1. Microbial genetics
Bio 433
By
Dr. Mona Othman Albureikan

2. Introduction
1- Genome: refers to the
complete genetic material of
a cell in all kinds of
organisms.
2- The complete genetic
material includes both the
genes and the non- coding
sequences of the DNA/RNA.
Genome

3. 3- Noncoding DNA are sequences of DNA that do not encode protein
sequences but can be transcribed to produce important regulatory
molecules.
4- Some noncoding DNA is transcribed into functional non-coding
RNA molecules (e.g. transfer RNA, ribosomal RNA, and regulatory
RNAs).
Introduction

4. 4- All cells have a genome composed
of DeoxyriboNucleic Acid (DNA).
5- Some viruses also contain DNA, but many
have genomes composed of RiboNucleic Acid
(RNA).
6- All living cells contain both DNA and RNA.
7- Viruses contain either one or the other but
not both.
Introduction

5. 8- The general pattern of nucleic acid structure
and function is similar among all organisms.
9- Chromosomes: A chromosome is a piece or a
molecule of DNA ( highly organized structures )
which store genetic information in living
organisms.
10- DNA in chromosomes is in the form of one
long double helix.
Introduction

6. 12- Small sections of the
chromosome, called genes, code for
the RNA and protein molecules
required by the organism.
13- More specifically, it is a certain
segment of DNA that contains the
necessary code to make a protein or
RNA molecule.
Introduction
Gene

7. 14- Genes vary greatly in size.
- The smallest viruses have 4 to 5 genes.
- The bacterium Escherichia coli has a single
chromosome containing about 4,000 genes.
- A human cell packs about 100,000 genes in 46
chromosomes.
15- Genomics: study of genomes.
Introduction

8. Introduction

9. Differences between eukaryotic and prokaryotic chromosomes
Eukaryotic CellProkaryotic CellCells Character
PresentAbsentNucleus
Many chromosomesSingle chromosome plus plasmidsNumber of chromosomes
Linear chromosomesCircular chromosomeShape of chromosomes
Found in nucleus in somatic cells.Found in cytoplasm in an area
called the nucleoid, attached to the
inside of the cell membrane.
Place of chromosomes
Present (introns vs. exons )Absent (No introns )Nuclear membrane
Wrap their DNA around proteins
called histones. Made of
chromatin, a nucleoprotein (DNA
coiled around histone proteins ).
Multiple proteins act together to
fold and condense prokaryotic
DNA. bacterial DNA binding
proteins or histone-like proteins.
DNA wrapping on proteins.
Copies chromosomes, then the cell
grows (G2 phase), then goes
through mitosis to organize
chromosomes in two equal groups.
Copies its chromosome and divides
immediately afterwards. Prokaryotic
Chromosome.
Reproduction

10. • In eukaryotes, the primary transcript is
modified via processing and splicing
before traveling to the ribosomes for
protein translation.5' end is capped
with 5-methyl guanosine, 3' end is
capped with a line of adenines.
• Introns are removed, and remaining
exons.
Introduction

11. Introduction

12. Viral genomes
1- Viruses are not plants, animals, or bacteria cell,, ( Acell ).
2- All viruses contain nucleic acid, either
DNA or RNA, and a protein coat, which
encases the nucleic acid. Some viruses are
also enclosed by an envelope of lipid and
protein molecules.

13. 3- Viral nucleic acid varies
– Double-stranded DNA , Single-
stranded DNA, Double-stranded
RNA or Single-stranded RNA.
4- Linear or circular molecule of
nucleic acid.
5- Smallest viruses have only 4 genes,
while largest have several hundred.
Viral genomes

14. Viral genomes ( replication )

15. The structure of nucleic acids
- Deoxyribonucleic Acid (DNA) contains all
the genetic information of an organism .
- DNA is a complex polymer,
polysaccharide , it is made up of monomers
or subunits called nucleotides.
- The molecule of DNA is made up of 2
strands of nucleotides (double-stranded)
that are complementary to each other.

16. The structure of nucleic acids
- A nucleotide is made up of 3 different molecules:
A)One of four nitrogen-containing bases.
B) A 5-carbon sugar - ribose or deoxyribose.
C) A phosphorous (phosphate group).
- Each combined
phosphate-sugar-nitrogenous base forms
a unit called a nucleotide.
- Nucleotides linked together compose a nucleoside.

