Student No: Student Name:
SCHOOL OF BIOMOLECULAR & BIOMEDICAL SCIENCE
SB13BMM - MOLECULAR AND APPLIED MICROBIOLOGY
SEMESTER II, 1997
THIS EXAMINATION PAPER MUST BE HANDED IN AT THE COMPLETION OF THE EXAMINATION
INSTRUCTIONS TO STUDENTS
Total marks allocated - 160 marks
Remember to write your name on the answer books before attempting any questions.
Answer questions from all the three sections.
Allocate your time wisely in relation to the number of marks assigned for each question and time available.
1. Answer any one (1) of the following three (3) questions.
(a) This question is composed of four (4) parts, all of which are to be answered.
(I) Why are 16S rRNAs thought to be the best molecules for undertaking phylogenetic studies?
(ii) What major evolutionary findings emerged from the study of 16S rRNA sequences?
(iii) Describe and discuss the structure of 16S rRNA with respect to its functions in a bacterial cell.
(iv) What are signature sequences and of what phylogenetic value are they?
in an ecosystem".
(c) The beneficial and harmful roles played by microbes in biogeochemical cycling.
2. Write notes on any four (4) of the following. Draw schematic diagrams wherever necessary.
(a) Sampling procedures in microbiology
(b) r and k strategists
(c) Microbiology of the gastrointestinal tract
(d) Skin microflora
(e) Hydrothermal vent communities
(f) Dental diseases
(g) Helicobacter pylori
(12 x 4 marks)
3. Answer all the following questions.
(a) How does Pulsed Field Gel Electrophoresis differ from conventional agarose gel electrophoresis? Compare at least 4 different Pulsed Field Gel Electrophoresis (PFGE) apparatus and discuss the advantages and disadvantages of each.
(b) Name three different cloning vectors you could use to clone DNA fragments greater than 60 kb in size. Describe one of these vectors in detail (including a diagram) and describe the special features that allow this vector to clone large DNA inserts.
(c) Why are microbial genomes particularly suitable for whole genome sequencing projects? Which particular types of microorganisms are undergoing or have undergone genome sequencing? Why were these micro-organisms chosen? Discuss some advantages and limitations of microbial whole genome sequencing and sequence analysis.
Answer all the following multiple choice questions. Write only the correct alphabet letter against the question number in your answer book
1. Lignin is broken down in the soil primarily by ______
(a) aerobic fungi
(b) anaerobic bacteria
2. The type of antagonism in which one species is suppressed by the products of another is called ______
3. Most of the methane in air is produced by ______
(a) photosynthetic processes
(b) aerobic oxidation of glucose
(c) reduction of carbonate
(d) anaerobic microbial processes
4. Which of the following substances is most resistant to microbial degradation?
5. The surface layer of soils usually have ______ microbial numbers to that of lower layers.
(c) The same
6. The most numerous bacterium associated with the skin gland is ______
(a) Staphylococcus epidermis
(b) Pityrosporum ovale
(c) Propionibacterium acne
(d) Pityrosporum orbiculare
7. ______is involved in periodontal diseases
(a) Streptococcus mutans
(b) Bacteroides gingivalis
(c) Escherichia coli
8. ______in the gastrointestinal tract is regarded as a barrier to the entry of pathogens.
Answer all the following questions in brief.
1. What is the general secondary structure of ribosomal RNA?
2. Name the organ of Riftia pachyptilla in which as yet uncultured symbiotic bacteria are found.
3. Do Gram +ve or Gram -ve bacteria predominate in soil?
4. Give the most important characteristics of marine microorganisms.
5. Name three (3) antibacterial agents present in the skin.
6. What is a biofilm? Cite an example.