1) James Watson and Francis Crick discovered the double helix structure of DNA in 1953, which showed that DNA is the genetic material that directs the inheritance of traits.
2) Experiments in the 1940s-1950s provided evidence that DNA, not protein, was the genetic material: Avery, McCarty, and MacLeod showed DNA was the transforming principle in bacteria; Hershey and Chase showed that DNA, not protein, enters the host cell during bacterial virus infection.
3) Watson and Crick developed the double helix model of DNA structure in 1953 based on evidence such as Chargaff's rules of base pairing and X-ray crystallography images from Franklin - their model explained
Chapter 16: Molecular Basis of InheritanceAngel Vega
KEY CONCEPTS
16.1 DNA is the genetic material
16.2 Many proteins work together in
DNA replication and repair
16.3 A chromosome consists of a DNA molecule packed together with proteins
Chapter 16: Molecular Basis of InheritanceAngel Vega
KEY CONCEPTS
16.1 DNA is the genetic material
16.2 Many proteins work together in
DNA replication and repair
16.3 A chromosome consists of a DNA molecule packed together with proteins
GENETIC MATERIAL refers to the material of which genes are made up of. It includes both DNA and RNA. Though in most of the organism DNA is playing this role, but in certain viruses RNA is storing all the genetic information of the individual. Here we are discussing about the discovery and property of these genetic material.
This ppt contains few solved questions of GATE 2010 examination along with explanations. This will be helpful for all those who are preparing for GATE, CSIR, UGC NET, etc. Complete set of questions along with answers and explanations can be viewed at http://purnasrinivas.weebly.com
al-salam alykom ..
this lecture starts with basic definitions in genetic , also talk about DNA & RNA ( structures , types , similarities and differences ) .
it talks about bacterial DNA ( chromosome structure / plamids structure and functions / transponon types )
later , discusses about central dogma / gene expression starting from genetic code/codons , then DNA replication , trancription and finally translation
prepared by Sumia Abdalsalam Alfitoury / Libya
GENETIC MATERIAL refers to the material of which genes are made up of. It includes both DNA and RNA. Though in most of the organism DNA is playing this role, but in certain viruses RNA is storing all the genetic information of the individual. Here we are discussing about the discovery and property of these genetic material.
This ppt contains few solved questions of GATE 2010 examination along with explanations. This will be helpful for all those who are preparing for GATE, CSIR, UGC NET, etc. Complete set of questions along with answers and explanations can be viewed at http://purnasrinivas.weebly.com
al-salam alykom ..
this lecture starts with basic definitions in genetic , also talk about DNA & RNA ( structures , types , similarities and differences ) .
it talks about bacterial DNA ( chromosome structure / plamids structure and functions / transponon types )
later , discusses about central dogma / gene expression starting from genetic code/codons , then DNA replication , trancription and finally translation
prepared by Sumia Abdalsalam Alfitoury / Libya
Replication (prokaryotes and eukaryotes) FN 312.pptsultanasadia912
The traditional monoclonal antibody (mAb) production process usually starts with generation of mAb-producing cells (i.e. hybridomas) by fusing myeloma cells with desired antibody-producing splenocytes (e.g. B cells). These B cells are typically sourced from animals, usually mice. After cell fusion, large numbers of clones are screened and selected on the basis of antigen specificity and immunoglobulin class. Once candidate hybridoma cell lines are identified, each "hit" is confirmed, validated, and characterized using a variety of downstream functional assays. Upon completion, the clones are scaled up where additional downstream bioprocesses occur.
DNA is the largest molecule known. A single, unbroken strand of it can contain many millions of atoms. When released from a cell, DNA typically breaks up into countless fragments. In solutions, these strands have a slight negative electric charge, a fact that makes for some fascinating chemistry.
Unit 1 genetics nucleic acids DNA (1) Biology aid Lassie sibanda
These slides will help those who love biology but yet find it so hard to break down see how easy and interesting life science is. hope these improve your knowledge
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
2. Overview: Life’s Operating Instructions
1953: James Watson & Francis Crick
- double-helix model
- structure of deoxyribonucleic acid (DNA)
DNA directs development of traits:
- biochemical
- anatomical
- physiological
- behavioral
3.
