- Blood Circulatory System
- Blood
- Bones of The Legs
- Bones of The Foot
- Bones of The Ankle
- Bones of Pelvis
- Blood Groups
- Scientific Name of Human Being
- Largest Organ In Human Body
- Largest Internal Organ in The Human Body
- Human Respiratory System
- Human Population
- Human Physiology
- Human Life Cycle
- Human Insulin
- Human Impact on the Environment
- Human Heart
- Human Health and Diseases
- Human Genome Project Goals Significance
- Human Excretory System
- Human Evolution Progress
- Human Ear
- Human Diseases
- Human Digestive System
- Human Circulatory System Transportation
- Anatomy and Physiology of the Human Body
- Effects of Air Pollution on Human Health
Difference between
- Difference between Turner Syndrome and Klinefelter Syndrome
- Difference Between Transpiration and Guttation
- Difference Between Transpiration and Evaporation
- Difference Between Tracheids and Vessels
- Difference Between Thorns and Spines
- Difference Between T Cells and B Cells
- Difference Between Sympathetic and Parasympathetic
- Difference Between Sporophyte and Gametophyte
- Difference Between Spermatogenesis and Oogenesis
- Difference Between Sperm and Ovum
- Difference between Species, Population, and Community
- Difference Between Sleep and Hibernation
- Difference Between Saturated and Unsaturated Fats
- Difference Between Rust and Smut
- Difference Between Right and Left Lung
- Difference Between Replication and Transcription
- Difference Between Renewable and Non Renewable Resources
- Difference Between Red and White Muscle
- Difference Between Radicle and Plumule
- Difference Between Prokaryotic and Eukaryotic Transcription
- Difference Between Plasma and Serum
- Difference Between Pharynx and Larynx
- Difference Between Organs and Organelles
- Difference Between Open and Closed Circulatory Systems
- Difference Between Ocean and Sea
- Difference Between Monocytes and Lymphocytes
- Difference Between Mitochondria and Chloroplast
- Difference Between Lytic and Lysogenic Cycle
- Arteries and Veins Difference
Cell
- Growth and Development of an organism
- Meiosis Cell Division
- Cellular Respiration Concept Map
- Cell Signalling
- Cell Organelles
- Cell Cycle and Cell Division
- Cell Biology
Energy, Enzymes and membrane
Plant
- Scientific Names of Animals and Plants
- Plant Respiration
- Plant Physiology
- Plant Life Cycle and Alternation of Generations
- Plant Kingdom Plantae
- Plant Growth Regulators
- Plant Fibres
- Mendelian Inheritance Using Seeds of Different Colours Sizes of Any Plant
- Grassland Dominant Plants
- Effects of Air Pollution on Plants
- Biodiversity In Plants and Animals
Botanical Name
- Mustard Botanical Name
- Marigold Botanical Name
- Chilli Botanical Name
- Botanical Name of Tea
- Botanical Name of Sugarcane
- Botanical Name of Soybean
- Botanical Name of Rose
- Botanical Name of Rice
- Botanical Name of Pea
- Botanical Name of Lady Finger
- Botanical Name of Groundnut
- Botanical Name of Grapes
- Botanical Name of Coffee
- Botanical Name of Cabbage
- Botanical Name of Banyan Tree
- Botanical Name of Bajra
Biodiversity
- Biodiversity Pattern Species
- Biodiversity Conservation
- Biodiversity and Conservation Concept Map
- Biodiversity
Symptoms, diseases
- Hormones Heart Kidney GI
- Blood Cancer
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- Aids and Hiv
- Nervous System Diseases
- Modes of Transmission of Diseases
- Migraine Symptoms
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- Lysosomal Storage Disease
- Lung Diseases
- Lung Cancer Symptoms
- Hyperthyroidism Symptoms
- Hypertension Symptoms
- Chicken Pox Symptoms
- Blood Pressure Symptoms
- Arthritis Symptoms
- Appendicitis - Formation, Symptoms, Treatment
