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Showing posts with the label Neurotransmitters Secretion

Make a chart of neurological disorder and associated neurosecretion

Neurological disorders are often caused by imbalances in specific neurotransmitters or neurosecretions in the brain. These chemicals help neurons communicate and their deficiency or excess can disturb normal brain function. Below is a detailed explanation of major neurological disorders and their associated neurosecretions: Parkinson's Disease:  Parkinson's Disease is mainly caused by a reduction in dopamine secretion. The dopaminergic neurons of the substantia nigra in the midbrain slowly degenerate, leading to low dopamine in the striatum. This causes tremors, rigidity, slow movements and posture imbalance. Alzheimer's Disease:  Alzheimer's Disease is linked with reduced secretion of acetylcholine. In this disorder, cholinergic neurons in the hippocampus and cortex degenerate. Acetylcholine is needed for learning and memory, so its deficiency results in memory loss and confusion. Myasthenia Gravis:  Myasthenia Gravis is an autoimmune disorder where the body produces a...
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What is the difference between excitatory and inhibitory postsynaptic potentials

When a nerve impulse reaches the axon terminal of a presynaptic neuron, neurotransmitters are released into the  synaptic cleft.  These neurotransmitters bind to specific receptors present on the membrane of the postsynaptic neuron. This binding leads to the opening of ion channels and causes changes in the membrane potential of the postsynaptic neuron. These changes can either increase or decrease the likelihood of generating an action potential. If the change leads to depolarization, it is called  Excitatory Postsynaptic Potential (EPSP)  and if it leads to hyperpolarization, it is known as  Inhibitory Postsynaptic Potential (IPSP).  Both are types of graded potentials and are crucial for the integration of synaptic inputs in the central nervous system. Here is the detailed comparison of EPSP and IPSP based on different criteria: 1. Based on Definition and Nature of Response EPSP (Excitatory Postsynaptic Potential) is a type of postsynaptic potential that...
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Write a brief note about the secretary glands of brain

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Secretory glands of the brain, also known as neuroendocrine glands, are specialized structures that secrete hormones directly into the bloodstream. These hormones affect various organs and tissues throughout the body and play a vital role in maintaining homeostasis. They help regulate important physiological functions such as growth, metabolism, sleep, reproduction and response to stress. The primary secretory glands of the brain are the  pituitary gland  and the  pineal gland.  These glands are located within the central nervous system but also act as  endocrine organs.  They are directly or indirectly controlled by the  hypothalamus  and are involved in the production and secretion of hormones that regulate body functions like stress response, reproductive cycles, circadian rhythms and metabolic activity. 1. Pituitary Gland (Hypophysis) The pituitary gland is a small  pea-shaped  endocrine gland located at the base of the brain in a bo...
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What a brief note about chemical and electrical neurotransmission

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Neurotransmission is the process by which neurons communicate with each other. It occurs mainly through two types:  chemical neurotransmission  and  electrical neurotransmission.  Both types serve the same basic function, that is, to transmit signals between neurons, but they differ in their mechanisms. These are two essential modes of  synaptic transmission  in the nervous system. Chemical Neurotransmission Chemical neurotransmission is the predominant form of signal transmission between neurons, involving the release and reception of neurotransmitters (chemical messengers). When an action potential reaches the presynaptic terminal of a neuron, it triggers the opening of voltage-gated  calcium channels,  allowing calcium ions (Ca²⁺) to enter the presynaptic neuron. This influx of calcium ions facilitates the fusion of synaptic vesicles with the presynaptic membrane, releasing neurotransmitters into the synaptic cleft. The neurotransmitters then d...
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What neurological condition is caused by inhibiting GABA?

When GABA is inhibited in the brain, it leads to a neurological condition called  epilepsy.  This happens because GABA normally controls brain activity by stopping too much nerve signalling. When GABA is not working properly, the brain loses its balance and nerve cells start becoming overactive. This overactivity can lead to  seizures,  which is the main feature of  epilepsy. Seizures  are sudden, uncontrolled electrical disturbances in the brain that can cause changes in behavior, movements, feelings, or consciousness. They may last from a few seconds to minutes and can be caused by epilepsy, fever, head injury, or other neurological conditions. Seizures vary in type and severity. Step-by-Step Explanation: How GABA Inhibition Leads to Epilepsy To understand how epilepsy is caused by inhibiting GABA, we can break the process into simple steps. These steps explain what GABA normally does, what changes happen when it is blocked and how those changes result in...
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Which neurological disorders are linked to increase dopamine secretion?

