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:منابع -استانسفیلد: ژنتیک- محمدتقی آساد: مبانی ژنتیک- حسن اکرمی: از کلاسیک تا ژنومیک-
و پاسخ صحیح ارائه راه حل حل مسائل و )/ نمره 5(فعالیت کلاسی -- 12-10آبان ماه ساعت 18) : نمره 5(کوییز -- )نمره 10(امتحان پایانی --
:زمان راهنمایی دانشجویان- صبح 10-8پنج شنبه ها -
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Genetic Terminology
Terminology Definition
DNAInheritance unit of an
organism.
GeneA sequence of DNA that
encodes a protein.
Genotype
A genotype is a heritable portion of a genome that
produces a specific phenotype.
PhenotypeA set of the observable
characteristics of an organism.
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Genotype+ Environment+ Epigenetics
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haploid - the condition of having only one set of chromosomes per cell (n)
diploid - the condition of having two sets of chromosomes per cell (2n)
gamete - a haploid (n) sex cell in plants and animals (egg or sperm)
zygote - diploid (2n) cell resulting from the union of two gametes in sexual reproduction
alleles - genes governing variations of the same characteristic (trait) that occupy corresponding positions (loci) on
homologous chromosomes; alternative forms of a gene.
dominant allele - an allele that is always expressed when present, regardless of whether the organism is homozygous
or heterozygous for that gene.
recessive allele - an allele that is only expressed when the organism is homozygous for that allele and not expressed
when heterozygous (when paired with a dominant allele).
homozygous - possessing a pair of identical alleles for a particular locus (gene).
heterozygous - possessing a pair of unlike alleles for a particular locus (gene).
carrier - a heterozygous individual not expressing a recessive trait but capable of passing it on to its offspring.
parent generation (P) - the generation that supplies gametes to the filial generation.
filial generation (F,) - the generation that receives gametes from the parental generation.
hybrid - an offspring resulting from the mating between individuals of two different genetic constitutions.
dihybrid cross - a genetic cross that takes into account the effect of alleles at two separate loci (two different genes).
monohybrid cross - a genetic cross that takes into account the effect of alleles at a single locus (single gene).
monoploid
phenocopyA phenocopy is a variation in phenotype (generally referring to a single trait)
which is caused by environmental conditions (often, but not necessarily, during the organism's development), such that the organism's phenotype matches a phenotype which is determined by genetic factors.
A phenocopy is defined as an environmental induced, non-heriditary phenotype of one individual which is identical to the genotype-determined phenotype of another individual. In other words, the phenocopy induced by the environmental conditions mimics the phenotype produced by a gene.
The term was coined by Richard Goldschmidt in 1935.
Genotype 1 Phenotype 1
Genotype 2 Phenotype 2
Genotype 1 Phenotype 2 (phenocopy)
A chemical or environmental condition
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Trait - any characteristic that can be passed from parent to offspring
Heredity - passing of traits from parent to offspring
Genetics - study of heredity…
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Genetics - study of gene and its function…
-The principle of inheritance
- The molecular nature of genetic material
- The regulatory mechanisms of genes metabolism
- The genes organizations in nucleus
- The pattern of genes behavior and their distribution across population
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History of Genetics:
- Blending inheritance
Mendel was the pioneer in experimenting and establishing the base of genetics and hence Gregor Johann Mendel is known as the father of genetics. During the period of 1856 to 1865, he experimented on pea plant and discovered the phenomenon of “inheritance of traits”.
The traits are now known as genes, that can be inherited from one generation to another generation. In 1866, he published his research paper describing the law of inheritance and independent assortment.
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Some of the milestone discoveries in the genetics are enlisted below,
1842: Wilhelm von Nageli, a Swiss botanist, observed the plant cell.
1866: Mendel’s research work published under the title of “experiments on plant hybridization.”
1869: Friedrich Miescher discovered the nucleic acid.
1888: Waldeyer identified the chromosome present in the cell.
1889: Richard Altmann purified DNA from the protein.
1900: The work of Mendel was again done by three other scientists Tschermak, DeVries & Correns.
1905: William Bateson coined the term “genetics”.
1908: discovery of Hardy-Weinberg’s law.
1910: Morgan T, explained that the genes are located on the chromosomes. Also, they experimented on Drosophila Melanogaster and determined the nature of sex-linked traits.
1923: Griffith F, experimented on bacteria and postulated that the DNA is the genetic material.
1927: X-rays were capable of producing mutations; Mullar demonstrated this idea.
1953: Watson and Crick identified the structure of DNA.
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1956:Levan presented that the normal human genome consists of 46 chromosomes.
1957:Franklen and Sange observed and analyzed the storage of genetic information of tobacco mosaic virus in RNA.
1958:Meselson and Stahl proved that the DNA replication actually happens in semi-conservative manner.Moreover, the same year Komberg isolated DNA polymerase enzyme from E.coli cells.
1961:Jacob presented the Operon model for regulation of gene expression.
1970:Temin and colleague Baltimore discovered the enzyme for gene cloning and the reverse transcriptase enzyme.
1977:Maxam Gilbert and Sanger presented the methods of gene sequencing.
1981:Researchers successfully developed the first transgenic organism.
1987:Kary Mullis successfully developed Polymerase chain reaction (PCR) using thermostable bacterial strain.
1995:Scientists completed the genome sequence of Haemophilus infulenzae.
1996:Ian Wilmut successfully cloned-Dolly sheep.
1998:Researchers released full genome sequence of multicellular eukaryote, Caenorhabditis elegans.
2000:Completion of full genome sequence of drosophila melanogaster.
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2001:The genetic researchers released first draft sequence of human genome project. After a while, completion of human genome project and Celera genomics.
Moreover, two researchers, Francisco Mojica and Rudd Jansen proposed the acronym CRISPR. CRISPR/Cas9 is genome editing tool based on bacterial cell’s defense mechanism.
2003:Researchers announced the completion of human genome project. The sequenced the 99% of human genome with 99.99% of accuracy of data.
2004:Merck introduced the vaccine for human Papillomavirus HPV. The vaccine proved effective against HPV 16 and 18 infection. both infections by HPV affects the tumor suppressor genes and cause cervical cancer in 70% cases.
2008:The geneticists developed first gene therapy based Houston based introgen Advexin. The food and drug FDA has not approved this yet. However, this is to curing Li-Fraumeni syndrome. Moreover, this utilizes adenovirus as vector to carry the replacement gene of natural tumor suppressor gene p53.
2010:Researchers used first transcription activator like effectors nucleases (TALENs) for restriction cutting and genome editing of DNA sequences.
2016:NASA astronaut and researcher Kate Rubins sequenced a genome sequence in outer space using a MinION device at International Space Station.
This is year 2020. The researches are ongoing…
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Branches of genetics:- Classic
- Cytogenetics
- Molecular genetics
Population genetics
Metagenomics
The branch of the genetics that deals with the study and identification of different microorganisms from the environmental sample using modern genetics techniques is called metagenomic studies.
Epigenetics
the study of alterations in an organism caused by gene expression rather than alteration caused by a gene mutation. In simple words, epigenetics is a study of gene expression.
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Transformation
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The cause ?
Avery, Macleod and McCarty Experiment
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Hershey and Chase Experiment
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In 1956, Gierer and Schramm demonstrated that a naked
RNA isolated from tobacco mosaic virus was infectious
and could induce the formation of new virus particles.
They introduce RNA as a genetic material
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