11.4. Evolutionary implications of mutations

Mutations and evolution

The mutations have occurred over time, by causes natural as radiation from the sun or minerals from the earth's crust. Although they are not very frequent, since they cover very large periods of time and very large populations, the probability that a mutation will appear is considerable.

Most are lethal and disappear with their carriers, but when they are beneficial they remain in the individuals of the population and are transmitted to their offspring. If natural selection acts on these genotypesand they are favorable to those environmental conditions, it can even become incorporated as a single homozygous character, making the old normal character of the population disappear. If the mutation is harmful, if they are recessive, they will remain in the population.

If the mutation is beneficial, it can improve the function of the enzyme it encodes, for example, by improving biological activity, facilitating the life of the organism that carries that mutation.

Neutral mutations neither improve nor harm the conditions of the individual who is the carrier of the mutated gene, but can be passed on to descendants. It can serve as a biological clock to know how long two species have separated since they had a common ancestor.

All cells can suffer some mutation, but the mutations that affect the gametes will affect the zygote that is formed after fertilization with another gamete and the cells that derive from it to form the new multicellular being. In addition, he will transmit the mutation to his descendants. Therefore, beneficial germline mutations will be those that cause the evolution of the species. The individual carrying the mutation has an advantage over those who do not have it, so they will be more likely to have offspring and transmit this advantageous characteristic to their descendants.

Harmful mutations only remain in the population when they are recessive. If the mutation occurs in a somatic (non-germ) cell, it will not be passed on to offspring.

When mutations appear in a certain population, the genotype changes from generation to generation, appearing individuals with characteristics different from those of their predecessors. This is how the population evolves, being able to originate new species. An example is bacteria that evolve after being subjected to antibiotics, becoming resistant.

Mutations that are detrimental to the carrier individual will be eliminated by natural selection.

In addition to natural selection, man has made artificial selection on domestic plants and animals, modifying them according to his own interest. It has achieved this by selecting the most productive individuals and crossing them with each other, obtaining different breeds, as in the dog, for example.

The evolution occurs because people change their "pool" gene, the set of genes formed by all allelesexist among individuals. If an individual has the most favorable alleles, he has an advantage over the rest, being able to survive more easily. Thus, it is more likely that it is reproduced and that these genes remain in the population.

Although mutation is the primary source of variation, it is not the only one. The gene recombination contributes to the variability gene in sexually reproducing organisms.

The evolution of species occurs because the changes produced by genetic mutations accumulate. Most mutations are harmful and their carriers die, but those that produce an improvement remain in the species and are essential in the evolutionary process.

When there is a separation between some members of a population, their genetic exchange is interrupted. Being in different environments, this differentiation is becoming more and more noticeable. With the passage of time, their genetic differences will be so great that they will have become different species, being unable to reproduce among them.

Factors involved in biological evolution

The gene pool of a population is made up of all the alleles of the individuals in the population. For evolution to occur, there must be genetic variability among individuals in a population, and that genetic variety can be inherited by future generations.

The factors that produce alterations in the gene and genotypic frequencies of certain alleles and, therefore, in the composition of the genes that make up the population are:

Natural selection

The natural selection acts when the selected environment those individuals best adapted to these environmental conditions. Those with those genes that are best adapted to the changes that take place will be the ones that will have the easiest survival and reproduction, and can pass these genes on to their descendants.

Mutations

The mutations occur when, due to an error in the process of DNA replication, there are changes in the sequence of nucleotides of the DNA and new alleles are generated. Mutations are random and are the main cause of genetic variability. The only heritable mutations are those that affect the gametes and can be harmful, neutral, or beneficial.

Crossover and genetic recombination

Gametes are produced through meiosis. In Prophase I, genetic crossover and recombination occurs between paternal and maternal genes, favoring variability. Furthermore, the randomness in the union of gametes further increases the variability.

Genetic drift

The genetic drift is the random fluctuation of the allelic frequencies occurs generation after generation. The effects of genetic drift are strongest in small populations, where genetic variability decreases markedly. For instance:

Founder effect: when some individuals of a population are isolated from the original population they reproduce and transmit their alleles to their descendants. Possibly, the gene frequencies of that group are not the same as those of the original population. For example, the Amish, a group that only had 12 founders of which only one had a gene that caused the combination of dwarfism and polydactyly, and at present, that allele is carried by 13% of the population of that group.
Bottleneck effect: when there is a sharp decrease in the number of individuals in a population, due to some type of natural or human disaster, the individuals that survive have different allelic frequencies than the original population.

