One of the first plausible models to account for the preceding observations was
formulated by Robin Holliday.
The key features of the Holliday model are the formation of heteroduplex DNA; the
creation of a cross bridge; its migration along the two heteroduplex strands,
termed branch migration; the occurrence of mismatch repair; and the
subsequent resolution, or splicing, of the intermediate structure to yield different
typesof recombinant molecules.
One of the first plausible models to account for the preceding observations was
formulated by Robin Holliday.
The key features of the Holliday model are the formation of heteroduplex DNA; the
creation of a cross bridge; its migration along the two heteroduplex strands,
termed branch migration; the occurrence of mismatch repair; and the
subsequent resolution, or splicing, of the intermediate structure to yield different
typesof recombinant molecules.
A complementation test (sometimes called a "cis-trans" test) can be used to test whether the mutations in two strains are in different genes. By taking an example of Benzer's work, complementation has been explained.
Dna supercoiling and role of topoisomerasesYashwanth B S
supercoiling is one of the important process to condenses the huge amount of DNA to fit inside the histone and its also plays a role during the replication ,transcription etc..,these activities is carried out by an enzyme called topoisomerases.
A complementation test (sometimes called a "cis-trans" test) can be used to test whether the mutations in two strains are in different genes. By taking an example of Benzer's work, complementation has been explained.
Dna supercoiling and role of topoisomerasesYashwanth B S
supercoiling is one of the important process to condenses the huge amount of DNA to fit inside the histone and its also plays a role during the replication ,transcription etc..,these activities is carried out by an enzyme called topoisomerases.
well, dis z again another ppt on molecular biology..
I know dis kinda luks boring bt pretty informative
thanks
let me know wat you think abt dis
don't forget to comment
This is a continuation of the earlier slide with a name "Nucleotides". Please refer to the previous mentioned slide before moving to this slide for a better overall concept on nucleotides and nucleic acids.
This is a lecture slide for MBBS, BDS, paramedical as well as for those who are interested in molecular biology, molecular life sciences, biochemistry, medical biochemistry, general biochemistry etc.
For the more elucidated and connected information, try to refer to the nucleic acids slides.
The lecturer content is based on the Kathmandu University course syllabus. But, can be used for any undergraduate medical course for MBBS, BDS and Nursing.
Richard's aventures in two entangled wonderlandsRichard 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.
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.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
2. Genetic recombination
Rearrangement of genetic information within and among
DNA molecules.
Why is it done and why is it necessary?
To alter the genome to understand the various disease
conditions.
Sunday, June 12,
2016
Rajesh Chaudhary
2
3. General classes of genetic recombination
3 general classes
1. Homologous genetic recombination / general
recombination
2. Site-specific recombination
3. DNA transposition
Sunday, June 12,
2016
Rajesh Chaudhary
3
4. Homologous genetic
recombination
Genetic exchange between any
two DNA molecules or segment of
same DNA molecule.
Its main function both in
prokaryotes and eukaryotes is to
repair the stalled damaged
replication fork.
Sunday, June 12,
2016
Rajesh Chaudhary
4
5. Homologous genetic recombination
Sunday, June 12,
2016
Rajesh Chaudhary
5
The recombination occurs with the
highest frequency during meiosis –
the process by which diploid germ-
line cells with two sets of
chromosomes divide to produce
haploid gametes (sperm and ova) in
animals.
6. Crossing over
Sunday, June 12,
2016
Rajesh Chaudhary
6
Genetic information is
exchanged between
closely related
homologous chromatids
by homologous genetic
recombination, a
process involving
breakage and rejoining
of the DNA.
7. So, what is the role of homologous
recombination?
Serves 3 major functions:
1. It contributes to the repair of several types of DNA damage.
2. It provides, in eukaryotic cells, a transient physical link
between chromatids that promotes the orderly segregation of
chromosomes at the first meiotic cell division
3. It enhances genetic diversity in a population.
Sunday, June 12,
2016
Rajesh Chaudhary
7
11. Recombination requires host of enzymes
and other proteins
Enzymes that catalyze various steps of the recombination process has been
identified and isolated from both E. Coli and Eukayortes.
