Slide Set for Unit

This slide set accompanies Biology, Homeostasis, and Type 2 Diabetes, written for high school biology classes. The unit uses the growth of type 2 diabetes as a phenomenon to teach core ideas about homeostasis, population traits, nutrition, how genes and the environment determine our traits, and more. It consists of 5 lessons, and formative and summative assessments.

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Lesson Resources:

• Unit overview with Enduring Understandings, lesson timings, teacher background materials, connections to science education standards, and more.
• Google folder containing teacher instructions, student worksheets, student roadmaps, and more.
• A PDF of everything in one place.

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Questions? Contact Joan

Lesson One

Entrance Activity:

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What do you know about type 2 diabetes?

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Think about….

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What is type 2 diabetes?

What causes it?

What happens to the body?

Who gets it?

Are there treatments available?

What social factors may contribute?

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Biology, Homeostasis, and Type 2 Diabetes

Diabetes: A Growing Concern

The following slides show the percentage of adults who have been diagnosed with diabetes in the US between 1994 and 2015. This table shows the color key for percentages in the next sides.

Biology, Homeostasis, and Type 2 Diabetes

1994

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

1995

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

1996

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

1997

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

1998

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

1999

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2000

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2001

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2002

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2003

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2004

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2005

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2006

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2007

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2008

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2009

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2010

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

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Major changes to the survey method in 2011

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more detail at http://www.cdc.gov/surveillancepractice/reports/brfss/brfss.html

2011

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2012

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2013

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2014

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

2015

Age-Adjusted Prevalence of Diagnosed Diabetes Among US Adults

<4.5%

Missing data

4.5%–5.9%

6.0%–7.4%

7.5%–8.9%

≥9.0%

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

Types of Diabetes

Incidence and Prevention

Data from the CDC

Age-adjusted Prevalence of Diagnosed Diabetes Among US Adults

CDC’s Division of Diabetes Translation. United States Surveillance System available at http://www.cdc.gov/diabetes/data

https://gis.cdc.gov/grasp/diabetes/diabetesatlas-surveillance.html

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Part A: Click ALL STATES next to red arrow to show a map of the � US. Explore the tabs circled in black.

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Part B: Click COUNTY and then choose Your State – All Counties.

Lesson One

What are the characteristics of type 2 diabetes?

Biology, Homeostasis, and Type 2 Diabetes

• result of chronic (long-term) high blood glucose levels
• can develop over time
• body is unable to maintain healthy ranges of glucose
• high glucose levels can damage nerves, heart, blood vessels, hands, feet, kidneys
• complications can even lead to death

Lesson One

Type 2 Diabetes:

A Complex Disease

Biological Concepts

Individual Choices

Social

Factors

Treatments and Solutions

What is glucose?

How does the body balance glucose?

Nature vs. Nurture

How can we stop

the growth?

What should

our priorities be?

How does my diet matter?

Does

exercise

matter?

Is it determined by genes,

the environment, or both?

How are

resources distributed?

How do we market foods and drinks?

Asking Questions

Lesson Two

Entrance Activity:

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What is glucose? Where does glucose come from in our diets?

Think about….

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What foods/drinks contain glucose?

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Where do other sugars come from?

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What is glucose used for in the body?

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Glucose can be described as both a fuel and a toxin. How can something so good also be so bad?

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Biology, Homeostasis, and Type 2 Diabetes

Lesson Two

Where is glucose in food? Part I

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This video may help.

Lesson Two

Including glucose, which is the primary energy molecule for the body.

Starch such as potatoes, wheat, corn, rice, cassava, sorghum

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Fiber, such as indigestible cellulose

Table sugar, milk sugar

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Paper model of Glucose

Pasta model of Glucose

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C₆H₁₂O₆

For the model we will be using next, glucose is represented by a pasta wheel.

Type 2 diabetes develops when blood glucose levels are too high for too long. The body is not maintaining blood glucose within a healthy range.

What does glucose have to do with type 2 diabetes?

Homeostasis:

Maintaining balance by regulating internal conditions

A balancing act happens many times a day—every time you have a meal or consume a drink with sugar. The ability of the body to maintain balance and regulate internal conditions is called homeostasis.

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Voiceover PowerPoint

Homeostasis allows organisms to maintain balance (stability) even as the external environment changes.

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You may have high blood glucose levels after eating a large meal, or low blood glucose levels between meals. Your body responds to how often you eat and what you eat in order to keep blood glucose levels within a healthy range.

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Feedback mechanisms maintain homeostasis

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Balance is maintained when different components of a system regulate each other.

How does the body balance blood glucose levels?

A feedback mechanism relying on two hormones:

Insulin

Allows glucose to leave the blood and enter some cells. Insulin is like a key that unlocks the cell membrane so that glucose can enter the cell. �Without insulin, most glucose stays in the blood.

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Glucagon

Allows glucose to leave some cells and enter � the blood

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3 pasta wheels represent a balanced amount of blood glucose

Feedback Mechanism

Insulin Released

Feedback Mechanism

Insulin causes glucose to leave the blood and enter cells

Insulin Released

Feedback Mechanism

Glucagon Released

Balance tips….