Migrations or gene flow

The migratory flows make the population acquires greater genetic variability, as new alleles from other populations, are incorporated into the gene pool of the population.

Reproductive or genetic isolation

When a population or group of individuals in a population is reproductively isolated from the rest of the individuals by barriers that prevent it, such as differences in behavior, habitats, etc., the speciation process can take place and a new species can emerge.

Questions that have come out in University entrance exams (Selectividad, EBAU, EvAU)

Aragon. September 2018, option A, question 4. September 2014, option B, question 1.

Mutations (2.5 points)

d) Relationship of mutations with evolution. (0.75 points)

Aragon. June 2016, option B, question 4.

Mutations: (2 points)

c) Are mutations random or directed toward a specific change? Reason for the answer. (0.5 points)

d) Why are mutations the basis of selection in species? (0.5 points)

Aragon. September 2015, option B, question 4.

Mutations (2 points)

b) Indicate the meaning of the mutations from the evolutionary point of view. (0.5 points)

Aragon. June 2010, option A. 4 .

About the processes of mutation and evolution: (2 points)

a) What is biological evolution?

b) What is the cause of genetic variability in organisms with asexual reproduction?

c) What is the cause of genetic variability in organisms with sexual reproduction?

Aragon. June 2007, option A. Question 4 .- (1 point).

Explain the implications of mutations in the evolution of living things.

