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
Nucleus” is a Latin word meaning Kernel
It is the “CONTROL CENTER” of the cell
Average diameter of nucleus is 6um, which occupies around 10% of cell volume
Nuclear Envelope
Nuclear Pores and complex
Nuclear lamina
Chromosomes & Chromatin
Nucleolus
Nucleoplasm
Nucleus” is a Latin word meaning Kernel
It is the “CONTROL CENTER” of the cell
Average diameter of nucleus is 6um, which occupies around 10% of cell volume
Nuclear Envelope
Nuclear Pores and complex
Nuclear lamina
Chromosomes & Chromatin
Nucleolus
Nucleoplasm
Let's explore the nucleus, starting from the nuclear envelope to the molecular organization of chromatin. The presentation is suitable for undergraduate students and has been started from the basics to enable easy understanding. It covers details of nuclear envelope, nuclear pore complex, nucleolus as well as DNA packaging.
Nucleus-the heart of the cell-cellular organellesbiOlOgyBINGE
In cell biology, the nucleus is a membrane-bound organelle found in eukaryotic cells.
The nucleus is found in all the eukaryotic cells of the plants and animals.
here u will find every detail of nucleus.
for more details ,visit @biOlOgy BINGE-insight learning (youtube channel)
STRUCTURE AND FUNCTIONS OF NUCLEUS OF A CELL.pptxRASHMI M G
The nucleus is the part of a cell that contains DNA organized into chromosomes and is located in the middle of the cell. It is surrounded by the nuclear envelope, which is a double membrane that separates the nucleus from the cytoplasm. The nuclear envelope contains nuclear pores, which are gateways that allow molecules to move into and out of the nucleus.
The Cell: The Histology Guide
Nucleus - The Cell: The Histology Guide - University of Leeds
The nucleus is found in the middle of the cells, and it contains DNA arranged in chromosomes. It is surrounded by the nuclear envelope, a double nuclear membrane (outer and inner), which separates the nucleus from the cytoplasm. The outer membrane is continuous with the rough endoplasmic reticulum.
open.baypath.edu
Nucleus – BIO109 Biology I Introduction to Biology
The boundary of the nucleus, called the nuclear envelope, is a double membrane that contains small openings called nuclear pores. These pores are gateways that allow molecules to move into and out of the nucleus, enabling it to communicate with the rest of the cell.
The nucleus has three main parts:
Nuclear membrane: A protective barrier of the nucleus
Nucleoplasm: The cytoplasm of the nucleus, which is a semifluid matrix that contains chromatin, the less condensed form of DNA that organizes into chromosomes during mitosis or cell division
Nucleolus: A spherical structure that produces and assembles the cell's ribosomes
The nucleus controls and regulates the activities of the cell, such as growth and metabolism.
What are the 4 types of nucleus?
What are the 3 parts of a nucleus?
How many nuclei are in a cell?
Ask a follow up
Homelearning behaviourInstinct and Learning Behavior
Instinct and Learning Behavior
MalaikaNovember 06, 2022
Learning and instinct have been compared throughout history and in folk biology.
While instinct focused on biologically preprogrammed mechanisms that emerge naturally in the absence of special environmental input, learning was meant to emphasise aspects of behavior and cognition that are the result of experience and training.
This distinction relates to those between learned and innate or inherited knowledge.
Instinct and learning behavior in animals
Instinct and learning in their biological setting
When viewed holistically, development's purpose is to help an animal build a repertoire of behaviours that are appropriate for its mode of existence and fit for success.
The stunning alignment of form and function is evident whether we are studying the muscular control of limb movement under negative feedback processes or the nest-building behaviours of birds, whether we are observing young animals or adults.
Animals do occasionally behave awkwardly and make mistakes, especially when placed in unnatural situations, but for the most part, their behaviour is perfectly matched to their way of life.
They find food, shelter, mate, and offspring by responding appropriately to the elements of their environment. How does behaviour develop this almost perfect fit? How is it able to grow so well?
People have been captivated by this query for centuries because we have always been animal observers. Of course, we have less often focused on how their behaviour changes than on their "nature" as beings that critically share the "spark of life" with us.
Even though we may take advantage of or ignore other species' needs in favour of our own, we cannot simply ignore them. This fact has caused some very different attitudes. Animals have occasionally been revered as deities.
How young animals grow up?
