The document discusses the structure and morphology of bacterial cells. It states that bacterial cells have a plasma membrane that is required for living organisms. The plasma membrane follows the fluid mosaic model and contains proteins and lipids. The morphology of bacterial cells is mainly defined by their size, shape, and arrangement, which can be bacilli, cocci, or spirals. Different bacterial cells vary in these characteristics.
A fimbria (Latin for 'fringe', plural fimbriae), also referred to as an "attachment pilus" by some scientists, is an appendage that can be found on many Gram-negative and some Gram-positive bacteria, that is thinner and shorter than a flagellum. This appendage ranges from 3–10 nanometers in diameter and can be up to several micrometers long. Fimbriae are used by bacteria to adhere to one another and to adhere to animal cells and some inanimate objects. A bacterium can have as many as 1,000 fimbriae. Fimbriae are only visible with the use of an electron microscope. They may be straight or flexible.
A pilus (Latin for 'hair'; plural: pili) is a hair-like appendage found on the surface of many bacteria and archaea.[1] The terms pilus and fimbria (Latin for 'fringe'; plural: fimbriae) can be used interchangeably, although some researchers reserve the term pilus for the appendage required for bacterial conjugation. All pili in the latter sense are primarily composed of pilin proteins, which are oligomeric.
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A fimbria (Latin for 'fringe', plural fimbriae), also referred to as an "attachment pilus" by some scientists, is an appendage that can be found on many Gram-negative and some Gram-positive bacteria, that is thinner and shorter than a flagellum. This appendage ranges from 3–10 nanometers in diameter and can be up to several micrometers long. Fimbriae are used by bacteria to adhere to one another and to adhere to animal cells and some inanimate objects. A bacterium can have as many as 1,000 fimbriae. Fimbriae are only visible with the use of an electron microscope. They may be straight or flexible.
A pilus (Latin for 'hair'; plural: pili) is a hair-like appendage found on the surface of many bacteria and archaea.[1] The terms pilus and fimbria (Latin for 'fringe'; plural: fimbriae) can be used interchangeably, although some researchers reserve the term pilus for the appendage required for bacterial conjugation. All pili in the latter sense are primarily composed of pilin proteins, which are oligomeric.
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Viruses that infect bacteria.
Occur widely in nature in close association with bacteria.
Readily isolated from faeces, sewage and other natural sources.
Tadpole shaped, with hexagonal head and a cylindrical tail.
Head consists of a tightly packed core of ds DNA surrounded by a protein coat or capsid.
The tail composed of a contractile sheath surrounding the hollow core
Terminal base plate having prongs or tail fibres attached.
Viruses that infect bacteria.
Occur widely in nature in close association with bacteria.
Readily isolated from faeces, sewage and other natural sources.
Tadpole shaped, with hexagonal head and a cylindrical tail.
Head consists of a tightly packed core of ds DNA surrounded by a protein coat or capsid.
The tail composed of a contractile sheath surrounding the hollow core
Terminal base plate having prongs or tail fibres attached.
Bacteria are small single-celled organisms. Bacteria are found almost everywhere on Earth and are vital to the planet's ecosystems. Some species can live under extreme conditions of temperature and pressure. The human body is full of bacteria, and in fact is estimated to contain more bacterial cells than human cells.
Ultrastructure and characterstic features of bacteria.Archana Shaw
Ultrastructure and characterstic features of bacteria: BACTERIA AS A MODEL ORGANISM
THIS WAS MY PRESENTATION TOPIC IN CLASS. THOUGHT OF SHARING IT AND HOPE IT HELPS.
What is bacteria?(Structures Present in Bacteria And their Functions | Prokar...sehriqayyum
Explains what bacteria is and where it exists.
A key feature of nearly all prokaryotic cells is the cell wall, which maintains cell shape, protects the cell, and prevents it from bursting in a hypotonic environment.
The cell walls of prokaryotes differ in structure from those of eukaryotes. In eukaryotes that have cell walls, such as plants and fungi, the walls are usually made of cellulose or chitin. In contrast, most bacterial cell walls contain peptidoglycan, a polymer composed of modified sugars cross-linked by short polypeptides.
