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1. Session – 2020-2021
GENETIC ANALYSIS OF YEAST
Guided by –MRS.NEETU DAS MAM
Submitted by-
YOGITA LOKHANDE
CLASS – M.Sc-2nd SEMESTER
(MICROBIOLOGY)

2. CONTENT
Introduction
Yeast genome
Yeast as a model organism
Life cycle
Methods of Genetic analysis
1.Temprature sensitive mutant
2.Complementation test
3.Molecular cloning
Summary
Reference

3.  Yeast are eukaryotic microorganism classify in the
kingdom fungi.
 The yeast are unicellular, degenerative, non-
mycelium saprobic fungi .
 Size is about 3-4 um in diameter.
 Also known as chemoorganotrophs.
 The cell wall is thin, delicate, chitinious in nature.
 Some of the properties that make yeast particularly
suitable for biological studies include rapid growth,
dispressed cell, well defined genetic system and most
important a highly verssetile DNA transformation
system.

4.  The simplest eukaryotic genome (1.2 ×107 base pair of
DNA) is found in the yeast saccharomyces cerevisiae.
 The saccharomyces cerevisiae genome contains about
6000 genes including 5885 pre-dicted protein coding
sequence,140 ribosomal RNA genes, 275 transfer RNA
genes and 40 genes encoding small nuclear RNAs
involved in RNA processing.
 2000 genes have no functions, known as orphans
genes.
 Yeast genome is 200 times smaller than the human
genome.

5.  In 1996 , it was the first organism to have its genome
sequenced.
 Yeast and mammals genes encode very similar
protein.
 With the entire yeast genome sequenced in hand, we
can estimate how many yeast genes have significant
mammalian homologs.
 Even through saccharomyces cerevisiae is among the
best study organism, 60% of its genes still have
significant mammalian homologs.
 Genetic manipulation in yeast is very easy and cheap,
whereas such manipulation even when possible in
mamalians system is neither easy nor cheap.

6.  Saccharomyces cerevisiae can grow in either in
haploid state or diploid state .
 Conversion between the haploid and diploid state is
mediated by mating and sporulation.
 There are two haploid cells types called a and alpha
cells.
 Under the reduced nutrients, a/alpha diploid
undergoes meiotic division to generate a structure
known as the ascus that contain four haploid spores.
 When growth condition improve, these spores can
germinate and grow as haploid cells or mate to re-
form a/alpha diploids.

8. METHODS OF GENETIC ANALYSIS
1.TEMPERATURE SENSITIVE MUTANTS
Yeast with defects in genes required for fundamental
processes can be isolated as temperature- sensitive
mutants.
Such mutants encodes proteins that are functional at the
one temperature but not another, whereas normal
protein are functional at both.
The ability to isolate such temperature sensitive mutants
has allowed to identification of yeast genes controlling
many fundamental cell processes, such as RNA synthesis
and processing, progression through the cell cycle and
transport of protein between cellular compartment.

10. 2.MOLECULAR CLONING
Molecular cloning allows for the creation of multiple
copies of gene, and study of specific genes.
Molecular cloning refers to a process in which a gene
of interest is ligated to a vector.
 Application:-
1. Identifying the genes in a genome sequence.
2. Determining the function of an unknown gene.
3. Studying protein-protein intraction.
4. To study the transcriptome and proteome.

11.  Complementation test developed by Edward H. lewis.
 Complementation test diagnostic test for allelism.
 Complementation refers to appearance of wild
phenotype when two mutants are crossed.
 Complementation test is used to determine whether two
mutant alleles belong to same gene or two different gene.
 If there is complementation, the mutants are located in
different genes, otherwise they are located in the same
gene.

13.  Meiotic analysis can be
used to determine of a
mutation is an alteration
at a single genetic locus,
and to determine genetic
linkage of the mutation.

14.  Sachromyces cerevisiae is a useful model system
with which to study cellular processes and pathways
have proven intaractable in higher eukaryotes.
 The genetic analysis of saccharomyces cerevisiae is
further enhanced by the availability of techniques
used to precisely and rapidly modify indivisual
genes.

15. 11. THE CELL – A molecular approach (5th –edition)
Geoffrey M. Copper and Robert E. Hausman.
2.MOLECULAR BIOLOGY OF THE GENE – (5th
edition) James D. Watson and Tania A. Baker.
3. http://www.ncbi,nlm.nih.gov/books/NBK21735/

16. THANK YOU