Methods of capturing animals
How many zoos does Pakistan have? and where?
The Egyptians kept a sacred bull named Apis and frequently depicted their writing god, Thoth, as a hamadryas baboon (Papio hamadryas). On the other hand, the Madagascan aye-aye (Daubentonia madagascariensis), a species of lemur, was hunted until recently because people believed it to be a devil's incarnation (Fig. 2).
The animal as god, the animal as devil.
(a) The animal as god, (b) The animal as devil.
Cats and toads were frequently accused of being the "familiars" of women accused of practising witchcraft in Europe. However, St. Francis was known for preaching to animals, referring to them as a part of Creation and perhaps even as having immortal souls.
We can now put superstitions to rest, but there is still much to learn about the sentience of animals, and we will discuss this in more detail later. Most pet owners will undoubtedly give their animal companions some human traits, even if in jest.
At one extreme, we might have animals like Badger, Ratty, Mole, and Toad fro
Young animals grow up
If the zygote can grow in and interact with a suitable environment, it contains all the information required to create a new organism. It stands to reason that some aspects of embryology must be considered when studying the development of behaviour. For instance, the way the nervous system's fundamental structure is built, but we must go much further than this.
Young animals grow up
It is entirely possible to argue that in some animals, behavioural development continues throughout life. Long after an animal is independent, its behaviour may still change. Learning could therefore be seen as a form of development, and young animals occasionally learn a lot as they grow. But in this section, we'll focus on other behavioural changes that frequently occur early in life, often quickly and dramatically.
It is important to understand that young animals must always be fully functional creatures capable of acting appropriately in their own worlds. They cannot simply be incomplete creatures or inadequate stages on the path to adulthood.
Some animals are protected during their early development by an eggshell or uterus or by watchful parents, but others are free-living and must care for themselves completely. Young animals may develop into miniature adults as they grow in size over time, but in order to keep up, their behavioural responses must also adapt.
Although young cuttlefish (Sepia) start out and continue to be carnivores, at first, they can only kill tiny crustacea that are disregarded as prey once the cuttlefish has grown. As they grow closer to adult size, they move on to food that is bigger and bigger, which requires a change in the behaviour patterns used to find and catch prey.
Even more drastic behavioural and morphological changes may occur in some cases because some young animals live entirely different lives than do adults. Tadpoles are herbivores that swim and breathe like fish before changing into land-dwelling carnivorous frogs or toads.
Eristalis tenax, an aquatic filter-feeding rat-tailed maggot that breathes through a long snorkel tube at its back, transforms into a flower-feeding hoverfly (see Fig. 2). Young and adult require almost entirely different behavioural repertoires for these life histories.
Rat-tailed maggot | Flower-feeding hoverfly
These alterations mean that development frequently has to produce patterns that only function for a portion of an animal's life before disappearing. The specific coordinated movements that cockroaches use to emerge from their individual eggshells as well as the protective case that bundles a group of eggs together were both described by Provine in 1976. These movements, which are only observed on this one occasion, consist of a series of reversed waves of contraction along the body from the tail to the head.
They appear at the exact right time, at the end of the egg stage's development, and are used to propel the young cockroach nymph into the following growth
Let's explore the nucleus, starting from the nuclear envelope to the molecular organization of chromatin. The presentation is suitable for undergraduate students and has been started from the basics to enable easy understanding. It covers details of nuclear envelope, nuclear pore complex, nucleolus as well as DNA packaging.
Nucleus-the heart of the cell-cellular organellesbiOlOgyBINGE
In cell biology, the nucleus is a membrane-bound organelle found in eukaryotic cells.
The nucleus is found in all the eukaryotic cells of the plants and animals.
here u will find every detail of nucleus.
for more details ,visit @biOlOgy BINGE-insight learning (youtube channel)
STRUCTURE AND FUNCTIONS OF NUCLEUS OF A CELL.pptxRASHMI M G
The nucleus is the part of a cell that contains DNA organized into chromosomes and is located in the middle of the cell. It is surrounded by the nuclear envelope, which is a double membrane that separates the nucleus from the cytoplasm. The nuclear envelope contains nuclear pores, which are gateways that allow molecules to move into and out of the nucleus.