Using a technique called the Gram stain, developed by the 19th-century Danish physician Hans Christian Gram, scientists can categorize many bacterial species according to differences in cell wall composition.
Gram-positive bacteria have simpler walls with a relatively large amount of peptidoglycan. Gram-negative bacteria have less peptidoglycan
and are structurally more complex, with an outer membrane
that contains lipopolysaccharides (carbohydrates bonded
to lipids).
LEARN ABOUT:
- Bacteria
- The number of viruses on earth is staggering
- Pathogenic yeasts
- Helminths
- Harnessing bacteria
- Microbes on the tree of life
- Living and working together
- Archaea
- Protozoa
LEARN ABOUT:
- Bacteria
- The number of viruses on earth is staggering
- Pathogenic yeasts
- Helminths
- Harnessing bacteria
- Microbes on the tree of life
- Living and working together
- Archaea
- Protozoa
The bacterial flagellum has three main parts (the motor, hook, and filament) that are themselves composed of 42 different kinds of proteins.The cells of prokaryotes are simpler than those of eukaryotes
in both their internal structure and the physical arrangement
of their DNA. The genome of a prokaryote is structurally different from
a eukaryotic genome and in most cases has considerably less DNA. Prokaryotes generally have circular chromosomes, whereas eukaryotes have linear chromosomes.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
2. Bacterial cell possesses a detailed internal
structure.
Membranes are an absolute requirement for
all living organisms. That covers the surface
of every cell and also surround most
organelles within cell.
Among the major characteristics of bacterial
cells are their size,shape,structure,and
arrangement. These characteristics constitute
the morphology of the cell.
3. FUNCTIONS
Control permeability.
Transport electrons and protons for cellular
metabolism .
Contain enzymes to synthesis and transport
cell wall substance and for metabolism.
Secrete hydrolytic enzymes.
Regulate hydrolytic enzyme.
4. Membranes contain both proteins and lipids.
Bacterial plasma membrane usually have a
higher proportion of protein
Phospholipid bilayer is present .
Are amphipathic: That have polar and non
polar ends.
The polar end is hydrophilic.
The non polar end is hydrophobic.
5.
6. Bacterial membrane in lacking sterols such as
cholesterol.
It contain pentacyclic sterol like molecule
called hapanoid-stabilize the bacterial
membrane
Cell membrane are very thin structure about
5-10 nm thick
Plasma membrane have a complex structure.
7.
8. The most widely accepted current model for
membrane structure is the fluid mosaic model.
Proposed by S.Jonathan singer and Garth Nicolsan.
They distinquish two types of membrane proteins.
Peripheral proteins: are loosely connected to the
membrane and easily removed. They are soluble in
aqueous solutions and make up about 20-30% of
total membrane protein.
Integral proteins: About 70-80% of membrane
proteins are integral proteins. They are not easily
extracted from membranes and are insoluble in
aqueous solutions when freed of lipids. They are
amphipathic.
9. The plasma membrane also serves as a
selectively permeable barrier : it allows
particular ions and molecules to pass, either
into or out of the cell, while preventing the
movement of others.
10.
11.
12. Bacteria are prokaryotic, unicellular
microorganisms, which lack chlorophyll
pigments. The cell structure is simpler than
that of other organisms as there is no nucleus
or membrane bound organelles.
Due to the presence of a rigid cell wall,
bacteria maintain a defnite shape, though
they vary as shape, size and structure.
13. The average diameter of spherical bacteria is
0.5-2.0 micrometer.
For rod shaped or filamentous bacteria length
is 1-10micrometer and diameter is
0.25-1.0 micrometer.
E.coli, a bacillus of about average size is 1.1-
1.5micrometer wide by 2.0-6.0 micrometer
long.
Spirochetes occasionally reach 500 in length
and the cyanobacterium.
Oscillatoria is about 7 in diameter.
14. The bacterium, Epulosicium fishelsoni, can be
seen with the naked eye (600 micrometer
long by 80 micrometer in diameter).
One group of bacteria,
called the mycoplasms, have individuals with
size much smaller than these dimensions.
