Name ______________________________ Period ______
CELL REPRODUCTION
Chromosomes and DNA Replication
CHROMOSOMES
1. What is the composition of chromosomes?
______________________________________________________________________________
2. Each chromosome is a _______________________ DNA molecule.
3. Define chromatin:
______________________________________________________________________________
4. What does DNA wrap around during the S phase? __________________________
5. Nucleosomes are ____________________________________ formed by multiple wrapped
histone proteins.
6. Long strings of nucleosomes form thick coils that pack together to make up ________________.
7. During what phase of mitosis are chromosomes visible under a microscope? ________________
8. What shape does DNA take in prokaryotic organisms? __________________________________
1
Chromatids and the Centromere
9. After replication each chromosome consists of _____________ identical copies called
______________________________ attached to one another at a region called
the___________________________.
Chromosome Numbers
10. Do all species have the same number of chromosomes in their cells? ________________
11. How many chromosomes are found in human cells? ____________
12. Chromosomes of the same size and shape with the same genes are called
__________________________________________.
DISCOVER OF DNA STRUCTURE
13. What is the genetic material of all life on Earth? ______________
Griffith Searches for the Genetic Material
14. What was he searching for?
__________________________________________________________________
15. Briefly explain the experiment that led to Griffith’s conclusion and discoveries.
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
16. Based on his observations, Griffith deduced that something in the killed S-strain was transferred
to the previously harmless R-strain, making the R-strain deadly.
What did he call that something? ___________________________
2
Avery’s Team Makes a Major Contribution
17. Whose experiments did his team replicate? ________________________________________________
18. Why did they replicate these experiments?
_____________________________________________________________________________________
_____________________________________________________________________________________
19. What conclusions did Avery come up with?
_____________________________________________________________________________________
_____________________________________________________________________________________
Hershey and Chase Seal the Deal
20. Briefly explain Hershey & Chase experiment.
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
21. What was their conclusion?
_____________________________________________________________________________________
Chargaff Writes the Rules
22. What did Chargaff study?
_____________________________________________________________________________________
23. What discovery did Chargaff make?
_____________________________________________________________________________________
_____________________________________________________________________________________
3
24. What name is giving to his discovery?
__________________________________________________________
The Double Helix
25. What did Watson & Crick discover? _______________________________________________________
26. In what year was this discovery made? ______________
27. What is the shape of a DNA molecule? __________________________________________
28. What type of bonds hold the nucleotides together? __________________________________________
29. What are the three parts of a nucleotide? __________________________________________________
30. Name the four nitrogenous bases found in DNA.
____________________________________________________________________________________
31. Which nitrogenous bases always pair together?
____________________________________________________________________________________
4
DNA REPLICATION
32. DNA replication occurs during the _________________ of the eukaryotic cell cycle.
33. Steps to DNA replication:
(1) ___________________________________________________________________________
(2) ___________________________________________________________________________
___________________________________________________________________________
(3) ___________________________________________________________________________
___________________________________________________________________________
(4) ___________________________________________________________________________
34. What is the name of the enzyme that opens the DNA molecule? _________________________
35. What is the name of the enzyme that “reads” the DNA molecule? _______________________
DNA Replication is Semi-Conservative
•
•
DNA replication of one helix of DNA results in two identical helices
– original DNA helix is called the "parental" DNA
– two resulting helices can be called "daughter" helices
DNA replication is semi-conservative, meaning that one parent strand is always passed on to
the daughter helix of DNA
5