The Cell: The Histology Guide
Nucleus - The Cell: The Histology Guide - University of Leeds
The nucleus is found in the middle of the cells, and it contains DNA arranged in chromosomes. It is surrounded by the nuclear envelope, a double nuclear membrane (outer and inner), which separates the nucleus from the cytoplasm. The outer membrane is continuous with the rough endoplasmic reticulum.
open.baypath.edu
Nucleus – BIO109 Biology I Introduction to Biology
The boundary of the nucleus, called the nuclear envelope, is a double membrane that contains small openings called nuclear pores. These pores are gateways that allow molecules to move into and out of the nucleus, enabling it to communicate with the rest of the cell.
The nucleus has three main parts:
Nuclear membrane: A protective barrier of the nucleus
Nucleoplasm: The cytoplasm of the nucleus, which is a semifluid matrix that contains chromatin, the less condensed form of DNA that organizes into chromosomes during mitosis or cell division
Nucleolus: A spherical structure that produces and assembles the cell's ribosomes
The nucleus controls and regulates the activities of the cell, such as growth and metabolism.
What are the 4 types of nucleus?
What are the 3 parts of a nucleus?
How many nuclei are in a cell?
Ask a follow up
Homelearning behaviourInstinct and Learning Behavior
Instinct and Learning Behavior
MalaikaNovember 06, 2022
Learning and instinct have been compared throughout history and in folk biology.
While instinct focused on biologically preprogrammed mechanisms that emerge naturally in the absence of special environmental input, learning was meant to emphasise aspects of behavior and cognition that are the result of experience and training.
This distinction relates to those between learned and innate or inherited knowledge.
Instinct and learning behavior in animals
Instinct and learning in their biological setting
When viewed holistically, development's purpose is to help an animal build a repertoire of behaviours that are appropriate for its mode of existence and fit for success.
The stunning alignment of form and function is evident whether we are studying the muscular control of limb movement under negative feedback processes or the nest-building behaviours of birds, whether we are observing young animals or adults.
Animals do occasionally behave awkwardly and make mistakes, especially when placed in unnatural situations, but for the most part, their behaviour is perfectly matched to their way of life.
They find food, shelter, mate, and offspring by responding appropriately to the elements of their environment. How does behaviour develop this almost perfect fit? How is it able to grow so well?
People have been captivated by this query for centuries because we have always been animal observers. Of course, we have less often focused on how their behaviour changes than on their "nature" as beings that critically share the "spark of life" with us.
Even though we may take advantage of or ignore other species' needs in favour of our own, we cannot simply ignore them. This fact has caused some very different attitudes. Animals have occasionally been revered as deities.
How young animals grow up?
Methods of capturing animals
How many zoos does Pakistan have? and where?
The Egyptians kept a sacred bull named Apis and frequently depicted their writing god, Thoth, as a hamadryas baboon (Papio hamadryas). On the other hand, the Madagascan aye-aye (Daubentonia madagascariensis), a species of lemur, was hunted until recently because people believed it to be a devil's incarnation (Fig. 2).
The animal as god, the animal as devil.
(a) The animal as god, (b) The animal as devil.
Cats and toads were frequently accused of being the "familiars" of women accused of practising witchcraft in Europe. However, St. Francis was known for preaching to animals, referring to them as a part of Creation and perhaps even as having immortal souls.
We can now put superstitions to rest, but there is still much to learn about the sentience of animals, and we will discuss this in more detail later. Most pet owners will undoubtedly give their animal companions some human traits, even if in jest.
At one extreme, we might have animals like Badger, Ratty, Mole, and Toad fro
Young animals grow up
If the zygote can grow in and interact with a suitable environment, it contains all the information required to create a new organism. It stands to reason that some aspects of embryology must be considered when studying the development of behaviour. For instance, the way the nervous system's fundamental structure is built, but we must go much further than this.
Young animals grow up
It is entirely possible to argue that in some animals, behavioural development continues throughout life. Long after an animal is independent, its behaviour may still change. Learning could therefore be seen as a form of development, and young animals occasionally learn a lot as they grow. But in this section, we'll focus on other behavioural changes that frequently occur early in life, often quickly and dramatically.
It is important to understand that young animals must always be fully functional creatures capable of acting appropriately in their own worlds. They cannot simply be incomplete creatures or inadequate stages on the path to adulthood.
