Bio Ch 13

Question 0

Operon

Answer 0

model that explains gene regulation in prokaryotes

Question 1

Structural genes

Answer 1

genes for a metabolic pathway; grouped on a chromosome and subsequently transcribed at the same time; code for the enzymes and proteins that are involved in the metabolic pathway of the operon; transcribed as a unit

Question 2

Regulator gene

Answer 2

normally located outside the operon; codes for a DNA-binding protein that acts as a repressor

Question 3

Repressor

Answer 3

controls whether the operon is active or not

Question 4

Promoter

Answer 4

short sequence of DNA where RNA polymerase 1st attaches to begin transcription of the grouped genes; signals the start of the operon and the location where transcription begins

Question 5

Operator

Answer 5

short portion of DNA where an active repressor binds

Question 6

Corepressor

Answer 6

molecule that binds to a repressor, allowing the repressor to bind to an operator in a repressible operon

Question 7

Inducer

Answer 7

molecule that brings about activity of an operon by joining with a repressor and preventing it from binding to the operator

Question 8

Epigenetic inheritance

Answer 8

an inheritance pattern in which a nuclear gene has been modified but the changed expression of the gene is not permanent over many generations the transmission of genetic information by means that are not based on the coding sequences of a gene

Question 9

Chromatin

Answer 9

stringy material that makes up DNA in eukaryotes; most evident in nucleus during interphase

Question 10

Barr body

Answer 10

small, darkly staining mass of condensed chromatin adhering to the inner edge of the nuclear membrane is an inactive X chromosome

Question 11

Transcriptional control

Answer 11

control of gene expression by the use of transcription factors, and other proteins, that regulate either the initiation of transcription or the rate at which it occurs

Question 12

Transcription factors

Answer 12

proteins that help regulate transcription by assisting the binding of the RNA polymerase to the promoter

Question 13

Transcription activator

Answer 13

DNA-binding protein; transcription cannot begin without this

Question 14

Enhancers

Answer 14

DNA sequence that acts as a regulatory element to increase the level of transcription when regulatory proteins, such as transcription activator bind to it

Question 15

Posttranscriptional control

Answer 15

occurs in the nucleus and includes alternative mRNA splicing and controlling the speed with which mRNA leaves the nucleus

Question 16

MicroRNAs (miRNAs)

Answer 16

small snippets of RNA that can bind to and dampen the translation of mRNA in the cytoplasm

Question 17

Small-interfacing RNAs (siRNAs)

Answer 17

join with an enzyme (an RNA-induced silencing complex, or RISC) to form an active silencing complex

Question 18

RNA Interference

Answer 18

cellular process that utilizes miRNA and siRNA molecules to reduce or inhibit the expression of specific genes

Question 19

Translational control

Answer 19

begins when the processed mRNA molecule reaches the cytoplasm and before there is a protein product

Question 20

Posttranslational control

Answer 20

begins once a protein has been synthesized and has become active

Question 21

Proteases

Answer 21

enzymes that breakdown proteins

Question 22

Proteasomes

Answer 22

to protect the cell, proteases are typically confined to the lysosomes or special structures called these

Question 23

Gene mutation

Answer 23

permanent change in the sequence of bases in DNA

Question 24

Spontaneous mutations

Answer 24

arise as a result of abnormalities in normal biological processes

Question 25

Induced mutations

Answer 25

may result from exposure to toxic chemicals or radiation, which cause changes in the base sequence of DNA

Question 26

Mutagens

Answer 26

environmental factors that can alter the base composition of DNA; cause induced mutations

Question 27

Carcinogens

Answer 27

cancer-causing mutagens

Question 28

DNA Repair Enzymes

Answer 28

constantly monitor DNA and fix any irregularities

Question 29

Point mutations

Answer 29

involve a change in a single DNA nucleotide and therefore a possible change in a specific amino acid

Question 30

Frameshift mutations

Answer 30

occur most often when one or more nucleotides are either inserted or deleted from DNA