F-NUCLEOSOMES.ppt
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Human DNA must be highly compressed to fit inside the nucleus. It achieves this by wrapping around proteins called nucleosomes, which act as spools. Each nucleosome contains an octamer of histone proteins around which 147 base pairs of DNA are wrapped. Multiple nucleosomes then coil further to form a 30nm fiber. This fiber is attached to a scaffold of RNA and proteins, forming loops that allow for further compaction of the DNA into chromosomes. The positioning of centromeres divides chromosomes into metacentric, submetacentric and acrocentric types in humans.
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DNA TOPOLOGY
DNA topology studies the geometric properties and spatial relationships of DNA that are unaffected by changes in shape or size. It includes phenomena like supercoiling, knots, and catenanes that involve the linking and twisting of the two DNA strands. DNA topology is characterized by parameters like the linking number, which represents the number of times the two strands are twisted around each other. Enzymes called topoisomerases regulate DNA topology by introducing temporary breaks in the DNA strands to allow strand passage and control supercoiling levels.
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Nucleosome and histones
The document discusses the nucleosome model of chromosome structure. It describes how DNA wraps around histone proteins to form nucleosomes, which are the basic units of chromatin. Specifically:
- Nucleosomes consist of 146-166 base pairs of DNA wrapped around an octamer of core histone proteins H2A, H2B, H3, and H4.
- Linker histone H1 binds to the DNA as it enters and exits each nucleosome, forming a structure known as a chromatosome.
- Adjacent nucleosomes are joined by 10-80 base pairs of linker DNA. The histone proteins and DNA interact via ionic bonds between negatively charged DNA and positively charged residues on
Mitochondrial genome
Mitochondria contain their own circular genome that is 16.5kb in size and located in the mitochondrial matrix. The mitochondrial genome contains 37 genes that encode 13 proteins, 22 tRNAs, and 2 rRNAs. These genes help produce enzymes and proteins that are crucial for oxidative phosphorylation and energy production in mitochondria. The control region of mitochondrial DNA contains signals that regulate mitochondrial DNA and RNA synthesis.
Transcription in prokaryotes
This document discusses the central dogma of biology and the process of transcription. It describes the three main steps of transcription - initiation, elongation, and termination. Initiation involves the RNA polymerase binding to the promoter sequence on DNA and separating the DNA strands to form an open complex. Elongation is the addition of nucleotides to synthesize RNA. Termination can occur via either Rho-independent or Rho-dependent mechanisms, with the former utilizing a terminator sequence and hairpin structure in the RNA and the latter involving the Rho protein.
Genomic library construction
A DNA library is a collection of DNA fragments that have been cloned into vectors. DNA libraries allow researchers to isolate and study specific DNA fragments of interest. To create a genomic library, DNA is extracted from an organism, cut into fragments, inserted into vectors, and introduced into host bacteria to generate clones containing all the organism's DNA sequences. This library can then be screened to identify and study particular genes. DNA libraries provide an efficient way to store, isolate, and analyze DNA sequences.
Dna replication eukaryotes
DNA replication is the process by which DNA copies itself in living cells. It occurs in three main steps: initiation, elongation, and termination. Initiation begins at origins of replication, where proteins assemble into pre-replication complexes. During elongation, helicase unwinds the DNA strands and DNA polymerase adds complementary nucleotides to each strand. Termination occurs when the replication forks meet, with telomerase ensuring complete replication of chromosome ends.
ENZYMES IN RECOMBINANT DNA TECHNOLOGY
DNA modifying enzymes play important roles in recombinant DNA technology. DNA polymerase synthesizes DNA from deoxyribonucleotides and is essential for DNA replication. It consists of subunits that carry out polymerase and exonuclease activities. Reverse transcriptase generates cDNA from an RNA template. Alkaline phosphatase, phosphatase, kinase and methyltransferases modify DNA through addition or removal of phosphate groups or methyl groups and are used in cloning experiments and DNA sequencing. Terminal transferase adds nucleotides to DNA ends. Restriction enzymes are inhibited by DNA methylation.
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- Nucleosomes consist of 146-166 base pairs of DNA wrapped around an octamer of core histone proteins H2A, H2B, H3, and H4.
- Linker histone H1 binds to the DNA as it enters and exits each nucleosome, forming a structure known as a chromatosome.