Glucose leaves cells to enter the blood

Feedback Mechanism

Insulin and glucagon work together to regulate blood sugar.

This feedback mechanism helps to maintain homeostasis in the system.

Feedback mechanisms are common in biology and nature.

Here’s an example with body temperature regulation

Feedback Mechanism

Body sweats, blood vessels dilate

Feedback Mechanism

Body sweats, blood vessels dilate

Temperature goes down

Feedback Mechanism

Shivering

Blood vessels constrict

Balance tips….

Temperature goes up

Feedback mechanisms maintain homeostasis

Model Board

Empty Board

Glucose enters the blood

Glucose back in balance after insulin release

Other resources for modeling Type 2 Diabetes

Model Board Pieces

Who’s who of diabetes:

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Glucose! Carbohydrates are broken down during digestion to this simple sugar. Glucose is carried to every cell in our body by the blood stream, where it is used as the source of energy for our bodies.

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In our model, the 6-sided glucose sugar is represented by a round pasta piece.

Glycogen! The stored form of glucose is called glycogen. Glycogen is made up of many connected units of glucose.

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Who’s who of diabetes:

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Insulin! This hormone is released into the blood when blood glucose levels are high. It enables glucose to be transported into the cell in some tissues.

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In our model, insulin is represented by a piece of I-shaped pasta

Glucagon! This hormone is released into the blood when blood glucose levels are low. It enables glucose to be released from some tissues back into the blood stream.

In our model, glucagon is represented by a piece of curvy-shaped pasta

Model Board Pieces

Model Board Organs

The body organs:

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Pancreas: One of the major players in glucose homeostasis, the pancreas releases the hormones, insulin and glucagon, that control blood glucose. The cells in the pancreas that produce insulin are called β (beta) cells.

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Liver: This organ takes up glucose when levels are high and releases glucose when levels are low. It stores glucose in chains as glycogen. It is key for glucose regulation.

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Model Board Organs

More body organs:

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Muscles: Our muscles are able to take up and store lots of glucose when insulin is present. More muscles mass means more of a reservoir for glucose.

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Fat cells: Fat cells take up glucose when insulin is present. Fat cells use glucose to make more fat.

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Brain: The brain takes up glucose whenever it needs energy, and doesn’t require insulin. Glucose is the fuel the brain normally uses.

All of these systems work together to keep our blood glucose level balanced.

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Homeostasis:

Maintaining balance by regulating internal conditions

High blood glucose triggers the pancreas to release insulin.

High Blood Glucose

Pancreas releases insulin

Blood vessels carry insulin and glucose to cells

Maintaining Blood Glucose

In the presence of insulin, glucose enters the cells and leaves the blood.

Blood glucose levels fall.

High Blood Glucose

Pancreas releases insulin

Maintaining Blood Glucose

Low blood glucose triggers the pancreas to release glucagon

Low Blood Glucose

Pancreas releases glucagon

Maintaining Blood Glucose

Balance tips….

Low blood glucose triggers the pancreas to release glucagon

Low Blood Glucose

Pancreas releases glucagon

Blood vessels carry glucagon to the cells which trigger the release of stored glucose back into the blood. Blood glucose levels rise.

Maintaining Blood Glucose

Glucose responses for two different foods.

Which graph best represents healthy blood glucose levels?

A

B

A graph of blood glucose levels that are well-controlled would look something like this:

Note: Glucose levels are not constant, but they vary within a range.

A graph for a person that is becoming diabetic may look like this, as blood glucose levels begin to rise:

Biology, Homeostasis, and Type 2 Diabetes

Lesson Three

Entrance Activity:

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We know that a healthy body keeps blood glucose levels regulated within a range, as homeostasis “tips the balance” many times a day.

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What factors can contribute to a loss of control of blood glucose?

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Think about….

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What is the role of the pancreas?

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What is the role of diet?

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What is the role of exercise?

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Scenario cards for the Homeostasis Model Board can be found here.

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Glucose out of balance

How is diabetes diagnosed? By measuring blood glucose levels.

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Fasting glucose test: After fasting for at least 12 hours, a person’s blood is drawn and tested for glucose. A healthy person would have a fasting blood glucose level of about 80-90 mg/dL.

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Oral Glucose Tolerance Test: After measuring fasting glucose, a person is given a glucose-rich drink. Blood is then drawn at time intervals to see how that person’s body is processing the glucose.

A third test, the A1C test, measures how much of a person’s hemoglobin is coated with sugar. Since red blood cells (which carry hemoglobin) turn over every few months, the A1C test gives an average blood sugar level over the past 2-3 months.

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Time (min)

Time (min)

Blood Glucose levels (mg/dl)

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Jensen CC et al: Diabetes 51:2170-2178; 2002

Oral Glucose Tolerance Test

Fasting

Contributions to type 2 diabetes

Insulin Resistance

in cells and organs

Beta Cell Damage

less insulin produced in the pancreas

High Blood Glucose Levels

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PREDIABETES

TYPE 2 DIABETES

Lesson Three Extension: Three mechanisms

Three ways type 2 diabetes damages cells and organs:

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1. Polyol Pathway

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• Advanced Glycation End Products (AGEs)

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• Atherosclerosis

1. Polyol Pathway

Cells in the kidney, eye, and nerves take up glucose in the absence of insulin

This is a key mechanism for nerve and retina damage

1. Polyol Pathway

TREATMENT

Cells in the kidney, eye, and nerves take up glucose in the absence of insulin

This is a key mechanism for nerve and retina damage

Can the enzyme that converts glucose into sorbitol be inhibited?