- Anemia Symptoms
- Acidity Symptoms Causes and Risk Factors involved
Causes
Other Topics
Bio Articles (Alphabetic order)
- Antigens and Immunology
- Scientific Name of Vitamins
- Scientific Name of Neem
- Schistosomiasis Life Cycle
- Scabies Life Cycle
- Salient Features of The Kingdom Monera
- Saddle Joints
- Root Modifications
- Role of Microbes In Food Processing
- RNA: World Genetic Material
- Rna Interference
- Ringworm
- Rigor Mortis
- Retrovirus
- Respiratory Quotient
- Respiratory and Lung Volumes
- Adolescence Secondary sexual characteristics
- Prolactin Hormone
- Productivity In Ecosystem
- Prions
- Principles of Treatment
- Principles of Prevention
- Principles of Inheritance and Variation
- Principles of Genetics
- Primary Ciliary Dyskinesia
- Prepare Pedigree Charts of Any One of the Genetic Traits Such as Rolling Of Tongue, Blood Groups, Ear Lobes, Widow’s Peak and Colour Blindness
- Prepare A Temporary Mount of The onion Root Tip To Study Mitosis
- Preparation and Study of Transverse Section of Dicot and Monocot Roots and Stems
- Pregnancy Parturition Lactation
- Neural Control and Coordination
- Nervous Tissue
- Nervous System Definition
- Nervous System Coordination
- Nervous System
- Nerves
- Nephron Function Renal Tubules
- Nephritis
- Nematoda
- Need For Hygiene and Sanitation
- Natural Selection Biological Evolution
- Natural Disasters
- National Parks and Sanctuaries
- Mycology
- Myasthenia Gravis
- Mutualism
- Mutation Genetic Change
- Mutagens
- Muscular Dystrophy
- Muscle Contraction Proteins
- Mountains and Mountain Animals
- Morphology and Anatomy of Cockroach
- Monohybrid Cross - Inheritance of One Gene
- Molecular Basis of Inheritance
- MOET Technology - Multiple Ovulation Embryo Transfer Technology
- Modern Synthetic Theory of Evolution
- Miller Urey Experiment
- Micturition - Urination Process
- Microfilaments
- Microbodies
- Metabolism Metabolic Pathways
- Metabolism Living State Basis
- Mendelian Disorders
- Melatonin Hormone
- Meiosis Phases
- Meiosis I - Stages and Process
- Megafauna
- Measles
- Mayfly Life Cycle
- Mass Flow Hypothesis
- Mass Extinctions
- Marine Biology
- Mammalia Diversity In Living Organisms
- Malthusian Theory of Population
- Male Sex Hormone
- Macromolecule
- Luteinizing Hormone
- Lung Cancer
- Love Hormone
- Locust Life Cycle
- Lizard Life Cycle
- Living Fossil
- Lipoproteins
- Lipids
- Lipid Peroxidation
- Linkage Recombination
- Life Cycle of Living Organism
- Lice Life Cycle
- Leprosy
- Length of Epididymis
- Leishmania Life Cycle
- Leg Muscles
- Law of Segregation and Law of Dominance
- Law of Independent Assortment
- Hypothyroidism
- Hypothalamus
- Hypogeal Germination
- Hypocalcaemia
- Hypertension
- Hyperparathyroidism
- Hydroponics
- Hydrarch Succession
- Horses and Donkeys Same Species
- Hormonal Disorders
- Hormones Secreted by Non-Endocrine
- Hookworm Life Cycle
- Honey Bee Life Cycle
- Homo erectus
- Homeostasis
- History of Clothing Material
- Characteristics and classification of Gymnosperms
- Guttation
- Griffith Experiment: The Genetic Material
- Grazing Food Chain
- Grasshopper Life Cycle
- Gram Positive Bacteria
- Gout
- Gonorrhea
- Gonads
- Goiter
- Embryology
- Embryo Development
- Elisa Technique
- Electron Transport Chain
- Electrocardiograph
- Effects of Water Pollution
- Effects of Waste Disposal
- Effects of Wastage of Water
- Effects of Plastics
- Life Cycle of Chicken
- Chemotrophs
- Chemiosmotic Hypothesis
- Centromere
- Central Dogma Inheritance Mechanism
- Cartilaginous Joints
- Carnivores and Herbivores
- Cardiac Output
- Carbon Cycle
- Carbohydrate Metabolism
- Can a Community Contain Two Populations of the Same Species?
