BIOL 1107 Lecture Notes - Lecture 16: Allosteric Regulation, Lac Operon, Repressor

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14 Oct 2016

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Cells are very selective about which genes they express, in which amounts genes are expressed, when genes are expressed. (based on environment) (based on cell cycle) Gene expression occurs when a gene product is synthesized and becomes active in a cell. Regulation of a gene expression is critical to a cell. E. coli use a wide array of carbohydrates to supply carbon and energy. (glucose is the main energy source) Control of gene expression allows e. coli to respond to its environment and switch its use of sugars. Genes can be under: transcriptional control - rna is only made for some genes, due to regulatory proteins at the promoter. Slowest method of regulation and occurs in the nucleus: translational control - not all rnas are translated. mrna won"t make it to the ribosome to be translated, post- translation control - proteins must be activated by chemical modification. All of these types of regulation occur in bacteria.

Related Questions

Please I need help answering those questions i always lose bunch of points i'm not doing it correctly.

Use information from Nature Reviews Microbiology to answer the following question.What is the role of EF-G and EF4 in protein synthesis? Under what circumstances does EF4 participate in translation and what is its role?

from this reading The Highly Conserved LepA Is a Ribosomal Elongation Factor that Back-Translocates the Ribosome Qin Y,Polacek N, Vesper O, Staub E, Einfeldt E, Wilson D.N, and Nierhaus N.H. Cell 127: 721-733 (2006).

Q2. In which species is Lep A found and in which ones is it absent? Is the result expected based on your knowledge of the endosimbiosis theory?

Q3.

3a What is the percentage of identity between LepA and its ortholog genes?

3b. (5pts) Indicate what domains are conserved between Ecoli EFG and LepA, and which ones are not.

3c. What do grey and black boxes in the sequence alignment indicate?

Q4. Analysis of in vivo experiments shown in Figure 3. Only analyze graph on the left side of the figure.

4a. What is the difference between the bacteria whose growth are shown by the blue and the green curves? What can be concluded about the effect of EFG on bacterial growth?

4b. Which protein is expressed by bacteria whose growth is shown by the yellow curve? Does the expression of this protein affect bacterial growth? Compare the yellow and blue curves. How can this result be explained?

4c. Explain why the addition of IPTG results in lower bacterial growth. Compare the yellow and red curves?

4d. Why is the green curve an important control of the experiment? The green curve.

The next questions are based on the reading of the article Elongation factor 4 (EF4/LepA) accelerates protein synthesis at increased Mg2+ concentrations.

Elongation factor 4 (EF4/LepA) accelerates protein synthesis at increased Mg2+ concentrations Pech M, Karim Z, Yamamoto H, Kitakawa H, Qin Y, and Nierhaus K. PNAS 108: 3199-3203(2011)

Studies done in E. coli using a knockout mutant of the lepA gene (ÎlepA , lepA gene has been deleted) did not show any phenotype when grown in rich LB medium. This result was unexpected due to the high level of conservation of EF-4 among species.

Q5. Equal amounts of wild type and mutant cells (lacking the lepA gene) were mixed and co-cultured for 24h. The population distribution was determined every 4 hours. Figure 1 indicates changes in the % of mutant cells over several generations.

Q5a. What is the question that researchers addressed in the experiments shown in Figure 1?

Q5b. Which curve represents the control of the experiment? Do the two strains grow at similar rate? How do you know?

Q5c. Do high salt concentration and/or low temperature have any effect on the growth of mutant cells?

Q5d. What can you conclude about the role of LepA on bacteria growth? When is this protein important?

Q6.

6a. (6pts) Where in the cell is EF4 located? Did you expect that this would be the EF4 location? Why or why not?

What is the question that the researchers want to address in the experiment shown in Figure 2?

6c. Analyze the green and red bars graph shown in Figure 2. What technique was used to detect EF4? Is there any change in EF4 localization?

Q7. Summarize the main points of the model shown in Figure 4

ochregerbil875

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The function of tRNA is to

Select one:

a. provide a site for polypeptide synthesis

b. transport amino acids to the ribosome

c. transcribe DNA

d. transform DNA

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The lipid bi-layer is

Select one:

a. hydrophilic

b. hydrophobic

c. hydrophilic and hydrophobic

d. depends on the surrounding medium

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Which of the following statements is FALSE?

Select one:

a. carbohydrates are generally hydrophilic molecules.

b. living things use carbohydrates for structure and for energy storage.

c. carbohydrates are composed principally of carbon, hydrogen, and oxygen.

d. none of the above â they are all true

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Which of the following terms correctly describes a compound featuring more than one double bond?

Select one:

a. saturated

b. polyunsaturated

c. monounsaturated

d. disaturated

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Eukaryotic mRNA transcripts are protected from modification by

Select one:

a. 5' caps

b. 5' poly-A caps

c. 3' caps

d. 5'-3' poly tails

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The methods of membrane transport that don't require protein channels or carriers are

Select one:

a. osmosis

b. diffusion

c. phagocytosis

d. exocytosis

e. all of the above

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Complete the following sentences: "Primary active transport is dependent on __________. Secondary active transport is dependent on __________ created by __________.

Select one:

a. channel proteins, electrochemical gradient, carrier proteins

b. electrochemical gradient, ATP, mitochondria

c. electrochemical gradient, ATP, primary active transport

d. ATP, electrochemical gradient, primary active transport

e. carrier proteins, electrochemical gradient, channel protein

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Which of the following is a reduced compound?