In E. Coli, RecB, RecC and RecD genes encode heterotrimeric RecBCD
enzyme which has both nuclease and helicase activity.
Rec A protein promotes all central steps in the recombination process:
1. Pairing of two DNA molecules.
2. formation of Holliday intermediates.
3. Branch migration
Sunday, June 12,
2016
Rajesh Chaudhary
11
12. Recombination requires host of enzymes and
other proteins
Ruv A and Ruv B proteins form a complex that binds to
Holliday intermediates, displaces RecA protein, and
promote branch migration at higher rates that does RecA.
Nucleases that often cleaves Holliday intermediates, often
called resolvases, has been isolated from bacteria and
yeast.
Sunday, June 12,
2016
Rajesh Chaudhary
12
14. DNA strand invasion catalyzed by RecA
protein
Sunday, June 12,
2016
Rajesh Chaudhary
14
15. Rec A promoted DNA
strand exchange in vitro
Sunday, June 12,
2016
Rajesh Chaudhary
15
RecX, DinX,
RecF, RecO,
and RecR
regulate
assembly and
disassembly
of RecA
filament.
16. Model for Rec A-mediated DNA strand
exchange
Sunday, June 12,
2016
Rajesh Chaudhary
16
17. Model for recombinational DNA repair of
stalled replication fork
Sunday, June 12,
2016
Rajesh Chaudhary
17
18. Model for recombinational DNA repair of
stalled replication fork
Necessary enzymes for single stranded repair
RecF, RecO, RecR proteins
Necessary enzymes for double stranded repair
RecBCD
Sunday, June 12,
2016
Rajesh Chaudhary
18
19. Site-specific genetic recombination
Second general type of recombination.
Recombination is limited to specific sequence.
Recombination of this type occurs in virtually every cells.
Each site-specific recombination involves:
Recombinase
A short (20-200 bp) unique DNA sequence where
recombinase act
Sunday, June 12,
2016
Rajesh Chaudhary
19
20. Site-specific DNA
recombination
Sunday, June 12,
2016
Rajesh Chaudhary
20
There are two general classes of site-
specific recombination system which relies
on either Tyr or Ser residues in active site.
Step 1.
Step 2.
Step 3.
Step 4.
Holiday junction or cross-strand exchange
22. Simplified view of branch migration
Sunday, June 12,
2016
Rajesh Chaudhary
22
• Catalyzed by specialized
proteins that continuously
breaks and seals the
nucleotides.
• ATP is used as the energy
source for branch migration.
• In meiosis, heteroduplex region
migrates 1000s of nucleotids
from the point of start site.
23. Gene conversion caused by mismatch
correction
Sunday, June 12,
2016
Rajesh Chaudhary
23
Heteroduplex DNA is formed at the sites of homologous
recombination between maternal and paternal
chromosomes. If the maternal and paternal DNA sequences
are slightly different, the heteroduplex region will include
some mismatched base pairs, which may then be corrected
by the DNA mismatch repair machinery. Such repair can
“erase” nucleotide sequences on either the paternal or the
maternal strand.
The consequence of this mismatch repair is gene conversion,
detected as a deviation from the segregation of equal copies
of maternal and paternal
alleles that normally occurs in meiosis.
24. Transposition and conservative site-specific
recombination
Site-specific recombination do not require substantial region of
sequence homology.
Transposition and conservative site-specific recombination largely
dedicated to moving specialized segment of DNA known as “mobile
genetic elements”.
Virtually all cells contain mobile genetic elements commonly known as
“jumping genes”.
Sunday, June 12,
2016
Rajesh Chaudhary
24
27. DNA hybridization
DNA hybridization is a random process where
hybridization occurs through hit-and-trial.
Hybridization depends on the random collision between
two homologous DNA strand complementary to each other.
Once helix nucleation is formed, then rapid zippering
leads to complete double helix.
Sunday, June 12,
2016
Rajesh Chaudhary
27