DNA replication is fundamental process occurring in all living organism to copy their DNA. The process is called replication in sense that each strand of dsDNA serve as template for reproduction of complementary strand.
DNA replication is an important process which takes place in every organisms, be it prokaryotic or eukaryotic. The DNA replication process produces two identical copies of daughter DNA molecules using the existing DNA molecule as template. Each daughter DNA molecule inherits one strand from the parent cell and the other strand is newly synthesized. This is known as semiconservative mode of replication, demonstrated by Meselson and Stahl.
DNA replication is an important process which takes place in every organisms, be it prokaryotic or eukaryotic. The DNA replication process produces two identical copies of daughter DNA molecules using the existing DNA molecule as template. Each daughter DNA molecule inherits one strand from the parent cell and the other strand is newly synthesized. This is known as semiconservative mode of replication, demonstrated by Meselson and Stahl.
DNA Replication In Eukaryotes (Bsc.Zoology)DebaPrakash2
This Slide Is explanation of Mechanism of DNA Replication In Eukaryotes.
As we know we all have DNA as the genetic material and So we should know how this DNA getting Duplicated so that it'll pass to daughter cells.
DNA Replication In Eukaryotes (Bsc.Zoology)DebaPrakash2
This Slide Is explanation of Mechanism of DNA Replication In Eukaryotes.
As we know we all have DNA as the genetic material and So we should know how this DNA getting Duplicated so that it'll pass to daughter cells.
DNA replication is the process by which DNA makes a copy of itself during cell division.The separation of the two single strands of DNA creates a 'Y' shape called a replication 'fork'. The two separated strands will act as templates for making the new strands of DNA.
75%-90% of the population in developing nations rely on herbal medicine as their only health care.
Medicinal herbs are sold alongside vegetables in village markets.
Practitioners of herbal medicine undergo extensive training to learn the plants, their uses, and preparation of remedies.
This is a process by which the genetic code contained within a messenger RNA (mRNA) molecule is decoded to produce a specific sequence of amino acids in a polypeptide chain.
Gene regulation can be defined as any kind of alteration in the gene to give rise to a different expression which might result in a change in the synthesized amino acid sequence.”
Gene expression is basically the synthesis of the polypeptide chain encoded by a particular gene.
Therefore the expression of the gene can be quantified in terms of the amount of protein synthesised by the genes.
Genetic code is a dictionary that corresponds with sequence of nucleotides and sequence of amino acids.
Genetic code is a set of rules by which information encoded in genetic material(DNA or RNA sequences) is translated into proteins by living cells.
Term given By ″ Goerge Gamow ʺ
DNA- deoxyribonucleic acid
A long molecule that looks like a twisted ladder made up of four types of simple units and the sequence of these units carries genetic information.
Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).
A plasmid is a small, circular piece of DNA that is different than the chromosomal DNA, which is all the genetic material found in an organism’s chromosomes.
A cell cycle is a series of events that a cell passes through from the time until it reproduces its replica.
Howard and Pelc (1953) first time described it.
It is the growth and division of single cell into daughter cells and duplication (replication).
In prokaryotic cells, the cell cycle occurs via a process termed binary fission.
In eukaryotic cells, the cell cycle can be divided in two periods-
a) interphase
b) mitosis
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
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/
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Deep Behavioral Phenotyping in Systems Neuroscience for Functional Atlasing a...Ana Luísa Pinho
Functional Magnetic Resonance Imaging (fMRI) provides means to characterize brain activations in response to behavior. However, cognitive neuroscience has been limited to group-level effects referring to the performance of specific tasks. To obtain the functional profile of elementary cognitive mechanisms, the combination of brain responses to many tasks is required. Yet, to date, both structural atlases and parcellation-based activations do not fully account for cognitive function and still present several limitations. Further, they do not adapt overall to individual characteristics. In this talk, I will give an account of deep-behavioral phenotyping strategies, namely data-driven methods in large task-fMRI datasets, to optimize functional brain-data collection and improve inference of effects-of-interest related to mental processes. Key to this approach is the employment of fast multi-functional paradigms rich on features that can be well parametrized and, consequently, facilitate the creation of psycho-physiological constructs to be modelled with imaging data. Particular emphasis will be given to music stimuli when studying high-order cognitive mechanisms, due to their ecological nature and quality to enable complex behavior compounded by discrete entities. I will also discuss how deep-behavioral phenotyping and individualized models applied to neuroimaging data can better account for the subject-specific organization of domain-general cognitive systems in the human brain. Finally, the accumulation of functional brain signatures brings the possibility to clarify relationships among tasks and create a univocal link between brain systems and mental functions through: (1) the development of ontologies proposing an organization of cognitive processes; and (2) brain-network taxonomies describing functional specialization. To this end, tools to improve commensurability in cognitive science are necessary, such as public repositories, ontology-based platforms and automated meta-analysis tools. I will thus discuss some brain-atlasing resources currently under development, and their applicability in cognitive as well as clinical neuroscience.
