Regulation of Gene Expression: Chp 18

Question 1

operon consists of three parts

Answer 1

operator, promoter, and genes of the operon

Question 2

operator

Answer 2

controls the access of RNA polymerase to the genes. found within the promoter sire or between the promoter and the protein coding genes of the operon

Question 3

promoter

Answer 3

where RNA polymerase attaches

Question 4

genes of the operon

Answer 4

this entire stretch of DNA required for all the enzymes produced by the operon

Question 5

regulatory genes

Answer 5

produce repressor proteins that may bind to the operator site. when a regulatory protein occupies the operator site, RNA polymerase is blocked from the genes of the operon. in this situation the operon is off

Question 6

repressible operon

Answer 6

normally on but can be inhibited. normally anabolic, building an essential organic molecule. the repressor protein produced by the regulatory gene is inactive. if the organic molecules being produced by the operon is provided to the cell, the molecule can act as a corepressor and bind to the repressor protein, activating it. the activated repressor protein binds to the operator site, shutting down the operon. (tryp operon)

Question 7

inducuble operon

Answer 7

normally off but can be activated. this type of operon is normally catabolic, breaking down food molecules for energy, the repressor protein produced by the regulatory gene is active. to turn an inducible operon on, a specific small molecule, called an inducer, binds to and inactivates the repressor protein. with the repressor out of the operator site, RNA polymerase can access the genes of the operon

Question 8

differential gene expression

Answer 8

the expression of different genes by cells with the same genome

Question 9

DNA methylation

Answer 9

the addition of methyl groups to DNA. it causes the DNA to be more tightly packed, thus reducing gene expression

Question 10

histone acetylation

Answer 10

acetyl groups are added to amino acids of histone proteins, thus making the chromatin less tightly packed and encouraging transcription

Question 11

epigenetic inheritance

Answer 11

the inheritance of triats transmitted by mechanisms not directly involving the nucleotude sequence

Question 12

the three interrelated processes of a zygote

Answer 12

cell division: the serios of mitotic divisions that increases the number of cells
cell differentation: the process by which cells become specialized in structure and function
morphogenesis: gives an organism its shape

Question 13

what controls differentation and morphogenesis

Answer 13

cytoplasmic determinants and cell-cell signals

Question 14

cytoplasmic determinants

Answer 14

maternal substances in the egg that influence the course of early development

Question 15

cell-cell signals

Answer 15

result from molecuels produced by one cell influencing neighboring cells, a process called induction, which causes cells to differentiate

Question 16

determination

Answer 16

the series of events that lead to observable differentation of a cell. caused by cell-cell signals and is irreversible

Question 17

pattern formation

Answer 17

sets up the body plan and is a result of cytoplasmic determinant and inductive signals

Question 18

homeotic genes

Answer 18

master control genes that control pattern formation

Question 19

oncogenes

Answer 19

cancer-causing genes

Question 20

proto-oncogenes

Answer 20

genes that code for proteins that are responsible for normal cell growth

Question 21

how do proto-oncogenes become oncogenes

Answer 21

when a mutation occurs that causes an increase in the product of the proto-oncogenes, of an increase in the activity of each protein molecule produced by the gene

Question 22

cancer

Answer 22

also can be caused by a mutation in a gene whose products nirmally inhibit cell division (the genes=tumor-suppressor genes)