Some animals are protected during their early development by an eggshell or uterus or by watchful parents, but others are free-living and must care for themselves completely. Young animals may develop into miniature adults as they grow in size over time, but in order to keep up, their behavioural responses must also adapt.
Although young cuttlefish (Sepia) start out and continue to be carnivores, at first, they can only kill tiny crustacea that are disregarded as prey once the cuttlefish has grown. As they grow closer to adult size, they move on to food that is bigger and bigger, which requires a change in the behaviour patterns used to find and catch prey.
Even more drastic behavioural and morphological changes may occur in some cases because some young animals live entirely different lives than do adults. Tadpoles are herbivores that swim and breathe like fish before changing into land-dwelling carnivorous frogs or toads.
Eristalis tenax, an aquatic filter-feeding rat-tailed maggot that breathes through a long snorkel tube at its back, transforms into a flower-feeding hoverfly (see Fig. 2). Young and adult require almost entirely different behavioural repertoires for these life histories.
Rat-tailed maggot | Flower-feeding hoverfly
These alterations mean that development frequently has to produce patterns that only function for a portion of an animal's life before disappearing. The specific coordinated movements that cockroaches use to emerge from their individual eggshells as well as the protective case that bundles a group of eggs together were both described by Provine in 1976. These movements, which are only observed on this one occasion, consist of a series of reversed waves of contraction along the body from the tail to the head.
They appear at the exact right time, at the end of the egg stage's development, and are used to propel the young cockroach nymph into the following growth
Circulation, Gas Exchange, and Temperature Regulation in Mammals.pdfMammalssite
The hear of birds and mammals are superficially similar. Both are four-chambered pumps that keep blood in the systematic and pulmonary circuits separate, and both evolved from the hearts of the ancient tetrapodomorphs. Their similarities, however, are a result of adaptations to active lifestyles. The evolution of similar structure structures in different lineages is called convergent evolutions. The mammalian heart evolved from the synapsid lineage, whereas the avian heart evolved within the diapsid archosaur lineage.
Vertebrate Heart Possible Sequence in the Evolution of the Vertebrate Heart. One of the most important adaptations in the circulatory system of eutherian mammals concerns the distribution of respiratory gases and nutrients in the fetus.
Exchanges between maternal and fetal blood occur across the placenta. Although maternal and fetal blood vessels are intimately associated, no blood actually mixes. Nutrients, gases, and waste simply diffuse between maternal and fetal blood supplies. Mammalian Circulatory System
(Figure 2) Mammalian Circulatory System. Blood entering the right atrium of the fetus is returning from the placenta and is highly oxygenated. Because fetal lungs are not inflated, resistance to blood flow through the pulmonary arteries is high. Therefore, most of the blood entering the right atrium bypass the right ventricle and passes instead into the left atrium through a valved opening between the atria. However, some blood from the right atrium does enter the right ventricle and the pulmonary artery. Because of the resistance at the inflated lungs, most of this blood is shunted to the aorta through a vessel connecting to the aorta and the left pulmonary artery. External Structure and locomotion in Mammals Excretion and Osmoregulation In Mammals Reproduction and Development in Mammals. At birth, the placenta is lost and the lungs are reduced, and blood flow to them increases. Flow through the ductus arteries decreases, and the vessels are gradually reduced valve of the foramen ovale closes and gradually fuses with the tissue separating the right and left arita (figure 2b). Gas Exchange in Mammal. For efficient gas exchange at high metabolic rates, adaptations are necessary. Most mammals have separate nasal and oral cavities and longer snouts, which provide an increased surface area of warming and moistening inspired air. Respiratory passageways are highly branched, and large surface areas exist for gas exchange. Mammalian lungs resemble highly vascular spongy, rather than saclike structures of amphibians and a few reptiles.
Mammalian lungs, like those of reptiles, inflate using a negative pressure mechanism. Mammals have a muscular diaphragm that separates the thoracic and abdominal cavities, unlike reptiles and birds. Inspiration results from the diaphragm's contraction and the rib cages' expansion, both of which decrease the intrathoracic pressure and allow air to enter the lungs. Expiration is normally by elastic rec
The Greek words "Chroma," which means colour, and "Soma," which means body, were combined to create the English word "chromosome." They are distinct cell organelles made of chromatin, the most significant and durable component of the cell nucleus. They have the ability to reproduce themselves. They are important for differentiation, heredity, mutation, and evolution and regulate the structure and metabolism of cells.
