What is nondisjunction? when homologous chromosomes fail to
separate, leading to a disorder of chromosome numbers
What happens as a result of nondisjunction? results in gametes
with an abnormal number of chromosomes
What is a trisomy? an individual is born with three copies of a
chromosome
Name 2 examples of sex chromosome disorders. Cite the karyotype
associated with the disorder. Turner’s syndrome- 45 X or 45 XO and
Klinefelter’s syndrome - 47 XXY
Why can a baby be born without a Y chromosome, but not without a X?
the X contains genes that are vital for the survival and development
of the embryo
What 3 techniques do scientists use to sequence DNA from a cell?
cut, separate, and replicate
Why do scientists cut DNA into smaller pieces? What do they use?
Where do they get it? What do they call the small pieces of DNA? DNA
molecules from most organisms are much too large to be analyzed,
restriction enzymes, bacteria , restriction fragments
What is a “sticky end”? What does it “stick” together? singlestranded overhangs of DNA, can “stick,” to a DNA fragment with the
complementary base sequence
What is gel electrophoresis used for? to separate and analyze the
differently sized fragments of DNA
What happens when an electric voltage is applied a gel containing
DNA samples? DNA molecules—which are negatively
charged—move toward the positive end of the gel
What does a gel look like after electrophoresis?
a pattern of bands based on fragment size
After DNA has been separated into pieces, what has to happen to
these fragments? researchers read, or sequence DNA
When single stranded DNA fragments are added to a mixture of the
four bases (A, C, T, and G), what enzyme is used to copy the single stranded
DNA fragments, one new DNA strand after another? DNA polymerase
When bases that have a chemical dye attached are added to a new
DNA strand, what happens? the synthesis of that strand stops
The resulting color-coded DNA fragments of different lengths can
be separated further by gel electrophoresis. Why is the order of
colored bands on the gel important? The order tells the exact
sequence of bases in the DNA
What is selective breeding? What is it used for? A technique
used to produce animals with certain desired traits by taking
advantage of naturally occurring genetic variation, to pass wanted
traits on to the next generation of organisms
Why can breeding by hybridization often be better than inbreeding?
individuals produced by such crosses are often hardier than either of
the parents
Why is inbreeding risky? It increases the chance that a cross between
two individuals will bring together two recessive alleles for a
genetic defect
What is genetic engineering? Name 3 things that can be done to
DNA through genetic engineering. the use of technology to
manipulate and change genes; insert, remove, or alter an
organism’s DNA
How can breeders increase the mutation rate of an organism?
Cite an example where this would be beneficial. by using
radiation or chemicals, strains of oil-digesting bacteria
What is a polyploid plant? Why is this advantageous over diploid plants?
Is polyploidy useful in animals? Plants that have many sets of
chromosomes, no-fatal
What is recombinant DNA technology? How is it accomplished?
joining together DNA from two or more sources; DNA is cut and
recombined in different ways
What is a transgenic organism? What is another name for
this organism? An organism containing genes from
other species; GMO
How are transgenic organisms created? the insertion of
recombinant DNA into the genome of a host organism
What is gene therapy? changing the DNA of a person with a
genetic disease or disorder by introducing working genes into the
nuclei of their cells
What is cloning? a technique that uses a single cell from an
adult organism to grow an entirely new individual that is
genetically identical to the organism from which the cell was taken
What is combined in nuclear transplantation? What is produced?
Name some species that have been created this way. an egg cell
with a donor nucleus; an embryo; cows, pigs, mice, cats