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.
4. DNA REPLICATION
DNA replication is fundamental process occurring in all
living organism to copy their DNA.The process is called
replication in sense that each strand of ds DNA serve as
template for reproduction of complementary strand.
5.
6. General feature of DNA replication
DNA replication is semi conservative
It is bidirectional process
It proceed from a specific point called origin
It proceed in 5’-3’ direction
It occur with high degree of fidelity
It is a multi-enzymatic process
7.
8.
9. Models of DNA replication
There were three models suggested for DNA
replication:
•Conservative,
•Semi-conservative, and
•Dispersive.
10.
11. Conservative Method
The conservative method of replication suggests that parental
DNA remains together and newly-formed daughter strands are
also together.
Semi-Conservative Method
The semi-conservative method of replication suggests that the
two parental DNA strands serve as a template for new DNA and
after replication, each double-stranded DNA contains one strand
from the parental DNA and one new (daughter) strand.
Dispersive Method
The dispersive method of replication suggests that, after
replication, the two daughter DNAs have alternating segments of
both parental and newly-synthesized DNA interspersed on both
strands.
12.
13.
14.
15.
16. DNA replication occurs by three steps
1. Initiation:
• Initiation complex formation
• Closed complex formation
• Open complex formation
2. Elongation:
• Leading strand synthesis
• Lagging strand synthesis
3.Termination
17. Initiation
DNA replication demands a high degree of accuracy because
even a minute mistake would result in mutations.Thus,
replication cannot initiate randomly at any point in DNA.
For the replication to begin there is a particular region called
the origin of replication.This is the point where the
replication originates. Replication begins with the spotting of
this origin followed by the unwinding of the two DNA strands.
Unzipping of DNA strands in its entire length is unfeasible
due to high energy input. Hence, first, a replication fork is
created catalyzed by polymerases enzyme which is an
opening in the DNA strand.
18. Elongation
As the strands are separated, the polymerase enzymes start
synthesizing the complementary sequence in each of the
strands.The parental strands will act as a template for newly
synthesizing daughter strands.
It is to be noted that elongation is unidirectional i.e. DNA is
always polymerized only in the 5′ to 3′ direction. Therefore, in
one strand (the template 3‘→5‘) it is continuous, hence called
continuous replication while on the other strand (the
template 5‘→3‘) it is discontinuous replication.They occur as
fragments called Okazaki fragments.The enzyme called DNA
ligase joins them later.
19. Elongation
Leading strand synthesis:
•Leading strand synthesis is more a straight forward process which
begins with the synthesis of RNA primer by primase at replication
origin.
•DNA polymerase III then adds the nucleotides at 3’end.
•The leading strand synthesis then proceed continuously keeping
pace with unwinding of replication fork until it encounter the
termination sequences.
Lagging strand synthesis:
•The lagging strand synthesized in short fragments called Okazaki
fragments.
•At first RNA primer is synthesized by primase and as in leading
strand DNA polymerase III binds to RNA primer and adds dNTPS
20. REPLICATION FORK
•The replication fork is a structure that forms within the
nucleus during DNA replication.
•It is created by helicases, which break the hydrogen bonds
holding the two DNA strands together.The resulting
structure has two branching "prongs", each one made up of a
single strand of DNA.
•These two strands serve as the template for the leading and
lagging strands, which will be created as DNA polymerase
matches complementary nucleotides to the templates; the
templates may be properly referred to as the leading strand
template and the lagging strand template.
21.
22. REPLICATION BUBBLE
•It is formed during replication in both eukaryotic and
prokaryotic DNA. It is the place where replication occurs
actively.
• It is otherwise known as replication bubble. Formation of the
replication eye provides the theta like structure to the circular
DNA during replication in prokaryotes.
•Each replication bubble found to have two replication forks,
each at the corner of an eye.
23. SINGLE-STRANDED DNA-BINDING PROTEIN
(SSB)
It was called a DNA-unwinding protein (M.W. 22,000).
Single-stranded DNA-binding protein, or SSB, binds to single-
stranded regions of DNA to prevent premature annealing, to
protect the single-stranded DNA from being digested by
nucleases, and to remove secondary structure from the DNA to
allow other enzymes to function effectively upon it
24. PRIMER
A primer is a strand of nucleic acid that serves as a starting
point for DNA synthesis. It is required for DNA replication
because the enzymes that catalyze this process, DNA
polymerases,
can only add new nucleotides to an existing strand of DNA.The
polymerase starts replication at the 3'-end of the primer, and
copies the opposite strand.
