1. Essential knowledge 3.B.2:
A variety of intercellular and intracellular signal transmissions mediate gene expression

2. Signal transmission within and between cells mediates gene expression
Cytokines regulate gene expression to allow for cell replication and division.

3. Signal transmission within and between cells mediates gene expression
Mating pheromones in yeast trigger mating gene expression.
Two haploid yeast of opposite mating types secrete pheromones, grow projections and mate.

4. Signal transmission within and between cells mediates gene expression
Ethylene levels cause changes in the production of different enzymes, allowing fruits to ripen.

5. Signal transmission within and between cells mediates gene expression
Seed germination and gibberellin
Gibberellins (GAs) are plant hormones that regulate growth and influence various developmental processes, including stem elongation, and germination

6. Signal transmission within and between cells mediates cell function.
Ex 1: HOX genes and their role in development.
Hox genes are a group of related genes that control the body plan of the embryo along the anterior-posterior (head-tail) axis.

7. Signal transmission within and between cells mediates cell function.
Ex 2: P53 is a tumor suppressor protein
p53 is crucial in multicellular organisms, where it regulates the cell cycle and, thus, functions as a tumor suppressor that is involved in preventing cancer.
As such, p53 has been described as "the guardian of the genome because of its role in conserving stability by preventing genome mutation

8. Signal transmission within and between cells mediates cell function.
                                 
Signal transmission within and between cells mediates cell function.
Morphogenesis “shape” and beginnign--is the biological process that causes an organism to develop its shape
Example 3: morphogen is a substance governing the pattern of tissue development in the process of morphogenesis, and the positions of the various specialized cell types within a tissue.
More precisely, a morphogen is a signaling molecule that acts directly on cells to produce specific cellular responses depending on its local concentration.