General History of Chromosomes
Nuclear filaments were found by W. Hofmeister in the Tradescantia pollen mother cells' nuclei in 1848. W. Flemming conducted the first precise chromosome count in a cell's nucleus in 1882. W. Flemming, Evan Beneden, and E. Strasburger showed in 1884 that the chromosomes double in number during mitosis through longitudinal division. Beneden discovered that each species had a fixed number of chromosomes in 1887. W. Waldeyer first used the term "chromosomes" for the nuclear filaments in 1888. The role of chromosomes in heredity was first proposed by W.S. Sutton and T. Boveri in 1902, and it was later supported by Morgan in 1933.
In viruses, prokaryotes, and eukaryotes, chromosome structures differ.
1. Viral chromosome- In viruses, each chromosome contains a single nucleic acid molecule (DNA or RNA), which is encased in a protein coat known as the capsid. It could be circular or linear. The term "DNA virus" refers to viruses with DNA as their genetic material, while the term "RNA virus" refers to viruses with RNA as their genetic material. The viral chromosome contains a small amount of genetic material that primarily regulates the generation of additional identical virus particles in the host cell. In RNA viruses, the RNA frequently instructs the host's reverse transcription process to create DNA that is complementary to itself.
The DNA then uses the RNA to create new viral particles by transcribing it. Retroviruses are one type of ribovirus. A retrovirus is what causes AIDS.
2. Prokaryotic chromosomes- A single circular two-stranded DNA molecule found on prokaryotic chromosomes, such as those found in bacteria, is not encased by any membrane. It is in direct contact with the cytoplasm and is protein-free.
Some RNA that seems to form a core encases the bacterial chromosome in the nucleoid. At some point, it is anchored permanently to the plasma membrane. Most bacterial cells also contain some extra-chromosomal DNA molecules that are double stranded and circular but much smaller in size than the main chromosome. Plasmids are the name for them.
The plasmid can appear on its own in the cytoplasm of cells or it can also be discovered in associated with the main chromosomal DNA and is known as an episome.
3. Eukaryotic chromosomes- The nucleus and some other organelles, like mitochondria and plastids, contain the eukaryotic chromosomes. Nuclear and extra nuclear chromosomes are the names given to these chromosomes, respectively.
Double-stranded, linear, long DNA molecules make up nuclear chromosomes. They are
Homecell divisionCell division
Cell division
Miller November 05, 2022
Every living organism depends on the growth and multiplication of its cells for growth and development because a multicellular organism begins as a single cell and undergoes repeated division. The characteristic trait of all living things is an increase in cell size brought on by growth. The cell starts to divide once its growth has reached its maximum. An organism grows vegetatively when its number of cells increases through cell divisions that follow a geometric progression. The three stages of cell division, which is a continuous and dynamic process, are as follows:
Replicating the genome or DNA
Karyokinesis, or nuclear division
Cytokinesis, also known as cell division
Based on the number of genomes present in the daughter cells in comparison to the dividing parent cell, there are two types of cell division: mitosis and meiosis.
1. Mitosis- W. Flemming first used the word mitosis in 1882. Mitosis, also known as somatic division, is the process by which a body cell divides into two daughter cells, each of equal size and with the same number of chromosomes as the parent cell.
2. Meiosis- J. Meiosis was the first to use the term. B. Farmer and J. Smith in 1905 Moore, E. Only the gonads (germ mother cells) undergo meiosis during the development of gametes like sperm and ovum. Meiosis is the process by which chromosomes go from having two copies, or 2N or diploid, to having only one copy, or N or haploid. Additionally known as the reduction process. Every cell that is able to divide undergoes a regular cycle of alterations known as the cell cycle. A cell is diploid when it begins its cycle.
Phases of cell cycle
The cell cycle has two phases: the long interphase, also known as Iphase, and the short mitotic, also known as M-phase, phases. 1. Interphase-
The interphase is the period of time between telophase's conclusion and the start of the following Mphase. The stage is long and complicated, lasting between 10 and 30 hours. The cell develops during this phase by producing biological molecules like lipids, proteins, carbohydrates, and nucleic acids.
First gap, also known as the G1 phase, second gap, also known as the G2 phase, and synthetic phase make up the interphase.
