Lesson 1: Introduction to Cytogenetics PDF

LESSON # 1: INTRODUCTION TO CYTOGENETICS MEDT- 07 1st SEMESTER | 2024-2025 | PROF. Andrea Llantos - It is a branch of gene...

LESSON # 1: INTRODUCTION TO CYTOGENETICS MEDT- 07 1st SEMESTER | 2024-2025 | PROF. Andrea Llantos - It is a branch of genetics that studies the function of the cell, specifically chromosomes, and how they relate to inheritance and development of genetic traits and diseases. - Among animal cells, Walther Flemming CYTOLOGY - a branch of biology dealing with the described chromosomes using salamander. structure function multiplication, pathology, and life - Theopilus Painter: 48 chromosomes X history of cells. GENETICS- a branch of biology concerned with the study of inheritance including the interplay of genes, DNA variation and their interactions with environmental factors. 1. Plant, Animal and Microbial Improvement - Tijo and Levan (1956): 46 chromosomes / 2. Medicine 3. Genetic Counselling 4. Legal Applications TRANSMISSION GENETICS - relationship between the transmission of genes from parent to offspring and the outcome of the offspring's traits. MOLECULAR GENETICS - The goal of molecular genetics is to understand how the genetic material works at the molecular level. POPULATION GENETICS - This field helps us to understand how process such as natural selection have resulted in the prevalence of individuals that carry particular 1. CHROMOSOME: a long thread-like structure in alleles. the cell nucleus that carries genetic information - Population geneticists are particularly interested (genes) in genetic variation is related to an organism’s 2. GENE: a specific segment of DNA that contains environment. In this field, the frequencies of the instructions for building a particular protein or alleles are of central importance. 3. RNA molecule which contributes to a specific trait or function. MEDT- 07:CYTOGENETICS LESSON # 1 INTRODUCTION TO CYTOGENETICS 1  LESSON # 1: INTRODUCTION TO CYTOGENETICS MEDT- 07 1st SEMESTER | 2024-2025 | PROF. Andrea Llantos 4. ALLELE: a specific variant of a gene that may differ in its DNA sequence that can lead to different traits/ characteristics. 1. KARYOTYPE: a complete set of chromosomes of an individual usually arranged in pairs according to their size, shape and banding patterns. 2. KARYOGRAM: a visual representation or photograph of an individual's karyotype, displaying the chromosomes in their characteristic order. 3. AUTOSOMES: chromosomes other than the sex chromosomes (X and Y). 1. SEX CHROMOSOMES: chromosomes (X and Y) that determine an individual's sex and carry genes related to sexual development and characteristics. 2. HOMOLOGOUS CHROMOSOME: chromosome pairs with similar size, shape and genetic content. 3. LOCUS (LOCI): a specific physical location of a MEDT- 07:CYTOGENETICS LESSON # 1 INTRODUCTION TO CYTOGENETICS 2  LESSON # 1: INTRODUCTION TO CYTOGENETICS MEDT- 07 1st SEMESTER | 2024-2025 | PROF. Andrea Llantos 1. DIPLOID: refers to cells or organisms that have two sets of chromosomes in their nucleus, one inherited from each parent. In humans, the diploid number is 46. 2. HAPLOID: refers to cells or organisms that have one complete set of chromosomes in their nucleus. Gametes (sperm and eggs) are haploid. 1. HYBRIDIZATION: combining different material from 2 different individuals or species to create gene on a with offspring chromosome. a mix of genetic characteristics. 2. P (PARENTAL GENERATION): consist of the original individuals or organisms whose genetic MEDT- 07:CYTOGENETICS LESSON # 1 INTRODUCTION TO CYTOGENETICS 3  LESSON # 1: INTRODUCTION TO CYTOGENETICS MEDT- 07 1st SEMESTER | 2024-2025 | PROF. Andrea Llantos traits are being studied or crossed in a breeding experiment. 3. F1 (FIRST FILIAL GENERATION): the immediate offspring resulting from the cross breeding of 2 parental individuals or strains. 4. pF2 (SECOND FILIAL GENERATION): offspring produced by crossing 2 F1 individuals. PHENOTYPE: the observable physical and functional characteristics of an organism, determined by its genotype and influenced by environmental factors. GENOTYPE: the genetic makeup of an organism, representing the combination of alleles at specific gene loci. 1. DOMINANT ALLELE: An allele that, when present, masks the effect of the recessive allele in a heterozygous individual. Its trait is expressed in the phenotype. 2. RECESSIVE ALLELE: An allele whose effect is masked by the presence of a dominant allele in a heterozygous individual. It is expressed in the phenotype only when homozygous. 3. CODOMINANT ALLELE: Alleles that are both expressed in the phenotype when they occur together in a heterozygous individual. MEDT- 07:CYTOGENETICS LESSON # 1 INTRODUCTION TO CYTOGENETICS 4  LESSON # 1: INTRODUCTION TO CYTOGENETICS MEDT- 07 1st SEMESTER | 2024-2025 | PROF. Andrea Llantos MUTATION: A permanent change in the DNA sequence of a gene or chromosome, which can result in altered genetic information and potentially lead to changes in phenotype or function. Mutations can be hereditary or occur spontaneously. 