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GeneticsExam2
| Question | Answer |
|---|---|
| Who discovered that DNA and RNA are nucleotides? Date? | Phoebus Levene- 1909 |
| Who used mice to prove that DNA is the molecule of heredity, and NOT proteins? Date? | Frederick Griffith- 1928 |
| What is the chemical makeup of nucleotides? | 5 carbon sugar, phosphate backbone and different nitrogenous base (adenine, thymine, cytosine, guanine, uracil (RNA only)) |
| Who proved DNA contains equal amounts of adenine & thymine and equal amounts of cytosine & guanine? Date? | Erwin Chargaff- 1950 |
| Who discovered that although quantity of DNA varies among species, it is constant in each species? Date? | Alfred Mirsky- 1951 |
| Who discovered that DNA is a double helix? Date? | Watson and Crick- 1953 |
| Who took x-ray diffraction pictures of the structure of DNA? | Rosalind Franklin |
| What is a double helix? | TWO strands of DNA are twisted together |
| Give the complementary base pairings found in DNA. | A (adenine) pairs with T (Thymine); G (guanine) pairs with C (Cytosine) |
| Name and describe the purines. | Have a 2-ring nitrogenous base: Adenine and Guanine. (Genetics is PURE AGony) |
| Name and describe the pyrimidines. | Have a SINGLE ring nitrogenous base: Cytosine, Uracil, Thymine. (I CUT King Tut from the pyramid single-handedly) |
| Does DNA have a parallel or antiparallel structure? | Antiparallel: one strand runs 3' to 5' and the other runs 5' to 3' |
| What does 3' (3 prime) refer to? | Refers to the 3rd carbon of the ribose sugar that is free to attach to another base (3' free ends are the bottom left and upper right on the diagram given in notes). |
| What does 5' (5 prime) refer to? | Refers to the 5th carbon of the ribose sugar that is NOT free to attach to another base. The 5' ends are the upper left and bottom right on the picture in the notes (with a P already on them. |
| What are histones? | They are proteins responsible for the first level of DNA packing; a group of 8 proteins that the DNA helix is wrapped around. |
| What is a nucleosome? | DNA wrapped around histones which makes a "bead on a string" shape. When condensed make chromatin; when condensed even more make a chromosome. |
| What is a looped domain? | Consists of 30 nanometers chromatin that form loops attached to nonhistone proteins; MOST INTERPHASE CHROMATIN. |
| What is it called when new DNA is made from old DNA? | Replication |
| Define semiconservative replication | The type of replication where the newly formed helix has 1 DNA strand and 1 new strand. The CORRECT way. |
| Define conservative replication | The incorrect belief that says the old helix stays together and a fully new helix is made. |
| What unwinds the DNA helix during replication? | DNA helicase |
| Describe the replication fork? | Where the DNA helix is open. |
| What is DNA Polymerase responsible for? | They assemble the growing DNA chain; (It is an enzyme that adds the correct complementary base pair). |
| DNA Polymerase can only add bases to the ______ end of the helix? | 3' (3 prime end) |
| Continuous strand synthesis continues in a ___to___ direction? | 5' to 3' direction |
| Discontinuous synthesis produces Okazaki fragments on the ___to___ template? | 5' to 3' template |
| After the Okazaki framents are made, _______ follows and hooks the Okazaki fragments together? | Ligase |
| What are Okazaki fragments? | Short fragment of DNA (with an RNA primer at the 5' terminus) created on the lagging strand during DNA replication. Each Okazaki fragment is initiated near the replication fork at an RNA primer created by primase and extended by DNA polymerase III. |
| What is polygenic inheritance? Give examples. | Multiple genes for a trait; ex: skin color, height, IQ, eye color. |
| This involves 3 sets of traits: | Trihybrid cross. |
| How many genes control eye color? | 4 genes--2 genes for green/blue and 2 genes for brown pigment. |
| What do you call genes that are influenced by the environment? | Multifactorial genes |
| T or F. Most genes can be controlled, somewhat, by your environment? | TRUE |
| What is PKU and what does it stand for? | Phenylketonuria. Unable to break down phenylalanine; causes mental retardation. Don't eat phenylalanine and don't have symptoms. |
| Name some somewhat environmentally controlled diseases: | PKU, Diabetes, High blood pressure |
| What is Heritability? | It estimates how much variation is due to genetics. Heritability of 1.0 means the variation is due entirely to genetics (thumb, tasting PTC). Heritability of 0.0 means that variation is due entirely to the environment (which shoe you put on 1st) |
| Define coefficient of relatedness. | the proportion of genes that 2 related people share; the more closely related, the more genes shared. |
| T or F. IQ is more than just genes? | TRUE |
| What are SRY's? | sex determining region of the Y chromosome. It seems to turn on genes coding for MALE characteristics. |
| What are Wnt4's? | Genes seemingly helping to regulate the process of being FEMALE. |
| What does Heterogametic and Homogametic mean? | Heterogametic means having 2 different sex chromosomes (XY or ZW). Homogametic means having 2 of the same sex chromosomes (XX or ZZ) |
| Female sex chromosomes in humans and in birds/snakes: | Human Female = XX; Female bird/snakes =ZW (w for woman/female) |
| Male sex chromosomes in humans and in birds/snakes? | Human male = XY; Male bird/snakes = ZZ |
| The X chromosome has more than ______ genes that code for many different proteins (not usually related to sex/reproduction? | 1500 genes |
| The Y chromosome only has _____ genes; ______% of which are male specific genes. | 231 genes; 95% male specific |
