Data has been collected from various sites is only a presentation

1. EHSAN HAIDER
ROLL NO.6004 7TH SEMESTER MORNING
PRESENTATION OF PLANT PHYSIOLOGY

2. GENE REGULATION IN EUKARYOTES
 Control of gene expression is called gene regulation
 Positive regulation ;gene expression quantitatively inecrease
 Negative regulation; gene expression quantitatively decrease
 Gene activity is controlled first and foremost at the level of
transcription
 Transcription takes place during interphase
 Nuclear material exists in form of chromatin(uncondensed
state)
 Chromatin have two types Euchromatin and heterochromatin

4. GENE REGULATION IN EUKARYOTES
 Euchromatin ;lightly packed form undergoes active gene
transcription
 Heterochromatin; tightly packed form inactive DNA
 Heterochromatin state can be changed by enzymes that modify
histones
 Addition of methyl and acetyl group to the terminal tails of the
histones
 Acetylation; reduces +ve charge on histone & loosening their
affinity to DNA
 Methylation increased the affinity of histones to bind with DNA

6. GENE REGULATION IN EUKARYOTES
 Genes pieces of DNA contain heridetary information
 Genes Have exons (coding)and introns (noncoding region)
 Each gene has its own start site and promoters
 Cis-acting sequences and trans-acting factors
 Transacting factors; proteins that bind to cis-sequences and
regulate transcription
 Cis-acting sequences ;DNA sequences involved control of
transcription

7. GENE REGULATION IN EUKARYOTES
 cis sequences includes
 1.Core promoter 2.regulatory sequences 3.enhancer
 core promoter ; sequence of DNA located 25-30bp upstream to
start site found in all eukaryotic genes
 Sequence is TATAAAA also called TATA box
 Site where RNA polymerase bind along with general
transcriptional factors
 Regulatory sequences ; DNA segments found upstream of the
core promoter CAAT box(-80bp) & GC box (-100bp)
 Activator and repressor bind here to regulate gene expression

9.  Enhancer; another cis acting sequence (distal regulatory
sequence )
 Located within 1000bp form start site either upstream or down
stream
 Activator and other complexes bind to enhancer to bring
enhancer to the promoter

12. EUKARYOTIC GENES CAN CO-ORDINATELY
REGULATED
• In this way a single transcription factor can control the
expression of many genes.
Example ; yeast Saccharomyces
cerevisiae
The GAL4 gene encodes a transcription
factor(GAL4protein) that binds to UAS elements of
all six genes involve in galactose metabolism and
transport

14. EUKARYOTIC GENES CAN CO-ORDINATELY
REGULATED
 Example ; yeast Saccharomyces cerevisiae. Several enzymes involved in galactose
transport and metabolism are induced by a metabolite of galactose.
 The genes GAL7, GAL10, GAL1, and MEL1 are located on chromosome II
 GAL2 is on chromosome XII
 GAL3 is on chromosome IV.
 GAL4 and GAL80, located on two other chromosomes, encode positive and
negative trans-acting regulatory proteins, respectively.
 The GAL4 protein binds to an upstream activating sequence located upstream of
each of the genes in the pathway, indicated by the hatched lines.
 The GAL80 protein forms an inhibitory complex with the GAL4 protein.
 In the presence of galactose, the metabolite formed by the GAL3 gene product
diffuses to the nucleus and stimulates transcription by causing dissociation of the
GAL80 protein from the complex.

15. REFERENCES
https://cnx.org/res7-REGULATION OF GENE EXPRESSION IN
EUKARYOTES.pdf Ho Huynh Thuy Duong University of Science
 www.csun.edu/~cmalone/pd.fCh20-1 euk gene reg.pdf
 /www.saylor.org/site/wp-content. Gene-Regulation-in-
Eukaryotes.pdf
 dls.ym.edu.tw/course/hb/doc/lecture8-(23)%2052-
Eukarylecture8-(23) 52-Eukaryotic Gene Regulation.pdf
 Plant physiology 5th edition by TEIZ &ZEIGER ch#14
 AK lecturer/youtube gene regulation in eukaryotes