Meiosis & Mendelian Genetics
Genetic Crosses
Pedigrees and Linkages Maps
Non-Mendelian Genetics
Unit 6 Gene Expression
100
(1) What is a section of DNA that provides instructions for making a protein?
(2) What is a different version of a trait-determining segment of DNA?
(1) Gene
(2) Allele
Ex. Both parents have the same gene for eye color, but Mom gave you an allele for blue eyes and dad gave you an allele for brown eyes.
100
What is the expected phenotypic ratio of a dihybrid cross between two heterozygous individuals (AaBb x AaBb) if the genes assort independently?
9:3:3:1
100
What inheritance pattern is represented in this pedigree?
Autosomal recessive
100
Which type of inheritance pattern is observed when two alleles are equally expressed in the phenotype, as seen in the ABO blood group system?
Codominance
100
What is the central dogma?
DNA-RNA-protein
200
What is one key difference between mitosis and meiosis?
Mitosis - 2 identical daughter cells, diploid somatic cells, one division
Meiosis - 4 different daughter cells, haploid gamete cells, two divisions
200
In humans, a gene for colorblindness is located on the X chromosome. A woman who is a carrier for colorblindness marries a man with normal vision. What is the probability that their son will be colorblind?
50%
200
Scientists analyzed data on the relationship between the genes for eye color and wing shape and determined a recombination frequency of 9%. Based on this information, what can the researchers conclude about the relationship between the genes?
The genes for eye color and wing shape are located close together on the same chromosome, and the recombination frequency of 9% indicates they are linked.
200
What is the most likely explanation for children exhibiting low viability for cellular respiration when their fathers are unaffected, but their mothers share the same condition?
Mitochondria, the organelles responsible for cellular respiration, have their own DNA, which is inherited from the mother. If the mother has a mutation in her mitochondrial DNA that impairs cellular respiration, she will pass it on to all of her children.
200
What is the effect of DNA methylation?
A) Promotes transcription
B) Increases histone acetylation
C) Inhibits transcription
D) Directly activates ribosomes
What is C. DNA methylation reduces transcription rates.
300
Which phase of meiosis is responsible for the separation of homologous chromosomes?
Anaphase 1
300
In dogs, brown fur is dominant to white fur. Cross two heterozygous doggos!
(1) Determine genotypic ratios.
(2) Determine the phenotypic ratios.
(3) Determine how many dogs, if 200 are born, will they have white fur.
(1) Genotypic ratio - 1:2:1 or BB 25%, Bb 50%, bb 25%
(2) Phenotypic ratio - 3:1 or Brown fur 75%, white fur 25%
(3) 50 dogs will have white fur
300
What are the most likely genotypes for both parents in this pedigree?
Heterozygous
300
In a chi-square test comparing observed and expected results for a genetic cross, you calculated a chi-square value of 2.34 with 1 degree of freedom. If the critical value at a 0.05 significance level is 3.84, what can you conclude?
The observed results are not significantly different from the expected results.
We fail to reject the null hypothesis or the null hypothesis is accepted
300
Which enzymes are critical in DNA replication?
Helicase unwinds, DNA Polymerase adds nucleotides, Ligase seals gaps
400
In a family, both parents are carriers (heterozygous) for the Tay-Sachs, a autosomal recessive disease. What principle of Mendelian genetics explains the inheritance pattern of Tay-Sachs disease, and what is the probability that a child of two carriers (Aa) will develop the disorder?
The Law of Segregation and 25% chance the child will develop Tay-Sachs disease
The Law of Segregations states that two alleles for the same trait (such as Tay-Sachs disease) separate randomly during gamete formation, ensuring that each gamete (sperm or egg) receives only one allele. When fertilization occurs, the zygote inherits one allele from each parent, resulting in a combination of genetic information from both.
400
In humans, hairy eyebrows (H) are dominant to thin eyebrows and having a unibrow (e) is recessive to separated eyebrows. Tom has a very thick unibrow, and is worried his future children will as well. He is surprised he even has one, since his mother has thin and separated eyebrows, just like his girlfriend Megan. In Megan's family, Megan's dad has a unibrow.
What is the chance that Tom has children who look like him? What is the chance they will look like Megan?
1/4 chance his kids look like Tom
1/4 chance his kids look like Megan
400
Make a linkage map using the recombination frequency data provided in the chart.
400
The arctic fox can change its fur color depending on the season. During the winter, its fur becomes white to blend in with the snow, and in the summer, it turns brown or gray to help it blend in with the rocky and grassy terrain. This is because foxes can have the same genotype to exhibit different phenotypes in response to environmental conditions. What phenomenon is this?
Phenotypic Plasticity
400
What is a frameshift mutation? Which mutations cause frameshifts?
Insertion or deletion of nucleotides that shifts the reading frame - changes all amino acides after mutation
500
How does meiosis create genetic variation? 3 ways
A: Through three mechanisms:
- Crossing Over (Prophase I): Homologous chromosomes exchange segments, creating recombinant chromosomes.
- Independent Assortment (Metaphase I): Homologous pairs align randomly, allowing maternal and paternal chromosomes to mix.
- Random Fertilization: Unique gametes fuse randomly.
500
What is a test cross? When would it be used?
Crossing an individual of unknown genotype with a homozygous recessive individual (aa) to determine if the unknown is (AA) or (Aa)
500
X-Linked Recessive characteristics include...
More common in males. Affected females must have an affected father. It skips generations.
500
How does human ABO blood typing work? Mention allele types and blood types.
It is an example of multiple alleles and codominance. IA and IB are codominant, while (O) is recessive.
IA and IAi are Type A, IB and IBi are Type B, IAIB Type AB, ii Type O
500
What is the role of plasmids in genetic engineering?
Plasmids are used as vectors to insert foreign DNA into bacteria for cloning