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Skip navigation Biology 2nd Baccalaureate Biology 2nd Bac. 1. Bioelements and biomolecules. Water and mineral salts 1.1. Chemical bonds in biology 1.1.1. Intramolecular bonds 1.1.1.1. Covalent bond 1.1.1.2. Ionic bond 1.1.2. Intermolecular bonds 1.1.2.1. Van der Waals forces 1.1.2.2. Hydrogen bonds 1.2. The chemical basis of life: inorganic and organic components 1.2.1. Primary bioelements 1.2.2. Secondary bioelements 1.2.3. Trace elements 1.3. The immediate principles or biomolecules 1.3.1. Water 1.3.1.1. Chemical structure of water 1.3.1.2. Properties and functions of water 1.3.2. Mineral salts 1.3.2.1. Functions of salts in solution 1.3.2.2. Colloidal solutions and dispersions 1.3.2.3. Properties of colloidal dispersions 1.3.2.4. Diffusion, osmosis and dialysis 1.3.2.4.1. Diffusion 1.3.2.4.2. Osmosis 1.3.2.4.3. Dialysis 1.4. Bibliography 2. Glucides 2.1. Glucid concept 2.2. Classification of carbohydrates 2.3. Monosaccharides 2.3.1. Trioses 2.3.1.1. Spatial isomerism or stereoisomerism 2.3.2. Tetroses 2.3.3. Pentoses 2.3.3.1. Monosaccharide cyclization 2.3.4. Hexoses 2.4. The N-glucosidic and O-glucosidic bonds 2.4.1. Substances derived from monosaccharides 2.5. Disaccharides 2.6. Polysaccharides 2.6.1. Homopolysaccharides 2.6.1.1. Reserve homopolysaccharides 2.6.1.2. Structural homopolysaccharides 2.6.2. Heteropolysaccharides 2.6.3. Heterosides 2.7. General functions of glucides 2.8. Bibliography 3. Lipids 3.1. Lipid concept 3.2. Classification of lipids 3.2.1. Fatty acids 3.2.1.1. Saturated and unsaturated fatty acids 3.2.1.2. Chemical properties of fatty acids 3.2.1.3. Physical properties of fatty acids 3.2.1.4. Fatty Acid Functions 3.2.2. Saponifiable lipids or with fatty acids 3.2.2.1. Simple lipids 3.2.2.1.1. Acylglycerides 3.2.2.1.2. Cerides 3.2.2.2. Complex lipids 3.2.2.2.1. Phospholipids 3.2.2.2.2. Glycolipids 3.2.3. Unsaponifiable lipids or without fatty acids 3.3. Lipid functions 3.4. Bibliography 4. Proteins 4.1. Introduction to proteins 4.2. Amino acids 4.2.1. Classification of amino acids 4.2.2. Properties of amino acids 4.3. The peptide bond 4.4. Protein 4.4.1. Protein structure 4.4.1.1. Primary structure of proteins 4.4.1.2. Secondary structure of proteins 4.4.1.3. Tertiary structure of proteins 4.4.1.4. Quaternary structure of proteins 4.4.2. Protein properties 4.4.3. Classification of proteins 4.4.3.1. Holoproteins 4.4.3.2. Heteroproteins 4.4.4. Protein functions 4.5. Enzymes 4.5.1. Structure of enzymes 4.5.2. The active center of enzymes 4.5.3. General Mechanism of Enzyme Catalysis 4.5.4. Regulation of enzyme activity 4.5.5. Allosteric enzymes 4.5.6. Nomenclature and classification of enzymes 4.6. The vitamins 4.6.1. Fat-soluble vitamins 4.6.2. Water soluble vitamins 4.7. Bibliography 5. Nucleotides and nucleic acids 5.1. The chemical composition of nucleic acids 5.1.1. Components of nucleic acids 5.1.2. Concept, types and functions of nucleic acids 5.1.3. Nucleosides 5.1.4. Nucleotides 5.1.4.1. Nucleotide functions 5.1.5. Nucleic acids 5.2. Deoxyribonucleic acid (DNA) 5.2.1. DNA structure 5.2.1.1. Primary structure of DNA 5.2.1.2. Secondary structure of DNA 5.2.1.3. Tertiary structure of DNA 5.2.1.3.1. Tertiary structure of DNA in prokaryotes 5.2.1.3.2. Tertiary structure of DNA in eukaryotes 5.2.1.4. Quaternary structure of DNA 5.2.2. DNA types 5.2.3. Genetic material: chromatin and chromosomes 5.2.3.1. Karyotype and karyogram 5.3. Ribonucleic acid (RNA) 5.3.1. RNA types 5.3.1.1. Transfer RNA 5.3.1.2. Messenger RNA 5.3.1.3. Ribosomal RNA 5.3.1.4. Nucleolar RNA 5.3.1.5. Small nuclear RNA 5.3.2. Functions of ribonucleic acids 5.4. Bibliography 6. Cell morphology 6.1. Cell concept 6.1.1. Cell history 6.1.2. Cell theory 6.2. Levels of cellular organization 6.2.1. General characteristics of cells 6.2.2. Prokaryotic cells 6.2.2.1. Prokaryotic cell morphology 6.2.2.2. Structure of prokaryotes 6.2.2.2.1. Bacterial capsule 6.2.2.2.2. Bacterial wall 6.2.2.2.3. Plasma membrane 6.2.2.2.4. Cytoplasm-Ribosomes-Inclusions 6.2.2.2.5. Bacterial DNA 6.2.2.2.6. Bacterial appendages 6.2.2.3. Bacteria Physiology 6.2.3. Eukaryotic cells 6.2.3.1. Animal and plant cell 6.2.3.1.1. Animal eukaryotic cell 6.2.3.1.2. Plant eukaryotic cell 6.2.3.2. Cell Evolution: Endosymbiont Theory 6.3. Size, shape and quantity 6.4. The plasma membrane 6.4.1. Chemical composition of the membrane 6.4.2. The structure of the membrane. The fluid mosaic model 6.4.3. Functions of the plasma membrane 6.4.4. Transport across the membrane 6.4.4.1. Small molecule transport 