- Adjacent nucleosomes are joined by 10-80 base pairs of linker DNA. The histone proteins and DNA interact via ionic bonds between negatively charged DNA and positively charged residues on
Mitochondrial genome
Mitochondria contain their own circular genome that is 16.5kb in size and located in the mitochondrial matrix. The mitochondrial genome contains 37 genes that encode 13 proteins, 22 tRNAs, and 2 rRNAs. These genes help produce enzymes and proteins that are crucial for oxidative phosphorylation and energy production in mitochondria. The control region of mitochondrial DNA contains signals that regulate mitochondrial DNA and RNA synthesis.
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Dna replication eukaryotes
DNA replication is the process by which DNA copies itself in living cells. It occurs in three main steps: initiation, elongation, and termination. Initiation begins at origins of replication, where proteins assemble into pre-replication complexes. During elongation, helicase unwinds the DNA strands and DNA polymerase adds complementary nucleotides to each strand. Termination occurs when the replication forks meet, with telomerase ensuring complete replication of chromosome ends.
ENZYMES IN RECOMBINANT DNA TECHNOLOGY
DNA modifying enzymes play important roles in recombinant DNA technology. DNA polymerase synthesizes DNA from deoxyribonucleotides and is essential for DNA replication. It consists of subunits that carry out polymerase and exonuclease activities. Reverse transcriptase generates cDNA from an RNA template. Alkaline phosphatase, phosphatase, kinase and methyltransferases modify DNA through addition or removal of phosphate groups or methyl groups and are used in cloning experiments and DNA sequencing. Terminal transferase adds nucleotides to DNA ends. Restriction enzymes are inhibited by DNA methylation.
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Prokaryotic transcription
Prokaryotic transcriptionMarudhar Kesari Jain College for Women Vaniyambadi - 635 751, Tamil Nadu, INDIA.
Transcription in prokaryotes involves RNA polymerase producing messenger RNA transcripts of genetic material in the cytoplasm. Unlike in eukaryotes, transcription and translation can occur simultaneously. Transcription is controlled by transcription factors and involves three main steps: initiation, elongation, and termination. Initiation requires RNA polymerase binding to promoter regions with sigma factors. Elongation adds complementary bases to the DNA template. Termination can occur via intrinsic terminator sequences forming stem-loop structures or with rho-dependent termination using a rho factor protein.Cot curve
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RNA polymerase
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chloroplast DNA
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Mitochondrial genome
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Restriction Mapping
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Topoisomerase
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This document provides information on the structure and organization of chromatin. It discusses three main levels of chromatin organization:
1) Nucleosomes, which involve DNA wrapping around histone proteins in "beads on a string" structures.
2) The 30nm chromatin fiber, where nucleosomes are further compacted into a solenoid structure through histone H1 binding.
3) Higher-order compaction into metaphase chromosomes, where DNA is organized into loops anchored to a protein scaffold.
The document also describes different chromatin types (euchromatin and heterochromatin), chromatin composition, and models of chromatin structure including the nucleosome model.
Chromatin Structure & Genome Organization by Shivendra Kumar
1. The document discusses the structure of chromatin and chromosomes. It describes how DNA is packaged into nucleosomes, which are composed of histone proteins wrapped around DNA.
2. Nucleosomes further compact the DNA to form a 30nm fiber, which is then folded into loops and domains to achieve higher order compaction into chromosomes. This compaction allows the long DNA molecules to fit inside cells.
3. Chromatin structure influences gene expression, with tightly packed heterochromatin generally transcriptionally inactive and loosely packed euchromatin more active. Histone modifications also impact chromatin structure and gene expression.
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Complementary DNA (cDNA) Libraries
This document discusses different strategies for cloning DNA fragments from complex sources like genomic DNA or cDNA. There are two major approaches - cell-based cloning, which divides the DNA into fragments that are cloned to create a library, and directly amplifying target sequences using PCR. The document focuses on cDNA library construction, explaining that cDNA libraries reveal gene expression profiles. It describes early cDNA cloning methods and their limitations, as well as improved directional and non-directional cloning techniques. Finally, it discusses various screening methods for identifying clones of interest from cDNA libraries, including colony hybridization, plaque lifts and immunological screening.
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This document discusses chloroplast DNA (cpDNA). Chloroplasts contain their own circular genome of double-stranded DNA ranging from 140-200kb. The cpDNA contains genes that code for proteins involved in photosynthesis as well as rRNA and tRNA. It has a quadripartite structure containing single copy and inverted repeat regions. Tobacco and liverwort were two of the first chloroplast genomes to be sequenced. Molecular studies of cpDNA regions have been useful for plant systematics. Replication of cpDNA is independent of nuclear DNA and involves enzymes like DNA polymerase and helicase.
