STUDY GUIDE – Genetics – Unit 6
1.
The picture below shows transcription involving an operon on a DNA strand. What type of organisms use operons as regulatory
mechanisms for protein synthesis?___________________________
A scientist is using an ampicillin-sensitive strain of bacteria that cannot use lactose because it has a nonfunctional gene in the lac
operon. She has two plasmids. One contains a functional copy of the affected gene of the lac operon, and the other contains the gene
for ampicillin resistance. Using restriction enzymes and DNA ligase, she forms a recombinant plasmid containing both genes. She
then adds a high concentration of the plasmid to a tube of the bacteria in a medium for bacterial growth that contains glucose as the
only energy source. This tube (+) and a control tube (-) with similar bacteria but no plasmid. They are both incubated under the
appropriate conditions for growth and plasmid uptake. The scientist then spreads a sample of each bacterial culture (+ and -) on each
of the three types of plates indicated above.
2.
Why did the scientist use restriction enzymes in the experiment described above?________________________________________
In the 1940’s, Avery, MacCleod, and McCarty transformed non-encapsulated bacteria into encapsulated forms by growing the nonencapsulated cells in a culture containing an extract made from dead encapsulated cells. The transformed cells produced colonies of
encapsulated bacteria. Three different procedures and their results are outlined below.
Procedure I:
Extract made from dead encapsulated cells added to culture medium. Non-encapsulated bacteria added to culture medium.
Results: Both non-encapsulated and encapsulated bacteria grow.
Procedure II:
Extract made from dead encapsulated cells treated with protein-degrading enzymes before adding exact to culture medium.
Non-encapsulated bacteria added to culture medium.
Results: Both non-encapsulated and encapsulated bacteria grow.
Procedure III:
Extract made from dead encapsulated cells treated with DNAse (an enzyme that selectively destroys DNA) before adding extract to
culture medium. Non-encapsulated bacteria added to culture medium.
Results: Only non-encapsulated bacteria grow.
3.
What conclusion could be made about DNA from the experiment described above?______________________________________
4.
An alternating pattern of white and black bars (barring) seen in the feathers of some chickens is a sex-linked dominant trait. How
would you match up males and females so that all chicks of one sex would be barred?____________________________________
5.
Why is it not completely accurate to say that the X and Y chromosomes determine sex?___________________________________
6.
How can you tell if DNA fragments have been cut by the same restriction enzyme or by different enzymes?___________________
7.
Look at the description of the experiment done in #3. Why was DNAse used in Procedure III?_____________________________
8.
If nondisjunction occurs in anaphase of meiosis I, how many chromosomes will be in each of the four gametes produced?_______
9.
How does a person get sickle cell anemia?_______________________________________________________________________
10. If one parent is heterozygous dominant, and one parent is homozygous recessive, what % of their offspring will express the
dominant trait, and what % will express the recessive trait?_________________________________________________________
11. Give an example of how Mendel’s rules or laws are limited in their ability to predict genotypes and phenotypes._______________
12. Experiencing more alternative splicing of the RNA, proteins combining into quarternary structures, and different combinations of
exons tend to be characteristics of the genome of what organisms?____________________________________________________
13. State Beadle and Tatum’s hypothesis, and tell what it means in the most modern interpretation._____________________________
14. Look at the description of the experiment done in #3. Why was the extract treated with protein-degrading enzymes in Procedure II?
15. Look at the description of the experiment done in #2. Which plates would be expected to have bacterial growth?________________
16. A mother has heterozygous brown eyes (Bb), heterozygous unattached earlobes (Uu), heterozygous dark skin (Dd), and a
heterozygous tall height (Tt). The father has homozygous brown eyes (BB), heterozygous unattached earlobes (Uu), heterozygous
dark skin (Dd), and homozygous tall height (TT). What is the probability that one of their offspring will have homozygous brown
eyes (BB), heterozygous unattached earlobes (Uu), homozygous light skin (dd), and heterozygous tall height (Tt)?
17. Explain the difference between the leading strand and lagging strand during DNA replication.
18. Give 3 reasons why the lagging strand in DNA replication is slower than the leading strand.
19. What are mutations that occur in somatic cells?____________________________________________________________________
20. Name and describe two types of gene mutations.
21. Name 5 mutagens.___________________________________________________________________________________________
22. Which process in the cell cycle would use the terms reduction and rearrangement? Explain how they apply.
23. How could a chromosomal abnormality occur during meiosis?________________________________________________________
24. Give an example of a chromosomal abnormality that occurs in meiosis, and tell how it affects the phenotype of a person.
25. What are the steps involved in cloning an animal? How does the genome of the clone compare with the genome of the original?