4. The Search for the Genetic Material
After Morgan’s research on genes & chromosomes,
DNA & protein became likely candidates for
the genetic material
The key factor was choosing appropriate
experimental organisms
The role of DNA in heredity was first discovered
by studying bacteria and the viruses that infect
them
5. 1928: Frederick Griffith worked with 2 bacterial
strains:
one pathogenic & one harmless
When he mixed heat-killed remains of the pathogenic
strain with living cells of the harmless strain:
some living cells became pathogenic
He referred to this as transformation
- we now define it as a change in genotype &
phenotype due to assimilation of foreign DNA
6. Living S cells
(control)
Living R cells
(control)
Heat-killed S cells
(control)
Mixture of heat-
killed S cells &
living R cells
Mouse diesMouse dies Mouse healthy Mouse healthy
Living S cells
RESULTS
EXPERIMENT
7. 1944: Avery, McCarty, & MacLeod announced
that DNA was the transforming substance
- based on experimental evidence showing only
DNA helped transform harmless bacteria into
pathogens
- many biologists remained skeptical, mainly
because little was known about DNA
9. 1952: Alfred Hershey & Barbara Chase
experiments:
- showed that DNA is the genetic material of T2 phage
- Results: only 1 of the 2 components of T2 (DNA or
protein) enters an E. coli cell during infection
Concluded that the phage’s injected DNA provides
the genetic information
12. EXPERIMENT
Phage
DNA
Bacterial cell
Radioactive
protein
Radioactive DNA
Batch 1:
radioactive
sulfur (35S)
Batch 2:
radioactive
phosphorus
(32P)
Empty
protein
shell
Phage
DNA
Centrifuge
Centrifuge
Pellet
Pellet (bacterial
cells and contents)
Radioactivity
(phage
protein)
in liquid
Radioactivity
(phage DNA)
in pellet
13. Additional Evidence
It was known that DNA is a polymer of
nucleotides:
- nitrogenous base, a sugar, & a phosphate
group
1950: Erwin Chargaff showed DNA composition
varies between species
- this evidence of diversity made DNA a more
credible candidate for the genetic material
16. Building a Structural Model of DNA
The next challenge was to relate DNA structure
with function
Maurice Wilkins & Rosalind Franklin: used X-ray
crystallography to study molecular structure
- took pictures of DNA
18. Franklin’s images of DNA enabled Watson to
deduce:
- shape: double helix
- width (double-stranded)
- spacing of N-bases
19. (c) Space-filling
model
Hydrogen bond 3 end
5 end
3.4 nm
0.34 nm
3 end
5 end
(b) Partial chemical
structure
(a) Key features of DNA
structure
1 nm
20. Watson & Crick built double helix models to match
the x-ray & chemical evidence
Franklin’s DNA structure hypothesis:
- 2 sugar-phosphate backbones
- paired nitrogenous bases in-between
Watson built a model in which the backbones
were antiparallel (their subunits run in opposite
directions)
21. Watson & Crick first thought bases paired “like
with like” (A-A, etc.)