6.4.4.2. Macromolecule transport 6.4.5. Plasma membrane differentiations 6.5. The cell wall of plant cells 6.5.1. Chemical composition of the cell wall 6.5.2. Cell wall structure 6.5.3. Cell wall differentiations 6.5.4. Cell wall functions 6.6. Extracellular matrix or glucocalyx 6.7. Cytosol or hyaloplasm 6.8. The cytoskeleton 6.8.1. Microfilaments or actin filaments 6.8.2. Intermediate filaments 6.8.3. Microtubules 6.9. Cell membrane and organelle systems 6.9.1. Membrane systems 6.9.1.1. The endoplasmic reticulum 6.9.1.2. Golgi apparatus 6.9.2. Cell organelles 6.9.2.1. Lysosomes 6.9.2.2. Peroxisomes 6.9.2.3. Vacuoles 6.9.2.4. Mitochondria 6.9.2.4.1. Functions of the mitochondria 6.9.2.5. Plastids 6.9.2.5.1. Chloroplasts 6.9.2.6. Ribosomes 6.9.2.7. Centrosome 6.9.2.8. Cilia and flagella 6.10. Cell motility 6.11. The cell nucleus 6.11.1. Characteristics of the cell nucleus 6.11.2. The interphase nucleus 6.11.3. The mitotic nucleus or nucleus in division 6.12. Bibliography 7. Metabolism 7.1. Metabolism 7.1.1. Energetic Aspects of Cellular Chemical Reactions 7.2. Catabolism 7.2.1. Catabolism and obtaining energy 7.2.2. Carbohydrate catabolism 7.2.2.1. Glycolysis 7.2.2.2. Cellular respiration 7.2.2.2.1. Oxidative decarboxylation 7.2.2.2.2. Krebs cycle 7.2.2.2.3. Electron transport chain 7.2.2.2.4. Energy balance of cellular respiration 7.2.2.3. Fermentations 7.2.2.3.1. Alcoholic or ethyl fermentation 7.2.2.3.2. Lactic fermentation 7.2.2.3.3. Other types of fermentations 7.3. Anabolism 7.3.1. Autotrophic anabolism 7.3.2. Photosynthesis 7.3.2.1. Photochemical or light phase 7.3.2.1.1. Photosystems 7.3.2.1.2. Photophosphorylation 7.3.2.1.2.1. Non cyclic photophosphorylation 7.3.2.1.2.2. Cyclic photophosphorylation 7.3.2.2. Biosynthetic or dark phase 7.3.2.3. Factors influencing photosynthesis 7.3.2.4. Products of photosynthesis 7.3.3. Chemosynthesis 7.4. Bibliography 8. Cell reproduction 8.1. The cell cycle 8.1.1. Interphase 8.1.2. Cellular division 8.2. Cellular division 8.2.1. Mitosis 8.2.1.1. Prophase 8.2.1.2. Metaphase 8.2.1.3. Anaphase 8.2.1.4. Telophase 8.2.1.5. Cytokinesis 8.2.1.6. More on mitosis 8.2.2. Meiosis 8.2.2.1. Meiosis I 8.2.2.2. Meiosis II 8.2.3. Meiosis and sexual reproduction 8.2.4. Meiosis and life cycle 8.2.5. Biological importance of meiosis 8.3. Differences and similarities between mitosis and meiosis 8.4. Bibliography 9. Classical genetics 9.1. Genetics basics 9.2. Mendelian genetics 9.2.1. The method 9.2.2. Mendel's Laws 9.2.2.1. Mendel's first law or principle of uniformity in the first generation 9.2.2.2. Mendel's second law or principle of segregation 9.2.2.2.1. Backcross and test crossover 9.2.2.3. Mendel's third law or principle of independent combination 9.3. Gene interaction 9.3.1. Gene interaction between allelic genes 9.3.2. Gene interaction between non-allelic genes that influence for the same trait 9.4. Chromosomal theory of heredity 9.5. Ligation and recombination 9.6. Complex mendelism 9.6.1. Multiple allelism 9.6.1.1. Lethal genes 9.6.2. Pleiotropy 9.6.3. Expressiveness and genetic penetrance 9.7. Sex-linked inheritance 9.7.1. Y-linked inheritance 9.7.2. X-linked inheritance 9.8. Heredity influenced by sex 9.9. Bibliography 10. Molecular genetics 10.1. DNA as hereditary material 10.2. DNA replication 10.2.1. The need for DNA replication 10.2.2. First hypotheses about DNA duplication 10.2.3. Meselson and Stahl experiment 10.2.4. The sense of growth of the new strands 10.2.5. Mechanism of DNA replication 10.2.5.1. Replication in prokaryotes 10.2.5.2. Replication in eukaryotes 10.2.6. Error correction 10.2.7. Enzymes involved in replication 10.3. Gene concept 10.4. "One gene-one enzyme" theory 10.5. Transcription 10.5.1. Mechanism of transcription 10.5.1.1. Transcription in prokaryotes 10.5.1.2. Eukaryotic transcription 10.6. Translation or protein biosynthesis 10.6.1. The genetic code 10.6.2. Mechanism of translation of RNA to proteins 10.6.2.1. Translation in eukaryotes 10.7. Regulation of gene expression 10.8. Bibliography 11. Genetics and evolution 11.1. Mutations 11.2. Types of mutations 11.2.1. Gene or point mutation 11.2.2. Chromosomal or structural mutation 11.2.3. Mutation at the genomic level 11.3. Causes of mutations 11.4. Evolutionary implications of mutations 11.5. Metabolic implications of mutations 11.6. Bibliography 12. Microbiology and biotechnology 12.1. Microbiology 12.2. Viruses 12.2.1. Viral morphology 12.2.2. Viral physiology 12.2.2.1. Lytic cycle 12.2.2.2. Lysogenic cycle 12.2.2.3. Cycles of viruses of special interest 12.2.2.3.1. Flu virus life cycle 