5.6 Environmental Effects on Phenotype
in AP Biology
Another departure from simple Mendelian genetics arises when the phenotype for a character depends on environment as well as genotype.
5.4-5 Non-Mendelian Genetics
in AP Biology
In the 1900s, geneticists extended Mendelian principles not only to diverse organisms, but also to patterns of inheritance more complex than those described by Mendel.
5.3 Mendelian Genetics
in AP Biology
Modern genetics began during the mid-1800s with a monk named Gregor Mendel, who discovered the basic principles of heredity by breeding garden peas in carefully planned experiments.
5.1-2 Meiosis and Genetic Diversity
in AP Biology
Gamete formation involves a type of cell division called meiosis. This type of cell division reduces the number of sets of chromosomes from two in the parent cell to one in each gamete, counterbalancing the doubling that occurs at fertilization.
4.6 Regulation of the Cell Cycle
in AP Biology
Levels of proteins called cyclins increase and decrease during the cell cycle. Cyclins were discovered in studies of mitosis in sea urchin gametes.
4.5 The Cell Cycle
in AP Biology
Mitosis is just one part of the cell cycle, the life of a cell from the time it is first formed during division of a parent cell until its own division into two daughter cells
4.4 Feedback in Cell Communication
in AP Biology
Negative feedback helps to maintain homeostasis. Positive feedback is self-reinforcing and amplifies responses.
4.3 Changes in Signal Transduction Pathways
in AP Biology
Food and drugs can be sources of chemicals that act as exogenous ligands in cell communication. Exogenous ligands can disrupt the usual activity of a signal transduction pathway, thereby altering the responses of target cells.
4.2 Signal Transduction
in AP Biology
Signal Transduction pathways differ in specific details, but have certain, unifying characteristics. All pathways follow a sequence: Reception，Transduction, Response
4.1 Cell Communication
in AP Biology
Cells communicate by sending and receiving chemical messengers. Cells can communicate over various distances