Genomic imprinting

Question 1

What type of cell do stem cells first differentiate into?

Answer 1

Progenitor cells

Question 2

How are specific genes activated in specific cell types and not in others?

Answer 2

Transcription factors

Question 3

Which type of cells have a haploid genome?

Answer 3

Sperm and egg (germ cells)

Question 4

What type of cell is formed when two haploid cells fuse?

Answer 4

Diploid cells

Question 5

How are haploid cells created from diploid cells?

Answer 5

The diploid cells divide by meiosis

Question 6

Advantages of having two sets of genes?

Answer 6

Genetic diversity and a backup set

Question 7

What did the cloning frogs experiment show?A

Answer 7

Each cell has the genetic information necessary to encode for a whole organism

Question 8

What is the name for a cell containing two male prouclei?

Answer 8

Androgenetic

Question 9

What is the name for a cell containing two female pronuclei?

Answer 9

Gynogenetic

Question 10

What is a parthenogenetic embryo?

Answer 10

One oocyte that doubles its haploid genome to become diploid

Question 11

Where can parthenogenesis occur?

Answer 11

Reptiles

Question 12

What happens if two female pronuclei fuse instead of a male and a female?

Answer 12

No extra-embryonic tissue is formed

Question 13

What happens if two male pronuclei fuse instead of a male and a female?

Answer 13

An excessive amount of extra-embryonic tissue and no embryonic tissue

Question 14

What can maternal genes not form?

Answer 14

A placenta

Question 15

What can paternal genes not form?

Answer 15

An embryo

Question 16

What are hydatidiform moles?

Answer 16

Growths that occur in the ovum that occur instead of pregnancy

Question 17

What causes hydatidiform moles?

Answer 17

Empty ovum (all genome is polar bodies and after fertilisation there is only a male contribution) or the ovum is fertilised by two sperm

Question 18

What causes prader willi/angelman syndrome?

Answer 18

A deletion in chromosome 15

Question 19

What condition comes about as a result of a deletion in the paternal chromosome 15?

Answer 19

Prader willi syndrome

Question 20

What condition comes about as a result of a deletion in the maternal chromosome 15?

Answer 20

Angelman syndrome

Question 21

Main symptoms of prader willi syndrome?

Answer 21

Obesity, metabolic issues

Question 22

Main symptoms of angelman syndrome?

Answer 22

Growth retardation, underweight

Question 23

What was observed after knocking a section of chromosome 15 out in male mice?

Answer 23

Male and female offspring had prader willi symptoms

Question 24

What was observed after knocking a section of chromosome 15 out in female mice?

Answer 24

offspring were carriers

Question 25

What are primordial gem cells?

Answer 25

Cells in the embryo that will become that organisms future gametes

Question 26

When are imprints established?

Answer 26

After the primordial germ cells have migrated to the genital ridge

Question 27

What are imprinting marks?

Answer 27

Methylation marks put on genes in primordial germ cells to help them differentiate into egg cells or sperm cells

Question 28

What is different from imprinted genes to normal methylation on genes?

Answer 28

The imprint remains on some genes in the egg and sperm after fertilisation

Question 29

What happens to imprinted genes during the development of the embryo?

Answer 29

They are read differently during the development of the embryo

Question 30

In which cells in the embryo are imprinted marks erased?

Answer 30

The primordial germ cells

Question 31

Which pronucleus is demethylated first?

Answer 31

The male

Question 32

What has happened to the male pronucleus before any cell division has occured?

Answer 32

It has rapidly lost its methylation

Question 33

What is responsible for the rapid demethylation of the male pronucleus?

Answer 33

TET enzymes

Question 34

What happens to imprinted genes post fertilisation?

Answer 34

The imprints are maintained

Question 35

Which type of epigenetic marks can be passed onto the next generation?

Answer 35

Imprinted marks

Question 36

When are imprinted genes not resistant to demethylation?

Answer 36

Prior to fertilisation

Question 37

What is the state of a gene on the opposite chromosome to the same gene that has been imprinted?

Answer 37

It is inactive

Question 38

Why do imprinted genes share regulatory elements?

Answer 38

They occur in clusters

Question 39

What is different between the imprinting control regions on different genes?

Answer 39

They are differentially methylated (i.e. one allele is methylated while the other isnt)

Question 40

How many genes can an imprinting control region?

Answer 40

Multiple

Question 41

What could happen if the imprinting control region at a certain locus is deleted?

Answer 41

All the imprinting at that locus may be lost

Question 42

What is different between the two genes in a differentially methylated region?

Answer 42

The methylation and thus the chromatin conformation (methylated allele will have a more closed, compacted less accessible chromatin conformation than the unmethylated one)

Question 43

Examples of genomic imprinting disorders?

Answer 43

Silver Russell and Beckwith Wiedemann syndromes, neonatal and maternal hypomethylation syndrome

Question 44

What is x inactivation?

Answer 44

After fertilisation, when you have two x chromosomes one is inactivated

Question 45

Difference between genomic imprinting and x inactivation?

Answer 45

Genomic imprinting is non-random whereas x inactivation is random