Cell Division and Heredity Presentation and...
Transcript of Cell Division and Heredity Presentation and...
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Welcome to AP BiologySaturday Study Session
Cell Division and Heredity
Question 1
bClue: sister chromatids dispersed in the cell and kinetochores attached to the
mitotic spindle
Mitosis is a continuous process with observable structural features
The Cell Cycle Question 2
cClue:
Time after Induction (hours) 0 2 4 6 8 10 12 14
Average Amount of DNA per Cell (fg)
24 40 47.5 48 24 13 12 12
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Question 3
aClue: non‐sister chromatids exchange
genetic material
Crossing Over Contributes to Genetic Variation Independent Assortment Contributes to Genetic Variation
Random Fertilization Contributes to Genetic Variation Question 4
cClue: abnormal number of chromosomes in sex cells
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NondisjunctionDown Syndrome
Chromosomal Abnormalities Question 5
dClue:
Roan = RWRed = RR
White = WW
RW RWRW RW
RR
W W
Question 6
bClue: 6:2 can be reduced to 3:1
Question 7
dClue: Males are more affected than
females
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Sex‐Linked Recessive Pedigree
• Males are more often affected than females.
• Affected fathers do not pass to their sons.
Question 8
cClue: Mendelian rules
Question 9
aClue: environment influences gene
expression
Math Grid In 1
The correct answer: 0.111Solution:• Both Karen and Steve are products of Aa x Aa crosses • Both Karen and Steve are either AA or Aa• Given the genotypic ratio of 1 AA : 2 Aa : 1 aa in a Aa x Aa cross, Karen and Steve each have a 2/3 chance of being carriers
• The overall probability of their child having the disease is 2/3 (the chance of Karen being a carrier) x 2/3 (the chance of Steve being a carrier) x 1/4 (the chance of two carriers having a child with the disease) = 1/9 = 0.111
Math Grid In 2
The correct answer: 1/32
Solution:AaBbCcDd x AaBBccDd
AaBBCcdd?
A a B b C c D d
½ Aa x ½ BB x ½ Cc x ¼ dd
AA Aa
Aa aa
Aa
BB Bb
BB Bb
Cc cc
Cc cc
DD Dd
Dd dd
BB
cc
Dd
Short Free Response 14 points possible
1 pt per bullet:• Prediction of a 1:1:1:1 ratio with correct phenotypes based on
independent assortment• Support for prediction with a diagram of the cross of BbEe x bbee• Correct application of chi‐square analysis to show that observed
results do not conform to expected Mendelian frequencies• Identification of body color and eye color as linked genes/loci• Use of ratios to show linkage and independent assortment of
wing type versus linked traits• Identification of the bottom two phenotypes as products of
crossing over (recombinant chromosome)• Mentioning that crossover rate is approximately 9‐10 percent
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Linked Genes
Short Free Response 23 points possible
Regulation: Correct description of checkpoints, which block cell cycle progress unless specific molecular and/or physiological conditions are satisfied – 1 pt each; 2 pts maximum:• Action of MPF and CDKs in checkpoint regulation• Contact inhibition of mitosis• Growth factor control of cell cycle activity
Correct discussion of the consequences of abnormal cell cycle regulation – 1 pt maximum:• Uncontrolled cell proliferation, as in cancer• Apoptosis• Non‐disjunction/aneuploidy/broken chromosomes from
abnormal spindle events
Checkpoints Regulate the Cell Cycle
Most cells exhibit anchorage dependence and density‐dependent inhibition of cell division
Long Free Response
Please see the rubric in the separate folder.
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