Epigenetics & the Environment

Identical Twins: Pinpointing Environmental Impact on the Epigenome

• Nature or nurture? --BOTH
• identical twins share all genes
• fraternal twins share half the genes
• as twins grow older, their chromosomes have different epigenetic tags attached
• when schizophrenia occurs in identical twins, in 50% of cases both develop the disease while in fraternal twins, only 10-15% of the time do both twins develop it
• both identical twins don't develop the disease 100% of the time = other factors involved

Lick Your Rats

• Highly nurtured (licked) rat pups = calm adults
• Little nurtured rat pups = anxious adults
• Anxiousness is a + in wild, while - in domesticated environment
• relaxedness is - in wild, while + in domesticated environment
• epigenetic patterns can be changed
• licking releases GR gene
• more of GR means more relaxedness and faster recovery from stress

Nutrition and the Epigenome

• mother's diet while pregnant affects embryo structure and critical factors that stay through adulthood
• agouti gene in mice is unmethylated = yellow coat color, obesity and prone to diabetes, cancer
• agouti gene is methylated = brown coat color, mouse has a low disease risk
• Shortage of food for grandfather = extended lifespan of grandchildren
• more food for grandpa = grandkids' lifespan shortened by diabetes, heart disease
• disease risk can be predicted by looking at family health history

Epigenetics and the Human Brain

• Child abuse and suicide may be epigenetically linked
• People who commit suicide have less-active ribosomal RNA
• the abused suicide victims had an epigenetic tag on the GR gene
• GR gene receives similar epigenetic tag in rat pups who receive low quality care mothers
• The gene for REELIN protein has is more active in schizophrenic brains than normal brains
• 60 genes = difference between psychiatric patients and healthy people
• drugs used to treat mental illness change gene expression sometimes
• Drugs of abuse trigger epigenetic changes, affect hundreds of genes at a time

Introduction:

1. DNA is unique for everyone. The only exception is if a person has what?
If that person has an identical twin.

2. What are DNA fingerprints used for?
It can be used to figure out biological relatives or solve a crime.

Part 1 “It Takes a Lickin”

3. What “crime” was committed?
A holographic NOVA lollipop belonging to Johnny was partly eaten.

4. What bodily fluid was removed from the “crime scene” to get DNA?
Saliva

Part 2 “DNA Fingerprinting at the NOVA Lab”

5. What does a restriction enzyme do?
Restriction enzymes split the DNA in different places.

6. What is agarose gel?
A molecular strainer for the larger DNA.

7. What is electrophoresis?
An electrophoresis machine moves molecules electricity.

8. Smaller fragments of DNA move ____________ than longer strands?
Faster.

9. Why do you need to place a nylon membrane over the gel?
The nylon membrane is needed because it is difficult to pick up the gel
without special equipment.


10. Probes attach themselves to __________
Probes attach to the DNA fragments on the nylon membrane.

11. Which chemical in your “virtual lab” is radioactive?
The probes are radioactive.

12. Sketch your DNA fingerprint.
It was a column of lines.


13. Based on your DNA fingerprint, who licked the lollipop?
Honey sweet is the thief.

Mitosis

Mitosis Tutorial
http://www.cellsalive.com/

1. Which stage does the following occur

Chromatin condenses into chromosomes

Prophase

Chromosomes align in center of cell.

Metaphase

Longest part of the cell cycle.

Interphase

Nuclear envelope breaks down.

Prometaphase

Cell is cleaved into two new daughter cells.

Cytokinesis

Daughter chromosomes arrive at the poles.

Telephase


Watch the video carefully.

2. The colored chromosomes represent chromatids. There are two of each color because one is an exact duplicate of the other.

--How many chromosomes are visible at the beginning of mitosis? 4

-- How many are in each daughter cell at the end of mitosis? 4

--The little green T shaped things on the cell are: Centrioles

-- What happens to the centrioles during mitosis? They move to the poles of the parent cell.

3 . Identify the stages of these cells:

a) Metaphase

b) Interphase

c) Telephase

Another Mitosis Animation
Go to www.johnkyrk.com/mitosis.html

View the animation and sketch the cell in:


Onion Root Tip - Online Activity
http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html

Read the introduction, then click the “next” button.

You will have 36 cells to classify. When you’re finished, record your data in the chart below.

Interphase Prophase Metaphase Anaphase Telophase Total


Number of cells 20 10 3 2 1 36


Percent of cells 55% 28% 8% 6% 3% 100%

Mitosis in Whitefish & Onion Roots
View 1 View 2 View 3 View 4 View 5


Whitefish Telophase Metaphase Prophase Anaphase


Onion Prophase Metaphase Interphase Telophase Anaphase