Chromosomes, genes, alleles and mutations

Chromosomes, genes, alleles and mutations
Centro Escolar Campoalegre María Gabriela Macz

CHROMOSOMES, GENES, ALLELES AND MUTATIONS
 When living things reproduce, they pass on characteristics to their offspring(the offspring inherit the parent’s characteristics)  Some characteristics may not be inherited  Inheritance has been discussed since the time of Hippocrates and earlier  Aristotleobserved that children sometimes resembled their grandparents more than their parents  Many of these theories involved blending inheritance, in which offspring inherit characteristics from both parents (intermediate characteristics)  Prokaryotes chromosomes are circular

PROKARYOTIC DNA

PROKARYOTIC DNA IN THE NUCLEOID REGION

 Prokaryotes have some DNA in the form of small loops calledPLASMIDS  Prokaryote DNA is found in the nucleoid area of the cell not in the nucleus  Prokaryotic chromosomes contain DNA but not proteins  Eukaryotic chromosomes are found inside the nucleus ( http://www.dnalc.org/resources/3d/07-how-dna-ispackaged-basic.htm or http://www.dnalc.org/resources/3d/08-how-dna-is-packaged-advanced.html )  There are usually more than one chromosome and they arelinear  Eukaryotic chromosomes contain DNA and protein (read Document 4.2 Meiosis)

Biology, 2011

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Chromosomes, genes, alleles and mutations
Centro Escolar Campoalegre María Gabriela Macz

THE PACKING OF CHROMATIN

EUKARYOTIC CROMOSOME

 Genetics is the study of variations and inheritance

Biology, 2011

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Chromosomes, genes, alleles and mutations
Centro EscolarCampoalegre María Gabriela Macz

 The basic unit of inheritance is the GENE  GENE: is an inheritable factor that controls a specific characteristic  Factor that controls a specific characteristic  Consists of a length of DNA  Atypical animal or plant chromosome contains about a 1000 genes  Arranged in linear sequence  In any particular type of chromosome the same genes are found arranged in thesame sequence  A total number of genes in a human chromosome is about 25000  Occupies a position on a chromosome known as locus  LOCUS: the particular position on homologous chromosomes of a gene  The term allele refers to one specific form of a gene, differing from other alleles by one or a few bases only and occupying the same gene locus as other alleles of a gene  Different forms of manygenes can be found  ALLELE: one of a number of different forms of a gene  They differ by a few bases at the most  A genome is the total genetic material of an organelle, cell or organism  The whole of the genetic inform ation of an organisms  Entire haploid complement of a genetic material  Every cell in an individual has a complete copy of the genome  Each specie has a unique genome  There isa small variation between individuals of the same species  In humans the average of genetic variation in one in every 500-1000 bases  Genes are almost passed from parents to offspring without being changes, occasionally genes do change  MUTATION: permanent change in the sequence of base pair in the DNA that makes up a gene (change to the base sequence of a gene)  Mutations originate newvariations  They create new alleles and form an important part of the evolutionary process  Most mutations are harmful, but there is a significant mutations that SILENT and do not appear to have any effect on the individual  There could be gene mutations or chromosome mutations

Biology, 2011

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Chromosomes, genes, alleles and mutations
Centro Escolar Campoalegre María Gabriela Macz

1.GENE MUT ATION:  Mutations may cause alteration in the genetic instructions coded in the DNA of chromosomes  Most mutations are harmful some are neutral while some provide some improveme nt on the earlier version of the gene  Mutations may be accumulated (inherited) over many generations 2. CHROMOSOME MUTATION:  Pieces of chromosomes may be rearrange during meiosis  Pieces may be turned...