Effect of UV Rays on the Colonial & Cellular Morphology and Catalase Activity of Baker’s and Wild Strains of Yeast

1. Effect of UV Rays on the Colonial
& Cellular Morphology and
Catalase Activity of Baker’s and
Wild Strains of Yeast
Amna Jalil
Roll No: 17

2. Objectives
 Effect of UV on the colonial morphology
of wild as well as baker’s yeast
 Effect of UV on the cellular morphology
of wild as well as baker’s yeast
 Effect of UV on the catalase activity of
wild as well as baker’s yeast

3. Introduction
 UV light -- electromagnetic radiation
 Wavelength shorter -- visible light
 longer -- X-rays
 400 nm and 10 nm.

4.  Does not break the DNA chain outright
 Selectively absorbed by the aromatic
rings of the purine and pyrimidine
bases
 Formation of pyrimidine dimers
 Two adjacent pyrimidines in the same
chain (T-T, C-C, or T-C) become
covalently bonded together
 These dimers disrupt the local
structure of the DNA double helix and
prevent normal DNA replication

6. Materials and Methods
Collection of the Yeast Sample
1. Soil sample
2. Baker’s Yeast
Spreading on YPD Agar plates
Isolation of Pure Strains
Exposure of UV Radiations
Analyzing the Effect of UV on Colony
Morphology and Cellular Morphology
Analyzing the effect of UV on Catalase Activity

7. Results & Discussion
 Effect of UV on the colonial morphology of
Baker’s Yeast Sample
Property Before UV Exposure
After UV Exposure
(1 min)
1. Form Circular Circular
2. Elevation Convex Raised
3. Margins Entire Entire
4. Color Cream colored Cream colored
5. Surface Smooth & Shiny Rough & Matt

8. Colony morphology of Baker’s yeast
before & after UV exposure
Before UV Exposure After UV Exposure

9.  Effect of UV on the colonial morphology
of wild Yeast Sample
Property Before UV Exposure
After UV Exposure
(1 min)
1. Form Circular Circular
2. Elevation Convex Raised
3. Margins Entire Entire
4. Color Cream colored Cream colored
5. Surface Smooth & Shiny Rough & Matt

10. Colony morphology of wild yeast before
& after UV exposure
Berore UV Exposure After UV Exposure

11. Effect of UV on the Cellular
Morphology of Yeast Sample
 The lethal effects of the UV radiation
Mutations of the genes or
chromosomes
Destruction of the cell-membrane
Some structures or cell organelles

12. Cellular morphology of Baker’s yeast
before & after UV exposure
Before UV Exposure After UV Exposure

13. Cellular morphology of wild yeast before
& after UV exposure
Before UV Exposure After UV Exposure

14. Effect of UV on the Catalase
Activity of Yeast Sample
 UV irradiation on the catalase activity
was divisible into 4 periods.
1. First, the period during which the
cells lost their ability to form colonies,
but during which no change in
catalase activity was noted.
2. Second, the period during which a
considerable rise in catalase activity
occurred.

15. 1. Third, a rather long period during
which irradiation led to no diminution
in the catalase activity of the
maximally active suspension.
2. Fourth, the period of
photoinactivation of the intracellular
enzyme, which was quite similar to
that of the crystalline enzyme in vitro.

16. Catalase activity of Baker’s yeast before
& after UV exposure
Before UV Exposure After UV Exposure

17. Catalase activity of wild yeast before &
after UV exposure
Before UV Exposure After UV Exposure