Practical Skills Assessment Overview

Microbiology and Molecular Biology (M20003) Practical Skills Assessment Overview

  • Assessment Date: Tuesday, 16/12/25

  • Location: KH 4.12

  • Weight: This assessment contributes 40% of the module grade.

  • Absence: In case of non-attendance, a request for Extenuating Circumstances Form (ECF) must be submitted.

Health and Safety Guidelines

  • Adhere to health and safety protocols during the assessment, including:

    • Aseptic Techniques: Essential for preventing contamination.

    • Personal Grooming: Long hair must be tied back to keep it out of the working area.

    • Appropriate Lab Attire:

    • Buttoned lab coat.

    • Appropriate shoes.

  • Additional resources available on Moodle:

    • Microbiology Laboratory Manual: Comprehensive guidance for lab work.

    • Risk Assessment: Outline of potential hazards and safety measures.

    • Control of Substances Hazardous to Health (COSHH) form: Documentation for hazardous substances used in the lab.

Materials Allowed in the Laboratory

  • Permitted items in the lab include:

    • MMB Lab Manual: Unlimited notes can be made in this manual.

    • Answer Sheets: Ensure all questions (pages 22-27) are completed prior to assessment.

    • Stationery: Only standard items such as a pen, pencil, ruler, and calculator.

  • Special requirements must be communicated via email to Athanasios Rizoulis (Athanasios.Rizoulis@port.ac.uk).

  • Independent work is required during the exam. If technical issues occur (e.g., faulty microscope), report them immediately for resolution.

Practical Skill Assessment Details

  • The practical skills assessment consists of:

    • 10 Marks: Questions identical to those in the answer sheets.

    • 10 Marks: Questions similar to those in the answer sheets.

    • 10 Marks: Streaking of an agar plate:

    • Provided with a bacterial culture on an agar plate to pick a colony and streak onto a Nutrient Agar plate.

    • 10 Marks: Gram staining and microscopy:

    • Working with an unknown bacterial culture (options A, B, C, or D) to perform Gram staining and microscopy to determine cell characteristics (Gram positive or negative, morphology, etc.).

Assessment Marking Criteria

Streak Plates Marking Criteria:

  • No Contamination: 3 marks.

  • Correct Streaking Technique: 4 marks.

    • Must show visible streak lines with less dense growth in the second and third streaked areas.

  • Single Colony Presentation: 3 marks.

Gram Staining and Microscopy Marking Criteria (of one unknown bacterium):

  • Colour Identification: 1 mark (pink or purple).

  • Gram Reaction: 2 marks (Gram positive or Gram negative?).

  • Cell Shape Identification: 2 marks (morphology).

  • Cell Arrangement Identification: 2 marks (grouping).

  • Genus Identification: 1 mark.

  • Species Identification: 1 mark.

  • Correct Binomial Species Name: 1 mark (e.g., Escherichia coli or E. coli, underlined).

Additional Information

Streak Plates

  • Purpose: To obtain single colonies through dilution.

  • Method: Flame the loop before each step to ensure aseptic conditions.

  • Resources for further understanding available on Moodle in the week of 17 November – 23 November.

Gram Staining Principles

  • Developed by Hans Christian Gram, a Danish bacteriologist.

  • Widely utilized method in microbiology to categorize bacteria into two major groups:

    • Gram-positive

    • Gram-negative

Staining Process:

  • Initial Step: All cells initially take on a purple stain.

  • Alcohol Washing Step:

    • Gram-positive cells retain the purple coloration due to their thick peptidoglycan layer.

    • Gram-negative cells decolourise and take on a pink counterstain with safranin post-wash.

Bacterial Morphology

  • Shapes:

    • a. Bacillus: Rod-shaped.

    • b. Coccus: Spherical.

    • c. Spirillum: Spiral-shaped.

    • d. Spirochaetes: Corkscrew-shaped.

    • e. Vibrio: Comma-shaped.

  • Arrangements:

    • f. Mono: Single cells.

    • g. Strepto: Chains (e.g., Streptococcus).

    • h. Staphylo: Clusters (e.g., Staphylococcus).

    • i. Diplo: Pairs (e.g., Diplococcus).

    • j. Strepto: Chains of bacilli (e.g., Streptobacillus).