Meiosis
At the end of meiosis, how many daughter cells are there?
4
What does it mean for something to be true breeding?
○True breeding: organisms that produce offspring of the same variety over many generations of self pollination
■Example: true breeding purple pea plants will only produce purple offspring with self pollination
If a pedigree shows mostly males being affected, does that lead to thinking the disease is x-linked or autosomal?
X-linked - colorblindness, muscular dystrophy, hemophilia, etc.
What is nondisjunction?
When homologous chromosomes or sister chromatids fail to separate during anaphase.
If a dragon's diploid number of chromosomes is 2n=22, how many chromosomes would be in each of the dragon's gametic cells?
11
Describe what a monohybrid cross looks like.
Then, tell me what goes on the outside and what goes on the inside.
Box with four smaller boxes. Parents' alleles on the outside and possible genotypes of their offspring on the inside.
If a pedigree skips a generation, is the disease likely to be dominant or recessive?
Recessive!
You have two individuals AABBCc and Aabbcc. What are the odds that their offspring will be ...
AaBbCc?
aaBbCc?
1/4
0
What is a karyotype?
What can you determine by looking at karyotypes?
It is a picture that shows homologous chromosomes ordered by size and length.
You can see if there was a mistake during meiosis like nondisjunction which could cause trisomy 21.
A shark species has grey scales (G) or black scales (g). If 2 heterozygous sharks are crossed and produce 56 offspring, how many will have grey scales and how many will have black scales?
42 grey
14 black
What is the difference between complete dominance, incomplete dominance, and codominance?
Complete: the dominant allele always overshadows the recessive allele
Incomplete: INBETWEEN phenotype (black and white make gray)
Codominance: CO=BOTH (black and white make black and white speckled)
What is a linkage map?
What is the highest amount of recombination frequency that could occur?
Linkage Map: genetic map that is based on recombination frequencies
-The distance between genes are map units
-One map unit is equivalent to a 1% recombination frequency
-Tells us the relative distance genes are away from each other
-50% recombination is the highest & means that the genes are far apart on the same chromosome or on 2 different chromosomes
What are 3 differences between asexual and sexual reproduction?
1. One individual vs Two
2. Clones vs Unique
3. Mitosis vs Meiosis
What is the chi-squared equation?
AND how do you determine degrees of freedom?
Chi-squared = summation ((O-E)^2/E)
Degrees of freedom = take the # of categories you have and subtract 1
What is epistasis? AND give an example.
Epistasis: the phenotypic expression of a gene at one locus affects a gene at another locus
●Example: coat color in labs and some mice
○One gene codes for pigment and a second gene determines whether or not that pigment will be deposited in the hair
When can you guarantee that the phenotypic ratio of the F2 offspring is 9:3:3:1?
(Hint: there must be 2 reasons)
Only when the F1 generation is heterozygous for both traits AND the traits are completely dominant (following Mendelian genetics)!
What are the 2 things that happen during Meiosis that make you unique? THEN, describe what happens during them.
Crossing over: Prophase I - the homologous chromosomes break off parts of their "limbs" and switch them to make the chromosomes unique. (they also form a tetrad during this time)
Independent Assortment: Metaphase I - the homologous chromosomes can line up on either side of one another
Brown fur color (B) is dominant in dogs to white fur color (b). Long tails (L) for dogs is dominant to short tails (l).
Cross a dog that is heterozygous for both traits with a dog that is true breeding white with a short tail.
What is the phenotypic ratio of the offspring?
1:1:1:1
What is polygenic inheritance? Give an example.
●Polygenic inheritance: the effect of two or more genes acting on a single phenotype
○Example: height, human skin color
Poly means many!!
What month AND day is Mrs. Lu's birthday?
(I'll give it to you if you're within 5 days of the actual day)
May 8