| T or F. The X and Y chromosomes are homologous and usually cross over during meiosis? | FALSE |
| What are pseudoautosomal regions (how many? where located?) | 63 genes on the tips of the Y chromosome have homologous genes on the X chromosome and can do crossing over. |
| What is Androgen Insensitivity Syndrome? | Occurs when a person has XY genotype and is producing testosterone, but is missing receptors to "hear" message, so develops as female. |
| What is Pseudohermaphroditism? | Condition where a child appears female at birth, but adrenal glands produce testosterone at puberty, which makes the clitoris enlarge to look like a penis. |
| T or F. Scientists aren't completely sure what causes transgender problems and homosexuality? | TRUE |
| Y linked Genes? | Genes found only on the Y chromosome; RARE; SRY |
| X linked recessive genes? | Genes found on the X chromosome; More common in males (hemophilia, red/green colorblindness, muscular dystrophy, hemophilia. |
| X linked dominant genes? | Genes more common in females because males are so severely affected that they die; if mom is affected half the children will have the disease; if dad is affected all the daughters are affected but no sons. (hypertrichosis--werewolf disease) |
| What are Barr bodies? | Random inactivation of ONE of the X's. |
| Calico cats are all female because... | you need an X chromosome with a black gene and an X chromosome with an orange gene. You see the results of Barr bodies in calico cats. |
| What are sex limited genes? | They are genes that are expressed in only 1 sex; testicular or ovarian cancer, preeclampsia |
| What is genomic imprinting? | Some genes behave differently depending on whether they are inherited from mom or from dad; fragile X syndrome is worst when inherited from mom. |
| What is Fragile X Syndrome? | symptoms include mental retardation and enlarged body parts: forehead, ears, jaw, testicles in males; incomplete dominance |
| T or F. You are more likely to have worse symptoms from Huntington's Disease if you get the Huntington's allele from your father. | TRUE |
| What genome controls placenta development? | The male genome |
| What genome controls embryo development? | The female genome |
| Hypertrichosis | werewolf disease; X linked dominant |
| Lethal allele combinations? | a genotype that causes death of the individual; ss sickle cell, HH hairless dogs |
| Multiple alleles? | more than just 2 alleles; A, B. o alleles for blood types, eye color, hair color. |
| Diseases that have multiple alleles: | PKU, cystic fibrosis, breast cancer |
| Which disease has almost 300 mutant alleles? | PKU |
| Which disease has at least 1000 mutant alleles? | cystic fibrosis |
| Incomplete dominance? | dominant allele isn't completely dominant over recessive and in the heterozygous offspring, you get a blending of the two; snapdragon flowers, palomino horses, fragile X syndrome |
| Codominance? | 2 dominant alleles produce a different phenotype, AB blood type |
| Epistasis? | one gene affects another gene's expression; albinism |
| Penetrance? | even though you have the genotype, you don't express the phenotype; polydactyl. |
| Expressivity? | degree to which you express your phenotype; having a full 6th digit is a different expressivity than having a small bump on the 6th digit. |
| Pleiltropy? | one gene affects an organism many ways; SRY gene, sickle cell hemoglobin, albinism |
| T or F. Sickle cell hemoglobin affects MANY body systems? | TRUE |
| Phenocopy? | an environmentally caused trait appears to be inherited. |
| Genetic Heterogeneity? | different genotypes are associated with the same phenotype; blood clotting disorders |
| Mitochondria and the mother? | while there are mitochondria in the midpiece of sperm, it stays outside of the egg; any mitochondria in the embryo come from the mom. |
| Mitochondrial DNA characteristics? | No repair mechanisms so mutates easily; NO crossing over; can be used in genetic or forensic studies. |
| Who discovered linked genes? | William Bateson and R.C. Punnett |
| Centimorgans (cM)? | unit to measure how far apart 2 genes are on a chromosome, smaller the number, closer the genes are, less recombinants there .are. |
| 1 cM = ______% recombination | 1% |
| Father genetics? Date? | Gregor Mendel, 1866 |
| Law of Segregation? | alleles will separate into different gametes during meiosis. |
| Gametes? | mature haploid sex cell; sperm, egg, pollen, pistol |
| True Breeding? | when self-fertilized, the offspring are of the same variety; homozygous for a trait. |
| Law of Independent Assortment? | if 2 genes are on 2 different chromosomes, the inheritance of one does not influence the chance of inheriting the other. |
| Huntington's chorea? | Dominant allele; nervous system degenerates. |
| Other dominant diseases are: | dwarfism, one form of Alzheimer's. one form of high cholesterol, Huntington's DZ. |
| Black circles represent ______; White circles represent ________. | females WITH a particular trait; Females WITHOUT the trait |
| Roman numerals (I, II) indicate _____ | generations |
| Arabic numbers (1, 2) indicate _____ | individuals |
| These will not appear in an offspring unless it also appears in at least one parent AND NO generations are skipped. | Dominant traits |
| These frequently will skip one or more generations in a direct ancestral line; but if both parents have the trait, ALL of the children should be affected | Recessive traits |
| Consanguinity? | blood relatives having children together; increases the risk of autosomal recessive disease. |
| Self-fertilization? | male part of plant fertilizes female part of same plant; cross to the same genotype. |
Created by:
mamcdonald
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