Dopamine is a crucial neurotransmitter in the brain that plays a significant role in controlling motor functions, emotional responses and reward pathways. It is involved in regulating mood, movement and several other physiological processes. However, when there is an imbalance in dopamine secretion or its activity, it can lead to several neurological and neuropsychiatric disorders. An increase in dopamine activity is linked to certain disorders, where excessive dopamine levels in specific brain regions can lead to abnormal behaviors and symptoms. Here are two neurological disorders closely associated with increased dopamine secretion: 1. Tourette Syndrome Tourette Syndrome (TS) is a neurological disorder characterized by repetitive, involuntary movements (motor tics) and sounds (vocal tics). It often begins in childhood and can persist into adulthood. In individuals with Tourette Syndrome, there is evidence of increased dopamine activity, particularly in the  basal ganglia,  a...
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Write the name of neurotransmitter which act as neuromodulator as well as inhibitor of neurotransmitter

One of the best-known neurotransmitters that shows both neuromodulatory and inhibitory functions is  GABA (Gamma-Aminobutyric Acid).  It is a major chemical messenger in the central nervous system (CNS) and plays a vital role in regulating brain activity. GABA is unique because it not only participates in fast synaptic transmission as an inhibitory neurotransmitter but also acts more broadly as a neuromodulator that controls the excitability of entire neural circuits. 1. GABA as a Neuromodulator As a neuromodulator, GABA works at a slower and more widespread level than fast synaptic transmission. Instead of targeting a single postsynaptic neuron, it can influence large groups of neurons or entire regions of the brain. Neuromodulatory action of GABA usually happens through GABA-B receptors, which are metabotropic and linked with second messenger systems. Through these pathways, GABA can regulate the activity of other neurotransmitter systems like: Glutamate (main excitatory neu...
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Which hormone is called as sleep hormone?

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The hormone that is called the sleep hormone is  Melatonin.  It is a naturally occurring hormone in the human body that controls the sleep-wake cycle, also known as the  circadian rhythm.  Melatonin is secreted by the  pineal gland,  which is a small, cone-shaped endocrine gland located deep in the brain, near the centre, just above the cerebellum and behind the third ventricle. Melatonin secretion is directly controlled by the amount of light the eyes receive. When the environment becomes dark, the retina sends signals to a special region in the hypothalamus known as the  suprachiasmatic nucleus (SCN).  This SCN then sends nerve signals to the pineal gland, which begins to release melatonin into the bloodstream. The rise in melatonin levels at night makes a person feel sleepy and relaxed, preparing the body for sleep. During the daytime, especially in the presence of sunlight or artificial light, melatonin secretion is stopped. This is why melato...
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Write the name of two glands are the main secretary gland of brain

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The brain is not only the central organ of the nervous system but also contains two major secretory glands that are directly involved in endocrine functions. These are: Pituitary gland (Hypophysis) Pineal gland (Epiphysis cerebri) These glands are part of the neuroendocrine system, which links the brain and hormonal regulation. They help in maintaining homeostasis, regulating growth, metabolism, stress response, sleep cycle, reproduction and many other vital processes. 1. Pituitary Gland: The Master Gland The pituitary gland is called the  "master gland"  because it controls the activity of almost all other endocrine glands in the body. It is located at the base of the brain, in a bony cavity called the sella turcica of the sphenoid bone. It is connected to the  hypothalamus  by a stalk called the  infundibulum,  which carries signals from the brain to control hormone secretion. The pituitary gland has two main lobes: i. Anterior Pituitary (Adenohypophysis)...
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What are non-coding genes? Give examples