17. The structure of nucleic acids

18. - Two of these bases, adenine and guanine,
are called purines and have a double-
carbon ring structure.
- The other two
bases, thymine and cytosine, are
called pyrimidines and have a single-
carbon ring structure.
The structure of nucleic acids
A) One of four nitrogen-containing bases (a nitrogenous base):

19. - Adenine on one nucleoside of
the DNA molecule can form two
hydrogen bonds with thymine on
the other nucleoside.
- Guanine can form three
hydrogen bonds with cytosine in
a similar fashion.
The structure of nucleic acids
A) One of four nitrogen-containing bases (a nitrogenous base):

20. - The two strands are held
together by Hydrogen bonds .
- Complementary means that if
the nucleotide of one strand
contains a purine, the nucleotide
in the opposite strand has to be a
pyrimidine.
The structure of nucleic acids
A) One of four nitrogen-containing bases (a nitrogenous base):

21. The structure of nucleic acids
B) A 5-carbon sugar :

22. - Two phosphate groups are
covalently bonded to each ring-
shaped sugar.
- One is linked to the third carbon
(3') on the molecule, while the other
is linked to the fifth (5') carbon,
forming a 3'-5' glycosidic bond.
The structure of nucleic acids
A) A phosphate groups :
The structure of nucleic acids
C) A phosphate groups :

23. - This confers directionality to each nucleoside, since one is constructed
(biosynthesized) from 3' to 5'and the
other from 5' to 3'.
- The physical torsion on the molecule
owing to this structure causes the DNA
molecule to twist, taking on a shape called a double helix.
The structure of nucleic acids
C) A phosphate groups :

24. The structure of nucleic acids
A) A phosphate groups :
- The length of a DNA molecule varies by species and is generally not
expressed in metric units. Instead, length is expressed as the number
of base pairs (bp, i.e. A-T, G-C) of nucleotides each molecule
contains.
- Sequences of DNA base pairs are carry information (code) for the
production of a specific product or regulate the activities of other
DNA sequences.

25. Summary of Differences Between DNA and RNA
1.DNA contains the sugar
deoxyribose, while RNA contains the
sugar ribose.
- The only difference between ribose
and deoxyribose is that ribose has one
more (hydroxyl, -OH) group than
deoxyribose, which has -H attached to
the second (2') carbon in the ring.

26. Summary of Differences Between DNA and RNA
2. DNA is a double stranded
molecule while RNA is a single
stranded molecule.
3. Base pairing is slightly different,
since DNA uses the bases adenine,
thymine, cytosine, and guanine;
RNA uses adenine, uracil, cytosine,
and guanine.

27. - Uracil differs from thymine in that it lacks a methyl group on its ring.
Summary of Differences Between DNA and RNA

28. 4. DNA is stable under alkaline conditions while RNA is not stable.
- Deoxyribose sugar in DNA is less reactive because of C-H bonds. DNA has
smaller grooves where the damaging enzyme can attach which makes it
harder for the enzyme to attack DNA.
- Ribose sugar is more reactive because of C-OH (hydroxyl) bonds. RNA on
the other hand has larger grooves which makes it easier to be attacked by
enzymes.
Summary of Differences Between DNA and RNA

29. 5. DNA is a double-stranded molecule consisting of a long chain of
nucleotides (over a million nucleotides). RNA usually is a single-strand helix
consisting of shorter chains of nucleotides (70-12,000 nucleotides).
6. In DNA, Purine and Pyrimidine bases are equal in number, but in RNA, the
number is not equal between Purine and Pyrimidine bases.
7. DNA is long lived Some. RNAs are very short lived while others have
somewhat longer life.
Summary of Differences Between DNA and RNA

30. Summary of Differences Between DNA and RNA
8. DNA and RNA perform different
functions in all organisms. DNA is
responsible for storing and
transferring genetic information while
RNA directly codes for amino
acids and as acts as a messenger
between DNA and ribosomes to make
proteins.

31. The different types and Functions of RNA:
There are three different types of
RNA:
– m-RNA (messenger) used as
template to make proteins
– r-RNA (ribosomal) makes up
ribosomes
– t-RNA (transfer) matches amino
acids to mRNA to help make proteins.

32. References
 Molecular Genetics of Bacteria ( 4th Edition ) (2013), Larry Snyder , Joseph E. Peters , Tina M. Henkin , Wendy
Champness ISBN 10: 1555816274 ISBN 13: 9781555816278.
 Molecular Genetics of Bacteria, 5th Edition, by Jeremy W. Dale, Simon F. Park ,April 2010, ©2010.
 Genetics of Bacteria, Sheela Srivastava,(2013) ISBN: 978-81-322-1089-4
 Microbial Genetics. (1994). Jones and Bartlett Series in Biology. Jones and Bartlett Publishers, Inc.; 2nd
edition, ISBN-10: 0867202483, ISBN-13: 978-0867202489, 484 pages.
 Microbial genetics. (2008). Jones and Bartlett series in biology
Series of books in biology. David Freifelder, publisher, Jones and Bartlett, 1987. 601 pages.
 Molecular Biology: Genes to Proteins Hardcover . (2007). Burton E. Tropp, Publisher: Jones & Bartlett Publishers; 3
edition, ISBN-10: 0763709166, ISBN-13: 978-0763709167, 1000 pages .