Biology Tutoring Session - 1/26/26

I had a tutoring session with a student yesterday. It was mostly focused on high school biology. Her teacher gives her a packet at the beginning of every unit. The class had just finished a section of the packet earlier that day. We didn’t have much else on the table, so we went ahead with what came next in the packet.

I found that, even when I knew what things were, I had two issues in translating that in a way that was beneficial to the student. I wasn’t able to string the pieces and concepts together in a cohorent narrative or tidy line of thought. I also second guessed myself and checked a lot of the material. Some of things I didn’t know.

I’m using this space to put together a cohecive line of thought related to some of things we covered.

How are chromosomes, genes, proteins, and DNA connected?

Your DNA includes the entirety of instructions for the way your body is structured and how it operates. Nearly every cell in your body has a copy of all of your DNA (also known as your genome) inside it’s nucless. Each gene is a specific section of DNA that provides the code for a particular protein.

For most of a cell’s life, this DNA is organized in a structure that resembles a very long pile of yarn, rope, or spaghetti. When DNA is ready to be duplicated or an organism starts the process of reproduction, the long yarns of DNA are organized into 23 separate tightly and neatly compacted sets of chromosomes. Each chromosome is made of a specific collection of genes, laid out in a very specific order.

I like how “Genes, DNA and Chromosomes explained” on the Science Explained YouTube channel summarizes the connections between all these moving parts and proteins.

The order of the bases in the DNA, along with the length and sequence of the gene determines the size and shape of the proteins it builds. The size and shape of the protein will determine the function that it has in your body. Proteins make up cells, cells make up tissues, and tissues make up organs.

Transcription vs. Translation

Transcription and translation are two steps in the same overarching process of protein synthesis. Transcription is where DNA is used to make RNA using RNA polyamerase. Translation is when RNA and ribosomes are used to make protein.

What do proteins do?

As stated in the book, Biology: Exploring life by Campbell, Williamson, and Heyden (Prentice Hall, 2004):

A protein is a polymer constructed from a set of just 20 kinds of monomers called amino acids. Proteins are responsible for almost all of the day-to-day functioning of organisms.

So proteins are really important. Here are some of the functions of proteins in the body.

• Enzymes - Influence rate of reaction and regulate cell processes.

• Structure - Provide structure and support to cells. Bone, muscle, hair, fur, etc.

• Messenger - Send signals from one cell to another.

• Transport and Storage - Transport substances in and out of the cell. Long-term nutrient storage.

• Antibody - Help fight disease.

Structure of a protein

From Biology by Stephen Nowicki (Houghton Mifflin Harcourt, 2018)

• primary structure - Sequence of amino acids in the polypeptide.

• secondary structure - Hydrogen bonds between amino acids cayse the chain to fold into zig-zag-shaped sheets and spirals

• tertiary structure - 3D shape of the protein

• quaternary structure - Formed when the protein contains multiple polypeptide chains.

Mutation, ACVR1, BMPR1 A, and FOP

The ACVR1 and BMPR1 A genes both provide coding for receptors related to the growth and development of bone and muscle in the human body. BMPR1A helps facilitate the development of new bone and muscle while ACVR1 receptors help regulate the growth and development of existing bone and muscle.

Mutations to the ACVR1 gene to receptors that constantly tell the body to grow bone matter. This, in turn, causes a genetic disorder called Fibrodysplasia Ossificans Progressiva (FOP). FOP turns muscle, tendons, tissues into bone. FOP can cause any manner of physical distortions, reduced functionality, pain, and potentially dangerous structural changes in the body of the effected organism

Mutations are errors in the sequence of DNA strand. Types of mutation include the following.

• Deletion - a codon or sequence is removed.

• Duplication - A segment is copied.

• Inversion - Segment is attached upside down.

• Transcolation - A chromosome breaks and is incorrectly placed rejoins onto another chromosome.

• Point mutation - A single nucleotide base in DNA or RNA is altered. Include substitution, insertion, deletions, framshifts.

The ACVR1 gene is most commonly mutated by a specific missense point mutation. Google AI breaks down these terms as follows.

• Point Mutation Definition: A change in a single nucleotide base pair.

• Missense Mechanism: A type of substitution (point mutation) that changes one codon to another, causing a different amino acid to be placed in the protein chain.

This particular missense point mutation substitutes the amino acid arginine with histidine at point 206.