Non-coding genes are segments of DNA that do not code for any protein but still play very important roles in the cell. These genes are transcribed into functional RNA molecules instead of mRNA. These RNAs do not get translated into proteins but perform regulatory, structural, or catalytic roles directly as RNA. Non-coding genes are a major part of the eukaryotic genome and help in many cellular processes such as gene regulation, RNA processing and maintaining genome stability. Many people think that only protein-coding genes matter, but non-coding genes also play a crucial role in regulating cellular activities. They help control when and how genes are turned on or off, assist in processing other RNAs and participate in building cell machinery like ribosomes and spliceosomes. There are several important types of non-coding genes, which can be grouped based on the RNA they produce and their functions. The main categories are: 1. rRNA Genes (Ribosomal RNA Genes) These genes produce ribos...
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What are the differences between gene enhancers and gene silencers? How do enhancers and silencers regulate eukaryotic gene expression?

Enhancers and silencers are two important types of regulatory DNA sequences that play opposite roles in controlling gene expression in eukaryotic cells. They are non-coding DNA elements which do not produce proteins but control when, where and how much a gene is expressed. They work by interacting with transcription factors and RNA polymerase to either increase or decrease the level of transcription. Differences Between Gene Enhancers and Gene Silencers Gene enhancers and gene silencers are both regulatory DNA elements found in eukaryotic genomes. Their main role is to control the level of gene expression, but they work in opposite directions. The differences between them can be explained based on the following criteria: 1. Based on Function Enhancers   increase  the transcription of a gene. They make the gene more active and allow it to produce more RNA. On the other hand,  silencers   reduce  or  completely block  transcription. They stop or decrease...
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Define and distinguish sex-linked, sex-limited and sex-influenced characters

In genetics, traits can be influenced or expressed differently depending on the sex of the individual. Some traits are linked to sex chromosomes, while others are affected by hormonal or physiological differences between males and females. To describe these traits more precisely, geneticists use three main terms:  sex-linked, sex-limited and sex-influenced traits.  Although these terms may sound similar, they refer to different types of genetic expression related to sex. Understanding the distinction among these three is important for grasping how certain traits are inherited and expressed differently in males and females. 1. Sex-linked characters: These are traits controlled by genes that are located on the  sex chromosomes,  usually on the X chromosome in humans. Because males have only one X chromosome (XY) and females have two (XX), the pattern of inheritance and expression is different in both sexes. Most sex-linked traits are X-linked, and very few are Y-linked...
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What are epigenetic modifications? Give examples

Epigenetic modifications are heritable and reversible changes in gene expression that occur  without altering the DNA sequence  itself. These changes play a major role in how genes are  turned on or off  in different cells and at different times. Epigenetics helps explain how the same DNA sequence can produce different types of cells like skin cells, nerve cells and liver cells in the same organism. These modifications are very important during development, cellular differentiation, X-chromosome inactivation in females, genomic imprinting, aging and in many diseases such as cancer. There are the following three main types of epigenetic modifications: 1. DNA Methylation This is the most studied and well-understood form of epigenetic modification. In this process, a methyl group (–CH₃) is added to the cytosine base in DNA, mainly at CpG dinucleotides. These CpG regions are often found in clusters called CpG islands, which are located near  gene promoters.  DN...
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Thomson's Plum Pudding Model of the Atom

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The Plum Pudding Model is one of the earliest models of atomic structure. It was built upon two major scientific contributions. The idea that atoms might contain both positive and negative charges was first proposed by William Thomson (commonly known as Lord Kelvin ) around the late 19th century. He suggested that positive and negative charges must be present together inside the atom to make it neutral. However, this idea remained a speculation until Sir Joseph John Thomson (Commonly known as J.J. Thomson ) made a major breakthrough in 1897 when he discovered a negatively charged particle, later called the electron, through his cathode ray tube experiments. He demonstrated that these rays were made of tiny, negatively charged particles that were much lighter than atoms. This was the first strong experimental evidence that atoms were divisible and had internal structure. After this discovery, in 1904,  J.J. Thomson  proposed a concrete atomic model to explain how these ele...
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Describe what happens when a nonsense mutation is introduced into the gene encoding transposase within a transposon

