Genetics Review

Flashcards to review key genetics concepts.

What are the characteristics of model organisms?

Small adult size, readily available, tractability, easily analyzed phenotypes, and rapid development.

Name five commonly used model organisms.

Planaria, House Mouse (Mus Musculus), E. coli, Soil Nematode, and Fruit fly.

Why is E. Coli used as a model organism?

It reproduces rapidly, shares DNA and mRNA similarities with other organisms, and is useful for understanding DNA organization and gene expression.

Why is C. Elegan used as a model organism?

Small size, hermaphroditic nature, rapid generation time, nervous system, and suitability for RNAi.

Why is Planaria a good model organism?

Due to its regenerative abilities and similarity of its stem cells to human stem cells.

Why is Mus Musculus a good model organism?

It serves as a mammalian model and provides a link between simpler and higher organisms.

Why is the Fruit Fly a good model organism?

Its life cycle is visible to the naked eye, it has a short lifespan, and it is inexpensive to house.

Why is Sordaria used as a model organism?

It is used to observe if crossing over has occurred during reproduction, indicated by spore arrangements (2:2 indicates crossing over, 4:4 indicates no crossing over).

What occurs during the G1 phase of the cell cycle?

Major growth period.

What occurs during the Synthesis phase of the cell cycle?

DNA replication.

What occurs during the G2 phase of the cell cycle?

The cell continues to grow and prepares for mitosis, ensuring all DNA is replicated correctly.

What occurs during the M Phase (mitosis) of the cell cycle?

The cell divides its copied DNA and cytoplasm to form two new daughter cells.

What are cell cycle checkpoints, and how are they regulated?

They determine whether the cell is ready to move onto the next generation and are enforced by CDK binding with cyclins.

Mitosis occurs in what type of cells, and what is the result?

Body cells; result in 2 identical cells.

Meiosis occurs in what type of cells, and what is the result?

Gamete cells; results in 4 unique cells.

Which scientists and organisms helped understand cell cycle checkpoints?

Tim Hunt used sea urchins, and Nurse and Hartwell used yeast to understand cell cycle checkpoints.

What is an example of an autosomal recessive genetic condition?

Sickle cell anemia.

What are the genotypic and phenotypic ratios of a monohybrid cross?

Genotypic ratio: 1:2:1; Phenotypic ratio: 3:1.

What is the typical phenotypic ratio of a dihybrid cross?

9:3:3:1.

What is the phenotypic ratio of a dihybrid test cross?

1:1:1:1.

What is the Law of Segregation?

Two alleles for one trait (gene) will segregate independently during gamete formation.

What is the Law of Independent Assortment?

Two unlinked traits will separate independently of one another during gamete formation.

What are the different types of dominance relationships?

Complete dominance, incomplete dominance, and co-dominance.

What is complete dominance?

One allele is completely dominant to another.

What is incomplete dominance?

One allele is not completely dominant to another, and the phenotype of the heterozygote is intermediate between the phenotypes for homozygotes for each allele.

What is co-dominance?

Alleles are co-dominant to one another, and the phenotypes of the heterozygote include the phenotype of both homozygotes.

What are sex-linked mutations?

Mutations that occur on the X chromosome; males with one recessive allele will display the mutant phenotype.

Name three examples of X-linked genetic conditions in humans.

Hemophilia, Fragile X, and Red-green color blindness.

Name two examples of Y-linked genetic conditions.

Male infertility and XYY syndrome.

What are the physical characteristics of female drosophila?

Larger in size, fatter belly, and striped bodies.

What are the physical characteristics of male drosophila?

Sex combs, smaller bodies, and a thick band at the bottom.

How is the probability (p-value) interpreted in Chi-square analysis?

If the probability is smaller than 0.05, the null hypothesis is rejected; if greater than 0.05, it is accepted.

How are degrees of freedom calculated?

n-1, where n equals the number of factors.

What are the three main categories of genes involved in establishing the body plan?

Maternal effect genes, segmentation genes, and homeotic selector genes (HOX).

What is immunostaining?

A technique to apply dyes to tissues in preparation for examination; an antibody-based method to detect a specific protein.

What is forward genetic screening?

Analyze phenotype first, then find the gene that produces this phenotype.

What is reverse genetic screening?

First find a specific gene, then find what phenotype this is producing.

What is RNAi (RNA interference)?

A method to study gene function by reducing expression (silencing) of a specific gene of interest.

What is the mechanism of RNA interference (RNAi)?

Double-stranded RNA is introduced and cut into smaller fragments called siRNA by Dicer; RISC binds to siRNA, unwinds the strands, and binds with mRNA.

Name two ailments for which RNAi-based treatments are being tested in research.

HIV and high cholesterol.

What is a mutagen?

A chemical or physical agent that directly or indirectly causes DNA mutations.