- but this does not result in a uniform width
Purine + purine: too wide
Pyrimidine + pyrimidine: too narrow
22. Watson & Crick concluded that:
- Adenine (A) paired only with Thymine (T)
- Guanine (G) paired only with Cytosine (C)
This model explains Chargaff’s rules:
“in any organism the amount of
A = T and the amount of G = C”
24. DNA Replication and Repair
Watson & Crick noted that the specific base-pairing
suggested a possible DNA copying mechanism
25. The Basic Principle: Base Pairing to a
Template Strand
• Since the 2 strands of DNA are complementary,
each strand acts as a template for building a
new strand in replication
• In DNA replication, the parent molecule
unwinds & 2 new daughter strands are built
based on base-pairing rules
26. A T
GC
T A
TA
G C
(a) Parent molecule
A T
GC
T A
TA
G C
(c) “Daughter” DNA molecules, each
consisting of one parental strand
& one new strand
(b) Separation of
strands
A T
GC
T A
TA
G C
A T
GC
T A
TA
G C
27. Semiconservative Model of Replication
• Predicts that when a double helix replicates,
each daughter molecule will have one old strand
(derived or “conserved” from the parent
molecule) & one newly made strand
Competing models:
- Conservative model: the 2 parent strands
rejoin
- Dispersive model: each strand is a mix of old &
new
29. • Experiments by Matthew Meselson & Franklin Stahl
supported the semiconservative model
• They labeled the nucleotides of the old strands with
a heavy isotope of N, while any new nucleotides
were labeled with a lighter isotope
31. • The 1st replication produced a band of hybrid DNA,
eliminating the conservative model
• A 2nd replication produced both light & hybrid DNA,
eliminating the dispersive model & supporting the
semiconservative model
33. • DNA replication is remarkable in its speed &
accuracy
• More than a dozen enzymes & other proteins
participate in DNA replication
34. Getting Started
• Replication begins at special sites called origins of
replication, where the 2 DNA strands are
separated, opening up a replication “bubble”
• A eukaryotic chromosome may have 100’s or
1000’s of origins of replication
• Replication proceeds in both directions from each
origin, until the entire molecule is copied
35. Origin of
replication Parental (template) strand
Daughter (new) strand
Replication fork
Replication
bubble
Double-stranded
DNA molecule
Two
daughter
DNA
molecules
(a) Origins of replication in
prokaryotes
0.5 µm
36. 0.25 µm
Origin of replication Double-stranded DNA molecule
Parental (template) strand
Daughter (new) strand
Bubble Replication fork
Two daughter DNA molecules
(b) Origins of replication in
eukaryotes
37. • At the end of each replication bubble is a
replication fork, a Y-shaped region where new DNA
strands are elongating
• Helicases are enzymes that untwist the double helix
at the replication forks
• Single-strand binding proteins bind to & stabilize
single-stranded DNA until it can be used as a
template
• Topoisomerase corrects “overwinding” ahead of
replication forks by breaking, swiveling, & rejoining
DNA strands
39. • DNA polymerases cannot initiate synthesis of a
polynucleotide
- they can only add nucleotides to the 3 end
• The initial nucleotide strand is a short RNA primer
(5–10 nucleotides long)
• The 3 end serves as the starting point for the new
DNA strand
40. • Primase: can start an RNA chain from scratch &
adds RNA nucleotides one at a time using the
parental DNA as a template
Topoisomerase
Primase
RNA
primer
Helicase
Single-strand binding
proteins
5
3
5
53
3
41. Synthesizing a New DNA Strand
• DNA polymerases catalyze the elongation of new
DNA at a replication fork
- most require a primer & a DNA template strand
• The rate of elongation is approx. 500 nucleotides
per second in bacteria & 50 per second in human
cells
42. • Each nucleotide that is added to a growing DNA
strand is a nucleoside triphosphate
• dATP supplies adenine to DNA & is similar to the
ATP of energy metabolism
- the difference is in their sugars: dATP has
deoxyribose while ATP has ribose
• As each dATP joins the DNA strand, it loses 2
phosphate groups as a molecule of pyrophosphate
43. A
C
T
G
G
G
GC
C C
C
C
A
A
A
T
T
New strand 5
end
Template strand 3
end 5 end 3 end
3 end
5 end5 end
3 end
Base
Sugar
Phosphate
Nucleoside
triphosphate
Pyrophosphate
DNA polymerase
44. Antiparallel Elongation
• The double helix has an antiparallel structure
- the 2 strands are oriented in opposite directions
- this affects replication
• DNA polymerases add nucleotides only to the free
3end of a growing strand
- therefore, a new DNA strand can elongate only in
the 5to3direction
45. • Along one template strand of DNA, the DNA
polymerase continuously synthesizes a leading
strand, moving toward the replication fork
Leading strand
Leading strandLagging strand
Lagging strand
Origin of replication
Primer
Overall directions of
replication
46. Origin of replication
RNA primer
Sliding clamp
DNA pol III
Parental DNA
3
5
5
5
5
5
5
3
3
3
Helicase
Single-strand
binding proteins
47. • To elongate the other new strand (the lagging
strand), DNA polymerase must work in the
direction away from the replication fork
• The lagging strand is synthesized as a series of
segments called Okazaki fragments, which are
joined together by DNA ligase
48. Origin of replication
Leading strand
Leading strand
Lagging strand
Lagging strand
Overall directions of
replication
1
2
49. Template
strand
RNA primer
for fragment 1
Okazaki
fragment 1
RNA primer
for fragment 2
Okazaki
fragment 2
Overall direction of replication
3
3
3
3
3
3
3
3
3
3
3
3
5
5
5
5
5
55
5
5
55
5
2
2
2
1
1
1
1
1
50.
