GMO entry level

BY 101 – Study Guide

DNA Essentials + GMO Lecture

PART 1 — DNA FUNDAMENTALS (FOUNDATION FOR GMOs)

DNA Structure

DNA (Deoxyribonucleic Acid) is the molecule that stores genetic information used to build and maintain an organism. DNA is located in the nucleus of eukaryotic cells and carries instructions for building proteins.

Double Helix Structure

DNA resembles a twisted ladder called a double helix.

Components:

Backbone

• Alternating sugar and phosphate molecules

Rungs of the ladder

• Nitrogen bases

Base pairing rules:

Adenine (A) pairs with Thymine (T)
Cytosine (C) pairs with Guanine (G)

These pairings allow DNA to replicate accurately.

Genes and Proteins

A gene is a segment of DNA that contains instructions for building a protein.

Proteins perform most functions in cells and determine traits such as:

• eye color

• plant characteristics

• growth rate

• resistance to disease

Central Dogma of Biology

Information flows in this order:

DNA → mRNA → Protein → Trait

DNA stores instructions
mRNA copies the instructions
Proteins carry out the function

This process explains how genes produce observable traits.

Enzymes

Enzymes are specialized proteins that speed up chemical reactions.

Examples important for GMOs:

Restriction enzymes
Cut DNA at specific sequences

Cas9 enzyme
Used in CRISPR to cut DNA at targeted locations

PPO enzyme
Causes browning in apples

Arctic Apples silence the gene that produces PPO.

Mutations

A mutation is any change in DNA sequence.

Types:

Substitution
One base replaced with another

Insertion
Extra bases added

Deletion
Bases removed

Important idea:

Not all mutations are harmful.
Some are neutral or beneficial.

Selective breeding and genetic engineering use beneficial mutations.

PART 2 — CHROMOSOMES & CELL GENETICS

DNA is packaged into structures called chromosomes.

Each chromosome is a long DNA molecule wrapped around proteins.

Humans have:

46 chromosomes
23 pairs

Half come from each parent.

Ploidy

Diploid (2n)
Two sets of chromosomes
Normal body cells

Haploid (n)
One set of chromosomes
Egg and sperm cells

Polyploidy
More than two sets of chromosomes

Common in crop plants.

Example:

Seedless watermelons are triploid (3n).

Important:
This technique is not considered GMO even though genetics are altered.

PART 3 — PROKARYOTES VS EUKARYOTES

Understanding this difference is essential for GMO technology.

Why it matters:

Scientists often use bacteria to deliver genes into plants.

Plasmids

A plasmid is a small circular DNA molecule found in bacteria.

Plasmids replicate independently of bacterial chromosomes.

Scientists can:

1. Cut open the plasmid

2. Insert a gene

3. Put it into a host cell

The cell then reads the new gene and produces its protein.

This method launched modern biotechnology.

PART 4 — GENE EXPRESSION

Not every gene is active at all times.

Genes can be:

Expressed ("ON")
Protein is produced

Silenced ("OFF")
Gene exists but is not used

Many GMOs work by turning genes on or off rather than removing them.

Examples:

Arctic Apples
Gene for browning enzyme is silenced

Bt Corn
Inserted gene produces insect-killing protein

Golden Rice
Inserted genes produce beta-carotene

PART 5 — WHAT IS A GMO?

A Genetically Modified Organism (GMO) is any plant or animal whose DNA has been deliberately altered using biotechnology.

Important concept:

GMO is not a single crop.
It is a technology used to create new traits.

PART 6 — WHY GMOs ARE CREATED

Scientists modify organisms to produce useful traits.

Common goals:

Prevent insect damage
Disease resistance
Herbicide resistance
Improve shelf life
Add nutrients
Increase crop yield

Examples include crops that tolerate:

Drought
Cold
Poor soil conditions

These modifications can help agriculture and food security.

PART 7 — GMO REGULATION

GMOs in the United States are regulated by three major agencies:

EPA
Regulates pesticides and biopesticides

FDA
Regulates food safety for humans and animals

USDA
Ensures GMOs do not harm other plants

This multi-agency system ensures safety before products enter the food supply.

PART 8 — GMO LABELING LAW

In 2016, the National Bioengineered Food Disclosure Law created a national standard for GMO labeling.

Products containing genetically engineered ingredients must disclose this using:

Text statement
Symbol
QR code or digital link

PART 9 — GMO EXAMPLES

Flavr Savr Tomato

Introduced in 1994.
Designed to soften more slowly and improve shelf life.

Demand was strong but production costs made it unprofitable.

Golden Rice

Rice engineered to produce beta-carotene.

Purpose:

Prevent Vitamin A deficiency, which can cause blindness and growth problems.

Inventors donated the patent for humanitarian use.

GMO Salmon (AquAdvantage)

Atlantic salmon engineered with genes from Chinook salmon.

Result:

Fish grows twice as fast.

Approved in 2015 and marketed in 2021.

Arctic Apples

Engineered to prevent browning.

The gene for polyphenol oxidase (PPO) is silenced.

GalSafe Pigs

Genetically modified pigs that do not produce alpha-gal sugar.

This allows people with alpha-gal allergy to eat pork safely.

Recombinant Insulin

One of the earliest GMOs.

Approved in 1982.

Human insulin gene inserted into bacteria to produce insulin for diabetes treatment.

Modified Mosquitoes

Genetic engineering is used to reduce mosquito populations or prevent malaria transmission.

PART 10 — GMO CONTROVERSIES

Common concerns include:

Allergic reactions
Gene transfer to other species
Outcrossing with wild plants
Environmental impacts on non-target organisms

However, research shows:

GMOs are no more dangerous than traditionally bred crops when properly regulated.

PART 11 — WHY PEOPLE SOMETIMES OPPOSE GMOs

Reasons include:

New technology fear
Large corporations controlling seeds
Farmers unable to reuse patented seeds
Media misinformation

Despite controversy, studies show GMOs have:

Reduced pesticide use by ~37%
Reduced soil erosion by ~93%
Increased crop yields by ~22%

KEY CONCEPTS YOU SHOULD KNOW FOR THE QUIZ

DNA structure
Base pairing rules

Central Dogma
DNA → RNA → Protein → Trait

Gene vs allele

Mutation types

Chromosome terminology

Diploid vs haploid

Plasmids in genetic engineering

Gene expression

Definition of GMO

Purpose of GMOs

US regulation agencies

Examples of GMO organisms

Benefits and controversies