Mitochondrial genome
The human mitochondrial genome is much smaller than the nuclear genome, consisting of 16,569 base pairs. It contains 37 genes, 13 of which code for proteins involved in cellular respiration. Mitochondrial DNA is inherited solely from the mother and encodes for transfer RNA, ribosomal RNA and proteins that are critical subunits of the oxidative phosphorylation complexes. The human mitochondrial genome has a highly condensed structure with minimal non-coding regions and some overlapping genes. It also differs slightly from the standard genetic code.
Gene silencing
Gene silencing is the regulation of gene expression in a cell to prevent the expression of a certain gene. Gene silencing can occur during either transcription or translation and is often used in research.
A, b, and z forms of dna
There are three main forms of DNA structure: A-DNA, B-DNA, and Z-DNA. B-DNA is the most common form found under physiological conditions, having a right-handed double helix with 10.5 base pairs per turn. A-DNA forms under dehydrating conditions and has a wider helix with 11 base pairs per turn. Z-DNA is a left-handed helix that forms with alternating purine-pyrimidine sequences, containing 12 base pairs per turn in a narrow, zig-zag structure. While B-DNA is most prevalent, the structure can vary depending on sequence and environmental conditions.
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Semiconservative replication
Meselson and Stahl conducted an experiment using E. coli bacteria to test the hypothesis that DNA replicates semi-conservatively. They grew the bacteria in medium containing a heavy isotope of nitrogen, then switched the bacteria to medium with a light isotope. Analysis of DNA densities over multiple generations provided evidence that DNA replication results in one old strand and one new strand in each daughter molecule, supporting the semi-conservative model.
Cosmids vector
1. A cosmid is a type of plasmid vector that contains sequences from bacteriophage lambda, specifically the cos sites. This allows DNA fragments up to 45kb to be packaged into phage particles and transduced into bacteria.
2. Cosmids are developed by combining features of plasmid and phage vectors. They can accept large DNA inserts through packaging and transduction while also replicating stably inside bacteria like plasmids.
3. Cloning with cosmids involves inserting DNA fragments into the cosmid, ligating to form concatemers, in vitro packaging into phage particles, and transducing the particles into bacteria where the cosmids replicate as plasmids.
Restriction Mapping
Restriction enzymes cut DNA molecules at specific recognition sites. Restriction mapping involves digesting an unknown DNA segment with restriction enzymes and analyzing the fragment sizes to determine the locations of restriction sites. One method involves single and double digestions with two enzymes followed by gel electrophoresis to separate the fragments by size. By comparing the fragment patterns between single and double digestions, the positions of each restriction site can be mapped, generating a restriction map of the DNA segment. Restriction mapping was previously important for characterizing cloned DNA but is now easier using DNA sequencing, though analysis of restriction sites remains useful for comparing chromosomal organization between strains.
Topoisomerase
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Similar to F-NUCLEOSOMES.ppt
STRUCTURE AND ORGANIZATION OF CHROMATIN
This document provides information on the structure and organization of chromatin. It discusses three main levels of chromatin organization:
1) Nucleosomes, which involve DNA wrapping around histone proteins in "beads on a string" structures.
2) The 30nm chromatin fiber, where nucleosomes are further compacted into a solenoid structure through histone H1 binding.
3) Higher-order compaction into metaphase chromosomes, where DNA is organized into loops anchored to a protein scaffold.
The document also describes different chromatin types (euchromatin and heterochromatin), chromatin composition, and models of chromatin structure including the nucleosome model.
Chromatin Structure & Genome Organization by Shivendra Kumar
1. The document discusses the structure of chromatin and chromosomes. It describes how DNA is packaged into nucleosomes, which are composed of histone proteins wrapped around DNA.
2. Nucleosomes further compact the DNA to form a 30nm fiber, which is then folded into loops and domains to achieve higher order compaction into chromosomes. This compaction allows the long DNA molecules to fit inside cells.
3. Chromatin structure influences gene expression, with tightly packed heterochromatin generally transcriptionally inactive and loosely packed euchromatin more active. Histone modifications also impact chromatin structure and gene expression.
7 DNA
Deoxyribonucleic acid is a molecule composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses.
