more mcqs Flashcards

1
Q

what do aminoacyl tRNA synthetases do?

A

catalyse the covalent attachment of amino acids to their corresponding tRNA molecules

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2
Q

do aminoacyl tRNA synthetases have proof-reading activity?

A

no

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3
Q

what allows viruses to initiate translation independently of the first AUG codon?

A

IRES

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4
Q

what mediates binding of aminoacyl-tRNAs to the A-site of the ribosome?

A

elongation factor protein Tu

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5
Q

what mediates 30S ribosomal subunit association with mRNAs in prokaryotes?

A

Shine-Dalgarno sequence

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6
Q

what is TFIID?

A

a general transcription factor

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7
Q

what is required for the synthesis of most rRNA precursors?

A

RNA polymerase I

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8
Q

what is the TATA box?

A

a core promoter element

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9
Q

what protein prevents parental DNA strands from re-annealing during DNA replication?

A

single strand binding protein

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10
Q

what is DNA polymerase III?

A

an RNA-dependent DNA polymerase

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11
Q

what is a bacterial enzyme that cuts DNA at/near specific recognition sequences?

A

restriction endonuclease

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12
Q

what do aminoacyl tRNA synthetases do?

A

catalyse the covalent attachment of amino acids to their corresponding tRNA molecules

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13
Q

how many DNA strands does Topoisomerase I cut?

A

single strand

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14
Q

how many DNA strands does Topoisomerase II cut?

A

both strands

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15
Q

what is an inherently error-prone double-strand break repair system?

A

non-homologous end joining

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16
Q

what is a human genetic disease caused by mutations in p53?

A

Li-Fraumeni syndrome

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17
Q

what is a human genetic disease caused by mutations in components of the nucleotide excision repair system?

A

Xeroderma pigmentosum

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18
Q

what does increasing length do to the melting temperature of DNA?

A

increases it

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19
Q

where do histones undergo post-translational modifications?

A

in their N-terminal sequences

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20
Q

what does GR binding to its ligand result in?

A

translocation of GR to the nucleus

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21
Q

what is the eukaryotic pre-initiation complex?

A

a set of specific DNA binding transcription factors bound to an enhancer element

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22
Q

what is the chemical interaction that holds strands together in the DNA double helix?

A

hydrogen bond

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23
Q

what is the chemical moiety at the 3’-end of a linear DNA molecule?

A

hydroxyl

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24
Q

what aromatic base is normally paired with guanine?

A

cytosine

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25
Q

what is a transposon?

A

mobile genetic element

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26
Q

what is the DNA region at each end of a chromosome?

A

telomere

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27
Q

what enzyme initiates nucleic acid synthesis in DNA replication?

A

primase

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28
Q

what is a distinguishing feature of a lariat?

A

2’-5’ phosphodiester bond

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29
Q

what is the core complex of RNAi?

A

RISC

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30
Q

what is the catalytic core of the spliceosome?

A

U2 and U6 snRNAs

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31
Q

what do base excision repair proteins do?

A

correct mismatch errors during DNA replication

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32
Q

when are RNA primers excised in DNA replication?

A

before ligation of the Okazaki fragments

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33
Q

how is CREB activated?

A

through cAMP dependent phosphorylation

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34
Q

what is transcription termination coupled to in eukaryotes?

A

mRNA polyadenylation

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35
Q

what is the packaging unit of chromosomal DNA in the nucleus of the cell?

A

nucleosome

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36
Q

what is a mutation in DNA that changes a purine nucleotide to another purine?

A

transition

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37
Q

what is the molecular basis of Huntington’s disease?

A

triplet nucleotide expansion

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38
Q

what is at the 3’ end of eukaryotic mRNA?

A

poly-A tail

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39
Q

what is the 5’-end of a nascent RNA transcript?

A

5’pppN

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40
Q

what is Rifamycin?

A

a potent RNA polymerase inhibitor

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41
Q

what mutational event would contribute most strongly to genetic instability and development of cancer?

A

loss of function of the MLH1 protein

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42
Q

what sort of mutations in tumor suppressor genes confer susceptibility to cancer?

A

inherited single allele mutations

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43
Q

what proportion of DNA on average would be shared between 2 half-siblings?

A

25%

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44
Q

which type of cancers tend to have more somatic mutations, adult or paediatric?

A

adult

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45
Q

can RNA hybridise with DNA?

A

yes

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46
Q

what is primase?

A

a DNA-dependent RNA polymerase

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47
Q

what is the heterogametic sex in birds?

A

females

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48
Q

what is the heterogametic sex in mammals?

