Chapter 5- Non-Mendelian Inheritance

Question 1

What are the four simple mendelian rules?

Answer 1

1. Genes in the offspring directly influence their trait.
2. Genes are passed unaltered from generation to generation.
3. Genes obey Mendel’s law of segregation
4. if more than one genes are crossed, genes follow Mendel’s law of independent assortment.

Question 2

Which type of inheritance break Mendel’s first rule?

Answer 2

Maternal effect.

Question 3

Which type of inheritance break Mendel’s second rule?

Answer 3

Epigenetic inheritance.

Question 4

Which type of inheritance break Mendel’s third rule?

Answer 4

Extranuclear inheritance

Question 5

Which type of inheritance break Mendel’s fourth rule?

Answer 5

Linkage

Question 6

Where does Maternal effect inheritance take place?

Answer 6

It involves genes located in the nucleus

Question 7

Where does the Epigenetic inheritance take place?

Answer 7

It involves genes located in the nucleus

Question 8

Where does the extranuclear inheritance take place?

Answer 8

It involves organelles other than the nucleus such as Mitochondria and chloroplast.

Question 9

Where does the Linkage inheritance take place?

Answer 9

It involves genes located in the nucleus.

Question 10

What is maternal effect?

Answer 10

It occurs when the genotype of the offspring doesn’t govern the phenotype as predicted by Mendel.

Question 11

When does gene get modified in the Epigenetic inheritance?

Answer 11

They get modified during Gametogenesis and Early embryonic development.

Question 12

When does linkage inheritance occur?

Answer 12

It occurs when two or more genes are close to each other on the same chromosome.

Question 13

Why does the phenomenon of Maternal effect occur?

Answer 13

It occurs due to the accumulation of gene product that the mother provide to her developing egg.

Question 14

What does the maternal effect encode?

Answer 14

It encodes RNA and proteins that play important role in the early stages of embryogenesis (Cell division, cleavage protein, and body axis orientation.)

Question 15

What is epigenetic inheritance?

Answer 15

It is a pattern in which a modification occurs to a nuclear gene or chromosome that alter gene expression.

Question 16

Is epigenetic inheritance permenant?

Answer 16

No, the expression is not permanently changed over the course of many generation.

Question 17

Is epigenetic inheritance reversible?

Answer 17

Yes, it is reversible and it doesn’t change the DNA sequence.

Question 18

When does Epigenetic changes occur?

Answer 18

They occur during oogenesis, spermatogenesis, or early embryonic development or throughout the life.

Question 19

What is dosage compensation?

Answer 19

It is specifically to offset differences in the number of active sex chromosomes

Question 20

When does X chromosome inactivation occurs?

Answer 20

It occurs early in development.

Question 21

What is the importance of Xic region?

Answer 21

For the inactivation process to occur, Xic region must be present.

Question 22

What are the three steps for inactivation?

Answer 22

1. Nucleation
2. spreading
3. maintenance

Question 23

What happens during nucleation process?

Answer 23

The nucleation occurs during embryonic development. One of the X chromosome stay active, and the other become target for inactivation.

Question 24

What happens during Spreading process?

Answer 24

The spreading occurs during embryonic development. one entire X chromosome become inactivated and turns into bar body.

Question 25

What happens during Maintenance process?

Answer 25

It occurs from embryonic development and throughout adult life. The inactivated X chromosome maintained as such during the cell development.

Question 26

What is genomic imprinting?

Answer 26

It is a phenomenon in which segment of the DNA get marked and the effect is maintained throughout the life of organisms inheriting the marked DNA.

Question 27

Can maternal effect and genome imprinting works in the same time?

Answer 27

No, only one of them is expressed and it depends on how genes are marked.

Question 28

What is monoallelic expression?

Answer 28

It occurs when only one allele is actively transcribed.

Question 29

In what species does the genomic imprinting occurs?

Answer 29

It occurs in insects, mammals and flowering plants.

Question 30

Where are the genetic material of mitochondria and chloroplasts located?

Answer 30

They are located in region called nucleoid.

Question 31

What are the genome composed of in mitochondria and chloroplast?

Answer 31

The genome is composed of a single circular chromosome containing double stranded DNA.