Biology-Genetics Lecture and Quiz Refresher PDF

Lecturer: Reglyn Mae Ylanan, CSE, LPT March 2023 Top 8 Genetics is the study of how genes and how traits are passed down from one generation to the next. Our genes carry information that affects our health, our appearance, and even our personality! "Gen" mea...

Lecturer: Reglyn Mae Ylanan, CSE, LPT March 2023 Top 8 Genetics is the study of how genes and how traits are passed down from one generation to the next. Our genes carry information that affects our health, our appearance, and even our personality! "Gen" means beginning. Every living thing has DNA.  Gene It is the basic unit of heredity. It carries instructions responsible for expression of traits. Alleles It is an alternative form of genes. Chromatid A chromatid is one of the two identical halves of a chromosome that has been replicated in preparation for cell division. Humans have 22 pairs of autosomes and one pair of sex chromosomes (XX or XY). Autosomes are numbered roughly in relation to their sizes. Karyotype an individual's complete set of chromosomes Pedigree Pedigree  Reginald Crundall Punnett Punnett devised the "Punnett Square" to depict the number and variety of genetic combinations.  “Father of genetics.” His extensive study of garden peas led him to many important conclusions about Gregor genetics, which is the scientific study of heredity. Heredity is the passing of Mendel characteristics from parents to offspring. Those specific characteristics are called traits. Pisum sativum MENDELIAN LAWS OF GENETICS  Substitution -during replication, one base is inserted erroneously, replacing the pair in that location on the complementary strand. Ex. Sickle cell anemia Gene Insertion Types of Mutation - In replicating DNA, one or more extra nucleotides are added, frequently Mutation -change is a causing a frameshift. single gene Ex. A form of beta-thalassemia. Deletion One or more nucleotides is skipped during replication or otherwise excised, often resulting to frameshift. Ex. Cystic fibrosis  Inversion -A chromosome’s one section is turned around and reinserted. Chromosome Deletion Mutation - When a chromosome segment is lost, -change in many all the genes in that segment are also Types of genes gone. Can be spontaneous Mutation or caused by Duplication - Repeating a section of a chromosome environmental increases the dosage of the genes in that mutagens (radiation, section; ex. Charcot-Marie-Tooth disease chemicals, etc.) Translocation - A section of one chromosome is abnormally joined to another; ex. Cancer (lymphoma and leukemia)  Missense -these substitutions change the codon so that a different amino acid is produced. This may result in the shape of the protein changing so that it cannot carry out its function. However, some changes in amino acid may not have any significant effect. Point Mutation Nonsense -Substitutions - these substitutions change the codon from an Types of result in a change amino acid to a stop codon. This results in a that only affect shorter protein being produced. The shortened Mutation one codon. This protein is generally non-functional, or its function is affected. is known as a Splice-site point mutation. -these substitutions affect the boundaries between exons and introns (splice sites). A mutation here can prevent splicing at that site. This will result in a very different protein being made due to the post transcriptional processing as some introns may be included or some exons removed. Hemophilia Phenylketonuria Sickle cell anemia Down Syndrome Edward’s Syndrome FamilyID=Office_ArchiveTorn Patau Syndrome  Turner Syndrome  a process that uses laboratory-based technologies to Genetic alter the DNA makeup of an organism. This may involve changing a single base pair (A-T or C-G), Engineering deleting a region of DNA or adding a new segment of DNA.  DNA is a group of molecules that is responsible for carrying and transmitting the hereditary materials or the genetic instructions from parents to offsprings. Each nucleotide is composed of a nitrogenous base, a five-carbon sugar (deoxyribose), and a phosphate group. Deoxyribonucleic acid Applications of Genetic Engineering Distant Hybridization  Transgenic Plants Transgenic (GM) plants are those that have been genetically modified using recombinant DNA technology. This may be to express a gene that is not native to the plant or to modify endogenous genes. The protein encoded by the gene will confer a particular trait or characteristic to that plant. Development of Root Nodules in Cereal Crops  Development of C4 Plants Why photosynthesis in C4 plant is more efficient than that in C3 plant? Due to their reduced rate of photorespiration and high rate of photosynthesis, C4 plants are more efficient than C3 plants. The main enzyme of carbon fixation in the Calvin cycle is RuBisCO. It shows an affinity for both CO2 and O2. Applications in Medicine Production of Antibiotics Production of Hormone Insulin Production of Vaccines Diagnosis of Disease Production of Enzymes Production of Transgenic Animals Other Applications of Biotechnology Stem Cell Gene Therapy In Vitro Fertilization Cloning Human Genome Project Molecular Genetics 1. Who provided the first conclusive evidence, in 1902, that chromosomes carry the units of inheritance and occur in distinct pairs? a. Walter Sutton b. Christiane Nüsslein-Volhard c. Clarence E. McClung d. Barbara McClintock Published in 1902, “On the Morphology of the Chromosome Group in Brachystola magna” provided the earliest detailed demonstration that the somatic chromosomes (those in cells other than sex cells) of a grasshopper occur in definite, distinguishable, and different pairs of like (or homologous) chromosomes. The paper ended with the hypothesis that chromosomes carry the units of inheritance. 