A

males

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49
Q

does necroptosis require Tumour Necrosis Factor alpha?

A

no

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50
Q

what does necroptosis require?

A

RIPK3, MLKL

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51
Q

what can necrosulfonamide inhibit?

A

necroptosis

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52
Q

what does an IRES do in eukaryptes?

A

facilitates CAP-independent translation

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53
Q

what is transcription termination directly coupled to in eukaryotes?

A

mRNA polyadenylation

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54
Q

what protein is most strongly associated with an inherited predisposition to cancer?

A

RB

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55
Q

what protein is most strongly associated with development of B-cell lymphoma in chickens infected with the avian leukosis virus?

A

MYC

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56
Q

what protein is most strongly associated with tumour angiogenesis?

A

VEGF

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57
Q

what type of genetic variation is frequently caused by polymerase slippage?

A

Indel

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58
Q

what type of genetic variation is frequently caused by unbalanced structural variants?

A

copy number variant

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59
Q

what are transitions and transversions examples of?

A

single nucleotide variant

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60
Q

what is a type of DNA repair coupled to DNA synthesis?

A

mismatch repair?

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61
Q

what is a type of DNA polymerase-dependent DNA repair?

A

translesion synthesis

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62
Q

what is the type of repair associated with meiosis?

A

homologous recombination

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63
Q

what is the peak absorption wavelength of DNA?

A

260nm

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64
Q

what process has a speed which inversely corresponds to DNA sequence complexity?

A

strand reannealing

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65
Q

what is the assay to detect a specific RNA in a nucleic acid sample?

A

Northern blot

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66
Q

what is a sex chromosome aneuploidy condition in females?

A

Turner Syndrome

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67
Q

what is a sex chromosome aneuploidy condition in males?

A

Klinefelter syndrome

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68
Q

what condition is caused by paternal uniparental disomy for chromosome 15?

A

Angelman syndrome

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69
Q

what cell death process doesn’t induce inflammation?

A

apoptosis

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70
Q

what type of cell death often depends on caspase 1?

A

pyroptosis

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71
Q

what type of cell death is induced by toxic lipid peroxides?

A

ferroptosis

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72
Q

what cells relate to the origin of adenocarcinomas?

A

glandular epithelial cells

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73
Q

how much of the euchromatic genome is composed of repeat sequences?

A

less than half

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74
Q

what do bacteria use DNA methylation for?

A

to control gene expression

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75
Q

what amino acid is ubiquitin covalently linked to?

A

lysine

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76
Q

what does canonical splicing require?

A

a large ribonucleoprotein complex

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77
Q

what does alternative splicing do to the diversity of the proteome?

A

increases it

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78
Q

can cells with unrepaired DNA become senescent?

A

yes

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79
Q

what sort of caspase is caspase 7?

A

executor

80
Q

is an aneuploid karyotype always abnormal?

A

no

81
Q

how many chromosomes does the mouse karyotype have?

A

40

82
Q

what sort of sample sizes are used in GWAS?

A

large

83
Q

what sort of disease variants do GWAS usually identify?

A

low risk disease variants

84
Q

what protein is activated by genomic amplification in neuroblastoma?

A

N-Myc

85
Q

what is the tumour virus protein responsible for binding to and inactivating p53?

A

HPV E6

86
Q

what protein is regulated by intramolecular interactions with a phospho-tyrosine?

A

Rb

87
Q

what is the region of attachment of 2 sister chromatids?

A

centromere

88
Q

what is the functional effect achieved by X-chromosome inactivation?

A

dosage compensation

89
Q

what is the DNA structure formed by telomeres?

A

G-quadruplex

90
Q

what is the enzyme which unwinds the parental DNA in replication?

A

DNA helicase

91
Q

what is the proof-reading activity of DNA polymerases?

A

3’-to-5’ exonuclease

92
Q

what is a required step in maturation of bacterial Okazaki fragments?

A

Nick translation

93
Q

what is the template of transcription in eukaryotes?

A

promoter

94
Q

what is a chromatin-modifying enzyme?

A

histone acetylase

95
Q

what is a cis-regulatory element that can be located far from the gene locus?

A

enhancer

96
Q

what protein inhibits G1-CDK?

A

p16^INK4a

97
Q

what protein kinase has activity critical for mitosis?

A

PLK1

98
Q

what transcription factor regulates expression of proteins and enzymes required for S phase?

A

E2F

99
Q

what is an individual composed of cells with different genotypes?

A

mosaic

100
Q

what is the point where exchange of genetic information occurs between homologous non-sister chromatids?

