Gene Regulation

Question 1

Two types of positive regulation

Answer 1

Enhancer and Activator

Question 2

Two types of negative regulation

Answer 2

Silencer and Repressor

Question 3

What is double negative regulation

Answer 3

inhibiting a negative regulator

Question 4

Three types of temporal regulation patterns

Answer 4

1) increased gene expression dependent on continued presence of signal
2) Increased gene expression transient even in presence of signal
3) Increased gene expression indefinitely after signal termination

Question 5

Grouped unit of genes and regulatory elements (prokaryote)

Answer 5

operon

Question 6

Alternative name for gene (prokaryote)

Answer 6

cistron

Question 7

Multiple genes on an operon (w/ individual start/stop)

Answer 7

Polycistronic

Question 8

Gene comes on in presence of signal

Answer 8

inducible

Question 9

Gene expression which is always on

Answer 9

constitutive expression

Question 10

LacZ codes for…

Answer 10

beta-galactosidase

Question 11

LacY codes for…

Answer 11

permease

Question 12

LacA codes for…

Answer 12

transacetylase

Question 13

LacI codes for…

Answer 13

the repressor

Question 14

Inducers which bind to the repressor (inactivating it) in the lac operon…

Answer 14

Lactose, allactose, isopropylthiogalactoside (IPTG)

Question 15

Which of the lac operon genes is constitutive?

Answer 15

LacI (repressor)

Question 16

What happens to the lac operon in the presence of glucose?

Answer 16

Low levels of cAMP. cAMP not bound to CAP in order to promote lac mRNA expression

Question 17

What happens to the lac operon in scare glucose conditions?

Answer 17

cAMP binds to CAP. CAP promotes expression of more lac mRNA

Question 18

Lysogenic phase of viral reproduction

Answer 18

Incorporation into host bacterium’s genome

Question 19

Lytic phase of viral reproduction

Answer 19

Destruction of the host cell while copying viral DNA

Question 20

Genetic switch of bacteriophage, what breaks down the constitutive repressor?

Answer 20

recA

Question 21

What triggers recA in the example given?

Answer 21

UV radiation

Question 22

Cis elements in gene regulation

Answer 22

in the immediate vicinity of the promoter/gene

Question 23

trans elements in gene regulation

Answer 23

coded elsewhere from the gene (usually something like a transcription factor)

Question 24

Heritable changes in gene expression that occur without a change in DNA sequence

Answer 24

epigenetics

Question 25

The three epigenetic mechanisms

Answer 25

1) DNA methylation 2) histone modifications 3) RNA-mediated epigenetic regulation

Question 26

What enzyme methylates cytosines in DNA?

Answer 26

DNA methyltransferase (DNMT1)

Question 27

What is methylated cytosine called

Answer 27

5-methylcytosine 5mC

Question 28

Where is DNA methylation common?

Answer 28

CG (or CpG) dinucleotides

Question 29

Exception to DNA methylation happening evenly?

Answer 29

X chromosome inactivation (random in placental mammals, paternal in marsupials) and imprinting (parent of origin dependent methylation)

Question 30

Regions of tightly packed nucleosomes (highly enriched for 5mC)

Answer 30

heterochromatin (AT rich)

Question 31

Less tightly packed nucleosomes, allowing binds of RNA polymerase and regulatory proteins controlling gene expression

Answer 31

euchromatin (GC rich)

Question 32

Why does histone acetylation increase gene expression?

Answer 32

It neutralizes the (+) charge on the lysine residues, which was previously electrically drawn to (-) charges on DNA.

Question 33

Do histone deacetylases (HDAC) increase or decrease gene expression?

Answer 33

decrease

Question 34

Do histone acetylases (HAT) increase or decrease gene expression?

Answer 34

increase

Question 35

Do histone methyltransferases increase or decrease gene expression?

Answer 35

decrease

Question 36

Mutated methyl-CpG binding protein (MECP2) causing severely disrupted neurological development and impaired motor skills. X-linked condition

Answer 36

Rett Syndrome

Question 37

677CT polymorphism linked to altered patterns of DNA methylation. Increased risk for breast and colorectal cancer

Answer 37

Methylenetetrahydrofolate reductase (MTHFR)

Question 38

Imprinting disorder on Chromosome 15, leading to paternal LOF

Answer 38

Prader-Willi syndrome

Question 39

Imprinting disorder on Chromosome 15, leading to maternal LOF

Answer 39

Angelman syndrome

Question 40

Activation of igf2 (insulin-like growth factor) on chromosome 11

Answer 40

Bechwith-Wiedermann syndrome

Question 41

Histone modification defect leading to severe retardation

Answer 41

Coffin-Lowry Syndrome

Question 42

Defect in DNA methylation leading to intellectual disability

Answer 42

Fragile X syndrome

Question 43

Two ways epigenetics leads to cancer

Answer 43

1) oncogenes upregulated (hypomethylation) | 2) downregulation of tumor suppressor genes (hypermethylation)

Question 44

Gene which checks genome for errors. It is hypermethylated in many cancers

Answer 44

p53

Question 45

What structure / protein complex brings genes closer and could possibly play a role in gene coordination

Answer 45

Enhanceosomes

Question 46

Three DNA binding motifs active in transcriptional control

Answer 46

1) zinc fingers 2) helix-turn-helix 3) leucine zipper

Question 47

Three methods of transcriptional control

Answer 47

1) cell signaling by ligand activation of an intracellular receptor (this would cross the cell membrane) 2) ligand activation of a plasma membrane receptor (would use second messengers) 3) ligand activation of a plasma membrane G protein receptor

Question 48

What processes are miRNA involved in?

Answer 48

early development, cell proliferation/death, fat metabolism, cell differentiation

Question 49

What complex do miRNAs need to function?

Answer 49

RNA induced silencing complex (RISC)

Question 50

How do miRNA and siRNA differ?

Answer 50

1) siRNA are manmade | 2) siRNA are double-stranded RNA typically whereas miRNA loop back on themselves

Question 51

Codeine is a prodrug for what active substance?

Answer 51

morphine

Question 52

Which gene is responsible for metabolizing codeine into morphine?

Answer 52

CYP2D6