Genetics Test 3

Front 1

Flowering locus C

Back 1

represses flowering, only if the the locus is acetylated

Front 2

Flowering locus D

Back 2

a histone deacetylase that inactivates the FLC locus (flowering is not supressed)

Front 3

transcription factor

Back 3

any transcription regulatory protein that binds a specific DNA sequence

Front 4

cis-acting elements

Back 4

DNA sequences that are necessary for the control of transcription (the regulatory regions of the chromosome)

Front 5

trans-acting factors

Back 5

any protein that is necessary for the control of transcription (the regulatory proteins that bind the cis-acting elements)

Front 6

What are the cis-acting elements?

Back 6

promoter, enhancers, silencers

Front 7

Where is the promoter located?

Back 7

Always upstream from the transcription initiation site (and in very close proximity)

Front 8

What is present in all mRNA coding genes?

Back 8

TATA box

Front 9

Promotors are sufficient for what type of transcription?

Back 9

basal (unstimulated)

Front 10

Enhancers are required for what type of transcription?

Back 10

stimulated (up-regulation)

Front 11

What is the role of enhancers?

Back 11

determine where, when, and how much transcription occurs

Front 12

Where can enhancers be found?

Back 12

distant upstream, downstream, or inverted position on same chromosome

Front 13

transcription factors have 2 domains:

Back 13

DNA-binding domain and trans-activating or trans-repressing domain

Front 14

What does luecine zipper (ZIP) do?

Back 14

allows protein dimerization

Front 15

What does zinc-finger do?

Back 15

interspersed cystesine and histidine residues that covalently bind zinc atoms, folding the amino acid chains into loops that interact with specific DNA sequences

Front 16

what are helix-turn-helix (HTH)?

Back 16

adjacent alpha helices seperated by turns of several amino acids that bind the DNA grooves

Front 17

What are the 3 dimensional structural motifs of DNA-binding domains?

Back 17

HTH, zinc finger, leucine zipper (ZIP)

Front 18

What must be pre-assembled on the promoter before transcription can begin?

Back 18

the transcription initiation complex

Front 19

Does RNA polymerase recognize specific DNA sequences?

Back 19

No

Front 20

GAL gene system: four structural genes

Back 20

GAL 1, 2, 7, 10. Encode proteins that transport the sugar galactose into the cell and metabolize it

Front 21

GAL gene system: the products of the regulatory genes

Back 21

GAL 4, 80, 3. positively and negatively control the transcription of the structural genes

Front 22

The transcription of the GAL structural genes is said to be what?

Back 22

Inducible; it occurs only in the presence of the substrate galactose

Front 23

The transcription of GAL 1 and 10 is controlled by?

Back 23

a central control region called UAS(little G) which is free of nucleosomes (DNA hypersensitive)

Front 24

UAS(little G) contains binding sites for what?

Back 24

the transcriptional activator GAL 4 protein

Front 25

GAL4 is negatively activated regulated by what? What does this do?

Back 25

GAL80, prevents transcription of GAL 1 and 10

Front 26

WHen galactose is available in the GAL gene system what does is activate?

Back 26

GAL3 which interacts with GAL4p/GAL80p complex, altering the structure and exposing GAL4p trans-activating domain

Front 27

How is iron transferred within the body?

Back 27

By the protein Transferrin

Front 28

What happens when levels of free cytoplasmic iron increase too much?

Back 28

The cell synthesizes Ferritin which is a protein that sequesters iron atoms.

Front 29

translational regulation of the transferrin receptor: int he absence of iron

Back 29

the iron regulatory protein binds the iron response element of the Transferrin receptor mRNA, stabalizing it and promoting translation

Front 30

translational regulation of Ferritin: in the absence of iron

Back 30

The iron regulatory protein binds the iron response element of the Ferritin mRNA, inhibiting translation

Front 31

endosymbiosis

Back 31

the mitochondria in eukaryotic cells and chloroplasts in plants where prokaryotes that entered eukaryotic cells and became adapted to preform specific cellular functions

Front 32

evidence for symbiosis

Back 32

- organelles contain their own DNA
- organelles resemble living prokaryotes
-organelle genomic sequences resemble those of living prokaryotes
-organelles are enclosed by double membranes

Front 33

Human mtDNA codes for?

Back 33

two rRNAs, 22 tRNAs, and 13 polypeptides necessary for the oxidative respiratory functions of the organelle

Front 34

The zygote receives the large number of mitochondria through the egg or the sperm?

Back 34

The egg

Front 35

What criteria must be met in order for a human disorder to be attributable to genetically altered mitochondria?