A

chiasma

101
Q

what event is a hallmark of apoptosis?

A

release of cyt c from the mitochondria

102
Q

can Bid be cleaved by caspase 8?

A

yes

103
Q

which host-cell protein is inactivated by the HPV E6 protein?

A

p53

104
Q

what does the Rb protein do for cell cycle progression?

A

inhibits it

105
Q

what do the strands of z DNA form?

A

a left-handed helix

106
Q

how does nucleotide excision repair not operate

A

direct replacement of the damaged nucleotide

107
Q

what does CREB do to activate transcription?

A

binds the CBP co-activator

108
Q

what is TFIID a complex of?

A

TATA binding protein (TBP) and 9 other general transcription factors called TAFs

109
Q

which X chromosome is the Xist non-coding RNA expressed from?

A

the one that will be inactivated

110
Q

does the human Y chromosome have a pseudoautosomal region?

A

yes

111
Q

what % of the mitochondrial genome makes functional gene products?

A

95%

112
Q

are cells with a mixture of normal and mutant mitochondria heteroplasmic?

A

yes

113
Q

what can elevated frequencies of monogenic disorders in a population be due to?

A

a founder effect

114
Q

what % of genetic material do dizygotic twins have in common on average?

A

50%

115
Q

which do genetic factors play a greater role in, schizophrenia or Parkinson disease?

A

schizophrenia

116
Q

what is inhibited by the Rb protein?

A

E2F1

117
Q

what is involved in the pathogenesis of Burkitt’s lymphoma?

A

c-Myc

118
Q

loss of function of what protein is responsible for some cases of hereditary colon cancer?

A

Msh2

119
Q

what is the technique used to detect a specific DNA sequence by hybridisation of complementary strands?

A

gel electrophoresis

120
Q

what is a chemical modification used by bacteria to protect their DNA from restriction enzymes?

A

methylation

121
Q

what is a common type of DNA lesion caused by UV light?

A

double strand DNA break

122
Q

what is the type of cell division that includes HR between parental chromosomes?

A

meiosis

123
Q

what enzyme recognises the damaged DNA in BER?

A

DNA glycosylase

124
Q

what is a distinguishing feature of a lariat?

A

a 2’-5’ phosphodiester bond

125
Q

what is the catalytic core of the spliceosome?

A

U2 and U6 snRNAs

126
Q

what defines the translation start site in prokaryotes?

A

Shine-Dalgarno sequence

127
Q

what is the standard approach for identifying genetic factors governing susceptibility to complex disease?

A

GWAS

128
Q

what is the phenomenon whereby disease phenotype is increasingly severe with each new generation of affected individuals?

A

anticipation

129
Q

what process causes genes to be expressed according to their parental origin?

A

uniparental disomy

130
Q

what is a trinucleotide repeat expansion disease (not Huntington’s)

A

spinocerebellar ataxia

131
Q

what common complex disorder is associated with more than 50 different loci on a single chromosome?

A

type 2 diabetes

132
Q

in what disease is the Philadelphia chromosome found inn 90% of individuals with the disease?

A

chronic myeloid leukaemia

133
Q

what does an IRES facilitate?

A

CAP-ndependent translation in eukaryotes

134
Q

what will make a cell less likely to undergo apoptosis?

A

increasing the concentration of Bcl-2

135
Q

which Bcl-2 family proteins have BH3 domains?

A

all of them

136
Q

what are all of the offspring produced by parthogenesis in a heterogametic female?

A

male

137
Q

mutation in which gene would contribute most significantly to cancer development, K-ras, p53, EGFR, Akt protein kinase, angiostatin?

A

EGFR

138
Q

protein involved in inherited pre-disposition to cancer?

A

c-Myc

139
Q

protein closely associated with pancreatic cancer?

A

K-Ras

140
Q

kinase that promotes cell survival?

A

c-Src

141
Q

distinguishing feature of an mRNA 5’ CAP in eukaryotes?

A

5’-5’ nucleotide bond

142
Q

what is the ubiquitin ligase?

A

a small ribosomal subunit

143
Q

what amino acid forms the bond between ubiquitin and a target protein?

A

internal lysine

144
Q

what sort of protein is DNA dependent RNA polymerase?

A

reverse transcriptase

145
Q

what is a mitochondrial disease with matrilineal inheritance?

A

Friedrich Ataxia

146
Q

what condition is XY individuals developing as phenotypic females?

A

complete androgen insensitivity syndrome

147
Q

what condition is commonly caused by the presence of the Philadelphia chromosome translocation?