They measure about 0.25 and are the
smallest cells known so far they were
formerly known as pleuropneumonia-like
organisms(PPLO).
Mycoplasma gallicepticum with size of
approximately 200-300 nm are thought to be
smallest bacteria.
15. Thiomargarita namibiensis is largest bacteria
gram negative.
Proteobacterium found in the ocean sedimets
off the coast of Namibia. Usually it is 0.1-0.3
nm (100-300 )across, bigger cells have
been observed up to 0.75 mm (750micro
meter).
Thus a few bacteria are much larger than the
average eukaryotic cell(typical plant and
animal cells are around 10-50micro meter in
diameter).
16.
17. When viewed under light microscope, most
bacteria appear variations of three major
shapes: the rod (bacilli),the sphere(coccus)
and the spiral type(vibrio). In fact,structure of
bacteria has two aspects, arrangement and
shape.
21. SPIRILLA
Or spirillum for a single cell
Are curved bacteria which can range from
gently curved shape to a corkscrew-like
spiral.
Many spirilla are rigid and capable of
movement. A special group of spirilla known
as spirochetes are long,slender,
22. Diplococci
The cocci are arranged in pairs.
Examples: Streptococcus pneumoniae,
Moraxella catarrhalis, Neisseria gonorrhoeae,
etc..
Streptococci
The cocci are arranged in chains, as the
divide in one plane
Examples: Streptococcus pyogenes,
Streptococcus agalactiae.
23.
24. Tetrads
The cocci are arranged in packets of four
cells, as the cells divide in two plains.
Examples: Aerococcus, Pediococcus,
Tetragenococcus
25. Sarcinae
The cocci are arranged in a cuboidal
manner,as the cells formed by regular cell
divisions in three planes and remain in
groupes cube like groups of eight.
Examples: Sarcina ventriculi, Sarcina ureae.
26. Staphylococci
The cocci are arranged in grape like clusters
formed by irregular cell divisions in three
plains
Examples: Staphylococcus aureus
27. Diplobacilli
Most bacilli appear as single rods.
Diplobacilli appear in pairs after division
Examples of single rod: Bacillus cereus
Examples of diplobacilli: Coxiella burnetti,
Klebsiella rhinoscleromatis
28. Streptobacilli
The bacilli are arranged in chains, as the cells
divide in one plane.
Examples: Streptobacillus moniliformis
29. Coccabacilli
These are so short and stumpy that they
appear ovoid.
They look like coccus and bacillus
Examples:Haemophilus
influenzae,Gardneralla vaginalis, and
Chlamydia trachomatis.
30. Palisades
The bacilli bent at the points of divisions,
resulting in a palisade arrangement
resembling a packet fence and angular
patterns that look like chinese letters
Examples: Corynobacterium diphtheriae
31. Vibrio
They are comma shaped bacteria with less
than one complete turn or twist in the cell.
Examples: Vibrio cholerae
32. Spirilla
They have rigid spiral structure. Spirillum
with many turns can superficially resembles
spirochetes. They do not have outer sheath
and endoflagella, but have typical bacterial
flagella.
Examples: Campylobacter jejuni, Helicobacter
pylori, Spirillum winogradskyi.
33. Spirochetes
Spirochetes have a helical shape and flexible
bodies. Spirochetes move by means of axial
filaments, which look like flagella contained
beneath a flexible external sheath but lack
typical bacterial flagella.
Examples: Lepto spira species, Treponema
pallidium.
34. Cell membranes are an absolute requirement
for all living organisms.
Most widely accepted current model cell
membrane structure is plasma membrane.
The morphology of bacterial cell mainly
constitutes size shape and arrangements.
35. Ananthanarayan&Paniker’s.2013.Text book of
Microbiology,9th edition. Universities
Press,India.Pg.No-9-16.
Madigan M,Martinko J,Parker J.2002.Brock
biology of Microorganisms,10th edition.
Prentice Hall.Pg.No-74-91.
Prescott,Harley,Klein.2004.Microbiology,6 th
edition.Mc Graw Hill
ScienceEngineeringMath Hard cover.Pg.No-
46-49.