Current Genetic Topics

Disorders, Cloning, Gene Therapy

Atypical meiosis

If something wrong happens during meiosis, this can impact many things.

If there is an error in the chromosomes, ALL the cells will be affected.

Nondisjunction

Nondisjunction: the failure to separate.

When two homologous chromosomes move to the same pole during meiosis instead of moving to opposite poles.

One of the resulting cells ends up with a chromosome missing, while the other has an extra.

These cells will not work as they should.

Nondisjunction

When a fertilized egg with an abnormal number of chromosomes divides, each cell in the body will also have an abnormal amount of chromosomes.

In most cases, the zygote will die.

However, sometimes a person with nondisjunction disorder is born.

Down Syndrome

An extra chromosome for chromosome pair 21 – too much genetic information.

Turner Syndrome

Occurs when sex chromosomes undergo nondisjunction in the male or the female parent.

Produces a female with one X chromosome instead of two.

Do not mature sexually and are often are small in stature.

Klinefelter Syndrome

Nondisjunction in egg or sperm cell

Inherits two X chromosomes and one Y chromosome

The resulting baby will be a male, but during puberty will begin to develop high levels of female sex hormones

These males are sterile.

Genetic Screening

Genetic screening is a process by which a doctor draws amniotic fluid from the sac that surrounds the fetus.

This fluid contains cells which doctors can now screen and determine whether the baby will be born with a genetic disorder.

https://www.youtube.com/watch?v=8eR4XdJSmqc

Genetic Screening in Canada

http://healthycanadians.gc.ca/health-sante/pregnancy-grossesse/gen-test-eng.php

Genetic Screening

Flip to page 225 and break into groups of 2.

Read through the points and counterpoints and then work through the “What do you think” section.

Eliminate the 3rd point.

Discuss these points as a class.

Cloning

What comes to mind?

Cloning

Cloning is a natural process that happens often in nature

Examples?

Binary Fission – the mother cell splits into two identical daughter cells

Budding, vegetative reproduction, etc

Cloning

Cloning is the process of forming identical offspring from a single cell or tissue.

ASEXUAL REPRODUCTION

Cloning a Plant

Frederick Stewart had great success taking a single carrot cell and growing it into a plant.

Isolated a portion from the root tip of the carrot

The key to success in cloning plants is to slow down the specialization process of the cells

Ex. Leaf cells, root cells, stem cells

Cloning Animals

Robert Briggs and Thomas King successfully cloned a frog.

Extracted nucleus from an unfertilized egg cell

Next, a nucleus was extracted from a frog embryo in early development

This nucleus was inserted into the unfertilized egg cell.

Mammal Cloning

See diagram on page 196

Dolly

Dolly

http://www.nytimes.com/2013/10/14/booming/the-clone-named-dolly.html?_r=0

Dolly was different because the clone originated from taking cells from an FULLY DEVELOPED SHEEP.

See diagram on page 197

Stem Cell

Stem cells are very special, powerful cells found in both humans and non-human animals. They have been called the centrepieces of regenerative medicine – medicine that involves growing new cells, tissues and organs to replace or repair those damaged by injury, disease or aging.

Source:

http://www.stemcellnetwork.ca/index.php?page=what-are-stem-cells

Gene Therapy

Gene therapy is an experimental solution for treating disease by changing the patient's genetic material.

Most often, gene therapy works by introducing a healthy copy of a defective gene into a person’s cells.

http://www.bbc.com/news/health-26473802

Discussion

Think-pair-share

Has science gone too far?

Should we continue with cloning, gmos, genetic screening?

Should governments be allowed to dictate whether this science is