Biology: Genetics, Reproduction, and Biotechnology - Genetic Modification, Cloning, Genome Mapping, and Tissue Engineering

In a genetic modification experiment, a scientist is looking at the probability of an offspring inheriting a specific modified gene. If both parents are heterozygous ($Gg$) for the gene, what is the probability that the offspring will express the recessive trait ($gg$)?

The probability is $\frac{1}{4}$ or $25\%$.

Using a Punnett square for a cross between $Gg$ and $Gg$: $\begin{array}{c|c|c} & G & g \\ \hline G & GG & Gg \\ \hline g & Gg & gg \end{array}$ The possible genotypes are $1 \times GG$, $2 \times Gg$, and $1 \times gg$. The probability of $gg$ is $1$ out of $4$ total outcomes.

If a DNA strand has $30\%$ Adenine ($A$), calculate the percentage of Cytosine ($C$) present in the DNA molecule based on Chargaff's rule.

$20\%$

According to Chargaff's rule, $A = T$ and $G = C$. If $A = 30\%$, then $T$ must also be $30\%$. Total $A + T = 30\% + 30\% = 60\%$. The remaining percentage for $G + C$ is $100\% - 60\% = 40\%$. Since $G = C$, the percentage of $C$ is $\frac{40\%}{2} = 20\%$.

Describe the core components required for Tissue Engineering an artificial skin graft.

Cells + Scaffold + Growth Factors

Tissue engineering requires three main pillars: 1. Cells (e.g., fibroblasts or stem cells to create the tissue), 2. Scaffold (a structural template for cells to grow on, often made of biocompatible polymers), and 3. Signals/Growth Factors (chemicals that tell the cells to divide and differentiate).