In most cases of natural DNA replication, the primer for DNA
synthesis and replication is a short strand of RNA.
25. OKAZAKI FRAGMENTS
Fragments synthesized during lagging strand formation of replication
was identified and proved by Rejis Okazaki. Hence, by his name these
fragments are called as Okazaki’s fragments.
They are short polynucleotides with 1000-2000 base pairs in length.
These fragments are synthesized by DNA polymerases.
Even though they are formed during replication, they are joined to form
larger DNA at the completion of replication by the action of DNA ligase.
The invention of Okazaki fragments lead to the proposal of
semidiscontinuous replication concept
31. Enzymes Involved In DNA Replication
DNA replication is a highly enzyme-dependent process.There are many enzymes involved in
the DNA replication which includes the enzymes DNA-dependent DNA polymerase, helicase,
ligase, etc. Among them, DNA-dependent DNA polymerase is the main enzyme.
DNA-dependent DNA polymerase
It helps in the polymerization and catalyzes and regularises the whole process of DNA
replication with the support of other enzymes. Deoxyribonucleoside triphosphates are the
substrate as well as the energy provider for the replication process. DNA polymerase is of three
types:
DNA Polymerase I
It is a DNA repair enzyme. It is involved in three activities:
5′-3′ polymerase activity
5′-3′ exonuclease activity
3′-5′ exonuclease activity
DNA Polymerase II
It is responsible for primer extension and proofreading.
DNA Polymerase III
It is responsible for in vivo DNA replication.
randed DNA and protects it from forming secondary structures
32. Enzymes Involved In DNA Replication
Helicase
Helicase is the enzyme which unzips the DNA strands by breaking the hydrogen
bonds between them.Thus, it helps in the formation of the replication fork.
Ligase
Ligase is the enzyme which glues the discontinuous DNA strands.
Primase
This enzyme helps in the synthesis of RNA primer complementary to the DNA
template strand.
Endonucleases
These produce a single-stranded or a double-stranded cut in a DNA molecule.
Single-stranded Binding Proteins
It binds to single-stranded DNA and protects it from forming secondary structures
33.
34. ENZYMES INVOLVED IN DNA REPLICATION
– DNA Helicase
– DNA Polymerase
– DNA clamp
– Single-Strand Binding (SSB) Proteins
–Topoisomerase / DNA Gyrase
– DNA Ligase
– Primase
35. DNA Helicase
• Helicases were discovered in E. coli in 1976 and are
a class of enzymes vital to all living organisms.
• Also known as helix destabilizing enzyme, they
separates the two strands of DNA at the Replication
Fork behind the topoisomerase.
•They are motor proteins that move directionally
along a nucleic acid phosphodiester backbone,
separating two annealed nucleic acid strands
(i.e., DNA,RNA, or RNA-DNA hybrid) using energy
derived from ATP hydrolysis.
•They have molecular weight 300,000, which
contain SIX identical sub units.
36.
37. DNA GYRASE
DNA gyrase, often referred to simply as gyrase, is an
enzyme that relieves strain while double-strand DNA
is being unwound by helicase.This causes negative
supercoiling of the DNA.The ability of gyrase to relax
positive supercoils comes into play during DNA
replication.The right-handed nature of the DNA
double helix causes positive supercoils to accumulate
ahead of a translocating enzyme, in the case of DNA
replication, a DNA polymerase.The ability of gyrase
(and topoisomerase IV) to relax positive supercoils
allows superhelical tension ahead of the polymerase
to be released so that replication can continue.
38.
39. DNA Polymerase
• DNA polymerases are enzymes that synthesize DNA molecules
from deoxyribonucleoti des, the building blocks of DNA.
•These enzymes are essential to DNA replication and usually work in
pairs to create two identical DNA strands from a single original DNA
molecule.
• During this process, DNA polymerase “reads” the existing DNA
strands to create two new strands that match the existing ones
• Also performs proof-reading and error correction.
40.
41.
42. DNA polymerases are enzymes that synthesize a new strand of DNA
complementary to an existing DNA or RNA template.
A polymerase enzyme, the terms ‘DNA- dependent’ or ‘RNA-
dependent’ may be used to indicate the type of nucleic acid template
that the enzyme uses:
DNA-dependent DNA polymerase copies
DNA into DNA
DNA-dependent RNA polymerase transcribes
DNA into RNA.
RNA-dependent DNA polymerase copies
RNA into DNA.
43.
