Exam 2 review sheet

Exam 2 Review Sheet: Fall 2007

Exam 2 will be on Wednesday November 7th

Material on exam:

Only the portions of the following chapters that are listed on the syllabus and that we spoke about in class will be on the exam. If their are pages on the syllabus that we did not discuss, it will not be on the exam.

Chapter 7

Chapter 8

Chapter 9

Chapter 10

Chapter 11

Chapter 12

Please let me know if you are having trouble with any of this and feel free to contact me by email (lrapp@stcc.edu) or phone (755-5254).

Chapter 7: Sex Determination

Klinefelter and Turner syndrome

	What are symptoms of these disorders?
	Be able to recognize a karyotype of these syndromes and correctly indicate the chromosome arrangement (number of chromosomes, sex chromosomes, deviation from normal)
	Both syndromes are the result of nondisjunction in meiosis
	What did these syndromes tell scientists about sex determination in humans?

47 XXX, 47XYY

What is the SRY? What would happen if a female had a copy of this gene? If a male lost this gene?

Dosage compensation by X inactivation

What are Barr bodies? Where are they located? How many are present in different individuals?

Mosaicism -- the Lyon hypothesis states that females are mosaics for all heterozygous X linked alleles.

Chapter 8: Variation in Chromosome Number and Structure

	Know what is meant by aneuploidy, monosomy, trisomy, euploidy
	Is monosomy tolerated in plants? Animals?
	Cri-du Chat syndrome = partial monosomy, loss of half of the short arm of chromosome 5.
	Downs syndrome = trisomy of chromosome 21, caused by nondisjunction
	Edwards syndrome = trisomy 18
	Patau syndrome = trisomy 13

	Polyploidy (triploid, tetraploid, etc)
	How is polyploidy tolerated in plants? Animals?
	Be able to distinguish between autoploidy and alloploidy
	How are tetraploids made artificially? Naturally?
	Why are some plant autoploids of commercial value?
	Why are some plant alloploids of commercial value?
	Be able to recognize a karyotype and correctly indicate the chromosome arrangement (number of chromosomes, sex chromosomes, deviation from normal) for the above disorders/conditions
	review the types of chromosomal rearrangements: deletion, inversion, duplication, nonreciprocal translocation, reciprocal translocation.
	What is the difference between a terminal deletion and an intercalary deletion?
	How can a duplication arise?
	How does a deletion result in gene redundancy or phenotypic variation?
	What is the difference between a paracentric inversion and a pericentric inversion?
	Review figures 8-21 and 8-22
	Review familial down's syndrome

Chapter 9: Extranuclear Inheritance

review sections 9.2, 9.3 and 9.5, and class notes

Chapter 10: Chemical Structure of DNA

DNA = the genetic material. Several important characteristics:

	replication
	storage of information
	expression of information
	variation by mutation

Know the purpose, design and outcome of Griffith's experiment

Know the purpose, design and outcome of the Hershey Chase experiment

Know the components of a nucleotide and be able to identify a nucleotide

What is the difference between ribose and deoxyribose?

The four nitrogenous bases in DNA are G, A, T , and C. A and G are the purine, C and T are the pyrimidines

What type of bond links nucleotides together?

Review and understand the features of the Watson and Crick Model of DNA:

	right handed double helix
	2 strands are antiparallel (5' to 3' and 3' to 5')
	the bases of both chains are perpendicular to the axis of the molecule
	nitrogenous bases paired by hydrogen bonding (A-T; G-C)
	given a given percentage of one nucleotide, be able to determine the percentage of the other nucleotides
	Complete turn of the helix = 34A^o
	20 A^oin diameter (= pyrimmidine + purine distance)
	major and minor grooves

Be able to appropriately label a diagram of DNA with the above features

How is molecule held together by "weak" hydrogen bonds?

How many hydrogen bonds between G and C? A and T?

~~Gel electrophoresis. DNA separated on basis of size and charge through gel.~~

Chapter 11: Replication of DNA

Know the difference between conservative, semiconservative, and dispersive replication.

How did the Messelson-Stahl experiment demonstrate that DNA replication is semiconservative?

Replication always occurs 5' to 3' (see Figure 10.8)

DNA Polymerase requires 3' end to initiate synthesis, so requires RNA primer (see Figure 11-11, 11-12

Leading strand synthesis is continuous, 5' to 3'

Lagging strand synthesis is discontinuous, 5' to 3'. Many points of initiation necessary because trying to replicate one way, and 5' to 3' is in the opposite direction.

Okazaki fragments --the short pieces of DNA synthesized from primers on the lagging strand.

DNA Polymerase = dimer, synthesizes both strands simultaneously

FIGURE 11-13. Know what all of the proteins illustrated are doing for the replication process and be able to identify them in a figure:

	helicase
	single stranded binding protein
	gyrase
	primase
	DNA Polymerase (In E. Coli, Pol III is main replication protein; Pol I is responsible for filling in gaps left after RNA primers are removed and for "proofreading" capabilities, Pol II repairs damage to the DNA from UV and mutagenic chemicals)
	Not included in figure, but important, is DNA ligase, which joins the Okazaki fragments after RNA primers are removed, and gaps are filled in by Pol I

Figure 11-16, 11-17. How does Telomerase deal with the problem of gaps at the ends of DNA?

Chapter 12: Chromosome structure

	Review chromatin structure info on pages 292-295
	What proteins are associated with DNA? What is the nature if the interaction?
	what experiments demonstrated chromatin structure?
	review Figure 12-9
	what is meant by chromosome remodeling?
	What does modification of histones by acetylation, methylation or phosphorylation do?