- Bt Crops
- Bryophyta
- Blastocyst
- Bird Life Cycle
- Biotechnology Jobs
- Biotechnology Agriculture
- Biosafety Issues
- Bioreactor Obtaining Foreign Gene
- Biopiracy
- Biomolecules In Living Organisms
- Biomes of The World
- Biomass Definition Ecology
- Biofortification
- Asteraceae Brassicaceae Poaceae
- Ascaris Life Cycle
- Artificial Pollination
- Archaebacteria
- Apoptosis Definition, Pathway, Significance, and Role
- Apoplast and symplast pathway
- AntiMullerian Hormone (AMH)
- Antimicrobial Resistance
- Antibiotics
- Ant Life Cycle
- Annelida Meaning, Classification, Types, and FAQs
- Animal Nervous System
- Animal Kingdom Concept Map
- Animal Kingdom : Animalia Subphylum
- Animal Kingdom
- Animal Husbandry: Types and Advantages
- Animal Husbandry and Poultry Farming & Management
- Angina Pectoris
- Anatomy and Morphology of Animal Tissues
- Anagenesis
- An overview of Anatomy, its types and their applications
- Amphibolic Pathway
- Amphibia
- Amoebiasis
- Ammonotelism
- Ammonification
- Amino acids Properties, Functions, Sources
- Amensalism
- Alternatives To Dams
- Allergies Autoimmunity
- Allee Effect
- Alimentary Canal Anatomy
- Algae Definition, Characteristics, Types, and Examples
- Alcohol and Drug Abuse Measures for Prevention and Control
- Air Pollution Definition, Causes, Effect and Control
- Agriculture Seeds Selection Sowing
- Agriculture Practices - Organic Farming & Irrigation
- Agriculture Fertilizers
- Agricultural Implements and Tools
- Aerobic and Anaerobic Respiration Major Differences
- Advantages of Dams
- Adolescence and Drug Abuse
- Adh Hormone
- Adaptive Radiation Evolution
- Acth Hormone
- Acromegaly Causes, Symptoms, Treatment
- Acquired and Inherited Traits
- Acoustic Neuroma Symptoms, Causes, Diagnosis
Reproduction is the reason for pfe’s continued existence on the face of Earth. Every organism needs to be able to reproduce so that it can classify as a pving being. Even viruses, whose pving nature has been debated for decades, can reproduce in the host’s body. The molecular basis of pfe, i.e., the DNA, needs to be reppcated for the reproduction of an inspanidual. There are two modes of cell spanision, namely, mitosis and meiosis, both of which lead to duppcation of the DNA.
Essentially, mitosis is a form of asexual reproduction wherein two genetically and morphologically identical inspaniduals are produced. Meiosis, on the other hand, defines sexual reproduction. If all organisms did reproduce by asexual reproduction, there would hardly be any variations among populations, and nature would not have been this spanerse! Meiosis allows for variations to occur in pving organisms and this is not only important to maintain biological spanersity but to also help organisms adapt and evolve.
Heredity and Accumulation of Variation During Reproduction
Heredity refer to the passing over of characters from the parent to the offspring. Variations in sexually-reproducing species result from three genetic processes− mutations, independent segregation of chromosomes, and genetic recombinations. Let s address these processes one by one.
Mutations − They are the random changes in the genes of any organism and can be a result of physical, chemical, or biological factors. These changes lead to the production of different forms of the same gene (i.e., alleles) among different inspaniduals of the same species. In asexually reproducing organisms, a mutation simply passes on to the next generation during mitosis.
However, in sexually-reproducing organisms, these mutations are incorporated and then are subjected to further reshuffpng during sexual reproduction.
Independent assortment of chromosomes.
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Diploid eukaryotes contain homologous pairs of chromosomes. One member of the pair is inherited from the mother and contains a particular set of alleles, the other from the father and contains a different set of alleles. During meiosis, these homologous pairs of chromosomes separate, and the members of the pair are segregated into a different daughter nucleus, resulting in haploid gametes. What each gamete receives is random and independent of the other pairs of chromosomes. The Independent assortment of chromosomes serves as the basis for classical genetics.
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Each parent has a particular set of characteristics that are encoded in the chromosomes of their gametes. The diploid inspanidual thus formed has features that it has inherited from both the parents. There are more than 8 milpon possible combinations across the 23 pairs of chromosomes in humans. Hence, no two homologous pairs in an inspanidual are ever the same! Further, this explains the genetic variations are seen in sibpngs, all of whom inherit their characters from the same parents, but what alleles they inherit are different.
Chromosomal crossing over.
Interestingly, just before the separation of homologous chromosomes occurs, the homologous chromosomes undergo the event of “chromosomal crossing over” which results in the recombination of genes on the chromosomes. During recombination, alleles of one chromosome are swapped with those of the other homologue. Chromosomal crossing over enhances the chances of variation in sexually reproducing organisms.
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The cumulative effect of the events of mutations, independent assortment, and crossing over is the accumulation of a plethora of variations which are not possible during asexual reproduction.
Why is it Important to have Variations?