44. DNA
Polymerase
s I
• This was firstly discovered in 1958 by Arthur Kornberg who received Noble Prize in
Physiology and Medicine in 1959
• DNA Polymerases I is mainly responsible for:
• Proofreading of DNA strand
• Repairing of damage DNA
• Filling the gap between the okazaki fragments
• Removal of RNA primer
45. DNA Polymerases II
• DNA Polymerases II was identified later during the experiment on mutant E.coli
cell line
• DNA Polymerases II have temporary function when DNA Polymerases I and DNA
Polymerases III are not functional
• Still capable for doing synthesis on damage template
• Participating in DNA repairing
46. DNA Polymerases III
• DNA Polymerases III was identified later during the experiment on mutant E.coli
cell line.
• DNA Polymerases III is heterodimer enzyme composed of ten different subunits
• It is true enzyme that is responsible for the elongation process
• It also responsible for the polymerization of Nucleotide and make most of the
DNA during replication.
47.
48.
49. RNA Polymerase
• Enzyme that synthesizes RNA using a DNA template through a process called
transcription
• RNA polymerase enzymes are essential to life and are found in all organisms and
many viruses
• It polymerizes ribonucleotide at the 3 end of an RNA transcript
50.
51.
52.
53.
54. Single-Strand Binding (SSB) Proteins
• Single stranded binding proteins prevent
reannealing (binding of complementary DNA
sequences), protect the single-stranded DNA from
being digested by nucleases, and prevent secondary
structure formation, thereby allowing other
enzymes to function effectively on the single
strand.
• Molecular weight of the SSB protein is 75,600.
• It contains FOUR identical subunits, which binds
single stranded DNA.
55.
56. Topoisomerase
• Every cell has enzymes that increase (or) decrease
the extent of DNA unwinding are called “Topoisomerases.
•Topoisomerase is also known as “DNA Gyrase” and
that act on the topology of DNA.
• “Topoisomerases bind to double-stranded DNA and
cut the phosphate backbone of either one or both the
DNA strands, this intermediate break allows the
DNA to be untangled or unwound, and, at the end of
these processes, the DNA backbone is resealed again.
•Topoisomerases” is an enzyme that can change the
“Linking number”(Lk).
57.
58. •The linking number (Lk) is a topological property, it can be
defined as “ the number of times the second strand pierces the
second strand surface”.
•There are two classes of topoisomerases.
―a)Type-ITopoisomerases
―b)Type-IITopoisomerases
a)Type-ITopoisomerases:
•This act by transiently breaking one of the two DNA strands,
rotating one of the ends about the unbroken strand, and
rejoining the broken ends; they change Lk in increments of 1.
b)Type-IITopoisomerases:
•The enzyme breaks both DNA strands and change Lk in
increments of 2.
63. DNA Ligase
• DNA ligase is a specific type of enzyme, a ligase, that
facilitates the joining of DNA strands together by catalyzing the
formation of a phosphodiester bond.
• DNA ligase is used in both DNA repair and DNA replication.
•The mechanism of DNA ligase is to form two covalent
phosphodiester bonds between 3’ hydroxyl ends of one
nucleotide, ("acceptor") with the 5' phosphate end of another
("donor").
• ATP is required for the ligase reaction, which proceeds in three
steps:
64. i. Adenylation (addition of AMP) of a lysine residue in the active
center of the enzyme, pyrophosphate is released;
ii.Transfer of the AMP to the 5' phosphate of the socalled donor,
formation of a pyrophosphate bond;
iii. Formation of a phosphodiester bond between the 5'
phosphate of the donor and the 3' hydroxyl of the acceptor.
65.
66. Primase
• DNA primase is an enzyme involved in the replication
of DNA and is a type of RNA polymerase.
• Primase catalyzes the synthesis of a short RNA (or
DNA in some organisms) segment called a primer
complementary to a ssDNA template.
• Primase is of key importance in DNA replication because no
known replicative DNA polymerases can initiate the synthesis
of a DNA strand without an initial RNA or DNA primer (for
temporary DNA elongation).
• After this elongation the RNA piece is removed by a 5'
to 3' exonuclease and refilled with DNA
71. Replication in eukaryotes is bidirectional, this type is
unidirectional.
Ideal example of this type is the circular plasmid of bacteria,
as it happens only in circular genomes
75. Elongation
For Elongation, -OH group
of broken strand, using the unbroken strand as a template.
The polymerase will start to move in a circle for elongation,
due to which it is named as Rolling circle model
end will be displaced and will grow out like a waving thread.
76. Termination
At the point of termination, the linear DNA molecule is
cleaved from the circle, resulting in a double stranded
circular DNA molecule and a single-stranded linear DNA
molecule.
The linear single stranded molecule is circularized by the
action of ligase and then replication to double stranded
circular plasmid molecule.