(i) G1 phase- The G1 phase represents the duration between the previous mitosis and the start of DNA synthesis. During this phase, a newly formed cell begins to grow. During this stage, a wide range of biological molecules—including RNAs, proteins, lipids, and some non-histones—are created.
In order to prepare for the DNA replication that will occur next to it, normal metabolism is carried out. This phase does not involve DNA synthesis. (ii) S Phase- Each chromosome is duplicated during this phase by replicating new DNA molecules using the existing DNA as a template. Only in S-phase do histone protein and their mRNA, some non-histone protein, and new nucleosome formation take place. Most eukary
All animals have external structures, or bodily organs on the outside. The majority of animals have a head, a body covering, limbs, and a tail of some kind. These body parts are all essential to an animal's ability to live and reproduce, despite the fact that they may appear differently on different animals.
The limbs of mammals may be modified for a particular movement. They could be taught how to swim, fly, climb, and run. More commonly known as "ricochetal locomotion," saltatory (leaping) movement has been observed in a variety of unrelated species (some marsupials, lagomorphs, and several independent lineages of rodents).
The skin of mammals, like that of other vertebrates, consists of epidermal and dermal layers. It protects against actual injury, microbiological invasion, and UV rays from the sun. skin is also important for temperature regulation, sensory perception excretion, and water regulation.
Hairs are a keratinized derivative of the epidermis of the skin and are uniquely mammalian. It is seated in an invagination of the epidermis called a hair follicle. Two distinct kinds of hair typically compose a pelage, a coat of hair. Long guard hairs protect a dense coat of shorter, insulating under hairs.
Hair must periodically molt because it is made mainly of dead cells. In some mammals (e.g., humans), molting occurs gradually and may not be noticed. Others have rapid hair loss, which could alter the characteristics of their pelage. In the fall, many mammals acquire a thick coat of insulting under hair, and the pelage color may change.
For example, the Arctic fox takes on a white or cream color with its autumn molt, which helps conceal the fox in a snowy environment. with its spring molt, the Arctic fox acquires a gray and yellow pelage
Hairs are also important for the sense of touch. The mechanical displacement of hair stimulates nerve cells associated with the hair root. Guard hairs may sometimes be modified into thick-shifted hairs called vibrissae. Vibrissae occur around the legs, nose, mouth, and eyes of very sensitive to displacement.
Air space in the hair shaft and hair trapped between hairs and the skin provides an effective insulating layer. A band of smooth muscle, called the arrector pili muscle, runs between the hair follicle and lower epidermis. when the muscle contract, the hair stands upright, increasing the amount of air trapped the in the pelage and improving its insulating properties.
Arrector pili muscles are under the control of the autonomic nervous system, which also controls a mammal's "fight-or-flight" response. In threatening situations, the hair stands on end and may give the perception of increased size and strength.
Hair color depend on the number of pigments (melanin) deposited in it and the quantity of air in the hair shaft. The pelage of most mammals is dark above and lighter underneath. This pattern them less conspicuous under most conditions. Some mammals advertised their defenses using aposematic (warning
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.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Safalta Digital marketing institute in Noida, provide complete applications that encompass a huge range of virtual advertising and marketing additives, which includes search engine optimization, virtual communication advertising, pay-per-click on marketing, content material advertising, internet analytics, and greater. These university courses are designed for students who possess a comprehensive understanding of virtual marketing strategies and attributes.Safalta Digital Marketing Institute in Noida is a first choice for young individuals or students who are looking to start their careers in the field of digital advertising. The institute gives specialized courses designed and certification.
for beginners, providing thorough training in areas such as SEO, digital communication marketing, and PPC training in Noida. After finishing the program, students receive the certifications recognised by top different universitie, setting a strong foundation for a successful career in digital marketing.
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
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.
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.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Unit 8 - Information and Communication Technology (Paper I).pdf
Structure of Nucleus
1. Structure of Nucleus
There is 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 (Fig. 1).
Structure of Nucleus
1. Structure of Nucleus
2. Chemical Composition
3. Nuclear Envelope
4. Nucleoplasm
5. Nuclear Matrix
6. Chromatin
7. Nucleolus (Little Nucleus)
Chemical Composition
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
2. 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:
1. By controlling the production of structural proteins, it keeps the cell alive.
2. By directing the synthesis of enzymatic proteins, it controls cell metabolism.
3. 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.