12.2.2.3.2. Life cycle of the AIDS virus 12.3. Other acellular forms 12.3.1. Viroids 12.3.2. Prions 12.4. Biotechnology 12.5. Bibliography 13. Immunology 13.1. Infection concept 13.2. Defense mechanisms against infections 13.2.1. Nonspecific mechanisms 13.2.1.1. Primary barriers: external defenses 13.2.1.2. Secondary barriers: internal defenses 13.2.2. Specific mechanisms 13.3. Immunity and immune system 13.3.1. Components of the immune system 13.3.2. Concept and nature of antigens 13.4. The immune response 13.4.1. Humoral immune response: the antibodies 13.4.1.1. Antibody-producing cells: B lymphocytes 13.4.1.2. Antibodies 13.4.1.2.1. Types of antibodies 13.4.1.2.2. Antigen-antibody reaction 13.4.1.3. Immune memory: primary and secondary responses 13.4.2. Cellular immune response: T lymphocytes 13.5. Types of immunity 13.5.1. Natural immunity 13.5.2. Artificial immunity 13.6. Immune system disorders 13.6.1. Autoimmunity 13.6.2. Hypersensitivity 13.6.3. Immunodeficiency 13.6.4. Transplants and the phenomenon of rejections 13.7. Bibliography « Previous \| Next » 11.4. Evolutionary implications of mutations Mutations and evolution The mutations have occurred over time, by causes natural as radiation from the sun or minerals from the earth's crust. Although they are not very frequent, since they cover very large periods of time and very large populations, the probability that a mutation will appear is considerable. Most are lethal and disappear with their carriers, but when they are beneficial they remain in the individuals of the population and are transmitted to their offspring. If natural selection acts on these genotypesand they are favorable to those environmental conditions, it can even become incorporated as a single homozygous character, making the old normal character of the population disappear. If the mutation is harmful, if they are recessive, they will remain in the population. If the mutation is beneficial, it can improve the function of the enzyme it encodes, for example, by improving biological activity, facilitating the life of the organism that carries that mutation. Neutral mutations neither improve nor harm the conditions of the individual who is the carrier of the mutated gene, but can be passed on to descendants. It can serve as a biological clock to know how long two species have separated since they had a common ancestor. All cells can suffer some mutation, but the mutations that affect the gametes will affect the zygote that is formed after fertilization with another gamete and the cells that derive from it to form the new multicellular being. In addition, he will transmit the mutation to his descendants. Therefore, beneficial germline mutations will be those that cause the evolution of the species. The individual carrying the mutation has an advantage over those who do not have it, so they will be more likely to have offspring and transmit this advantageous characteristic to their descendants. Harmful mutations only remain in the population when they are recessive. If the mutation occurs in a somatic (non-germ) cell, it will not be passed on to offspring. When mutations appear in a certain population, the genotype changes from generation to generation, appearing individuals with characteristics different from those of their predecessors. This is how the population evolves, being able to originate new species. An example is bacteria that evolve after being subjected to antibiotics, becoming resistant. Mutations that are detrimental to the carrier individual will be eliminated by natural selection. In addition to natural selection, man has made artificial selection on domestic plants and animals, modifying them according to his own interest. It has achieved this by selecting the most productive individuals and crossing them with each other, obtaining different breeds, as in the dog, for example. The evolution occurs because people change their "pool" gene, the set of genes formed by all allelesexist among individuals. If an individual has the most favorable alleles, he has an advantage over the rest, being able to survive more easily. Thus, it is more likely that it is reproduced and that these genes remain in the population. Although mutation is the primary source of variation, it is not the only one. The gene recombination contributes to the variability gene in sexually reproducing organisms. The evolution of species occurs because the changes produced by genetic mutations accumulate. Most mutations are harmful and their carriers die, but those that produce an improvement remain in the