A

chronic myeloid leukaemia

148
Q

what is an ultrasound test contributing to prenatal Down Syndrome diagnosis?

A

exome sequencing

149
Q

what is the initiator of dosage compensation in female mammals?

A

Xist non-coding RNA

150
Q

what organ can make but not use ketones?

A

liver

151
Q

where does gluconeogenesis take place?

A

liver and kidney

152
Q

difference in chemical formula of D-glucose and D-fructose?

A

they are the same

153
Q

most stable conformation of the four bases?

A

planar- not puckered rings

154
Q

what is histidine able to do in enzyme mechanisms?

A

act as an acid and a base

155
Q

effect of fructose-2,6-bisphosphate on phosphofructokinase-1?

A

activates it

156
Q

role of calcium activated PDH phosphatase?

A

stimulates PDH activity

157
Q

what vitamin is used by amino transferases?

A

vitamin B6

158
Q

what pathway is ornithine found in?

A

urea cycle

159
Q

what is the electron donor for FA synthesis?

A

NADP

160
Q

what is the acyl carrier group?

A

ACP

161
Q

where is the final orientation of a plasma protein established?

A

endoplasmic reticulum

162
Q

what is genomic amplification of N-Myc associated with?

A

childhood neuroblastoma

163
Q

result of the expression of Programmed Death-ligand 1 (PD-L1) by tumour cells?

A

suppression of T cell dependent immune surveillance

164
Q

what defines the start site of transcription in eukaryotic transcription?

A

the pre-initiation complex (PIC)

165
Q

how many steps of transesterification are required in intron splicing?

A

2

166
Q

what is the Rb protein (functional description)

A

a transcriptional co-repressor

167
Q

what process is most likely to become defective during aging-related female infertility in mammals?

A

chromosome cohesion

168
Q

what does Angelman Syndrome result from?

A

loss of a maternally expressed imprinted gene

169
Q

cause of cerebrocortical necrosis in ruminants/Wernickes encephalopathy in humans?

A

net deficiency of thiamine

170
Q

what is widely used as a perfusion imaging agent?

A

Gd-DOTA

171
Q

amino acids that are exclusively ketogenic?

A

lysine and leucine

172
Q

method used to find new protein interactions?

A

coimmunoprecipitation

173
Q

gel based method used to detect presence of specific protein in a cell extract?

A

Western blot

174
Q

enzyme with anaplerotic function in gluconeogenesis?

A

pyruvate carboxylase

175
Q

enzyme which catalyses the NADH-generating step in glycolysis?

A

glyceraldehyde 3-phosphate dehydrogenase

176
Q

enzyme which phosphorylates blood-supplied glucose in the brain?

A

hexokinase

177
Q

primary enzyme for catalysing conversion of triglyceride to diacylglyceride?

A

ATGL

178
Q

electron acceptor for acyl-CoA dehydrogenase?

A

FAD+

179
Q

what is acetoacetate?

A

a ketone

180
Q

main product of FA synthesis?

A

palmitate

181
Q

what facilitates movement of acetyl-CoA from mitochondria to cytoplasm?

A

tricarboxylic acid transporter

182
Q

what covalently regulates acetyl-CoA carboxylase?

A

AMPK

183
Q

what organelle receives fully folded protein imported from cytosol?

A

nucleus

184
Q

where are sugar residues first attached to secreted proteins?

A

endoplasmic reticulum lumen

185
Q

location of the Sec61 translocon complex?

A

endoplasmic reticulum membrane

186
Q

what mediate recovery from receptor activated intracellular signalling?

A

Ca2+ pumps and cyclic nucleotide phosphodiesterases

187
Q

what activates protein kinase C?

A

diacylglycerol

188
Q

what is a lesion recognised by nucleotide excision repair?

A

cyclo-pyrimidine dimer (CPD)

189
Q

what is an enzyme of base excision repair?

A

DNA glycosylase

190
Q

what is an initial step in the process of double strand break repair?

A

DNA-end resection

191
Q

what can arise from nondisjunction of the X and Y chromosomes in meiosis I?

A

Turner syndrome

192
Q

what can arise from mutation of the SRY gene?

A

Swyer syndrome

193
Q

what can arise from uniparental isodisomy of chromosome 7?

A

cystic fibrosis

194
Q

what is the term for the degree to which a phenotype manifests in an individual carrying a particular genotype?

A

expressivity

195
Q

what is the state occurring when cells derived from 2 different fertilised eggs co-occur in the same body?

A

chimerism

196
Q

what is the state whereby contribution of both alleles is visible in the heterozygous phenotype?

A

co-dominance