Download Chapter 17- Transcription and Translation

Chapter 17 - Transcription and Translation
HW 4-6- Read Chapter 17 pp. 325-331 (Powerpoint: Intro to Genetic Code )
1) Distinguish between replication, transcription and translation.
2) What is the central dogma of molecular biology?
3A) Compare and contrast the function and cellular locations of mRNA, tRNA and rRNA.
3B) What is the approximate % in the cell for each type of RNA? Why is rRNA so abundant?
4A) Describe where transcription and translation occur in prokaryotes and eukaryotes.
4B) What is a primary transcript in eukaryotes?
4C) Explain the significance of, transcription and translation being separated in space and time in
eukaryotes.
5A) What is the sense strand of the DNA? What is the antisense strand? Is the sense strand
or the antisense strand defined as the gene? Which serves as the template for the RNA, the
sense strand or the antisense strand?
5B) How many amino acids must be coded for?
5C) What is a codon?
5D) What does it mean to say that the flow of information from DNA to protein is based on a
triplet code? Why is it impossible to have a singlet or doublet code?
5E) What does it mean to say the genetic code is universal? What important implication does this
have for biotechnology?
6A) What does it mean to describe the genetic code as redundant and unambiguous?
6B) What does it mean to describe the genetic code as “universal?” What is the evolutionary
significance of this? (remember, evolution is a major theme in biology.) What important
implication does this have for biotechnology?
6C) What is the wobble effect?
HW 4-7 –Read Chapter 17, pp. 331-336. (Powerpoint: Introduction to Transcription 2010)
1) Campell’s Concept Check 17.2, p. 334 #1-4.
2A) Name and briefly describe, the 3 steps of transcription.
2B) Describe the steps for formation of the transcription initiation complex. Word bank: TATA
box, promoter, transcription factors, RNA polymerase
3) Circle the correct choice in the ( ): Elongation of the mRNA by RNA polmerase always
procedes in the (3’ to 5’ or 5’ to 3’) direction?
4) Compare termination in eukaryotes and prokaryotes.
5) mRNA processing in Eukaryotes: How is eukaryotic RNA modified between transcription and
translation? Where does processing take place in the cell? What are the purposes of these
modifications?
HW 4-8
TRANSLATION : READ CHAPTER 17, pp. 337- 348. (Powerpoint 2010)
1) Coupled transcription and translation – Campbell’s p. 347, Concept Check 17.6, #1.
2A) Describe the role of tRNA in translation.
2B) What is an anticodon?
2C) Draw the structure of tRNA and label the amino-acid attachment site and the anti-codon site.
3) Fill in the following table using figure 17.4 on p. 330 of Campbell’s
DNA triplet 5’ DNA triplet 3’ to mRNA codon 5’
tRNA anticodon
to 3’
5’ (template or
to 3’
(sense strand
antisense strand)
or gene)
ATG
TAC
AUG
UAC
GGA
TTC
UAG
Amino acid
methionine
4) Describe the role of the enzyme aminoacyl tRNA synthetase in translation.
5A) Describe and draw the structure of a ribosome. Label the small and large subunits and the E,
P, A sites.
5B) Describe the roles of the E, P, and A sites of the large ribosomal subunit.
6A) Describe, using diagrams and words, the process of translation initiation. What amino acid
allows starts a an amino acid chain?
6B) ELONGATION- describe using diagrams and words how an amino acid moves through the
different site of the ribosome.
6C) TERMINATION – include in your answer a discussion of the stop codon and release factor.
7) Campbell’s p. 344, Concept Check 17.4, #2.
8) Campbell’s p. 346, Concept Check 17.5, #1 and 2.
9) Describe the signal hypothesis (Campbell’s Concept Check 17.4, p.344, #3)
10) What are posttranslational modifications? What is the purpose of a posttranslational
modification? Give specific examples to support your answers.
HW 4-9 Bacterial Operons – 18.1
Chapter 18 – Regulation of Gene Expression – Read in Campbell’s pp. 351-356.
Powerpoints: Try Operon, Lac Operon
1) What is an operon?
2) What is an operator?
3) Why would a bacterial cell need to control the expression of a gene based on
environmental conditions?
4) Explain the differences between inducible and repressible operons.
5) Campbell’s p. 356, Concept Check 18.1, #1,2,3 and p. 379, #1 & 3.
HW 4-10 Chapter 18: Eukaryotic Gene Regulation 18.2 and 18.3
Reading: Campbell’s pp. 356-366 (Powerpoint: Eukaryotic Gene Expression)
1) Complete the following table by filling in the appropriate description of each property
associated with prokaryotes vs. eukaryotes.
Property
Prokaryote
Size of Genome (large or small)
Eukaryote
Single Cell vs. Specialized Cell
% of genes expressed
(20 % vs. almost 100%)
% of DNA that codes for Genes
(1.5% vs. vast majority)
2) Describe the structure/function of DNA sequences that do not code for genes.
3) Compare DNA sequence in cells and. expression of genes for different types of cells in human
body, e.g. eye vs. skin.
4) Which step in the production of proteins (gene expression) is the most heavily regulated?
5) Is the default condition for eukaryotic genes on or off?
6) Describe how chromatin structure is related to gene expression. Specifically address histoneDNA interactions.
7) What is epigentic inheritance?
8) DNA Methylation
A) Describe the chemical structure of a methyl group. To what part of the DNA does the
methyl group attach?
B) Is heavily methylated DNA associated with actively transcribed genes or silenced genes?
C) What enzymes are recruited by methylated DNA?
9) DNA Acetylation
A) Describe the chemical structure of an acetyl group. To what part of the histone does the acetyl
group attach?
B) Explain how the charge of the histone is changed is response to acetylation and how this
impacts DNA histone interactions and ultimately accessibility of the gene to transcription
factors.
10) Initiation of transcription.
A) What is a transcription factor?
B) What region of the DNA do general transcription factors bind to?
C) What is an activator protein (specific transcription factor)?
D) What region of the DNA do the activator proteins bind to?
E) How is the binding of transcription factors and activator proteins impacted by the how tightly
DNA is bound to histones (level of DNA packing)?
F) Are protein-protein interaction between transcription factors important or only the protein
binding to the DNA?
G) How can the presence of different enhancer regions change the expression of different genes?
In your answer refer to figure 18-10 in your textbook, which compares the gene expression in a
liver cell and the lens cell in your eye.
H) Activator proteins and some transcription factors are allosteric proteins. Explain what the
term allosteric protein means in this context.
I) Explain how the rate of transcription initiation can be regulated by the small signal molecules
such as hormones.
11 RNA processing
A) Explain how alternative splicing patterns can result in different gene expression, e.g. different
proteins produced from the same “gene”.
B) Describe the relationship between the 5’ Cap and Poly A tail sequences and the lifetime of
the mRNA in the cytosol?
12) Campbell’s, Concept Check 18.2, p. 364 # 1-4;