2. Who first identified individual genes by studying the giant chromosomes in the salivary gland cells of fruit flies? a. Charles Atwood Kofoid b. Francis Crick c. James D. Watson Theophilus Shickel Painter, an American d. Theophilus Shickel Painter zoologist and cytologist, first identified individual genes in the chromosomes of fruit flies. Painter realized that the unusually large chromosomes in the salivary gland cells of Drosophila fruit flies are particularly well suited for studies of genes and chromosomes. 3. Which of the following is not part of the DNA strand? a. Deoxyribose sugar b. Uracil c. Phosphate d. Thymine 4. Who deduced that the sex of an individual is determined by a particular chromosome? a. Theodor Schwann In 1905, after experiments with the yellow mealworm, she b. Nettie Maria Stevens published a paper in which she announced her finding that a c. A.D. Hershey particular combination of the chromosomes known as X and Y d. Sylvia Earle were responsible for the determination of the sex of an individual. 5. Duchenne muscular dystrophy (DMD) is an X-linked recessive condition that causes rapid muscle degeneration. DMD occurs in approximately 1 in every 3500 males, but it rarely affects females. Which statement most accurately explains why DMD affects males more often than females? a. Replication of the X chromosome occurs more often in males. b. Males only have one copy of the X chromosome. c. Male hormones cause the expression of X-linked traits. d. The Y chromosome is slower to mature than the X chromosome.  X-linked recessive inheritance Fragile X-syndrome Hemophilia A and hemophilia B Duchenne muscular dystrophy (DMD) (Becker BMD) Ocular albinism Hunter syndrome Retinitis pigmentosa If men have the altered gene they are generally affected. Women with the altered gene may be affected to a varying degree dependent on the activity of the normal gene. 6. A woman who is a carrier for a sex-linked recessive trait has children with a man who does not have that trait. What is true about their offspring? a. All of their children will be unaffected carriers. b. They have a 50% chance of having an affected daughter. c. No son they have would be affected. d. They have a 25% chance of having an affected son. 7. Red-green colorblindness is a recessive X-linked trait in humans. Which of the following pairs of parents is most likely to produce a daughter with red-green colorblindness? a. An unaffected, non-carrier mother and a colorblind father b. A carrier mother and a colorblind father c. A carrier mother and an unaffected father d. A colorblind mother and an unaffected father 8. Which of the following statements about sex determination in humans is true? a. Sex of the child is affected by age of the parents. b. Sex of the child is determined by the genetic content of gametes. c. Sex of the child develops after birth. d. Sex of the child is affected by the environment in which pregnant mother lives. 9. In a flowering plant, blue flowers (B) are dominant over white flowers (b). A true-breeding plant with blue flowers (BB) is crossed with another true-breeding plant with white flowers (bb). What percentage of offspring are expected to have blue flowers? a. 0 percent b. 50 percent c. 75 percent d. 100 percent 10. When white-coated cattle (W) are mated with red-coated cattle (R), the offspring are roan (WR), meaning their coats contain both white and red hairs. This is an example of codominance. A farmer breeds two roan cattle with one another. What is the chance that their offspring will be roan? a. 50 percent b. 75 percent c. 25 percent d. 0 percent 11. In humans, three alleles affect blood type. The A and B alleles are codominant, and the O allele is recessive. Which of the following answer choices is true? a. The O blood type is the least common in the human population. b. Human blood type is an example of a single allele inheritance. c. Human blood type is an example of incomplete dominance. d. The A and B alleles are codominant because both alleles are simultaneously expressed in the heterozygote. 12. In what ways does a dominant trait differ from a recessive trait? a. A dominant trait can be expressed by a single allele whereas recessive traits need two alleles for expression. b. A dominant trait is more common in a population than a recessive trait. c. A dominant trait allele is less effective in producing proteins and enzymes than a recessive trait allele. d. A dominant trait is more useful than a recessive trait. 