Mutations (Khan Academy)

Question 1

What is a mutagen?

Answer 1

A chemical substance or physical event that can cause genetic mutations.

Question 2

How are mutagens classified in terms of source?

Answer 2

endogenous
exogenous

Question 3

What are reactive oxygen species (ROS)?

Answer 3

A type of unstable molecule that contains oxygen and that easily reacts with other molecules in a cell. It’s produced in a cell.

Question 4

What are the types of DNA damage by ROS?

Answer 4

Double strand break - breaking DNA into segments
Base modification - swapping of nuleic acid

Question 5

What are intercalators?

Answer 5

A type of exogenous mutagens, molecules which fit themselves between the two strands of DNA and cause deformation.

Question 6

What are base analogues?

Answer 6

A type of exogenous mutagens, molecules which “impersonate” bases but act differently.

Question 7

What are the most common types of anneuploidy in humans?

Answer 7

monosomy - missing one copy of a chromosome in a pair
trisomy - having a third copy of a chromosome

Question 8

What is the cause of aneuploidy?

Answer 8

Nondisjunction of chromosomes - failure of homologous chromosomes to separate during meiosis I or sister chromatids during meiosis II or mitosis.

Question 9

What are the types of chromosomal rearrangements?

Answer 9

duplication
deletion
inverison
translocation

Question 10

What takes place during duplication in a chromosome?

Answer 10

A part of a chromosome is copied more than one time.

Question 11

What happens during deletion in a chromosome?

Answer 11

A part of a chromosome is removed.

Question 12

What happens during inversion in a chromosome?

Answer 12

A chromosomal region is flipped around so that it points in the opposite direction.

Question 13

What happens during translocation in chromosomes?

Answer 13

A piece of one chromosome gets attached to another chromosome.

Question 14

What are the types of chromosomal translocation?

Answer 14

Translocation can be reciprocal or non-reciprocal.
A reciprocal translocation involves two chromosomes swapping segments.
A non-reciprocal translocation means that a chunk of one chromosome moves to another.

Question 15

What are the ways bacteria can share genes?

Answer 15

transformation
transduction
conjugation

Question 16

What happens in bacterial transformation?

Answer 16

A bacterium takes in DNA from its environment, often DNA that’s been shed by other bacteria.

Question 17

What happens in bacterial transduction?

Answer 17

Viruses that infect bacteria move short pieces of chromosomal DNA from one bacterium to another “by accident.”

Question 18

What happens in bacterial conjugation?

Answer 18

DNA is transferred from one bacterium to another. After the donor cell pulls itself close to the recipient using a structure called a pilus, DNA is transferred between cells. In most cases, this DNA is in the form of a plasmid.

Question 19

What is a fertility factor in bacteria?

Answer 19

A chunk of DNA that codes for the proteins that make up the sex pilus. It also contains a special site where DNA transfer during conjugation begins.

Question 20

What are transposable elements?

Answer 20

Chunks of DNA which “jump” from one place to another within a genome, cutting and pasting themselves or inserting copies of themselves in new spots.

Question 21

What are the two sources of genetic variation in viruses?

Answer 21

recombination - swapping fragments of DNA between viruses
random mutation