MICRB320 Lecture Notes - Lecture 7: Dna Extraction, Dna Replication, Molecular Ecology
Document Summary
Get access
Related Documents
Related Questions
GENETICS QUESTION: For this experiment we focused on forward genetics: First, his- mutants were identified and then complementation analysis was used in order to determine which of the 7 his genes was mutated. ( The exact data can be seen at the bottom). In this experiment we screened for his- mutants that were generated via a random mutation process resulting from errors in DNA replication or induced by EMS aka Ethyl methanesulfonate. We compared a mutagenized culture that was treated with EMS and an un-mutagenized culture that was not treated with EMS. However, both cultures went trhough an enrichment process to increase the frequency of his- mutants.
Point mutations involve the substitution of one type of base pair for another. If the substitution replaces a purine with a purine (or a pyrimidine with a pyrimidine), it is called a transition. If the substitution replaces a purine with a pyrimidine (or a pyrimidine with a purine), it is called a transversion. Many mutagenic chemicals cause this type of mutation by alkylation of a nucleotide base. The chemically altered base can then be misread during replication or repair. For example the mutagen, ethyl methanesulfonate (EMS), adds an ethyl (-CH2-CH3) group to both guanine or thymine bases causing the modified guanine to pair with thymine and the modified thymine to pair with guanine.
1. Why might one gene be more susceptible to EMS mutagenesis than another gene?
2. Why might we have expected to find a higher frequency of polar mutants (his4A-B-C-) in the unmutagenized culture compared to the mutagenized culture?
Table 2. Experiment 1B class data summary (number of his-mutants by section) Unmutagenized | |||||||||||
Section | 1 | 2 | 3 | 4ABC | 4A | 4B | 4C | 5 | 6 | 7 | Total his- mutants |
Tuesday | 7 | 1 | 5 | 4 | 2 | 1 | 9 | 2 | 3 | 1 | 35 |
Wednesday | 2 | 1 | 14 | 0 | 4 | 2 | 2 | 4 | 8 | 2 | 39 |
Total | 9 | 2 | 19 | 4 | 6 | 3 | 11 | 6 | 11 | 3 | 74 |
% each mutant | 12.1 | 2.7 | 25.7 | 5.4 | 8.1 | 4.1 | 14.9 | 8.1 | 14.9 | 4.1 | ~100% |
Mutagenized | |||||||||||
Section | 1 | 2 | 3 | 4ABC | 4A | 4B | 4C | 5 | 6 | 7 | Total his- mutants |
Tuesday | 2 | 5 | 4 | 2 | 6 | 5 | 5 | 0 | 4 | 1 | 34 |
Wednesday | 9 | 1 | 15 | 0 | 9 | 1 | 2 | 2 | 9 | 4 | 52 |
Total | 11 | 6 | 19 | 2 | 15 | 6 | 7 | 2 | 13 | 5 | 86 |
% each mutant | 12.8 | 7.0 | 22.1 | 2.3 | 17.4 | 7.0 | 8.1 | 2.3 | 15.1 | 5.8 | ~100% |
QUESTION 30
The function of centrosome is:
1. | Microtubule initiation and organization in animal cells | |
2. | Organization of thin filaments | |
3. | Depolymerization of microtubules | |
4. | Organization of intermediate filaments |
2.5 points
QUESTION 31
The destinations of proteins synthesized on "free" ribomsomes include:
1. | Endoplasmic reticulum | |
2. | Nucleus | |
3. | Mitochondria | |
4. | Lysosomes |
2.5 points
QUESTION 32
Microtubules can be assembled and disassembled quickly in response to the cellular changes is because:
1. | Cells synthesize tubulin proteins very fast. | |
2. | Cells can turn other cytoskeletal filaments into microtubules | |
3. | Microtubules have an instable plus end and microtubules are probably organized by weak non-covalent interactions | |
4. | The motor proteins of microtubules can organize the microtubules in response to the cellular changes |
2.5 points
QUESTION 33
Both signal recognition particle and a translocon in rough endoplasmic reticulum membrane can recognize and bind to the signal sequence of a secretory protein, so they play the exact same role during protein co-translational translocation.
True
False
2.5 points
QUESTION 34
Rough endoplasmic reticulum is so named is because:
1. | It has many proteins associated with its surface. | |
2. | It has ribosomes associated with its cytosolic surface. | |
3. | It is associated with nuclear membrane. | |
4. | It has vesicles budding off its surface. |
2.5 points
QUESTION 35
The membrane vesicles that transport materials between membrane compartments have a protein coat. The protein coat has similar functions in different vesicles. These functions include:
1. | Help the enclosed material fold correctly. | |
2. | Help degrade the protein in the vesicles | |
3. | Maintain the internal pH of the vesicles | |
4. | Function as mechanical device to form a vesicle and select the components to be carried by a vesicle. |
2.5 points
QUESTION 36
Lysosomes are important for:
1. | Receptor-mediated endocytosis. | |
2. | Breaking down foreign particles brought into the cells by endosomes | |
3. | Regulating the process of organelle turnover. | |
4. | Protein trafficking between membrane compartments |
2.5 points
QUESTION 37
Which of the following is correct about membrane biosynthesis?
1. | Membranes are synthesized in Golgi Complex. | |
2. | Membranes arise from preexisting endoplasmic reticulum membranes. | |
3. | Membranes are synthesized on ribosomes. | |
4. | Membranes of all organelles have the same composition of proteins and lipids, since they all originate from endoplasmic reticulum. |
2.5 points
QUESTION 38
During skeletal muscle contractions, the shortening of the muscle fibers is because of:
The shortening of the thin and thick myofilaments. | ||
The shortening of the cytoskeletal filaments. | ||
The kinesin proteins moving over microtubules. | ||
The actin and myosin filaments sliding over each other. |
2.5 points
QUESTION 39
The assembly and disassembly of microtubules is regulated by rate of growth and shrinkage of the plus end.
True
False
2.5 points
QUESTION 40
The functions of Golgi complex include:
1. | O-linked oligosaccharides and most of a cellâs complex polysaccharides are assembled in Golgi complex | |
2. | Cis Golgi complex sorts proteins | |
3. | Trans Golgi complex segregates proteins in different types of vesicles for dilevery. | |
4. | N-linked oligosaccharides are further processed in Golgi complex |