4. It is where ribosome subunit formation takes place.
5. By keeping only a select few genes active, it causes cell differentiation.
6. It produces genetic changes that lead to evolution.
Nuclear Envelope
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.
● Centriole
● Lysosomes
● Endoplasmic reticulum
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 (Fig. 2).
3. Ultra structure of nucleus
Nuclear Pores: The nuclear pores, which regulate the passage of some molecules and
particles, typically leave small openings in the nuclear envelope. The nuclear envelope's
inner and outer membranes combine to form the pores. Per nucleus, there could be
1000–10,000 pores.
A device known as the pore complex is attached to each nuclear pore, filling a sizeable
portion of the pore. The nearly cylindrical pore complex extends beyond the pore's rim over
the nuclear envelope and into both the cytoplasm and the nucleoplasm.
Two rings, called annuli, make up the pore complex; one is found at the cytoplasmic rim and
the other at the nucleoplasmic rim. Eight symmetrically arranged subunits make up each
annulus, which sends a spoke into the pore.
100 to 200 wide channel is enclosed by the spoke. The nucleus and cytoplasm can freely
exchange ions and small molecules the size of monosaccharides, disaccharides, or amino
acids.
The passage of larger molecules, including RNA, proteins, and ribosomal subunits, is indeed
regulated by the pore complexes. Some molecules, like the DNA in chromosomes, are also
blocked by the pore complexes.
Functions
4. 1. The nucleus's shape is preserved.
2. It preserves the nuclear material and keeps it separate from the cytoplasm.
3. By using active transport and out pocketing, it controls the movement of materials
into and out of the nucleus.
4. Ribosomal subunits created in the nucleolus, as well as tRNA and mRNA
synthesised on the chromosomes, can all exit through its pores.
Nucleoplasm
The transparent fluid substance in the nucleus is called nucleoplasm. It contains nucleoli and
chromatin fibres suspended in it. For the synthesis of DNA and RNA, it contains the building
blocks (nucleotides), the enzymes (polymerases), and the metal ions (Mn++, Mg++). Lipids
and proteins are also present.
The proteins that interact with the DNA molecules include basic histones and acidic or
neutral non-histones. Additionally, proteins are needed for the synthesis of ribosomal
subunits. Nuclear pores allow the RNAs (rRNAs, tRNAs, and mRNAs) and ribosomal
subunits synthesised in the nucleoplasm to enter the cytoplasm (Fig. 2).
Functions
1. It is where DNA, RNA, ribosomal subunits, ATP, and NAD are all synthesised.
2. It supports the chromatin, nucleoli, and nuclear matrix.
3. The nucleus gains turgidity as a result.
Nuclear Matrix
The nuclear matrix is made up of a web of tiny, crisscrossing protein-containing fibrils that
are joined to the nuclear envelope at their ends. It creates a kind of nuclear framework. Even
after the DNA and chromatin have been taken out, it is still present.
Functions
1. The nucleus's shape is maintained.
2. Nuclear matrix is where chromatin fibres are anchored.
3. The matrix is connected to the machinery for various nuclear processes like
transcription and replication.
4. Additionally, it has been linked to the transport of freshly formed RNA molecules
through the nucleus and to their processing.
Chromatin
In 1879, Flemming was the first to use the term "chromatin." The chromatin is found as tiny
filaments, or chromatin fibres, in an interphase (non-dividing) nucleus. The fibres cross each
other to resemble a diffuse network that is frequently referred to as the nuclear or chromatin
reticulum. The majority of the nucleus is taken up by chromatin.
5. Simply put, the chromatin fibres are very long chromosomes. A chromatin fibre typically has
a diameter of 100Å. A fibre that is thicker than 100 appears to be coiled or folded, whereas a
fibre that is thinner than 100 appears to contain less protein. Chromatin fibres typically have
a diameter of 250Å.
The chromatin fibres condense and tightly coil to form short, thick rod-like bodies known as
chromosomes during cell division. This diffuse network of chromatin material exhibits light
and dark stained regions after staining. The chromosomes transform back into chromatin
fibres following cell division.
The majority of the chromatin fibres spread out in the nucleoplasm, uncoil, and extend.
These are the interphase nucleus's true chromatin, or euchromatin. They have a light stain.
The chromosomal regions that stain darker than others are referred to as heterochromatin.
