Card Set Information

2012-11-06 19:43:37
Bio 101

biotechnology, Chromosomes, Cell Division, Mendelian Inheritance
Show Answers:

  1. What two important features of DNA were discovered between 1900-1950?
    • (1) molecules of DNA from parent to offspring
    • (2) the instructions on how to create a body and control its growth and development are encoded in the DNA molecule.
  2. Which two scientists deduced the exact structure of DNA? 
    Francis Crick

    James Watson
  3. What type of macromolecule is DNA. What is DNA's building unit and what are its three (3) components?
    DNA is a macromolecule of nucleic acid. The building unit of DNA is termed a nucleotide whose three components are (1) a sugar molecule, (2) a phosphate group and (3) a nitrogen-containing molecule called a base
  4. Describe a Double Helix
    A double helix is like a spiral ladder with two railings, consisting of a phosphate group and a sugar, that holds it together, and steps or rungs, consisting of two base base pairs held together by hydrogen bonds.
  5. What are the (4) bases of DNA, and how are they paired?
    • The four bases of DNA are adenine (A) thymine (T), guanine (G), and cytosine (C).
    • A-T
    • G-C
  6. How is DNA like a cookbook?
    DNA is like a cookbook in that just as a cookbook contains detailed instuctions on how to make a variety of foods, and organism's DNA carries detailed instructions to build an organism and keep it running.
  7. What is a genome, and how is the genome related to chromosomes?
    A genome is a full set of DNA, which are in manageable pieces called chromosomes.
  8. Define a gene
    A gene is a sequence of bases in a DNA molecule that carries the information necessary for producing a protein or RNA molecule.
  9. What are alleles?
    Alleles are alternative versions of a gene that code for the same feature.
  10. Is the size of a genome related to the complexity of an organism?
    There does not seem to be any relationship between the size of an organism's genome and the organism complexity.
  11. What percentage of DNA is actually genes?
    Only 5% of human DNA is actually genes
  12. What is the function of non-coding DNA?
    The function of the non-coding DNA is a big mystery. Perhaps it is a reservoir of potentially useful sequences, or it may function in regulating when genes are turned on or off.
  13. Define genotype and phenotype, and relate this to cookbook metaphor.
    If the genes that an organism carries for a particular trait-its genotype-are like a recipe in a cookbook, the physical manifestation of the instructions is the organism's phenotype-the cookies or macroni and cheese.
  14. What are the (2) main steps in going from a gene to the production of a protein?
    The two main steps in going from a gene to the production of a proteins are (1) transcription, and (2) translation
  15. What is transcription and where in the cell does it occur?
    In transcription, one specific gene is copied and made into a specific RNA. This occurs in the nucleus where the DNA is located.
  16. What does the enzyme RNA polymerase do in step 1 of transcription? Where does RNA polymerase bind on the DNA molecule?
    In step 1 of transcription, the enzyme RNA polymerase is responsible for copying a gene and making the specific RNA molecule. To do this it must recognize and bind with a promoter site, a part of the DNA molecule that indicates the start of a gene.
  17. How does RNA polymerase transcribe DNA in step 2?
    In transcription, RNA polymerase builds a messenger RNA (mRNA) using the gene as a template. The complementary bases are the same as DNA, except where the DNA has an adenine, the RNA is made with a complementary base of uracil.
  18. What is the RNA called that has been transcribed from a gene?
    The RNA that has been transcribed from a gene is always mRNA.
  19. What is a termination sequence and where is it located?
    A termination sequence is always at the end of a gene, the RNA polymerase stops transcribing.
  20. Why is the messenger RNA (mRNA) capped and tailed?
    The mRNA is capped and tailed to protect it from damage, and help the protein-making machinery recognize it's a mRNA.
  21. Where does translation occur?
    Translation occurs in the cytoplasm at the ribosomes.
  22. What ingredients are required for translation?
    The ingredients required for translation are (1) free amino acids, (2) ribosomes (3) transferRNA (tRNA) molecules that carry the building blocks (amino acids) of proteins.
  23. What is a codon and which RNA possesses them?
    Each three-base sequence in the mRNA is a codon, which always matches with tRNA that carries the amino acids.
  24. How does a cell know to start translation?
    mRNA always carries the same three-base sequence (AUG) to start translation.
  25. How does a cell know to stop translation?
    mRNA has a specific three-base sequence that terminates translation.
  26. How does a cell measure how old it is?
    A cell measures how old it is with an end section of each DNA called a telomere. Each time a cell divides the telomere gets a bit shorter, until it starts losing essential DNA, which then causes almost certain death for the cell.
  27. What is the basic problem with Hutchinson-Gifford progeria syndrome.
    Individuals with Hutchinson-Gilford progeria syndrome are born with shorter than normal telomeres, which causes them to age rapidly.