Transposons,  also known as  jumping genes,  are segments of DNA that can move from one position in the genome to another. This movement depends on a special enzyme called  transposase,  which is produced by a gene located inside the transposon itself. The transposase enzyme performs important functions like cutting the transposon from one place and helping it to insert into another. For the transposon to move, the transposase must be produced correctly and completely. When a  nonsense mutation  occurs in the transposase gene, it replaces a codon that normally codes for an amino acid with a  stop codon.  This causes the ribosome to stop protein synthesis early, resulting in a shortened and usually non-functional transposase enzyme. This leads to several important changes inside the cell. These changes are mainly: 1. Early Termination of Transposase Production The nonsense mutation introduces a premature stop codon in the transposase gene. Thi...
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Describe the components of the promoter region of a eukaryotic gene

In eukaryotic genes, the promoter region is a special stretch of DNA that lies just before the gene. Its main job is to control when and where transcription starts. It does this by providing binding sites for RNA polymerase II and other transcription factors. The promoter region can be divided into two main parts: Core Promoter Proximal Promoter Elements Each of these parts has different types of DNA sequences that help start and regulate transcription. 1. Core Promoter This is the most essential part of the promoter and lies near the transcription start site  (called the +1 position).  It directly helps in assembling the transcription machinery. The core promoter usually includes the following elements: TATA Box: A short DNA sequence (TATAAA) usually located 25–35 base pairs upstream from +1 site. It helps in positioning  RNA polymerase II.  A special protein called TBP (TATA-binding protein) binds here to start the transcription complex. Initiator (Inr) Sequence: F...
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PYQ – MZOE-001: Parasitology (Solved Q&A) | MZOE-001 | MSCZOO | M.Sc.Zoology | IGNOU | December 2024

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M.Sc. (Zoology) (MSCZOO) Term-End Examination December, 2024 MZOE-001 : PARASITOLOGY Time : 2 Hours| Maximum Marks : 50 Note: (i)  Attempt any five questions.            (ii) All questions carry equal marks. 1. (a) What are endoparasites? Give any two examples. (2 Marks) Endoparasites are parasites that live inside the body of their host. They usually infect internal organs like the intestine, liver, lungs, or blood. These parasites depend on the host for nutrients and often cause harm by damaging tissues, stealing nutrients, or releasing toxins. They are commonly found in vertebrates, including humans and may be transmitted through contaminated food, water, or direct contact. Examples: 1. Taenia solium (pork tapeworm) – It lives in the human intestine and causes taeniasis. 2. Plasmodium vivax – A blood parasite that causes malaria in humans, transmitted by female Anopheles mosquitoes. (b) What is the difference between mechanical vector and biologic...
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What are transcription factors? Describe the different categories of transcription factors

Transcription factors are special types of proteins that control the process of  transcription  in eukaryotic cells. Transcription is the first step of gene expression where the DNA is copied into RNA. These factors do not make RNA directly but help the enzyme RNA polymerase to start, stop or control the speed of this process. Transcription factors help the cell know when to turn a gene ON, when to turn it OFF and how much product the gene should make. They play a very important role in development, cell cycle, cell differentiation, stress response and hormone signaling. Transcription factors are mainly divided into two broad categories: Based on their function Based on their structure and DNA-binding domain 1. Types Based on Their Function There are the following two types: a) General Transcription Factors These transcription factors are needed for the transcription of almost all protein-coding genes. They help in forming the transcription initiation complex near the promoter...
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How is the organisation of genes different between prokaryotes and eukaryotes?

The organisation of genes in prokaryotes and eukaryotes is quite different due to their structural, functional and evolutionary differences. These differences are seen in the way genes are arranged on the DNA, how they are regulated and how they are transcribed and translated. Below is a detailed explanation of their gene organisation based on major points: 1. Arrangement of Genes Prokaryotes: Genes are often arranged in clusters called  operons.  An operon is a group of genes under the control of a single promoter and transcribed together as one mRNA. These genes usually have related functions. For example, the lac operon in E. coli includes genes required for lactose metabolism. Eukaryotes: Genes are usually arranged individually. Each gene has its own promoter, enhancer and regulatory elements. Eukaryotic genes are not usually grouped by function. They are transcribed separately into different mRNAs. 2. Coding and Non-coding Regions Prokaryotes: Their genes are mostly made ...
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