1. Van Beneden, Flemming, Strasburger, Boveri and others- observed germ cells which supported the theory of the continuity of the germ plasm proposed by Weisman in 1883. 1. HOMOZYGOUS CHROMOSOME: 2. GERM THEORY: states that the transference of Chromosomes that have the same alleles (gene hereditary factors from one generation to the next variants) at a specific gene locus. takes place through the continuity of what he 2. HETEROZYGOUS CHROMOSOME: called 'germ plasm', located on the sex elements Chromosomes that have different alleles at a (Sperm and Egg), and not through somatic cells. specific gene locus. 3. Discovery of Fertilization in Animals- foreseen 3. HEMIZYGOUS CHROMOSOME: Refers to the by O. Hertwig but observed directly by H. Fol presence of only one allele at a particular gene (1879). locus in a diploid organism. 4. Discovery of Fertilization in Plants- observed by Strasburger.; both discovery led to the theory that the cell nucleus is the bearer of the physical basis of heredity 5. Roux- postulated that chromatin, the substance of the nucleus that constitutes the chromosome, must have a linear organization 6. Weismann- stated that hereditary units are disposed along the chromosomes in an orderly manner 7. Gregor Mendel- discovered the Fundamental Laws of Heredity in 1865, but at that time cytologic changes produced in the sex cells were not sufficiently known to permit an interpretation of the independent segregation of hereditary MEDT- 07:CYTOGENETICS LESSON # 1 INTRODUCTION TO CYTOGENETICS 5  LESSON # 1: INTRODUCTION TO CYTOGENETICS MEDT- 07 1st SEMESTER | 2024-2025 | PROF. Andrea Llantos characters. For this and other reasons, little that X-rays can be used to study the attention was paid to Mendel's work until the molecular structure of simple crystals, such as botanists Correns, Tschermack and De Vries in salt 1901 independently rediscovered Mendel's La 1865/ Gregor Mendel published his investigations 1926 Morgan published the 'Theory of the Gene' 1866 into inheritance of pea plants 1928 Frederick Griffith discovered 'transformation' 1890 Theodor Boveri suggested that chromosomes in bacteria are involved with inheritance 1944 Oswald Avery, Colin MacLeod, and Maclyn 1900 Walter Sutton observed chromosomes in Mccatty used bacteria to show that DNA is the grasshopper cells hereditary material 1900/ Mendel's work was rediscovered by three 1949 Erwin Chargaff finds that the amounts of 1901 scientists: Hugo De Vries, Erich von adenine and thymine in DNA are about the Tschermack, and Carl Correns same, as area the amounts of guanine and cytosine 1902 Archibald Garrod discovered that some diseases must be inherited 1953 James Watson and Francis Crick proposed that the DNA molecule is a double-stranded helix 1903 Sutton and Boveri, working independently, suggested that each egg of sperm cell contains 1963 Marshall Nirenberg and Heinrich Matthaei only one of each chromosome pair - work out the genetic code 1966 1905 Edmund Beecher Wilson and Nettie Stevens, working independently, proposed that certain 1977 DNA from virus is sequenced for the first time chromosomes determine sex. They show that by Frederick Sanger, Walter Gilbert and Allan a single Y chromosome determines maleness, Maxam, working independently and two copies of the X chromosome determine femaleness 1983 Kary Mullis discovered the Polymerase Chain Reaction (PCR), enabling lengths of 1906 Bateson gave the term 'genetics' DNA to be multiplied 1909 Wilhelm Johannsen used the term 'gene' to 1987 Rebecca Cann, Mark Stoneking, and Allan describe the carrier of heredity, Wilson analyze mitochondrial DNA in 'genotype' to describe an organism's genetic different human races. They declared that make-up, and 'phenotype' to describe an humans have a common ancestor who lived organism's outward appearance 200,000 years ago 1910 Thomas Hunt Morgan proved that genes are carried on chromosomes. He also showed that some characteristics are carried on the sex 1989 The first Human gene is sequences by Francis chromosome Collins and Lap-chee Tsui. It is the gene that cause cystic fibrosis 1911/ Alfred Henry Sturtevant mapped the genes of 1913 the fruit fly's sex chromosome 1990 The Human Genome Project is launched 1912 Sir William Henry Bragg and his son discover 1993 Cystic fibrosis became the first genetic disease MEDT- 07:CYTOGENETICS LESSON # 1 INTRODUCTION TO CYTOGENETICS 6  LESSON # 1: INTRODUCTION TO CYTOGENETICS MEDT- 07 1st SEMESTER | 2024-2025 | PROF. Andrea Llantos to be treated using gene therapy. 1995 The genome of H.influenzae is sequenced. This is the first complete genome of an organism. 2000 First draft sequences of the human genome are released at the same time by the Human Genome Project and Celera genomics. 2003 The Human Genome Project was successfully completed on 14" of April. MEDT- 07:CYTOGENETICS LESSON # 1 INTRODUCTION TO CYTOGENETICS 7