NUCLEOSOME MODEL OF CHROMOSOME
Basics of Undergraduate/university fellows
Nucleosome model of chromosome is proposed by ROGER KORNBERG (son of Arthur
Kornberg) in 1974.
It was confirmed and crystalised by P. Oudet et al., (1975).
Nucleosome is the lowest level of Chromosome organization in eukaryotic cells.
Nucleosome model is a scientific model which explains the organization of DNA and
associated proteins in the chromosomes.
Nucleosome model also explains the exact mechanism of the folding of DNA in
thenucleus.
It is the most accepted model of chromatin organization.
organization of DNA in chromosomes.
Chromosomes contain an organism's genetic material and come in different structures depending on the organism. Bacteria typically have a single circular chromosome while eukaryotes have multiple linear chromosomes in the nucleus. Genetic material is highly compacted through various mechanisms to fit inside cells. In eukaryotes, DNA is wrapped around histone proteins to form nucleosomes, which further compact to form a 30nm fiber and loop domains that attach to a nuclear matrix, compacting the DNA over 1000-fold to fit in the nucleus.
Chromosome structure
Chromosomes are organized structures found in cells that contain DNA and proteins. They are located in the nucleus and are passed from parents to offspring. Chromosomes ensure DNA is accurately copied and distributed when cells divide. They exist in pairs and are made up of DNA wrapped around histone proteins to form structures called nucleosomes. Nucleosomes further compact to form higher order chromatin and chromosome structures.
Nucleosome and chromatin structure
DNA is highly compacted in cells through various levels of supercoiling and chromatin structure. At the most basic level, DNA wraps around histone proteins to form nucleosomes, introducing negative supercoiling. Nucleosomes are then packed into a beads-on-a-string structure and further compacted into the 30nm fiber. Additional folding compacts the DNA over 10,000-fold into the final chromosomes. The two main types of supercoiling that facilitate compaction are plectonemic and solenoidal, with solenoidal supercoiling allowing the greatest degree of compaction and found in chromatin.
LEVELS OF CHROMATIN ORGANIZATION
This document discusses the organization of chromatin and DNA packaging in the cell nucleus. It describes four main levels of chromatin organization: 1) DNA wraps around histone proteins to form nucleosomes, the basic unit of chromatin, 2) Nucleosomes further organize into 30nm fibers, 3) The 30nm fibers then organize into looped domains, and 4) During cell division, the loops compact into mitotic chromosomes. Nucleosomes consist of about 150 base pairs of DNA wrapped around an octamer of core histone proteins, and act to tightly package DNA inside the nucleus.
flow of genetic information
This document summarizes the flow of genetic information from DNA to RNA to proteins. It discusses macromolecules and how nucleic acids like DNA and RNA are polymers made up of nucleotides. DNA stores genetic information as a double-stranded molecule, while RNA processes this information and helps express proteins. The document goes on to describe properties of nucleic acids like stability, absorption of UV light, and thermal denaturation. It also discusses chromatin structure and how DNA is packaged into chromosomes using histone proteins and nucleosomes.
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The document discusses several key concepts related to DNA packaging and gene expression. It describes the central dogma where genetic information flows from DNA to RNA to proteins. It also discusses how DNA is packaged in cells through nucleosomes and chromatin, and how chromatin exists in two forms - euchromatin which is loosely packed and transcriptionally active, and heterochromatin which is tightly packed and transcriptionally inactive. It provides information on calculating DNA length and the number of base pairs.
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Amar genetics
The document discusses how DNA is packed into eukaryotic chromosomes. DNA first wraps around histone proteins to form nucleosomes, compacting the DNA 7-fold. Nucleosomes then interact to form a 30nm fiber compacting the DNA another 7-fold. Additional compaction occurs through interactions between the 30nm fiber and the nuclear matrix, forming radial loop domains that attach to the nuclear lamina and internal matrix, further condensing the DNA. This hierarchical packaging allows the long eukaryotic chromosomes to fit within the nucleus.
Amar genetics
The document discusses how DNA is packed into eukaryotic chromosomes. DNA first wraps around histone proteins to form nucleosomes, compacting the DNA 7-fold. Nucleosomes then interact to form a 30nm fiber compacting the DNA another 7-fold. Additional compaction occurs through interactions between the 30nm fiber and the nuclear matrix, forming radial loop domains that attach to the nuclear matrix and compact the DNA up to 50-fold total. This highly compacted structure allows chromosomal DNA to fit within the nucleus.
