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

Objectives Effect of UV on the colonial morphology

of wild as well as baker’s yeast

Effect of UV on the cellular morphologyof wild as well as baker’s yeast

Effect of UV on the catalase activity ofwild as well as baker’s yeast

Introduction UV light -- electromagnetic radiation

Wavelength shorter -- visible light

longer -- X-rays

400 nm and 10 nm.

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

Materials and MethodsCollection of the Yeast Sample1. Soil sample

2. Baker’s Yeast

Spreading on YPD Agar platesIsolation of Pure StrainsExposure of UV RadiationsAnalyzing the Effect of UV on Colony

Morphology and Cellular MorphologyAnalyzing the effect of UV on Catalase Activity

Results & Discussion Effect of UV on the colonial morphology of

Baker’s Yeast Sample

Property Before UV ExposureAfter 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

Colony morphology of Baker’s yeast

before & after UV exposure

Before UV Exposure After UV Exposure

Effect of UV on the colonial morphology of wild Yeast Sample

Property Before UV ExposureAfter 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

Colony morphology of wild yeast before

& after UV exposure

Berore UV Exposure After UV Exposure

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

Cellular morphology of Baker’s yeast

before & after UV exposure

Before UV Exposure After UV Exposure

Cellular morphology of wild yeast before

& after UV exposure

Before UV Exposure After UV Exposure

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.

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.

Catalase activity of Baker’s yeast before

& after UV exposure

Before UV Exposure After UV Exposure

Catalase activity of wild yeast before &

after UV exposure

Before UV Exposure After UV Exposure