Lecture 18 - Genetic Variation & Disease #2

Question 1

What are monogenic traits?

Answer 1

An inherited trait/characteristic that is controlled by a single gene

Question 2

What patterns do monogenic traits follow?

Answer 2

Usually simple dominant/recessive inheritance patterns

Question 3

Can environment influence monogenic traits?

Answer 3

Yes (e.g how many freckles you have)

Question 4

What are polygenic traits?

Answer 4

Inherited trait/characteristic that is controlled by multiple genes.

Question 5

What patterns do polygenic traits follow?

Answer 5

They do not follow an obvious inheritance pattern

Question 6

Can environment influence polygenic traits?

Answer 6

Yes

Question 7

What are continuous traits?

Answer 7

Traits that will be measures as a range (e.g height)

Question 8

What are dichotomous traits?

Answer 8

Traits that will be measured by either yes or no to having it. (e.g myopia)

Question 9

After a certain point in ranging of phenotypes it is considered what?

Answer 9

That you have the disease/trait

Question 10

What both contribute to polygenic traits?

Answer 10

Genes and Environment

Question 11

What is an example of 100% genetics?

Answer 11

eye colour

Question 12

What is an example of 100% environment?

Answer 12

Tattoo’s

Question 13

What is an example of 50% genetics, 50% environment?

Answer 13

Heart disease

Question 14

Majority of traits are?

Answer 14

Polygenic

Question 15

How many different genes contribute to eye colour?

Answer 15

16 (two main ones)

Question 16

Monogenic traits are usually?

Answer 16

Rare (6% of people with any monogenic disease)

Question 17

Polygenic traits are usually?

Answer 17

Common
(people can be affected by more than one complex disease at once)

Question 18

What are the two key concepts of polygenic traits?

Answer 18

1. Any type of protein can have a genetic variant/change in function.
2. Proteins anywhere in a pathway/process can be affected.

Question 19

What is Phenylketonuria (PKU) an example of?

Answer 19

Loss of an enzyme at the START of a pathway

Question 20

What does Phenylketonuria (PKU) lead to?

Answer 20

Increased Phenylalanine, decreased concentrations of all other products in pathway.

Question 21

What is ALDH2 deficiency (asian flush syndrome) an example of?

Answer 21

Loss of an enzyme at the END of a pathway

Question 22

What does ALDH2 deficiency (asian flush syndrome) lead to?

Answer 22

Increased Acetaldehyde (toxic), Decrease Acetate

Question 23

What is Human purine metabolism as example of?

Answer 23

Loss of an enzyme (uricase) in the MIDDLE of a pathway

Question 24

What does Human purine metabolism lead to?

Answer 24

Increased uric acid

Question 25

What is Hyperuricaemia?

Answer 25

Polygenic condition: “too high” levels of uric acid

Question 26

What do genetic studies look for?

Answer 26

Inheritance patterns

Question 27

What do genetic studies of polygenic traits look for?

Answer 27

correlations and/or associations

Question 28

Pros of genetic studies:
(polygenic)

Answer 28

Polygenic traits are usually common
- can find a lot of people with the condition you’re studying
- can design studies to account for environmental factors

Question 29

Cons of genetic studies: (polygenic)

Answer 29

Not looking for one gene/variant
- multiple ways to get the same phenotype

Range of phenotypes available
- how you measure traits/conditions can change the result

Question 30

What does GWAS stand for?

Answer 30

Genome Wide Association Studies

Question 31

What do GWAS see?

Answer 31

If genetic variants are associated with a phenotype of interest

Question 32

What do GWAS use?

Answer 32

Many variants spread throughout the genome (>1,000,000 SNPs)

Question 33

What is cancer caused by?

Answer 33

Uncontrolled growth of cells, forming a tumour

Question 34

What are the steps of cancer?

Answer 34

1. Normal cells
2. Increased division
3. Uncontrolled growth
4. Increasingly uncontrolled growth
5. Spread

Question 35

Genetic variant:

Answer 35

Specific difference in DNA sequence between individuals

Question 36

Mutation:

Answer 36

Process by which new genetic variants arise
(permanent change in base sequence of DNA)

Question 37

Somatic:

Answer 37

All the type of body cells

Question 38

Germline:

Answer 38

Reproductive cells, can be passed to next generation.

Question 39

What is cancer a result of?

Answer 39

Accumulation of mutations

Question 40

What can cause mutations?

Answer 40

Errors in DNA replication, Exposure to carcinogenic chemicals or agents (damages DNA)

Question 41

Risk of cancer increases with?

Answer 41

Age (cells undergo more cell divisions)

Question 42

What are proto-oncogenes?

Answer 42

Genes that normally help cells grow and divide to make new cells, or to help cells stay alive

Question 43

What are oncogenes?

Answer 43

Mutated proto-oncogenes, Genes encoding proteins that promote cell growth.

Question 44

What are tumour suppressor genes?

Answer 44

Genes encoding proteins that prevent uncontrolled cell growth.

Question 45

Oncogenes are?

Answer 45

Gain of function mutations, (Dominant.)

Question 46

Tumour suppressor genes are?

Answer 46

Loss of function mutations,
(Recessive.)

Question 47

What do Proto-Oncogenes and tumour suppressor genes work together to do?

Answer 47

Control normal cell growth.

Question 48

Mutation to only one oncogene causes?

Answer 48

Accelerated cell growth, increased risk of cancer, tumour suppressor genes still working to prevent uncontrolled cells growth.

Question 49

Mutation to both tumour suppressor genes causes?

Answer 49

No prevention to uncontrolled cell growth, increased risk of cancer, Proto-Oncogenes working normally (cells growing at ‘regular’ rate)

Question 50

What does mutation to both Proto-Oncogenes and tumour suppressor genes cause?

Answer 50

Uncontrolled cell growth, increases mutation rate of cancer cells.

Question 51

What can increase a persons chance of developing cancer?

Answer 51

Inherited genetic variants