Chromosomes: Packaging of genome
- Human cells normally contain 23 pairs of chromosomes, including 22 pairs of autosomes and 1 pair of sex chromosomes. Autosomes are the same in males and females, while sex chromosomes are XX in females and XY in males.
- Chromosomes must be highly compacted to fit inside cells. DNA is packaged into nucleosomes containing histones, then further condensed into 30nm filaments and looped domains. Additional coiling and folding results in the tightly packaged chromosomes visible during cell division.
- This extensive folding and packaging allows the long DNA molecules to be compacted over 100,000-fold to fit inside nuclei while still allowing access to genes for expression and replication.
Structure of Nucleus
There are different components in the nucleus. A thin but distinct covering called the nuclear envelop, also known as the karyotheca, defines its perimeter. The solutes of the nucleus are dissolved in a clear fluid substance inside the envelope known as nucleoplasm, nuclear sap, or karyolymph.
The nuclear matrix, a network of protein-containing fibrils, the chromatin, which is made up of finely entwined nucleoprotein filaments, and one or more spherical structures known as nucleoli are all suspended in the nucleoplasm (singular, nucleolus). The nucleus is devoid of microtubules and membranes.
However, the nuclei of protozoans that form a mitotic spindle within the nuclear envelop contain microtubules. The nucleus is made up of 9–12% DNA, 5% RNA, 3% lipids, 15% simple basic proteins like histone or protamines, and 65% complex acid or neutral proteins. It also contains organic phosphates, inorganic salts or ions like Mg++, Ca++, and Fe++, as well as polymerases for the synthesis of DNA and RNA.
Functions
The nucleus serves as the cell's administrative hub. It performs the following primary purposes: By controlling the production of structural proteins, it keeps the cell alive. By directing the synthesis of enzymatic proteins, it controls cell metabolism. In addition to information about structure and metabolism, it also contains genetic material for the organism's behaviour, development, and reproduction. When necessary, it causes cell replication. It is where ribosome subunit formation takes place. By keeping only a select few genes active, it causes cell differentiation. It produces genetic changes that lead to evolution. The nuclear envelop separates the cytoplasm from the nucleoplasm. It is made up of an outer and an inner unit membrane. Each unit membrane is a trilaminar lipoprotein, similar to the plasma membrane, and is about 75Å thick. The inter membrane or perinuclear space, which divides the two unit membranes, is present between them. Its width is about 250Å. Ribosomes and polysomes are found in abundance on the outer, or cytoplasmic, surface of the outer membrane, which is also rough. These ribosomes continue to produce proteins. RER and the outer membrane occasionally blend together. As a result, the channels of the RER are continuous with the perinuclear space. Ribosomes are absent from the inner membrane of the nuclear envelope, but it has a thick layer called the nuclear lamina that is closely connected to its inner or nucleoplasmic surface.
The nuclear lamina is a network of filaments that ranges in thickness from 30 to 100 nm and is made up of lamin A, B, and C proteins. The inner membrane is supported and given shape by the nuclear lamina. The majority of the chromosomes are kept outside the nucleus by this connection between chromatin and the inner membrane. During mitosis, it also affects how the nuclear envelope degrades and then reforms. Nuclear Pores: The nuclear pores, which regulate the passage of some molecules and parti
8 Basic Genetic Mechanisms
1. DNA carries genetic information that is stored in genes located on chromosomes within cells.
2. The structure of DNA was determined in 1953 by Watson and Crick to be a double helix with complementary nucleotide base pairing.
3. Genes contain the instructions to make proteins and RNA and are arranged linearly along chromosomes in eukaryotic cells.
Human Genome presentation.pptx
The document summarizes the history and key aspects of the Human Genome Project. It began in the 1980s with the sequencing of important genes. In the 1990s, the first whole bacterial genome was sequenced. The project, carried out from 1990-2003, was a large international collaboration that sequenced the entire human genome. It involved mapping the genome using markers and then determining the base sequence using shotgun sequencing and Sanger sequencing. The outcomes included discovering that most of the genome is non-coding junk DNA, and identifying around 25,000 human genes located across 23 chromosome pairs.