Back 35

1. A maternal inheritance pattern
2. The disorder must reflect a deficiency in the bioenergetic function of the organelle
3. There must be mutations in one or more of the mitochondrial genes

Front 36

heteroplasmy

Back 36

cells with a variable mixture of both normal and abnormal organelles

Front 37

Example of mitochondrial genetic disorders

Back 37

Myoclonic epilepsy, ragged red fiber disease and Leber's hereditary optic neuropathy

Front 38

MERRF is caused by?

Back 38

an A to G substitution in the mitochondrial tRNA Lyse gene

Front 39

MERRF symptoms

Back 39

ataxia (lack of muscular coordination), deafness, dementia, and epileptic seizures
ragged reed skeletal musle fibers exhibit blotchy red patches due to the proliferation of abnormal mitochondria

Front 40

LHON is caused by?

Back 40

more than 50% is due to a mutation in a mitochondrial gene that encodes a subunit of NADH dehydrogenase, affecting oxidative phosphorylation

Front 41

What happens to patients with LHON?

Back 41

individuals experience sudden bilateral blindness at age less than 27

Front 42

Blue colonies in the Xgal blue-white assay

Back 42

Xgal positive; carry plasmid vectors without cloned foreign DNA (original nonrecombinant plasmid)

Front 43

white colonies in the Xgal blue-white assay

Back 43

no Xgal reaction; carry plasmids with cloned foreign DNA (recombinant plasmid)

Front 44

What plasmid can be used to transfer genes into plants?

Back 44

Ti plasmid

Front 45

What is glyphosphate?

Back 45

a herbicide that kills plants by inhibiting EPSP synthase

Front 46

What is EPSP synthase?

Back 46

a chloroplpast enzyme that is essential for amino acid biosynthesis

Front 47

Which promoter help plants resistance to glyphosphate?

Back 47

The cauliflower mosaic virus (CMV) promotor in a Ti plasmid vector

Front 48

What can be used as gene therapy to correct SCID?

Back 48

the SAX virus

Front 49

What causes SCID?

Back 49

a hereditary disease caused by a defect in the hADA gene

Front 50

What are STRs (short tandem repeats)?

Back 50

clusters of tandem repeats of 2 to 9 nucleotide sequences

Front 51

What does CODIS stand for?

Back 51

Combined DNA Index System

Front 52

How many core CODIS STRs are there?

Back 52

13

Front 53

What protein is found in developing tooth enamel?

Back 53

Amelogenin

Front 54

requirements for transcription

Back 54

template DNA, RNA polymerase, free NTPs, no primers

Front 55

transcription

Back 55

the transfer of genetic information from DNA by the synthesis of an RNA molecule copied from the DNA template

Front 56

Which is the transcribe strand of DNA?

Back 56

the template strand (antisense)

Front 57

What is the non-template strand called?

Back 57

sense

Front 58

Components of a transcription unit:

Back 58

promoter, RNA coding region, terminator

Front 59

promoter

Back 59

the binding site for RNA polymerase and the transcription apparatus

Front 60

RNA-coding region

Back 60

a sequence of DNA nucleotides that is copied into an RNA molecule

Front 61

terminator

Back 61

a sequence of nucleotides that signals where transcription is to end

Front 62

pyriminidines

Back 62

C and T

Front 63

purines

Back 63

A and G

Front 64

In a consensus sequence, what are pyriminidines indicated by?

Back 64

Y

Front 65

In a consensus sequence, what are purines indicated by?

Back 65

R

Front 66

What is a consensus sequence?

Back 66

comprises the most commonly encountered nucleotides at each site

Front 67

a holoenzyme

Back 67

an active enzyme with several polypeptide components. ex. RNA polymerase

Front 68

What does the sigma factor do in transcription of bacteria?

Back 68

recognizes the promoter and directs the core RNA polymerase to it

Front 69

Termination in bacteria depend on?

Back 69

the formation of a hairpin loop at the terminator site

Front 70

Termination of transcription of protein-encoding genes in eukaryotes requires what?

Back 70

the activity of the Rat1 exonuclease.

Front 71

What does Rat1 do?

Back 71

binds the 5' end of the trailing RNA fragment and begins to degrade it until it catches up to the RNA polymerase. This terminates transcription

Front 72

Concept of colinearity

Back 72

suggests that the number of nucleotides ina gene should be proportional to the number of amino acids in the protein encoded by that gene
- this is true for most bacterial and viral genes

Front 73

introns

Back 73

DNA sequences within a gene that are transcribed but do not appear in the final mRNA product

Front 74

exons

Back 74

the translated sequences of a gene

Front 75

how are introns removed?

Back 75

RNA splicing

Front 76

What is our largest gene?