51. The DNA Replication Complex
• The proteins that participate in DNA replication
form a large complex called a “DNA replication
machine”
• Recent studies support a model in which DNA
polymerase molecules “reel in” parental DNA &
“extrude” newly made daughter DNA molecules
52. Parental DNA
DNA pol III
Leading strand
Connecting
protein
Helicase
Lagging strandDNA
pol III
Lagging
strand
template
5
5
5
5
5
5
3 3
3
3
3
3
53. Proofreading & Repairing DNA
• DNA polymerases proofread newly made DNA &
replace any incorrect nucleotides
• DNA can be damaged by chemicals, radioactive
emissions, X-rays, UV light, & certain molecules (in
cigarette smoke for example); it can also undergo
spontaneous changes
• Mismatch repair: repair enzymes correct errors in base
pairing
• Nucleotide excision repair: a nuclease cuts out &
replaces damaged stretches of DNA
55. Evolutionary Significance of Altered
DNA Nucleotides
• Error rate after proofreading repair is low but not zero
• Sequence changes may become permanent & can be
passed on to the next generation
• These changes (mutations) are the source of the
genetic variation upon which natural selection
operates
56. Replicating the Ends of DNA
Molecules
• Limitations of DNA polymerase create problems for
the linear DNA of eukaryotic chromosomes
• The usual replication machinery provides no way to
complete the 5 ends
- repeated rounds of replication produce shorter
DNA molecules with uneven ends
57. Ends of parental
DNA strands
Leading strand
Lagging strand
Last fragment Next-to-last fragment
Lagging strand RNA primer
Parental strand
Removal of primers and
replacement with DNA
where a 3 end is available
Second round
of replication
Further rounds
of replication
New leading strand
New lagging strand
Shorter and shorter daughter molecules
3
3
3
3
3
5
5
5
5
5
58. Telomeres
• Nucleotide sequences at the ends of eukaryotic
chromosomal DNA molecules
• Telomeres do not prevent the shortening of DNA
molecules, but they do postpone the erosion of
genes near the ends of DNA molecules
- the shortening of telomeres is thought to be
connected to aging
60. • If chromosomes of germ cells became shorter in
every cell cycle, essential genes would eventually be
missing from the gametes they produce
• Telomerase: catalyzes the lengthening of telomeres
in germ cells
61. • The shortening of telomeres might protect cells
from cancerous growth by limiting the number of
cell divisions
• There is evidence of telomerase activity in cancer
cells, which may allow cancer cells to persist
62. • The prokaryotic chromosome is a double-stranded,
circular DNA molecule associated with a small
amount of protein
- the DNA is “supercoiled” & found in the nucleoid
region of the cell
• Eukaryotic chromosomes have linear DNA molecules
associated with a large amount of protein
63. • Chromatin: a complex of DNA & protein found in the
nucleus of eukaryotic cells
• Chromosomes fit into the nucleus through an
elaborate, multilevel system of packing
• Histones: proteins responsible for the 1st level of
DNA packing in chromatin
64. • 10-nm fiber (diameter) – “thin” fiber
– DNA winds around histones to form strings of
nucleosome “beads”
• 30-nm fiber (diameter) – “thick” fiber
– interactions between nucleosomes cause the thin
fiber to coil or fold into this thicker fiber
65. DNA double helix
(2 nm diameter)
Nucleosome
(10 nm “thin” fiber)
Histones
Histone tail
H1
Nucleosomes, or “beads on
a string” (10 nm fiber)
67. • Most chromatin is loosely packed euchromatin in
the nucleus during interphase & condenses prior
to mitosis
• During interphase a few regions of chromatin
(centromeres & telomeres) are highly condensed
into heterochromatin
- this dense packing of chromatin makes it
difficult for the cell to express genetic
information coded in these regions
• Though interphase chromosomes are not highly
condensed, they still occupy specific restricted
regions in the nucleus