Lecture-Adv Molecular Biology-MSc-Chromatin I-2023-24.pdf
This document provides an overview of chromatin structure and remodeling. It discusses how DNA must be packaged to fit inside the cell nucleus, resulting in chromatin which compacts DNA around histone proteins. The basic repeating subunit of chromatin is the nucleosome, which contains approximately 200 base pairs of DNA wrapped around an octamer of histone proteins. Digestion of chromatin with micrococcal nuclease reveals a repeating "ladder" pattern of nucleosome fragments separated by linker DNA. The nucleosome and higher-order folding compact DNA thousands of times to fit inside the nucleus.
Chromosomes structure and function, Dr.Kamelsh shah, PSSHDA, KADI
Chromosomes have a complex hierarchical structure that allows long DNA molecules to fit inside cells. At the most basic level, DNA wraps around histone proteins to form nucleosomes, which resemble "beads on a string". Nucleosomes further compact to form higher-order chromatin structures. Chromatin contains both euchromatin, which is loosely packed, and heterochromatin, which is highly condensed. Non-histone proteins also aid in DNA compaction and genetic processes like transcription and replication. Chromatin packaging allows meters of DNA to fit within microscopic nuclei.
Similar to F-NUCLEOSOMES.ppt (20)
Chromatin Structure & Genome Organization by Shivendra Kumar
Chromatin Structure & Genome Organization by Shivendra Kumar
Lecture-Adv Molecular Biology-MSc-Chromatin I-2023-24.pdf
Lecture-Adv Molecular Biology-MSc-Chromatin I-2023-24.pdf
Chromosomes structure and function, Dr.Kamelsh shah, PSSHDA, KADI
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Brinjal.pptx
This document summarizes the symptoms and characteristics of various insect pests that affect plants. It describes pests such as the shoot and fruit borer that cause withering of terminal shoots and bore holes in shoots and fruits. It also mentions stem borers that cause drooping and withering of young plant tops and stunting of older plants. Descriptions of other pests include the hadda beetle, leaf roller, lace wing bug, bud worm, hairy caterpillar, brinjal mealy bug, tobacco caterpillar, whitefly, spiraling whitefly, serpentine leaf miner, and striped mealybug. For each, it outlines the visual symptoms of damage caused and sometimes includes details on the
pests on millet.pptx
The document summarizes various pests that affect millet crops, including shoot flies, stem borers, pink borers, white borers, white grubs, root aphids, caterpillars, ear head caterpillars, web worms, gall midges, ear head bugs, ear head beetles, weevils, leaf beetles, flea beetles, leaf rollers, slug caterpillars, chafer beetles, grasshoppers, aphids, and whiteflies. It describes the symptoms, appearance of larvae and adults, and in some cases the specific crops affected for each pest.
Linkage and Recombination.ppt
Genes located on the same chromosome tend to be inherited together due to their physical linkage on the chromosome. However, linkage can be broken during meiosis via recombination between homologous chromosomes through the process of crossover. Recombination results in new combinations of parental alleles and limits the types of gametes produced under conditions of complete linkage. Morgan's experiments with Drosophila provided evidence of this by demonstrating non-Mendelian inheritance ratios when genes were linked versus unlinked.
Genetic mapping.ppt
The document discusses various methods used for physical and transcript mapping including somatic cell hybrids, radiation hybrid maps, fluorescence in situ hybridization, flow sorting chromosomes, pulsed field electrophoresis, clone contig mapping, chromosome walking, inverse PCR, bubble PCR, and PCR-based screening. It also discusses genetic mapping techniques such as identifying genetic markers and recombinants, calculating genetic vs physical distances, multipoint mapping, and autozygosity mapping.
mendelian genetics.ppt
Mendel observed patterns of inheritance in pea plants through experimentation with traits such as flower color, seed shape, and pod color. His work provided evidence that heritable traits are specified by discrete units (later identified as genes) that are transmitted from parents to offspring in predictable patterns. Through experiments involving one trait (monohybrid crosses) and two traits (dihybrid crosses), Mendel deduced that genes assort and transmit independently during gamete formation and fertilization. Later work showed that traits are influenced not only by genes but also environmental factors and that variations exist in patterns of gene expression and dominance.
DNA damage.ppt
There are five main types of endogenous DNA damage including oxidation of bases from reactive oxygen species, alkylation of bases such as methylation, and hydrolysis of bases through deamination, depurination, and depyrimidination. DNA can also be damaged through alkylation and oxidation by exogenous sources like radiation exposure. Various mutagens including base analogs, intercalating agents, and UV light-induced thymine dimers further contribute to DNA damage that must be repaired.