Variation is an indispensable part of expanding the gene of a population. It leads to increased genetic spanersity. In fact, heredity, coupled with the variation of the inheritable genes (i.e., “descent with modification”), is the basis for the entire evolutionary history of the earth!.
Heredity and variations are the basis for.
Diversified generations of the same pneages.
The evolutionary advantage in adverse conditions.
Adaptations of organisms .
Evolution of new species.
For tracing the evolutionary history and classification of an organism s.
Molecular basis of inheritance (DNA and RNA)
Mendel’s experiments with garden peas were a setting stone in genetics. He knew that some “factor” was responsible for the characteristics observed in organisms and each of these factors had two “variants”, only one of which was passed down from each parent to the offspring. However, he wasn’t aware of what this factor was.
Certain ground breaking experiments, including those by Fredrick Griffith (1928), Averty, MacLeod, and McCarty (1944), and by Hershey and Chase (1952) laid conclusive evidence that it is certainly the DNA, and not the RNA or proteins, which is the molecular basis of inheritance.
Nucleic acids (DNA, Deoxyribonucleic Acid and, RNA, Ribonucleic Acid) are the basis for the continuity of pfe. The DNA bears the information in the form of genes that are passed from the parent to the offspring. In eukaryotes, DNA is present in the nucleus and is organized into chromosomes. Each chromosome contains genes that encode specific characters for the inspanidual. Depending upon what variant of a particular gene (i.e., what allele) is present on the chromosome, the phenotypic traits between inspaniduals vary for that character.
Differences between the DNA and the RNA
Each DNA or RNA molecule is a polymer of single units known as nucleotides. Hence, the nucleic acids are polynucleotide molecules. Each nucleotide monomer contains.
A nitrogenous base (Adenine, Guanine, Cytosine or Thymine. Note that in RNA, Thymine is replaced by Uracil).
A ribose sugar (Deoxyribose sugar in DNA, Ribose sugar in RNA).
A phosphate group.
DNA | RNA |
---|---|
Comprises two polynucleotide strands, coiled around a common axis in a right-handed manner | SIngle polynucleotide strand |
Adenine pairs with Thymine | Adenine pairs with Uracil |
Cytosine pairs with Guanine | Cytosine pairs with Guanine |
Contains a 2’-deoxyribose sugar | Contains a ribose sugar |
Carries hereditary information in the form of nucleotide segments known as genes | Translates the gene transcripts (mRNA) from DNA into proteins |
While DNA is the inheritable genetic material in all pving organisms, there are few viruses which carry the RNA as their genetic material.
Conclusion
This is seen under the following conditions −.
Heredity is the transfer of characters from parents to offspring.
Variation refers to the differences among inspaniduals of any species. It may due to genetic or environmental reasons.
Variations accumulate during sexual reproduction during the events of independent assortment of chromosomes and crossing over.
Independent assortment of chromosomes ensures random inheritance of characteristics from the parents.
Crossing over and recombination is imperative in constructing new genetic combinations and variations among inspaniduals of the same species.
Variations are important for adaptation and evolution of species, for enhancing the biospanersity, and for.
DNA is the molecular basis of the inheritance of all organisms and carries information in the form of genes. Each gene has variant forms known as alleles which adds to the genetic variation across different inspaniduals.
FAQs
Q1. How does the genetic composition of gametes determine the sex of humans?.
Ans. In humans, sex is determined by the sex chromosomes. Males have the XY combination of sex chromosomes (one X from the mother and the Y from the father) while females carry the XX chromosome pair (one X chromosome from each parent).
Q2. Are both parents always involved in the inheritance of all characters?.
Ans. No. There are some traits, especially some diseases that are sex-pnked and can be present on the sex chromosomes. Moreover, we know that the mitochondria have their DNA. This mitochondrial DNA is in fact, inherited from the mother ONLY. In the inheritance of all other nuclear traits, both parents are involved.
Q3. What is meant by sex-pnked traits?.
Ans. The sex chromosomes don’t just determine the gender of an inspanidual. They carry other alleles which encode traits such as colour bpndness, haemophipa, etc.
Q4. What does the term somatic variation mean?.
Ans. An offspring acquires or inherits its genetic information from its parents. However, during the development of the zygote its somatic (non-gametic) cells may acquire mutational changes which are not integrated into the germpne. These traits will not be inherited by the inspanidual’s offspring.
Q5. Does crossing over always result in genetic variations?.
Ans. Crossing over may occur between the same allele of a gene, on the non-sister chromatids of a homologous pair. In such a case, crossing over may happen but it won t lead to any new variation unless the alleles on both chromosomes are different.