutate; store information that determines the characteristics of a cell; use this information synthesize proteins.
Provide two examples of how a cell uses transcription to control gene expression.
Cells determine: a. when a gene is transcribed by using regulatory proteins. b. how much a gene is transcribed by using regulatory proteins. c. the quality of the protein produced by alternative splicing.
Chromosomal mutation occur in the DNA
Chromosomal mutations are changes in large numbers of nucleotides in the DNA strand so that the change is visible at the level of the chromosome.
Why is DNA replication necessary?
DNA replication makes a copy of the cell's genetic information so that one of these copies can be passed on during cell division.
How does the manufacture of an RNA molecule differ from DNA replication?
DNA- Replication RNA Manufacturing DNA- Replication happens once RNA Produces many times or not at all DNA- Replication copies the entire length RNA Manufacture only copies part of
point mutations occur in DNA.
Point mutations are changes in one nucleotide of the DNA strand and are so small that they can not be observed at the level of the chromosome.
What role does RNA play in the cell?
RNA is made in the nucleus and then moves into the cytoplasm of the cell where it becomes directly involved in the process of protein assembly.
What is a silent mutation? Provide an example.
Silent mutations are changes in DNA that do not cause changes in the amino acid sequence of a protein. Mutations can happen frequently when the mutation is found in the third position of the codon.
Provide an example of why it is advantageous for a cell to control gene expression.
The advantages of controlling gene expression fall into two broad categories: a. Producing only what is needed conserves resources and energy. b. Inappropriate expression of genes may create ill effects in the cell or organism.
What are the differences among a promoter sequence, termination sequence, and release factor?
The promoter sequence attracts the RNA polymerase to the site of the gene and then directs the RNA polymerase to proceed along the DNA strand in the correct direction to find the gene. The termination sequence signals the RNA polymerase to end mRNA transcription, so that the RNA can leave the nucleus to aid in translation. A release factor will move into position over a termination codon causing the ribosome to let go of the completed amino acid chain.
What is the base pairing rule?
The rule states that in DNA adenine (A) pairs with thymine (T) and guanine (G) pairs with cytosine (C). In RNA T is replaced by U.
List the sequence of events that takes place when a DNA message is translated into protein.
The steps of protein synthesis are: a. RNA polymerase finds the gene's promoter region. b. RNA polymerase makes mRNA. c. (Only in eukaryotes) Modifications are made to the mRNA. Example: splicing out of introns. d. (Eukaryotes) The mRNA is moved from the nucleus to the cytoplasm. e. The ribosome attaches to the mRNA. f. The first amino acid, methionine, is brought in to start the protein at the AUG codon. g. Additional amino acids are added to the protein by adding one amino acid per codon (3 nucleotides) until the termination codon is read by the ribosome. h. The protein is released by the ribosome.
What is the product of transcription? Translation?
Transcription produces various types of RNA from a DNA template. Translation produces protein using mRNA as a template.
B)Histone clustes
are called nucleosomes.
How do tRNA, rRNA, and mRNA differ in function?
tRNA- matches amino acids with correct codon sequence. rRNA- is part of the ribosome structure. mRNA- determines the order that the amino acids are incorporated into the protein.
What factors stabilize the DNA double helix?
• The double helix is stabilized because nitrogenous bases are only able to match up (pair) with certain other nucleotides on the opposing strand. • Pairing is determined by the molecular shape of the bases and their ability to form hydrogen bonds.