GENETIC CODONS.ppt
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lampbrush chr.ppt
Polytene chromosomes are large chromosomes found in secretory cells like salivary glands that contain thousands of identical DNA strands aligned in parallel. This gives them a banded appearance with dark bands and clear interbands when viewed under a microscope. The bands represent regions of condensed and transcriptionally active DNA. B chromosomes are nonessential supernumerary chromosomes that are found in some populations but not others and can provide adaptive advantages in some species and environments.
polyploidy ..ppt
The document discusses euploidy, or changes in the number of sets of chromosomes, in animals and plants. It notes that while most animal species are diploid, some natural variations exist, including polyploidy in certain tissues and endopolyploidy. Polyploidy is more common and tolerated in plants, with 30-35% of ferns and flowering plants being polyploid. Examples are given of polyploid crops like wheat, cotton, and strawberries that are important agricultural products.
Micro RNA.ppt
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EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
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among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
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Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
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Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
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The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
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Disclaimer: No one is perfect, so please mind that there might be mistakes and typos.
dtubbenhauer@gmail.com
Corrected slides: dtubbenhauer.com/talks.html
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aziz sancar nobel prize winner: from mardin to nobel
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F-NUCLEOSOMES.ppt
- 1. NUCLEOSOMES
- 2. Chromosome Structure • Human DNA’s total length is ~2 meters! • This must be packaged into a nucleus that is about 5 micrometers in diameter • This represents a compression of more than 100,000! • It is made possible by wrapping the DNA around protein spools called nucleosomes and then packing these in helical filaments
- 3. Electron micrograph of extended chromatin showing "beads- on-a-string" organization. The "beads" are DNA-histone complexes called nucleosomes, and the "string" is double- stranded DNA. Micrograph of extended chromatin
- 4. Nucleosome structure (a) Four pairs of Histone protein monomers namely H2A,H2B,H3,H4 make up the histone core (octamer). (b) Each nucleosome is composed of a core (octamer) particle, histone H1 and linker DNA. Nucleosome core particle is composed of histone octamer and 146 base pairs of DNA. Linker DNA consists of 54 base pairs. Histone H1 binds to core particle and linker DNA.. DNA forms left-handed wraps around the histone octamer. These coils are topologically equivalent to negative super coils.
- 5. Structure of chicken nucleosome core particle The surface of the histone octamer that contacts the phosphate backbone of DNA double helix has high percentage of positively charged amino acids, aiding in DNA binding. Ribbon structure of chicken histone octamer Histone octamer bound to DNA-
- 6. 30 nm chromatin fiber 30nm chromatin fiber model shown as a solenoid, or helix, formed by individual nucleosomes. The nucleosomes associate through contacts between adjacent histone H1 molecules. This solenoid is left handed, with net topological effect of introducing negative super coils into the DNA. The 30nm fiber attaches to an RNA-protein scaffold that holds the fibers in large loops.
- 7. Electron micrographs of a histone-depleted chromosome (a) Entire protein scaffold of the histone-depleted chromosome is visible. The swirls are DNA double-helices. (b) Magnification of a portion of (a), individual loops attached to the protein scaffold can be seen. Each loop would form a solenoid attached to the protein scaffold. The degree of compacting of DNA by formation of nucleosomes is significant.
- 9. CHROMOSOMES
- 11. Chromosome: a very long DNA molecule and associated proteins, that carry portions of the hereditary information of an organism. Structure of a chromosome (Typical metaphase chromosome): A chromosome is formed from a single DNA molecule that contains many genes. Chromosomal DNA molecule contains three specific nucleotide sequences which are required for replication: Origin replication of DNA Centromere to attach the DNA to the mitotic spindle Telomere located at each end of the linear chromosome.
- 12. Gene can be defined as a region of DNA that controls a hereditary characteristic. Usually a sequence leads to the production of a specific protein or RNA. A gene carries biological information that is copied, transmitted from cell to all its progeny. This includes the entire functional unit: coding DNA sequences, non-coding regulatory DNA sequences, and introns. Genes can be as short as 1000 base pairs or as long as several hundred thousand base pairs. Genes
- 13. CHROMOSOME MORPHOLOGY : THE POSITION OF THE CENTROMERE Metacentric Acrocentric Telocentric Submetacentric
- 14. IN HUMAN : Metacentric Submetacentric Acrocentric