Back 76

the dystrophin gene, 2.6 million nucleotide pairs long; about .01% of the human genome

Front 77

Shine-Dalgarno sequence

Back 77

In prokaryotes only. A consensus sequence that serves as the ribosome-binding site during translation.

Front 78

Postranscriptional modifications to eukaryotic pre-mRNA

Back 78

addition of 5' cap, 3' cleavage and addition of poly(A) tail, RNA splicing, RNA editing

Front 79

Function of addition of 5' cap

Back 79

facilitates binding of ribosome to 5' end of mRNA, increases mRNA stability, enhances RNA splicing

Front 80

Function of 3' cleavage and addition of poly(A) tail

Back 80

increases stability of mRNA and facilitates binding of ribosome to mRNA

Front 81

Function of RNA splicing

Back 81

removes non coding introns from pre-mRNA, facilitates export of mRNA to cytoplasm, allows for multiple proteins to be produced through alternative splicing

Front 82

Function of RNA editing

Back 82

alters nucleotide sequence of mRNA

Front 83

What happens in the addition of the 5' cap to mRNA?

Back 83

one of 3 phosphate groups is removed and replaced with a guanine nucleotide with phosphate group. methyl groups are then added to position 7 of the terminal guanine molecule and to the 2' position of the sugar in the 2nd and 3rd nucleotides

Front 84

What did the Beadle and Tatum experiment establish?

Back 84

The concept of a direct relationship between gene expression and proteins

Front 85

What did the Beadle and Tatum experiment figure out?

Back 85

Nutrition auxotrophic mutants require a specific nutrient for survival (each gene is responsible for coding a single enzyme). Found that mutant cells could only grow on minimal medium with arginine. Concluded that the mutation in the auxotroph affects an enzyme that is required for the synthesis of the amino acid arganine.

Front 86

What did the Srb and Horowitz experiments do?

Back 86

Deduced the biochemical pathway for the synthesis of the amino acid arginine. Studied 3 groups of Neurospora auxotrophic mutants, all requiring arganine for growth.

Front 87

start codon

Back 87

AUG

Front 88

Stop codons

Back 88

UAA, UAG, UGA (do not code for amino acids)

Front 89

reading frame

Back 89

a linear sequence of codons in a nucleic acid defined by a start codon

Front 90

substitution mutations: silent

Back 90

the resulting codon codes for the same amino acid as the original codon

Front 91

substitution mutations: missense

Back 91

the new codon codes for a different amino acid

Front 92

substitution mutations: nonsense

Back 92

the new codon is a stop codon (resulting in a shorter polypeptide)

Front 93

frameshift mutation

Back 93

the insertion of a single base pair, all codons from the insertion site are changed

Front 94

translation requirements

Back 94

mRNA, ribosome, charged transfer RNAs (tRNAs), initiation factors, elongation factors, and energy sources

Front 95

the wobble hypothesis

Back 95

The 3rd position of the codon-anticodon is less critical and less constrained

Front 96

The Svedberg unit

Back 96

a measure of the rate at which particles sediment in a centrifugal field.

Front 97

svedberg values

Back 97

large subunit: 50S
small: 30S
complete ribosome: 70S

Front 98

lacY gene product

Back 98

permease; facilitates the entry of lactose into the bacterial cell

Front 99

What happens when tryptophan level is low

Back 99

ribosome will stall at Trp codons because of low availability of charged tRNA. region 2 and 3 bind forming antitermination hairpin. region 4 cannot pair with 3. The attenuator never forms and transcription continues

Front 100

What happens when tryptophan level is high

Back 100

ribosome will not stall, charged tRNA will be available. Attenuation hairpin will form with regions 3 and 4. This will signal the interruption of transcription and will not proceed to structural genes.

Front 101

5' UTR involves what

Back 101

trp operon (tryptophan)

Front 102

classification of eukaryotic genes according to the RNA polymerases that can transcribe them: RNA polymerase I

Back 102

larger rRNA genes

Front 103

classification of eukaryotic genes according to the RNA polymerases that can transcribe them: RNA polymerase II

Back 103

all mRNA coding genes (all protein coding genes)

Front 104

classification of eukaryotic genes according to the RNA polymerases that can transcribe them: RNA polymerase III

Back 104

small rRNA and all tRNA genes

Front 105

What does histone acetylation do?

Back 105

destabalizes the interaction between basic amino acids and the acidic DNA molecule, causing chromatin decondensation. May permit some transcription factors to bind to DNA

Front 106

Histone acetyl transferases act as?

Back 106

coactivators, but do not bind DNA

Front 107

Histone deacetylases act as?

Back 107

corepressors but do not bind DNA