  28. What does it lead to when cells rebuild their telomeres?
    When cells rebuild their telomeres after each cell division, the cell then doesn't know when to stop dividing, a condition called cancer.
  29. How do chromosomes differ between prokaryotes and eukaryotes?
    The prokaryotes have a single circular piece of DNA that is attached to one side of the cell membrane, while eukaryotes have multiple free floating linear strands of DNA contained in the nucleus.
  30. What is the method of cell division called in prokaryotes? Is the replicated DNA identical? What kind of reproduction is it called?
    The method of cell division in prokaryotes is called binary fission, and the replicated DNA and subsequent cell are genetically identical, and is therefore called asexual reproduction, since the division of the cell is also the reproduction of the individual.
  31. Cells that don't divide once an organism matures, like muscle and neuron cells, are in what stage of interphase?
    Cells that don't divide once an organism matures, like muscle and neuron cells are in the Gap 1 (G1) stage of interphase.
  32. If a cell is going to divide, it must prepare for this by replicating its...
    If a cell is going to divide, it must prepare for this by replicating its DNA or chromosomes.
  33. The division of the nuclear contents is called mitosis. What is the division of the rest of the cells contents called ...
    The division of the nuclear contents is called mitosis, while the division of the rest of the cells contents is called cytokinesis.
  34. When DNA replicates itself are the two double helices identical and why?
    When DNA replicates itself the two DNA double helices are identical because of complementary base pairings.
  35. What is the one purpose of mitosis?
    The one purpose of mitosis is to enable existing cells to generate new, genetically identical cells.
  36. What is it called when a cell of your body dies on purpose? Why is this necessary, and name a few of your cells that do this?
    The purposeful dying of a cell is called apoptosis, and is necessary for those cells which can accumulate significant genetic damage over time, which include cells lining the digestive tract and liver.
  37. Are sister chromatids identical?
    Sister chromatids are identical
  38. What pulls apart in anaphase of mitosis?
    Sister chromatids of a chromosome are pulled apart during anaphase of mitosis.
  39. Why are malignant tumors so harmful?
    Malignant tumors are very harmful because they metastasize and spread throughout the body.
  40. What must meiosis do in anticipation of fertilization
    The chromosomes must be reduced in half in the gametes in anticipation of combining one individual's genome with another's during fertilization.
  41. In all, what are the two important outcomes of meiosis?
    In all, the two important outcomes of meiosis are (1) reduce the amount of genetic material in gametes and (2) produce gametes that differ from one another with respect to the combinations of alleles they carry.
  42. What separates during the 1st division of meiosis? What separates during the 2nd division of meiosis?
    Homologous chromosomes separate during the second division of meiosis, while sister chromatids separate during the second division of meiosis.
  43. In prophase 1 of meiosis, after the homologous chromosomes pair up, what occurs to make every sperm or egg cell genetically unique?
    In prophase 1 of meiosis, after the homologous chromosomes pair up, crossing-over occurs, and makes very sperm and egg genetically unique.
  44. What occurs in Anaphase 1 of meiosis that also makes the sperm and eggs unique?
    In Anaphase 1 random assortment occurs between the homologous pairs, which also makes sperm and egg unique.
  45. What is the advantage of sexual reproduction, and what are the three sources of variation? What is the disadvantage of sexual reproduction?
    Sexual reproduction leads to offspring that are all genetically unique, which allows the population of organism to cope better with changes in their environment. The sources of genetic variation are crossing over and the reassortment of homologs during meiosis, and the combining of alleles from two parents during fertilization. The disadvantage is an inefficient transfer of genetic information, which might lead to many offspring not surviving.
  46. What is the advantage of asexual reproduction? What is the disadvantage of asexual reproduction?
    The advantage of asexual reproduction is an efficient transfer of genetic information, which will lead to many offspring surviving. The disadvantage is the environment changes the less suited they will be as a population.
  47. Who, male or female, determines the sex/gender of the human, and why?
    The male determines the sex/gender of the child because half his sperm contain the Y-chromosome and half the X-chromosome, while the female eggs contain X-chromosomes. If the Y-chromosome sperm fertilizes the egg the baby becomes a female, and if the X-chromosome sperm fertilizes the baby becomes a male.
  48. If the "Y" chromosome is present, what do the fetal gonads turn into? If the "Y" chromosome is not present, what do the fetal gonads turn into?
    If the Y-chromosome is present the gonads become testes and, if not they become ovaries.
  49. What is the name of the procedure for removing cells from the amniotic fluid and what is it checking for?
    Amniocentesis is the procedure for removing cells from the amniotic fluid, and used to check for chromosomal abnormalties in the fetus.
  50. Which chromosome # do down syndrome people have an extra copy of, and what is it called?
    Down syndrome people have an extra copy of chromosome #21,and is called a Trisomy 21.
  51. Down syndrome and other disorders caused by missing a chromosome, or having an extra copy of a chromosome, are the consequence of...
