2nd LAB Practical 4 Guide Flashcards
(30 cards)
What is the Law of Segregation?
During the formation of gametes, the two alleles for a trait separate, so each gamete carries only one allele for each trait.
How does random fertilization contribute to genetic variation?
Any sperm can fuse with any ovum, increasing genetic variation.
What is the Law of Independent Assortment?
Different chromosomes assort independently into gametes due to the random orientation of homologs during metaphase of meiosis I.
What happens if genes are located on different chromosomes?
The different genes will assort independently into gametes.
What is crossing over?
Crossing over produces recombinant chromosomes by combining genes inherited from each parent.
When does crossing over begin?
Crossing over begins early in prophase I as homologous chromosomes pair up gene by gene.
What is the significance of crossing over?
Crossing over contributes to genetic variation by combining DNA from two parents into a single chromosome.
How does the distance between genes affect recombination?
Genes that are very close together are less likely to undergo recombination than genes that are farther apart.
What does a recombination/crossover frequency of 50% indicate?
The genes will assort independently as if they were located on different chromosomes.
What traits did Mendel study in pea plants?
All traits were located on different chromosomes and controlled by a single gene with two alleles in a simple dominant/recessive manner.
What is Drosophila melanogaster?
A commonly used genetic model organism, specifically fruit flies.
How many pairs of chromosomes do Drosophila have?
Drosophila have 4 pairs of chromosomes: 3 pairs of autosomes and 1 pair of sex chromosomes.
What are ‘pure-breeding’ strains?
Strains that are all homozygous for trait(s) of interest, created by inbreeding for many generations.
What are ‘tester’ strains?
Homozygous recessive strains used in crosses to test whether genes assort independently or are linked.
What does it mean for genes to be ‘partially linked’?
Genes are located on the same chromosome but far enough apart that some crossing over can occur.
How can the proportion of recombinant progeny be used?
It can estimate how far apart two loci are from one another on the chromosome.
What is probability in genetics?
The fraction of the time a particular chance event will occur.
What is the Sampling Rule?
The probability of any chance event is the number of events in question divided by the total number of events possible.
What does the Product Rule state?
The probability that two independent chance events will occur in a defined order equals the product of their individual probabilities.
What is an example of the Product Rule?
The probability of getting two tails when tossing a coin twice is (½)(½) = ¼.
What is the Sum Rule?
The probability of either of two mutually exclusive events occurring is the sum of their individual probabilities.
How do you calculate the probability of an unordered sequence of events?
Using the Binomial Expansion Equation.
What are the three main reasons for discrepancies between expected and observed results?
- Experimental error * Incorrect hypothesis * Sampling error
What is the null hypothesis in a Chi-Squared Test?
There is no statistically significant difference between the observed and expected data.
