Genetics Study Guide PDF

Genetics Study Guide: Vocabulary: Locus- the location of a gene on a chromosome. Alleles- different forms of the same gene. Homologous Chromosomes- two pieces of DNA within a diploid organism which carry the same genes, one from each parental source Homozygous- carrying two copies of the same a...

Genetics Study Guide: Vocabulary: Locus- the location of a gene on a chromosome. Alleles- different forms of the same gene. Homologous Chromosomes- two pieces of DNA within a diploid organism which carry the same genes, one from each parental source Homozygous- carrying two copies of the same allele. Heterozygous- an individual carrying two different alleles for a trait. Gregor Mendel- Father of modern genetics P- the parental generation in a genetic cross. F1- the offspring of the Parental generation in a genetic cross. F2- the offspring of the F1 generation in a genetic cross. Monohybrid cross- a genetic cross involving only a single gene or trait. Dihybrid cross- a genetic cross involving two different genes or traits. Dominant -a trait that will appear in the offspring if one of the parents contributes it. In other words a trait that is expressed when a single copy is present. Recessive- a trait that is expressed only in the homozygous state. Genotype an individual's collection of genes. Phenotype-he set of observable characteristics of an individual resulting from the interaction of its genotype with the environment. Punnett Square-a square diagram that is used to predict the genotypes of a particular cross or breeding experiment Law of segregation every organism has two alleles per trait and that these alleles separate during meiosis, so each gamete gets one allele. Dibhybrid cross- cross between two different lines/genes that differ in two observed traits. Law of Independent assortment genes do not influence each other with regard to the sorting of alleles into gametes; every possible combination of alleles for every gene is equally likely to occur. Test cross- a way to explore the genotpye of an organism…usually involves crossing the organism with the unknown genotype to a homozygous recessive individual. Complete dominance -form of dominance in heterozygous condition wherein the allele that is regarded as dominant completely masks the effect of the allele that is recessive. Incomplete dominance-when a dominant allele, or form of a gene, does not completely mask the effects of a recessive allele, and the organism's resulting physical appearance shows a blending of both alleles Codominance- a form of inheritance in which two or more alleles are both expressed in the phenotype of the organism. Polygenetic inheritance the heredity of complex characters that are determined by a large number of genes, each one usually having a relatively small effect. ABO Bloodtype- classification of human blood as determined by the presence or absence of A and B antigens on red blood cells. Type A-blood type that has the A blood antigen. Type B -blood type that expressed the B blood antigen. Type AB-blood type that expresses both the A and B blood type antigens. Type O- blood type that expresses neither the A nor the B blood type antigen. Pleiotropy-e production by a single gene of two or more apparently unrelated effects. SRY gene- the gene which expresses the SRY protein which controls production of male characteristics Albinism- a genetic disorder cause by mutation of the tyrosinase gene leading to lack of pigmentation in hair, skin, and eyes. Epistasis- the interaction of genes that are not alleles, in particular the suppression of the effect of one such gene by another. Genes a distinct sequence of nucleotides forming part of a chromosome which encode for a trait. Locus -a locus is a specific, fixed position on a chromosome where a particular gene or genetic marker is located. Autosomes-any chromosome that is not a sex chromosome. Sex Chromosomes- the X or Y chromosomes in mammals. Y Chromosome- the sex-determining chromosome in many species since it contains the SRY gene. X Chromosome-one of two sex chromosomes. Hemizygous- males have only one copy of genes found on the X. XX- the chromosomal combination for a female normally. XY-the chromosomal combination for a male normally. Karyotype-the number and visual appearance of the chromosomes in the cell nuclei of an organism or species. Syndrome-a group of symptoms which consistently occur together, or a condition characterized by a set of associated symptoms. X-Linked Recessive- a type of inheritance in which males are normally affected more than females due to a gene being carried on the X-chromosome. Color Blindness- an X-linked recessive trait. Hemophilia an X-linked recessive trait associated with lack of blood clotting. Hutchinson-Guilford Progeria-an autosomal dominant genetic disorder characterized by accelerated aging. Autosomal dominant- a dominant form of inheritance in which the affected gene is on a non-sex chromosome. Gene duplication- a type of mutation that involves the production of one or more copies of a gene or region of a chromosome. Inversion a chromosome rearrangement in which a segment of a chromosome is reversed Deletion a deletion is a mutation in which a part of a chromosome or a sequence of DNA is left out during DNA replication. Translocation- when part of a chromosome is transferred to another