lecture 6 - genetics and epigenetics

Question 1

who studied peas and proposed the idea of dominant traits?

Answer 1

Gregor Mendel

Question 2

what did the study of meiosis reveal in 1905

Answer 2

sex is based on
chromosomes, thread-like structures inside the nucleus of animal
and plant cells

Question 3

function of histones

Answer 3

allow long strand of DNA to be curled up and fit into chromosomes

Question 4

genome

Answer 4

any organism’s complete set of DNA, including all its genes.

An organism’s genome contains all the information needed to build and maintain the organism

Question 5

what allowed sequencing of DNA?

Answer 5

CRSPR

Question 6

true or false; all cells in the body are genetically identical

Answer 6

true, but body has cells w diff forms and functions

Question 7

how are changes to DNA sequences passed along

Answer 7

through generations

Question 8

genotype

Answer 8

part of genetic makeup of an individual which determines their potential characteristics

Question 9

homozygous

Answer 9

if alleles are the same

Question 10

heterozygous

Answer 10

if alleles are different

Question 11

phenotype

Answer 11

set of observable characteristics of an individual resulting from the interaction of the genotype with the environment

Question 12

different alleles code for different _______

Answer 12

phenotypes

Question 13

what are 3 examples of dominant phenotype traits

Answer 13

polydactyly (6 fingers) (dom over 5 fingers)
lobed ears
brown eyes (dom over blue)

Question 14

what are 3 broad categories of genetic diseases discussed in lecture?

Answer 14

single gene disorders

chromosomal disorders

complex/multifactorial disorders

Question 15

what are single gene disorders + examples

Answer 15

these are gene mutations

cystic fibrosis, sickle cell disease

Question 16

chromosomal disorders + example

Answer 16

abnormal number of structural arrangement of chromosomes

downs syndrome

Question 17

complex / multifactorial disorders

Answer 17

acquired mutations (cells dont replicate like they should)

have exogenous causes like environment, diet, etc

Question 18

who made the Lamarckian theory

Answer 18

jean baptiste lamark

Question 19

lamarckian theory

Answer 19

acquired traits in response to environment experienced over the lifetime will be transmitted to offspring

Question 20

epigenetics

Answer 20

the study of heritable changes caused by mechanisms other than changes in underlying DNA sequence

Question 21

factors influencing epigenetic variation

Answer 21

stress
drug use
social interactions
pesticides
smoking
nutrition
hormones

Question 22

what can epigenetic inheritance system also be described as?

Answer 22

soft inheritance

Question 23

what can genetic inheritance also be described as?

Answer 23

hard inheritance

Question 24

Changing what DNA gets read leads to…

Answer 24

expression of diff genes

producing diff proteins

results in diff physiological outcomes

impacts behaviour

Question 25

are epigenetic changes potentially reversible?

Answer 25

yes

Question 26

are genetic changes potentially reversible?

Answer 26

no

Question 27

behavioural epigenetics

Answer 27

experiences in our environment that can lead to long term effects on the brain and subsequently behaviour

Question 28

can epigenetic behavioural changes be passed across generations?

Answer 28

yes

Question 29

define nurture

Answer 29

experiences occurring during fetal development can have long term effects brain and body are developing rapidly, providing window of opportunity for variation

Question 30

when dna is read, it is also _____

Answer 30

expressed

Question 31

when gene expression is repressed or turned off, what happens?

Answer 31

methylation occurs, meaning a methyl group is added

Question 32

when gene expression is expressed or turned on, what happens

Answer 32

acetylation acetyl group added

Question 33

describe the Michael Meany study on rat mothering and how it callibrates brain response to stress in rat pups

Answer 33

Rats raised by less-nurturing moms have more methyl groups attached to promoter region (the ‘on’ switch) of the GC receptor gene o These methyl groups block access by transcription factors that turn the gene on As a result, fewer receptors are produced, and rat cannot shut down stress response as easily o Good news: enzymes that reverse DNA methylation of GC receptor gene also reverse effects of unenthusiastic mothering on pups hormonal and behavioral responses to stress (The Seductive Allure of Behavioural Epigenetics, SCIENCE, 2010)

Question 34

1998 quebec ice storm

Answer 34

DNA methylation in offspring o Epigenetic change due to objective levels of hardship vs. sustained subjective stress ^not the mother’s perceived experience - Ex. epigenetics and agouti yellow mouse o Agouti genes🡪 obese, yellow, disease-susceptible ▪ Can be turned off if silencing epigenetic marks around it accumulate around the agouti gene o How the maternal environment influences disease in offspring o Agouti rats and healthy diet o Obesity in agouti mice ▪ Healthy foods ▪ Supplement with Vitamin B12, folic acid, choline, betains

Question 35

rat study on exercising and epigenetic changes

Answer 35

exercised vs. non-exercised rats then exposure to swim stress test ▪ Both conditions freaked out that they couldn’t find the platform ▪ Took rats out for 24 hours and put them back in the same situation ▪ Found that rats that were exercising didn’t struggle as much in the pool (they remembered that the pool didn’t have a platform), non-exercised rats still struggled the same amount ▪ Exercised rats had higher number of neurons in the dentate gyrus (which is a brain region related to memory) * The histones behaved differently in exercised rats

Question 36

human study on exercising and

Answer 36

Exercising encourages demethylation (ie., reading) of genes that encourage energy (carb, fat, etc) metabolism - Ex. environmental experiences o Exposure to pesticides induces epigenetic variation in sperm, leading to infertility o These effects persist over multiple generations

Question 37

There is a third influence besides nature and nurture:

Answer 37

epigenetics

Question 38

histones + DNA =

Answer 38

chromatin

Question 39

what determines how cells differentiate into their specific functions?

Answer 39

epigenetics

Question 40

transgenerational inheritance of epigenetic marks

Answer 40

epigenetic marks can be transmitted to multiple generations if the marks are put down on our sperms or eggs

Question 41

how can epiugenetic marks accumulate AFTER our birth? (rat stuff)

Answer 41

Glucocorticoid receptors in rats brain help rat cope with stressful situation (more receptors = better coping) o Rat pups at birth have silencing around receptors, but if rat mother extensively grooms pups during first week, the silencing marks can be removed from the gene. o Gene is turned on and it stays on throughout their lives.

Question 42

are epigenetic marks reversible? how? implications?

Answer 42

Too many silencing marks around tumour suppressor genes = gene turned off (more likely to get tumours/cancer) o Scientists can target these silencing marks are remove them o Also could be used for lupus, alzheimers, diabetes etc