Select one:

a. CO2

b. O2

c. N2

d. NAD +

e. NADH

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Gel electrophoresis separates DNA fragments according to their:

Select one:

a. base sequence

b. size

c. percentage of labelled nucleotides

d. electrical charge

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G0 is:

Select one:

a. part of interphase

b. the phase of the cell cycle where DNA replication occurs

c. the phase of the cell cycle where two identical daughter cells are created

d. a special "resting" phase in which cells are in a non cycling state

e. a special phase where the number of chromosomes in a parent cell is reduced by half such that each daughter cell contains only one member of a pair of homologous chromosomes

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At which pH will the concentration of hydrogen ions be equal to the concentration of hydroxide ions?

Select one:

a. pH 1

b. pH 5

c. pH 7

d. pH 9

e. pH 14

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Which of the following enzymes has proofreading activity?

Select one:

a. Ligase

b. Helicase

c. Topoisomerase

d. DNA polymerase

e. Peptidyl transferase

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The process of _______________ cuts introns from the primary transcript and the final "processed" mRNA is produced.

Select one:

a. RNA cleaving

b. RNA translocation

c. RNA elongation

d. RNA splicing

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Transcription is initiated when RNA polymerase binds to

Select one:

a. a promoter

b. an initiator

c. a transciptor

d. a codon

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Complete the following sentences: "__________ connect the extracellular matrix with microfilaments. __________ connect intermediate filaments from adjacent cells."

Select one:

a. Cadherins, Integrins

b. Connexins, Cadherins

c. Integrins, Cadherins

d. Integrins, Connexins

e. Connexins, Integrins

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Which of the following regions of RNAs are translated?

Select one:

a. 5' UTR

b. exons

c. introns

d. 3' UTR

e. poly-A

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Control of gene expression in eukaryotic cells occurs at which level(s)?

Select one:

a. only the transcriptional level

b. epigenetic and transcriptional levels

c. epigenetic, transcriptional, and translational levels

d. epigenetic, transcriptional, posttranscriptional, translational, and posttranslational levels

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Cellular organelles containing hydrolytic enzymes are called:

Select one:

a. peroxisomes

b. lysosomes

c. ribosomes

d. mesosomes

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______ are chemicals or combinations of chemicals that take up excess hydrogen ions or hydroxide ions in order to keep the pH constant.

Select one:

a. acids

b. bases

c. salts

d. buffers

e. carbohydrates

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Which of the following proteins appear in some stages of the cell cycle and are degraded at other stages?

Select one:

a. kinases

b. cyclins

c. nucleotides

d. phosphatases

e. none of the above

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Which of the following correctly matches an organelle with its function?

Select one:

a. mitochondrion photosynthesis

b. nucleus cellular respiration

c. ribosome manufacture of lipids

d. lysosome movement

e. central vacuole storage

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What is the sequence corresponding to the following electropherogram obtained by Sanger sequencing (green: A; red:T; black: G; blue: C)?

Select one:

a. CCGTTATGAAC

b. GGCTTATGAAG

c. CAACTATTGCC

d. GGCAATAGTTG

e. CCGTTATCAAC

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Which of the following statement is true

Select one:

a. the two DNA strands are parallel and complementary

b. the two DNA strands are anti parallel and non-complementary

c. the two DNA strands are anti-parallel and complementary

d. none of these

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The energy-requiring process by which small molecules are joined to form larger molecules is specifically called

Select one:

a. metabolism

b. anabolism

c. catabolism

d. enzymatic reactions

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When DNA replication starts

Select one:

a. the phosphodiester bonds between the adjacent nucleotides break

b. the bonds between the nitrogen base and deoxyribose sugar break

c. the leading strand produces Okazaki fragments

d. the hydrogen bonds between the nucleotides of two strand break

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A(n)_______ is the movement of a segment of a chromosome from one chromosome to another nonhomologous chromosome

Select one:

a. inversion

b. translocation

c. deletion

d. duplication

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Complete the following sentences: "Replication forks from the same origin of replication extend __________. __________ DNA strand is used as template for the leading strand at one fork and for the lagging strand at the second fork. New DNA is synthesized from 5' to 3' on the __________."

Select one:

a. unidirectionally, A different, both the leading and lagging strands

b. bidirectionally, The same, leading strand

c. bidirectionally, The same, lagging strand

d. unidirectionally, A different, leading strand

e. bidirectionally, The same, both the leading and lagging strands

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Manufacturing recombinant DNA molecules involves cutting a gene from its normal location, inserting it into a circular piece of DNA from a bacterial cell, and then transferring the circle of DNA to cells of another species. Which of the below describe the circular piece of DNA?

Select one:

a. restriction enzyme

b. plasmid

c. bacteriophage

d. transposon

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Complete the following chemical equation to make it balanced: glycerol + ___ ? triacylglycerol + ___

Select one:

a. 3 fatty acid, 3 H2O

b. fatty acid, H2O

c. 3 OH-, 3 H+

d. 3 H2O, 3 fatty acid

e. fatty acid, 3 H2O

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Which structure is found in plant cells but not animal cells? Check all that apply.

Select one or more:

a. Cell wall

b. Chloroplast

c. Plastid

d. Central vacuole

e. Lysosomes

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BIOL 1107 Lecture Notes - Lecture 16: Allosteric Regulation, Lac Operon, Repressor

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