Question | Answer |
How is it possible to have things with genetically identical hemoglobin appear differently? | Differences at other genes may affect expression & environmental influence |
How is it possible to have things with genetically identical hemoglobin appear the same? | Dominance, environmental influence |
Vp | Phenotypic variance |
Vg | Genetic variance |
Ve | Environmental variance |
What's the equation for phenotypic variance? | Vp = Vg + Ve |
What is sickle cell anemia? | An inherited disease of red blood cells (predominantly found in people o |
How does sickle cell work at the genetic level? | The sickle cell allele is a point mutation that changes a single amino acid in hemoglobin B |
What are the three types of genetic & phenotypic hemoglobin? | SS = normal hemoglobin, Ss = both normal & sickled hemoglobin, ss = sickled hemoglobin only |
How can S seem dominant in an Ss hemoglobin individual if these people have both normal & sickled hemoglobin? | People with Ss genotypes have enough functional red blood cells that they may not suffer the severe effects of the sickle cell |
Why's hemoglobin important? | Hemoglobin holds 4 oxygen molecules to take to different parts of the body |
How does sickle cell work on a cellular level? | An amino acid changes causes the chemical to form long strings when it lets loose its oxygen, causing the red cell to become deformed into a sickle shape |
Describe the shape, hardness, flow, and lifetime of normal hemoglobin | disc-shaped, soft (like a bag of jelly), easily flows through small blood vessels, & lives for 120 days |
Describe the shape, hardness, flow, and lifetime of sickle hemoglobin | sickle-shaped, hard (like a piece of wood), often gets stuck in small blood vessels, & lives for 20 days or less |
Pleiotropy | One gene has many phenotypic effects |
What are the phenotypic effects of someone sickle cell anemia (ss)? | Enlarged spleen, anemia or shortage of red blood cells, pain episodes, stroke or brain damage, kidney failure, pneumonia, increased infections |
How are people who are SS, Ss, & ss with sickle cell malaria different in terms of malaria? | ss = malaria resistant but die before adulthood, SS = susceptible to malaria, Ss = malaria resistance b |
Population | Group of sexually interbreeding or potentially interbreeding organisms (= deme(?)) |
Gene | physical stretch of DNA encoding some product (= locus(?)) |
Allele | Different forms of gene products at the same locus |
Which allele is dominant for flower color in snapdragons? | Neither because they're codominant |
Snapdragon: red (RR) + white (rr) | all pink (Rr) |
Snapdragon: What happens when you cross-pollinate two pink flowers (Rr)? | ¼ white (rr), ½ pink (Rr), ¼ red (RR) |
Why do you get a ratio of 1:2:1 after crossing two Rr's? | Mendel's law of segregation |
Punnet square | A probability matrix that takes the gametes from 2 parents and combines them randomly |
“Randomly” | It means that each allele will be found in 50% of all gametes |
How do you do the math for finding the probability of getting a heterozygote using a punnet square cross of two Rr's? | 0.5 (R) x 0.5 (r) x 2 = 0.5, 50% |
How do you determine the proportions of the colors of flowers of the next generation? | Determine the frequency of each genotype & allele |
How do you calculate allele frequency of R in Rr? | p(R) = [(2*#RR)+(#Rr)] |
How do we know if genotypic frequencies have achieved equilibrium? | They're the same as in the parents |
Hardy-Weinberg Principle | If there are no disturbances in the system, allele & genotype frequencies will remain constant through time |
What's an important conclusion of Hardy & Weinberg? | Mendel's laws can result in stability of allele frequencies over time at the population level |
What are possible disturbances of Hardy-Weinberg equilibrium? | finite population size (causing sampling error), mutation, selection, migration, & nonrandom mating (assortive mating |
What's a second important conclusion of Hardy & Weinberg? | Segregation & random union of gametes means that probability of different genotypes (x, y, z) is determined by allele frequences (p, q) |
At equilibrium, what do we expect to find in terms of genotypic frequencies? | p^2 + 2pq + q^2 = 1 |
How can we tell if a population is in equilibrium? | Observed & expected values are the same |
How can we statistically test to see if a population's in equilibrium? | The chi-square goodness of fit test: x^2 = sum[(#observed-#expected)^2 |
What does a chi square work and not work on? | Works on count but not on frequencies |
Degrees of freedom (df) | #classes - #independent values obtained from data (for example: df = 3 (RR, Rr, rr) – 2 (sample size, p) = 1) |
How do we define an event as significant? | We look at the probability the event will occur by chance (alpha = 0.05) |