Chapter 4, How Cells Work Video Solutions, Bioprocess Engineering

Problem 1

Consider the aspartic acid pathway shown in Fig. 4A.1. Assume you have been asked to develop a high-lysine-producing mutant. What strategy would you pursue? (That is, which steps would you modify by removing feedback inhibition, and what changes in medium composition would you make over a simple mineral salts-glucose base medium?)

Ramesh Singh

Numerade Educator

01:49

Problem 2

Why is $m$-RNA so unstable in most bacteria (half-life of about $1 \mathrm{~min}$ )? In many higher organisms, $m$-RNA half-lives are much longer $(>1 \mathrm{~h})$. Why?

Alexander Clippinger

Numerade Educator

05:27

Problem 3

What would be the consequence of one base deletion at the beginning of the message for a protein?

Bryan Valdivia

Numerade Educator

02:04

Problem 4

How many ribosomes are actively synthesizing proteins at any instant in an $E$. coli cell growing with a 45 -min doubling time? The birth size of $E$. coli is $1-\mu \mathrm{m}$ diameter and $2-\mu \mathrm{m}$ length. The water content is $75 \%$. About $60 \%$ of the dry material is protein, and the rate of amino acid addition per ribosome is 20 amino acids per second. The average molecular weight of free amino acids in $E$. coli is 126 .

Dominador Tan

Numerade Educator

02:13

Problem 5

Describe simple experiments to determine if the uptake of a nutrient is by passive diffusion, facilitated diffusion, active transport, or group translocation.

Alexander Burbelo

Numerade Educator

02:31

Problem 6

For the $m$-RNA nucleotide code below: (a) Deduce the corresponding sequence of amino acids. (b) What is the corresponding nucleotide sequence on the chromosome? This sequence codes for a part of insulin.
CCG UAU CGA CUU GUA ACA ACG CGC

Danielle Ashley

Numerade Educator

03:12

Problem 7

Consider the pathway in Fig. 4A.1 for production of lysine, methionine, isoleucine, and theronine. You need to produce lysine. Describe a strategy for making large amounts of lysine. Your strategy can consist of adding various amino acids to the medium and choosing the mutant cells altered in regulation. Say you can identify up to two points of mutation (e.g., removal of feedback inhibition).

Ummatul Choudary

Numerade Educator

02:01

Problem 8

Suggest an experiment to determine if the uptake of a compound is by either facilitated or active transport.

Arwen Xu

Numerade Educator

01:16

Problem 9

What is catabolite repression, and how does it affect the level of protein expression from the lac operon?

Precious

Numerade Educator

01:12

Problem 10

. Explain the difference between feedback inhibition and feedback repression.

John Nicolle

Numerade Educator

03:31

Problem 11

4.11. You are asked by your boss to produce a human protein in $E$. coli. Because you have learned some of the differences in the way that procaryotes and eucaryotes make proteins, you worry about at least two factors that could complicate production of an authentic protein for human use.
a) What complication might you worry about if the human DNA encoding the protein were placed directly in E. coli?
b) Assume that the correct primary sequence of amino acids has been produced. What posttranslational steps do you worry about and why?

Dennis Howard

Numerade Educator

00:50

Problem 12

Consider the process of N-linked glycosylation.
a) What organelles are required?
b) What is the residual sugar on a glycoprotein that has simple glycosylation?
c) If glycosylation is complete, what will be the final sugar on the glycoform?
d) Why may N-linked glycosylation be important?

Mishal Gul

Numerade Educator