13. Who laid the mathematical foundation of the science of genetics? a. Gregor Mendel b. Dorothy Hodgkin c. Erich von Tschermak d. Carl Correns 14. Gregor Mendel’s discovery of basic hereditary principles was not realized until the early 20th century. Who were the scientists who rediscovered his work? a. Francis Crick, James Watson, and Rosalind Franklin b. Hugo de Vries, Carl Correns, and Erich Tschermak von Seysenegg c. Charles Darwin and Herbert Spencer d. Marie Curie and Irène Curie 15. How many pairs of chromosomes are found in the human body? a. 28 pairs b. 23 pairs c. 46 pairs d. 21 pairs 16. Who laid the foundation for James Watson and Francis Crick to suggest the helical structure of DNA? a. Alexander Fleming b. Hippocrates c. Rosalind Franklin d. George Cuvier 17. There are several DNA repair mechanisms in place to help detect and correct DNA damage. Which of the following is true regarding these DNA repair mechanisms? a. DNA damage from chemical reactions cannot be undone. b. Proofreading from DNA polymerase reduces the error rate in DNA to about 1 in 100 nucleotides. c. Copying errors not caught by the replication machinery can be corrected by mismatch repair. d. Non-homologous end joining is less likely to produce mutations than homologous recombination. 18. In DNA replication, DNA "unwinds" to form two template strands: the leading strand and the lagging strand. Which of the following statements about these strands is true? a. Okazaki fragments are used to synthesize the leading strand of DNA. b. The leading strand of DNA is synthesized continuously. c. DNA polymerase can only synthesize DNA on the leading strand. d. The lagging strand can only be synthesized once the leading strand has been completed. 19. There are several enzymes involved in DNA replication. Which of the following correctly pairs the DNA replication enzyme with its function? a. Topoisomerases work ahead of the replication fork to prevent supercoiling. b. DNA polymerase 1 opens up the DNA at the replication fork. c. Helicase seals gaps between DNA fragments. d. DNA primase extends primers by adding nucleotides to the end. 20. Which of the following statements is true regarding the discovery of the double helix? a. It was discovered that double-stranded DNA is a parallel molecule. b. Rosalind Franklin’s x-ray crystallography provided Watson and Crick with important data that helped determine the structure of DNA. c. The experiments that led to the discovery of the double helix ultimately disproved Chargaff's rules regarding nitrogenous bases. d. James Watson, Francis Crick, Maurice Wilkins, and Rosalind Franklin were awarded the Nobel Prize in Medicine for their discovery of the double helix. 21. What molecule carries the genetic instructions for life? a. Lipids b. Carbohydrates c. Proteins d. Nucleic acid 22. What is a segment of DNA that contains instructions for building proteins called? a. Chromosomes b. Allele c. Gene d. Genome 23. What is the observable trait or characteristic of an organism called? a. Genotype b. Phenotype c. Allele d. Genome 24. According to Mendel's Law of Segregation, how many alleles does each gamete carry for each gene? a. One Law of segregation is the second law of inheritance. This law explains that the pair of b. Two alleles segregate from each other during meiosis cell division (gamete formation) so that c. Three only one allele will be present in each gamete. d. Four 25. What is a mutation? a. A type of chromosome b. A process of DNA replication c. A change in the DNA sequence d. A type of protein synthesis 26. Which is a genetic disorder that is caused by an abnormality in the genetic code? a. Influenza b. Diabetes c. Cystic fibrosis d. Hypertension  Type 1 Diabetes: The body's immune system attacks and destroys the insulin- producing cells in the pancreas. As a result, people with Type 1 diabetes produce little or no insulin and need to take insulin every day. Type 2 Diabetes: The body doesn't use insulin properly. At first, the pancreas makes extra insulin, but over time it can't keep up, and blood sugar levels stay high. This type is more common and often related to lifestyle factors like diet and exercise. Gestational Diabetes: This type occurs during pregnancy and usually goes away after the baby is born, but it can increase the risk of developing Type 2 diabetes later in life. 27. What is the process of modifying the genetic material of organisms to achieve desired traits called? a. Cloning b. Genetic Engineering c. Natural Selection d. Mitosis 28. What does DNA profiling help with in forensic science? a. Determining nutritional values b. Identifying individuals c. Creating new species d. Mapping genomes 29. What is a potential ethical issue raised by advancements in genetics? a. Increased crop yields b. Improved medical treatments c. Genetic discrimination d. Better understanding of evolution 30. What does the study of genetic variation help scientists understand? a. The chemical properties of DNA b. How populations adapt to their environments c. The function of ribosomes d. The structure of proteins