Even in the interphase, they continue to be compacted and coiled. The chromosomes'
heterochromatin represents their largely dormant regions. Compared to euchromatin, it
contains more RNA and less DNA.
There are not many mutations in this region. Here, very little to no mRNA is produced. Most
of the highly repeated DNA in heterochromatin is never or very infrequently transcribed.
There are two types of heterochromatin: constitutive and facultative.
Constitutive heterochromatin's is inactivated forever and is always in a condensed state. It
can be found near the centromere of a chromosome, at the ends of chromosomes
(telomeres), in some regions of euchromatin, and next to the nuclear envelope, among other
locations.
Facultative heterochromatin is inactivated and partially condensed. In female mammals, one
X chromosome is compressed to form the heterochromatic Barr body. Nucleosomes: In
1974, Kornberg and Thomas suggested that a chromatin fibre is made up of a series of
related subunits known as nucleosomes (Fig. 3).
Nucleosome
6. A DNA strand surrounds a core particle that makes up the nucleosome. Eight histone
molecules, two of each histone H2A, H2B, H3, and H4, make up the core particle. The 140
nucleotides of the DNA strand are arranged in 112 or 134 turns around the core. A 60
nucleotide-long DNA linker connects each nucleosome to the one before it.
Together, a nucleosome and a linker make up a chromatosome, which has an average
length of 200 nucleotides. Each DNA linker has a molecule of histone H1, which is used to
pack nucleosomes tightly together. A chromatin fibre is essentially a chain of nucleosomes,
each of which is about 100Å in width and 140Å in length.
The lowest level of chromatin organisation is represented by nucleosomes. In electron
micrographs, chromatin fibre measures about 250 nm thick. which implies that the
100-nanometer-thick chromatin fibre is either packed in solenoids with six nucleosomes per
turn or is organised into a cluster, or super bead, with six nucleosomes, increasing the DNA
packing by five times.
The H1 histone protein keeps the thicker filament in place. The nucleosome structure of
chromatin does not contain the non-histone proteins. Prokaryotes do not produce
nucleosomes.
Functions
1. When cells divide, the chromatin fibres shape chromosomes.
Nucleolus (Little Nucleus)
F. Fontana found the nucleolus in eel skin slime in the year 1781. Most cells have it in their
nuclei, but muscle and sperm cells lack it completely or barely notice it. Though it can take
on other shapes, it is typically spherical.
Different species have varying numbers of nucleoli in their nuclei. At specific locations on
specific chromosomes, known as the nucleolar organisers or nucleolar organiser regions
(NORs), the nucleoli, which vanish during cell division, are formed again before the
chromosomes become diffuse.
The nucleolus' position within the nucleus is frequently eccentric. The nucleolus, a dense,
somewhat rounded, dark-staining organelle, does, however, occupy a particular location on
the chromosome. There is no limiting membrane in it. The ions in calcium keep it whole.
There are four of them.
1. Fibrillar Region or Nucleolonema- It has fuzzy fibrils with a diameter of 50 to 100Å. The
long rRNA precursor molecules are represented by the fibrils at an early stage of processing,
before the processing enzymes have severed segments from them.
2. Granular Region- It contains spherical, electron-dense particles with a fizzy outline that
range in diameter from 150 to 200Å. The ribosomal subunits (rRNA + ribosomal proteins)
that make up the granules are almost prepared to be transported to the cytoplasm.
7. 3. Amorphous Region or Pars Amorpha- The proteinaceous matrix, in which the granular
and fibrillar regions are suspended, lacks any structure.
4. Nucleolar Chromatin- It is made up of chromatin fibres that are 100 thick. These latter
ones make up a segment of the nucleolar chromosome that winds its way through the
granular and fibrillar regions of the nucleolus. This component has numerous copies of the
DNA that controls the production of ribosomal RNA. The nucleoplasm contains the
remaining portion of the nucleolar chromosome.
Functions
1. In the nucleolus, rRNA is created and stored.
2. Ribosomal proteins that it receives from the cytoplasm are also stored there. By
encasing the rRNA in ribosomal proteins, it creates ribosomal subunits.
3. The nuclear pores allow the ribosomal subunits to exit and enter the cytoplasm.
When necessary, the subunits here combine to form ribosomes. Therefore, the
nucleolus is where the ribosomes necessary for protein synthesis are found.
4. Cell division also involves the nucleolus.