chromosome. Philadelphia Chromosome - The chromosome abnormality that causes chronic myeloid leukemia (CML). Nondisjunction- Failure of paired chromosomes to separate (to disjoin) during cell division, so that both chromosomes go to one daughter cell and none go to the other. Turner’s syndrome- a condition that affects only females, results when one of the X chromosomes (sex chromosomes) is missing or partially missing. Turner syndrome can cause a variety of medical and developmental problems, including short height, failure of the ovaries to develop and heart defects. Trisomy X- characterized by the presence of an additional X chromosome in each of a female's cells. Although females with this condition may be taller than average, this chromosomal change typically causes no unusual physical features. Kleinfelder’s syndrome- A genetic condition in which a male is born with an extra copy of the X chromosome. Males born with Klinefelter syndrome may have low testosterone and reduced muscle mass, facial hair, and body hair. Most males with this condition produce little or no sperm. XYY Male- a genetic condition in which a male has an extra Y chromosome. There are usually few symptoms. Autosomal Nondisjunction failure of paired chromosomes to separate (to disjoin) during cell division Trisomy 21/Down’s Syndrome A genetic chromosome 21 disorder caused by nondisjunction causing developmental and intellectual delays. Amniocentesis- a procedure in which amniotic fluid is removed from the uterus for testing or treatment. Chorionic Villus Sampling- prenatal test that is used to detect birth defects, genetic diseases, and other problems during pregnancy by taking cells from the chorionic villus. DNA -deoxyribonucleic acid, the molecule of inheritance. Nucleotides- the building block of nucleic acids; consists of a 5-carbon sugar, a phosphate, and a nitrogenous base. Nitrogenous Bases- the bases found in RNA or DNA. Rosalind Franklin- performed the X-Ray crystallography that proved DNA was a double stranded alpha helix. Watson and Crick- “discovered” the structure of DNA. Anti-parallel- when the two strands of a molecule run in opposite directions as in DNA. Base Pairing- the nitrogenous base interactions in DNA…A to T, G to C. DNA Replication-the process by which one molecule of DNA is copied to make two DNA molecules. Semi-Conservative Replication the mechanism of DNA replication in which each copy contains one original strand and one newly-synthesized strand. DNA Polymerase- the enzyme that replicates DNA. Cloning- molecular biology technique that makes many identical copies of a piece of DNA, such as a gene Somatic Nuclear Transfer laboratory strategy for creating a viable embryo from a body cell and an egg cell. This is how Dolly the sheep was made. Biotechnology- the exploitation of biological processes for industrial and other purposes. Production of alcohol, antibiotics, and various foods are examples. Genetic Engineering the deliberate modification of the characteristics of an organism by manipulating its genetic material. Recombinant DNA- DNA that has been formed artificially by combining constituents from different organisms. Restriction Enzymes- protein produced by bacteria that cleaves DNA at specific sites along the molecule. RFLPS- a variation in the length of restriction fragments produced by a given restriction enzyme in a sample of DNA. DNA fingerprinting is based on this. PCR- polymerase chain reaction. a technique used to "amplify" small segments of DNA. Gene Therapy- an experimental technique that uses genes to treat or prevent disease. Important Concepts/Short Answer Questions: 1. How did the choosing of the garden pea impact upon the success of Mendel’s experiments? 1.Other research showed that pea hybrids could be produced 2. Many pea varieties were available 3. Peas are small plants and easy to grow 4. Peas can self-fertilize or be cross-fertilized How were Mendel’s experiments and experimental analysis different from those of his peers? His work was quantitative and studied only one or two traits at a time. What is the importance of a 3:1 ratio in a monohybrid cross? It is the sign of a dominant recessive gene relationship. What is the importance of a 9:3:3:1 ratio in a dihybrid cross? It is the ratio found when two genes that are simple dominant/recessive are studied. Skill: a) You will need to be able to read a genotype to determine if the genotype is heterozygous or homozygous for a trait. b) You will need to be able to work Punnet squares involving monohybrid and dihybrid crosses. c) You will need to be able to interpret a pedigree. What are the five elements in Mendel’s model of inheritance? 1. Parents transmit discrete factors (genes) 2. Each individual receives one copy of a gene from each parent 3. Not all copies of a gene are identical 4. Alleles remain discreet 5. Presence of allele does not guarantee expression. What are the goals of biotechnology? 1. To understand more about the processes of inheritance and gene expression 2. Treatment of various diseases, particularly genetic disorders 3. To generate economic benefits What are three instances of natural DNA Recombination in nature? Sexual Reproduction—crossing over in Meiosis I Bacterial transformation—pick up pieces of DNA from environment Virus—transfers genetic material to a host cell (host cell now manufactures virus)