Still working on it…

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This is a key mechanism for eye and kidney damage.

2. Advanced Glycation End Products (AGEs)

This is a key mechanism for eye and kidney damage.

2. Advanced Glycation End Products (AGEs)

TREATMENT

Drugs that inhibit the formation of AGEs have been tested, but…none have been shown to reduce kidney damage. Yet.

This makes the blood vessel stiff and narrows the channel. Atherosclerosis leads to high blood pressure, causing the heart to work harder.

This is a key mechanism for heart failure and stroke. It also contributes to kidney failure.

3. Atherosclerosis

3. Atherosclerosis

TREATMENT

Pathways to organ damage

Chronic Elevated Blood Glucose

Nerve damage

Capillary damage

Large blood vessel damage

EYES LIMBS KIDNEYS HEART BRAIN

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Pathways to organ damage

Chronic Elevated Blood Glucose

Nerve damage

Capillary damage

Large blood vessel damage

EYES LIMBS KIDNEYS HEART BRAIN

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Where should money for treatment and/or prevention be spent?

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Prevention and Treatment

Elevated Blood Glucose

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PREDIABETES

TYPE 2 DIABETES

with severe complications such as organ damage

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Normal Blood Glucose Levels

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$$$$$

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Less Reversible

More Reversible

Lesson Four

Entrance Activity:

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A Taste of Home

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By Monica

https://www.youtube.com/watch?v=yuhhxTj5od0

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What are some environmental risk factors for type 2 diabetes in Monica’s family?

To think about….

How does culture impact risk?

How does product marketing impact risk?

How have these changed over time?

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Biology, Homeostasis, and Type 2 Diabetes

Student Sheet 4.1: Genetic risk factors

You could draw…

The beans in the bag represent the gene pool

of the population.

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For each gene you will draw from 2 possible alleles

One of each color is neutral 0

Student Sheet 4.1: Genetic risk factors

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Two white beans increase RISK + 1

Two red beans are PROTECTIVE

(decrease risk)

Possible Allele Combinations:

Egg carton represents 12 genes that contribute to type 2 diabetes

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Each gene contains 2 alleles

- 1

or

What is the probability of inheriting ONLY risk alleles (white beans) for these 12 genes?

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For each cup, the chance of drawing two white beans is ¼, or 25%.

To get two white beans in two cups, the probability is ¼ x ¼ = 1/16

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For all 12 cups…

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¼ x ¼ x ¼ x ¼ x ¼ x ¼ x ¼ x ¼ x ¼ x ¼ x ¼ x ¼ =

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1 in 16,777,216 or ~0.000006% chance

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Over 150 genes have been associated with type 2 diabetes.

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That is a lot of different allele combinations!

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These combinations lead to tremendous variation of traits in a population.

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Limitations in the model: 1) Each allele associated with type 2 diabetes is present in the population at the same frequency (50:50), and alleles vary in frequency in a population. 2) Alleles are sometimes linked and don’t always sort independently of each other. 3) Environmental impacts on genes are not addressed.

Student Sheet 4.2: Environmental Risk Factors

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Environmental and Genetic Risk Factors

+1

+2

For complex diseases, variations in many genes may add to risk of getting that disease.

People without t2d

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People with t2d

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Low-risk allele

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High-risk allele

Fletcher & Houlston (2010) Nat Rev Cancer

Genetic factors:

Small variations in many genes

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Fraction of people

More risk alleles for type 2 diabetes

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GENETICS

GENETICS

GENETICS

ENVIRONMENT

ENVIRONMENT

ENVIRONMENT

(Little) Likelihood of getting Type 2 Diabetes (Lots)

Person A

Person B

Person C

Jablonski K A et al. 2010; Diabetes 59:2672-2681

Copyright © 2011 American Diabetes Association, Inc.

Diabetes Prevention Program Data

Allele combinations:

Diabetes incidence rate

Lesson Five

Entrance Activity

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If current trends continue, 1 in 3 U.S. adults will have diabetes by 2050.

Biology, Homeostasis, and Type 2 Diabetes

How would you distribute money and resources towards prevention and/or treatment of diabetes?

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To think about….

• How old will you be in 2050?
• Will you be at risk for type 2 diabetes?
• How and when should your future self take steps to prevent you from developing type 2 diabetes?

Options

Food Labelling and Marketing

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Lifestyle Changes

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Medications

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Soda Ban

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Surgery

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Is this a treatment, a prevention, or both?

Is this driven by individuals or society?

Who benefits? What is the cost? Who is harmed?

Back to the Beginning

1 2 3 4 5 6 7 8 9 10

I think that solutions to the growth of type 2 diabetes lie mostly with:

Individuals

Society