species and are essential in the evolutionary process. When there is a separation between some members of a population, their genetic exchange is interrupted. Being in different environments, this differentiation is becoming more and more noticeable. With the passage of time, their genetic differences will be so great that they will have become different species, being unable to reproduce among them. Factors involved in biological evolution The gene pool of a population is made up of all the alleles of the individuals in the population. For evolution to occur, there must be genetic variability among individuals in a population, and that genetic variety can be inherited by future generations. The factors that produce alterations in the gene and genotypic frequencies of certain alleles and, therefore, in the composition of the genes that make up the population are: Natural selection The natural selection acts when the selected environment those individuals best adapted to these environmental conditions. Those with those genes that are best adapted to the changes that take place will be the ones that will have the easiest survival and reproduction, and can pass these genes on to their descendants. Mutations The mutations occur when, due to an error in the process of DNA replication, there are changes in the sequence of nucleotides of the DNA and new alleles are generated. Mutations are random and are the main cause of genetic variability. The only heritable mutations are those that affect the gametes and can be harmful, neutral, or beneficial. Crossover and genetic recombination Gametes are produced through meiosis. In Prophase I, genetic crossover and recombination occurs between paternal and maternal genes, favoring variability. Furthermore, the randomness in the union of gametes further increases the variability. Genetic drift The genetic drift is the random fluctuation of the allelic frequencies occurs generation after generation. The effects of genetic drift are strongest in small populations, where genetic variability decreases markedly. For instance: Founder effect: when some individuals of a population are isolated from the original population they reproduce and transmit their alleles to their descendants. Possibly, the gene frequencies of that group are not the same as those of the original population. For example, the Amish, a group that only had 12 founders of which only one had a gene that caused the combination of dwarfism and polydactyly, and at present, that allele is carried by 13% of the population of that group. Bottleneck effect: when there is a sharp decrease in the number of individuals in a population, due to some type of natural or human disaster, the individuals that survive have different allelic frequencies than the original population. Migrations or gene flow The migratory flows make the population acquires greater genetic variability, as new alleles from other populations, are incorporated into the gene pool of the population. Reproductive or genetic isolation When a population or group of individuals in a population is reproductively isolated from the rest of the individuals by barriers that prevent it, such as differences in behavior, habitats, etc., the speciation process can take place and a new species can emerge. Questions that have come out in University entrance exams (Selectividad, EBAU, EvAU) Aragon. September 2018, option A, question 4. September 2014, option B, question 1. Mutations (2.5 points) d) Relationship of mutations with evolution. (0.75 points) Aragon. June 2016, option B, question 4. Mutations: (2 points) c) Are mutations random or directed toward a specific change? Reason for the answer. (0.5 points) d) Why are mutations the basis of selection in species? (0.5 points) Aragon. September 2015, option B, question 4. Mutations (2 points) b) Indicate the meaning of the mutations from the evolutionary point of view. (0.5 points) Aragon. June 2010, option A. 4 . About the processes of mutation and evolution: (2 points) a) What is biological evolution? b) What is the cause of genetic variability in organisms with asexual reproduction? c) What is the cause of genetic variability in organisms with sexual reproduction? Aragon. June 2007, option A. Question 4 .- (1 point). Explain the implications of mutations in the evolution of living things. Licensed under the Creative Commons Attribution Share Alike License 4.0 « Previous \| Next » These pages are semi-automatically translated from the web Biology 2nd Baccalaureate. 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