    Down Syndrome and other disorders caused by missing a chromosome, or having an extra copy of a chromosome, are the consequence of nondisjunctions, or the unequal distribution of chromosomes during meiosis.
  52. When people get an extra chromosome and survive, is that extra chromosome likely to be a long one or a short one, and why?
    When people get an extra chromosome and survive, it is likely that that extra chromosome is a short one, because long ones carry more genes, which enables more things to go wrong.
  53. Describe the sex-chromosome combination of Turner's syndrome, Klinefelter's syndrome, super males and metafemales.
    • Turner's syndrome=XO (deficient one X-chromosme=45 chromosomes
    • Klinefelter's syndrome=XXY (one too many X-chromosomes=47 chromosmes
    • Super males=XYY (one toomany Y-chromosomes)
    • Metafemales=XXX, or XXXX, etc
  54. How successful can we be in selecting the sex of our offsprig using weight or fluorescent dyes?
    By using the differences in weight, and fluorescent dyes, initial result suggest a 70-90% success rate in selecting the sex of our offspring.
  55. Each of the two copies of a gene is called an...
  56. Traits that are determined by the instructions a person caries on one gene are called...
    Single-gene traits
  57. How did Mendel describe the pea plant that he labeled as a true breeder?
    Mendel described true-breeders as plants that produced offspring with the same variant of the trait as the parents.
  58. How did Mendel figure out which trait was dominant and recessive when it came to pea plant flower colors?
    To figure out which trait is dominant and recessive, Mendel cross a pure-breeding Purple flowered pea plants with pure-breeding white flowered pea plants. Because all the offspring had purple flowers, purple flowers is a dominant trait.
  59. What results did Mendel get when he crossed the offspring of these pure-breeders? 
    Because 1/4 of the offspring had white flowers, he found that these purple flowered pea plants were not pure-breeders.
  60. What were the three hypothesis' made by Mendel to explain the pattern of Inheritance he observed?
    Mendel's three (3) hypothesis were (1) Each parent put only one copy of gene into a sperm or egg, (2) the offspring receive two copies of gene, one from each parent, and (3) the trait observed in an individual depends on the two copies of the gene.
  61. When an individual inherits the same two alleles for a gene the individuals genotype is said to be...
  62. When the individual inherits a different allele for a gene (both alternatives) the individuals genotype is said to be...
  63. The idea that, of the two copies of each gene everyone carries, only one of the two alleles gets put into each gamete, is significant and important enough that it is called the Law of...
  64. What is the outward appearance called?  What is the organisms genetic composition called?
    The outward appearance is called the phenotype, while the organisms genetic composition is called the genotype.
  65. What is a test-cross?
    A test cross, using a know genotype, the recessive trait that is always due to homozygosity, is used to determine the genotype of an organism that has the dominant trait, whose genotype is either homozygous dominant, or herterozygous. If any of the offspring exhibit the recessive trait then the genotype of the dominant trait was heterozygous.
  66. What is incomplete dominance, and how is this displayed when you cross a pure-breeding red flowered snapdragon with a pure-breeding white flowered snapdragon?
    Incomplete dominance is exhibited when the heterozygote appears to be intermediate between the two homozygotes. When you cross a true-breeding red flowered snapdragon with a true-breeding white flowered snapdragon all the heterzygote are pink flowered.
  67. What is codominance, and how is this displayed in the heterozygous individual for sickle-cell anemia?
    Codominance occurs when the heterozygote displays characteristics of both homozygotes. In sickle cell anemia the individual blood has both normal red blood cells, and sickle celled red blood cells.
  68. Describe multiple allelism with regard to the ABO blood types.
    Multiple allelism is where a trait is due to three or more alleles, but the individual can only posses two at a time. In the ABO blood types, there is the A-allele, the B-allele, and the O-allele. Individuals are either AA, AO, BB, BO, AB or OO.
  69. Give some examples of polygenetic inheritance.
    Polygenetic inheritance is due to two or more pairs of alleles which usually have an additive effect. Eye and skin color, and height are good examples.
  70. What is pleiotropy and how does it apply to the sex-determining region of the Y-chromosome.
    Pleiotropy is where one gene can influence multiple unrelated traits such as the gene that produces male. Maleness is solely due to one gene on the Y-chromosome called the sex-determining region of the Y-chromosome (SRY), and causes all male characteristics.
  71. When a trait is sex-linked and due to a recessive allele, which gender has the trait more frequently? When a trait is sex-linked and due to a dominant allele, which gender has the trait more frequently?
    When a trait is sex-linked and is due to a recessive gene, males have the trait more frequently. When a trait is sex-linked and is due to dominant gene, females get itmore frequently.
  72. Why does the red-hair trait seem to go along with freckles/light skin trait?
    Because they are the same chromosome and closely linked to one another, making it virtually impossible for crossing-over to occur between them.