CONS 302 Module 4 Complete

Why do scientists perform genetic modifications?

To create new organisms or traits that do not exist in nature

To combine good traits from different individuals or even across species.

To eliminate undesirable traits.

Genetic modification (GM) refers to:

The direct manipulation of an organism's genome using biotechnology

The first genetically modified organism was:

A bacterium created in 1972 by Herbert Boyer and Stanley Cohen

The first GM animal was:

A mouse modified in 1974 with foreign DNA in its embryo

The first GM plant was:

A tobacco plant resistant to antibiotics (1983)

The first commercial GM pet was:

Glofish in 2003

Applications of GM in research include:

Creating transgenic organisms for gene function analysis (knockout, gain of function, expression studies)

Applications of GM in medicine include:

Producing insulin and growth hormones

Applications of GM in industry include:

Producing enzymes

Applications of GM in crops aim to:

Add resistance to pests

BT corn was created by inserting a gene from:

Bacillus thuringiensis

Over 60% of global GM crops are modified for:

Herbicide tolerance

Golden rice was developed to:

Produce vitamin A precursor to prevent childhood blindness

Four major GM crops in Canada are:

Canola, soybean, corn, sugar beet

A gene introduced to Arctic apples reduces:

Enzymes that cause browning

GM rice developed in China can:

Yield 40–70% more with less nitrogen

Main concerns about GMOs include:

Food safety, gene escape, respect for nature

Scientific consensus on GM food safety states:

Current GM foods are as safe as conventional foods

Gene escape refers to:

Unintended transfer of GM genes to wild or non-GM crops

Two main causes of gene escape are:

Pollen drift and seed dispersal

Gene escape can be prevented by:

Buffer zones or sterilization techniques

Respect for nature concerns include:

Biodiversity, ecosystem integrity, cultural and ethical perspectives, sustainability

The Cartagena Protocol on Biosafety (2000) ensures:

Precautionary GMO regulations and national control

Gene guns are used to:

Shoot target genes into plant cells for transformation

Agrobacterium tumefaciens is used in GM because:

It transfers target genes into dicot plant genomes

Electroporation introduces DNA by:

Using electric pulses to create temporary pores in cells

Virus-mediated transformation is used for:

Gene therapy and vaccine development

Main GM limitations include:

Low insertion rate, no control on DNA location target, one gene at a time, expensive and slow, strict regulation

Genome editing uses molecular scissors to:

Make site-specific cuts in DNA for targeted mutation

The CRISPR/Cas system was adapted from:

The immune system of bacteria

CRISPR stands for:

Clustered Regularly Interspaced Short Palindromic Repeats

CAS genes in CRISPR are responsible for:

Cutting foreign DNA

Guide RNA’s role in CRISPR is to:

Find the target DNA

What are the two main types of gene transfers in GM?

Transferring genes within or across species

What are the sources of new genes in GM?

Isolating/copying genetic material or synthesizing DNA.

What does “knocking out existing genes” mean in GM?

Disabling or deleting a gene to study or change its function.

What is the purpose of the CRISPR region?

To acquire foreign DNA segments and guide CAS proteins to cut.

What is spacer acquisition?

When a bacterium captures a piece of viral DNA and inserts it into its own genome.

What two molecules form the CRISPR complex?

Guide RNA and Cas9 protein.

How is CRISPR applied in eukaryotic cells?

By using a plasmid carrying the guide RNA and Cas9 into target cells.

What advantage does CRISPR have over traditional GM?

It can target specific genes precisely and edit multiple genes at once.

How many genes can CRISPR disable at once?

From 5 to as many as 62 genes.

What is the main tool used in modern genome editing?

CRISPR/Cas9.

What is the purpose of genome editing?

To make precise targeted changes in an organism’s DNA sequence

What was the goal of the CRISPR babies experiment?

To make embryos resistant to HIV infection.

Why was the CRISPR babies experiment criticized?

Because of ethical issues and the technology’s unreliability.

What are some technical problems with CRISPR in humans?

Unintended DNA changes, deletions, and rearrangements.

What was the conclusion of the scientific commission about human CRISPR use?

The technology is not yet ready for clinical application.

