Download Contemporary Biology Per

Contemporary Biology Per. 4
Halliwell/Mortara
Study Guide - Test #7, Section 8.4 & Chapter 9
1. Cells regulate gene transcription because they do not always need a gene’s
product. A gene is said to be __________ or “turned on” when it is
____________ to mRNA.
2. E. coli contains about 2000 genes, three of which are called ____ genes, each
coding for a protein that tells the cell how to use ________, a sugar. The lac
genes are only expressed in the presence of lactose.
3. The ___________ is a special region of DNA on one side of the lac genes that
acts as the binding site for RNA polymerase. RNA polymerase recognizes the
promoter and then moves along the DNA until it finds the first gene, when
transcription begins.
4. The lac genes are regulated by a __________, a DNA-binding molecule that
blocks a gene’s transcription.
5. The lac repressor binds to another special DNA region called the
___________. When the repressor is bound to the operator, RNA polymerase
________ move past the operator to the lac genes – like a lock.
6. The lac genes can only be expressed if the repressor is __________ from the
operator. Lactose binds to the repressor when present, allowing the repressor
to change shape and fall off the operator – ___________ can now occur.
7. In 1976. scientists compared mRNA sequences with the corresponding DNA
sequences, expecting them to match. They actually were very different, and
after much research scientists found that there is a complex editing processes
that occurs where segments of the molecule called _________ are removed,
and the remaining ________ are spliced together to form the final mRNA.
8. Introns = ____________ sequences
Exons = _____________ sequences
9. Selective breeding is when individual organisms with _________
characteristics are _________ to produce the next generation.
10. Selective breeding is the concept behind pure bred dogs and cats, but it is
also used for _______ ________.
11. ________________ is a cross between dissimilar individuals. It is a way to
combine the best characteristics.
12. ________________ is a cross between similar individuals. It is the way to
maintain a breed of organisms once it is established.
13. The problem with inbreeding is that because the members of the breed are
so genetically similar, crossing individuals of the same breed increases the
chances of _______ alleles pairing, which can lead to an increase in genetic
________.
14. A ___________ is an inheritable change in genetic information. Though
most of the time DNA replication occurs perfectly, every once in a while there
may be a mistake, or a mutation.
15. Changes involving the number or structure of a cell’s chromosomes are
called ________ _____________.
16. Chromosome number problems occur in ________ when an entire set of
chromosomes fails to ___________. This can lead to _____________, meaning
that an organism has 3 or more sets of chromosomes. In animals, polyploidy is
fatal, but in plants, it often makes them larger and stronger.
17. Chromosome structure mutations include:
 Deletions: an entire gene is ______
 Duplications: one gene in a sequence is ___________
 Inversions: pieces of the ______ chromosome switch places
 Translocations: a piece breaks off _____chromosome and attaches to
_______ chromosome
18. Another type of mutation is called a gene mutation. These mutations affect
only a _________ gene. The mutation may involve one or many
nucleotides and can have dramatic consequences.
19. Two types of gene mutations 

Point mutations: A substitution occurs when one nucleotide is
____________ for another nucleotide, causing a change in one of the
amino acids in a sequence
Frameshift mutations: Involve the insertion or deletion of a nucleotide. The
“reading frame” is ________, throwing off the whole sequence past the
point of the mutation.
The fat cat ate the rat
Deletion  Tef atc ata tet her at
Insertion  Thh efa tca tat eth era t
20. ___________ have tools to cut, separate, and read DNA sequences,
and to splice together those sequences in almost any order.
Tool #1: Cutting DNA
21. ____________ enzymes are proteins that can _____ DNA at specific
places. DNA can be cut into smaller, precisely sized fragments, which are
easier to work with.
Tool #2: Separating DNA
22. _____________ is a technique used to separate the DNA fragments
cut by restriction enzymes.
23. First, DNA fragments are placed on one end of the gel. Second, the gel
is placed in an _________ field. Since the DNA fragments are negatively
charged, they move from toward the ________ charged electrode. The
________ fragments move through the gel faster than the larger fragments.
Tool #3: Reading DNA
24. Once the DNA is cut into pieces using restriction enzymes, the pieces
are placed in test tubes with ____ polymerase, an enzyme that synthesizes
a complementary DNA strand.
25. The complementary DNA strand is made using chemically modified
nucleotides that _____ the assembly of the new strand at certain places,
allowing the pieces to be separated using gel electrophoresis.
26. The gel produces a _________ of bands that shows the sequence of
the original DNA strand. This research is now completed and analyzed by
computers.
27. This was the method used by the scientists working on the _______
_________ __________, completed in 2003.
Tool #4: Splicing DNA
28. When some restriction enzymes cut DNA, they leave short, singlestranded regions on each side of the cut called _________ _______.
29. When DNA fragments that have been cut by the same restriction
enzyme are mixed together, the sticky ends match up and enzymes can be
used to permanently _____ the fragments.
30. The newly joined pieces of DNA are like an entirely new DNA molecule
called ____________ DNA.
31. After recombinant DNA molecules are assembled, they can be put into
a living cell. Cell _______________ involves inserting new genes into a
cell, changing the cell’s genetic makeup.
32. Some bacteria have regular chromosomes along with small, circular
DNA molecules called _________.
33. Using ____________ enzymes, the plasmid is cut at a certain point,
and pieces of DNA are spliced into the plasmid. These recombinant
plasmids are mixed with a culture of bacteria that do not contain plasmids,
and under the right conditions, some of the bacteria will take up the
plasmids. The bacteria that take up the plasmids will then produce more
bacteria with the plasmids.
34. Eukaryotes are more _________ because it is harder to get a
eukaryotic cell to accept new DNA molecules.
35. __________ contain plasmids like bacteria, and they can be used for
transformation as well.
36. Animal and plant cells without plasmids can be transformed by
________ new DNA into the cell.
37. ______________ _____________ is the cutting and splicing of DNA from
different sources.
38. A ___________________ organism is one that has been transformed from with
genes from another organism.
39. How have bacteria and yeasts been “tricked” into creating human proteins?
40. Give an example of a human protein created by transgenic bacteria.
41. Give three examples of transgenic plants.
A.
B.
C.
42. How do scientists create transgenic animals? (two steps)
43. How is human gene therapy being studied?