What is a “designer baby”?

A genetically engineered child with selected traits.

What is “prime editing”?

A refined CRISPR tool that can make precise base-pair substitutions and small insertions/deletions.

What is RNA editing?

A temporary form of gene editing that alters RNA instead of DNA.

Why is RNA editing safer than DNA editing?

Because RNA errors are temporary and degrade quickly.

How many genes can traditional GM modify at once?

Usually one gene at a time.

How does CRISPR compare with traditional GM in speed and cost?

It is faster and cheaper.

Why is CRISPR easier to approve than traditional GM?

It’s more precise and causes fewer off-target effects.

Traditional GM uses what kind of gene insertion?

Random.

CRISPR uses what kind of gene targeting?

Guide RNA-based specific targeting.

How does gene drive alter inheritance?

It allows a gene to be passed on to nearly 100% of offspring.

What tool is used in gene drive systems?

CRISPR/Cas9.

What is the purpose of gene drive?

To rapidly spread a desired gene through a population.

What are two main uses of gene drive?

Controlling disease vectors and altering wild populations.

Why might a normal introduced gene disappear?

Due to genetic drift over generations.

How does a gene drive copy itself?

It inserts into the homologous chromosome so both copies carry the change.

Gene drives function only in what type of species?

Sexually reproducing species.

Why do gene drives spread faster in some species?

Because they reproduce quickly.

Name limitations of gene drives.

They require multiple generations to spread.

Mutations could occur mid-drive and cause unwanted traits.

Escape of the gene drive beyond its target population.

Unintended effects on non-target organisms and ecosystems.

What is synthetic genomics?

Creating new DNA

How many base pairs did the first synthetic bacterial genome contain?

582,970

What is the goal of a minimal genome?

To include only genes essential for life.

How many yeast chromosomes have been synthesized so far?

About 6.5 of 16.

What is the Human Genome Project – Write (HGP-Write)?

A 10-year project to synthesize the human genome.

What is the goal of HGP-Write?

To develop methods for writing and assembling large genomes.

What are two specific goals of HGP-Write?

Creating virus-resistant human cells and testing unknown gene variants.

Why can’t we synthesize a functional human genome yet?

Because we cannot insert or control large DNA segments in mammalian cells.

What is the first step in reviving an extinct species?

Sequencing the extinct species’ genome.

Editing the DNA of a close living relative to match the extinct species.

What are two major challenges in de-extinction?

Creating embryos and bringing them to term in surrogate mothers.

How many extinct species’ genomes have been sequenced so far?

About 20.

Has any extinct species been successfully revived yet?

No

What is breeding?

Sexual reproduction aimed at producing offspring with desired traits.

What are the two components of breeding?

Selection and mating (breeding).

What is the basic equation of phenotype?

Phenotype = Genotype + Environment.

What are the three components of genotype?

Additive, Dominant, Epistatic Effects

What does “additive effect” mean?

The sum of individual genes’ contributions to a trait.

What does “dominant effect” mean?

When one allele masks the effect of another.

What is “epistatic effect”?

Interaction between genes that affects a trait.

Which effects are used in controlled crosses?

Additive + Dominant.

What is the first step in a breeding program?

Selecting elite individuals (plus trees) based on phenotype.

What traits are often selected for in trees?

Growth, stem form, and health status.

What are selected parent trees called?

Plus trees.

Why are many plus trees selected?

To maintain genetic diversity.

What is the science behind selection?

Genetic variability and selection intensity.

What is the purpose of open pollination?

To allow natural cross-breeding among selected elite individuals.

What type of genetic effect does open pollination rely on?

Additive genetic effects.

What is collected from plus trees after selection?

Scions (twigs) and seeds.

Why are scions collected?

For grafting in clone banks to preserve genotype.

Why are seeds collected?

For progeny testing to evaluate genetic value.

What is a clone bank?

A collection of grafted or rooted copies of plus trees used for further breeding.

What is the purpose of a clone bank?

To serve as a breeding population and genetic reservoir.

What is progeny testing?

Testing offspring (progeny) to determine the breeding value of parent trees.

What does “breeding value” mean?

The additive genetic effect an individual contributes to its offspring.