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Molecular biology (Updated 2016) > Glossary P-R > Flashcards

Glossary P-R Flashcards

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1
Q

paralogs

A

Multiple copies of the same gene within the genome of individual species.

The multiple different copies of arose through gene duplication events and mutations subsequent to speculation, often leading to alternate activities or even different roles within the cell or organism as a result.

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2
Q

paratope

A

That region within the antigen-binding site of immunoglobulin module responsible for recognition epitope of structure

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3
Q

PCR

polymerase chain reaction

A

An efficient, simple, and rapid technique involving sequential logarithmic amplification of a segment of DNA in a test tube

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4
Q

Penetrance

A

Refers to the proportion of individuals heterozygous for a given dominant allele, or homozygous for a given process of allele, that expresses the affected phenotype

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5
Q

peptide-binding groove

A

that region of a Class I or II MHC molecule that is responsible for binding processed antigen peptides for presentation

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6
Q

peptidyl transferase

A

An enzymatic activity of the ribosome responsible for formation of the peptide bond between the nascent polypeptide chain and the amino acid carried by the charged tRNA in the A site of the ribosome. In so doing, the ribosome is moved along the mRNA by one codon.

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7
Q

peptidyl-tRNA

A

the form of a tRNA molecular that is actively involved in polypeptide elongation, and has the nascent polypeptide chain attached

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8
Q

phage

A

A virus that infects a bacteria host, used in the laboratory as a cloning vector

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9
Q

phase variation

A

Alternation in the type of the flagellum produced by bacterium

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10
Q

Phenotype

A

The physical characteristics of a cellular organism that results from its unique genotype

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11
Q

phosphodiester bond

A

The two sequential mixed ester bonds formed between two ribose (RNA) or two 2-deoxyribose (DNA) molecules and the phosphate group between them, in the “backbone” of a nucleic acid

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12
Q

physical map

A

Analysis of the distance, between base pairs, between loci

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13
Q

planar molecule

A

A molecule that has an overall “flat” structure, such as benzene or its derivatives

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14
Q

plasmid

A

A class of circular extrachromosomal elements found in many bacteria. Contain origins of replication to ensure their maintenance.

Often modified for use in gene cloning or to alter the characteristics of the bacteria

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15
Q

Point mutation

A

a mutation in a single base pair within a DNA molecule

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16
Q

polarity

A

in this context, this term refers to the orientation of the sugar-phosphate backbone of a nucleic acid molecule. The 5’ end is terminated by a phosphate group, whereas the 3’ end is terminated with a hydroxyl group

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17
Q

polyacrylamide

A

a sieving matrix made by chemically cross-linking acrylamide, usually with bis-acrylamide, and free radical generators

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18
Q

Polyadenylation

A

The first to the addition of numerous non-templated “A” bases to the 3’ end of a nascent hnRNA transcript

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19
Q

Polycistronic

A

refers to a form of gene organization resulting in transcription of an mRNA that contains the coding sequences for multiple gene products, each of which is independently translated from the mRNA

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20
Q

polygenic disease

A

a disease that may be caused by mutations in any of several genes, but does not require mutation of more than one gene

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21
Q

polypeptide

A

The unique string of amino acids created by the translation of mRNA sequences.

This may require additional polypeptides subunits and/or functional groups in order to form a complete holoprotein

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22
Q

polyprotein

A

The giant polypeptide that contains multiple individual proteins sequences embedded within it and which is proteotypically cleaved to yield the individual proteins

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23
Q

polytene chromosome

A

Multiple, precisely aligned, identical copies of interphase chromosomes. Appear with light and dense alternating bands, characteristic of the chromosome and organism, based on localized states of condensation

24
Q

primase

A

an DNA-dependent RNA polymerase function that synthesizes a short RNA primer used during DNA replication by DNA polymerase.

does not require a primer, only a template

25
Q

prion

A

an infectious agents thought to be composed solely of protein

The prion protein is a normal protein, PrPc, that is expressed within neural tissues. In the abnormal prion state, the PrPc protein has undergone covalent modification and confirmational changes that render resistant to cellular degradation and autocatalytic, resulting in PrPsc (for scrapie form). PrPsc is thought to induce the re-folding of PrPc to make more of itself.

26
Q

Processivity

A

refers to the degree and pace at which continuous synthesis of a nascent nucleic acid occurs

27
Q

Promoter (site)

A

Region of a DNA molecule 5’ to a coding sequence that is responsible for assembly of an RNA polymerase complex and the initiation of transcription

28
Q

proof-reading

A

Mechanism for correction of errors made during synthesis of nucleic acids or polypeptides by scrutiny of the products after the nucleotides or amino acids have already been incorporated

29
Q

proteasome

A

A specialized organelle within the cytoplasm of the cell that is responsible for degradation of cytoplasmically situated proteins. The proteasome plays a key role in normal protein turnover and in peptide presentation by MHC Class I anigen

30
Q

protein

A

refers to the complete, assembled form of a holoprotein, containing all necessary apoprotein subunits. For example, hemoglobin is comprised of two α and two β subunits, each of which contains a heme prosthetic group

31
Q

proto-oncogene

A

Normal gene that may become an oncogene; also called cellular ocogene

32
Q

purine

A

An orgnanic molecule the structure of which forms the basis in the nucleic acid bases adenine and guanine

33
Q

pyrimidine

A

An orgnanic molecule the structure of which forms the basis in the nucleic acid bases cytosine, thymine, and uracil.

34
Q

pyrimidine dimers

A

Covalent adducts formed between two pyrimidine basis, usually adjacent to one another in the same strand. Often involves formation of a cyclobutane ring structure.

35
Q

Reading frame

A

The register in which a nucleic acid sequence is read, in 3-base increments, for translation into polypeptide.

May be either a real or virtual translation.

36
Q

recessive

A

allele that determines phenotype only when homozygous; does not affect phenotype when heterozygous with a dominant allele

37
Q

recombinant

A

Slang referring to an organism that carries a recombinant DNA molecule, often with some alteration in its phenotype

38
Q

recombinant DNA

A

The combination of a foreign DNA insert with a vector DNA (e.g. plasmid, phage, cosmid, etc.) to produce a clone within a host organism

39
Q

recombinase

A

enzymatic activity responsible for facilitating intra- or intermolecular recombination of DNA molecules

40
Q

recombination

A

the rearrangement of DNA by breaking and re-ligations of the DNA strands

also called crossovers

41
Q

replication

A

the act of a cell making a copy of all or some part of its genomic DNA

42
Q

replicon

A

a segment of genomic DNA that contains an origin of replication and is replicated under the control of that origin

43
Q

Repression

A

A form of gene regulation wherein the promoter is prevented from assembling and RNA polymerase, so that transcription does not occur

derepression refers to a loss of repression

44
Q

restriction mapping

A

The creation of a physical map by ordering and enzymatilcally cut DNA fragments

45
Q

restriction endonucleases

A

an enzyme, isolated from bacteria, that recognizes specific base-pair sequences within DNA and causes endonucleolytic cleavage of the DNA at a site determined by the recognized DNA sequences.

The sites vary from frequent to rare cutting, depending upon the length of the restriction site

46
Q

Restriction fragment length polymorphism (RFLP)

A

Variation in the distance between restriction enzyme cleavage sites that exist within a population producing unique DNA fingerprint patterns

47
Q

Reverse transcriptase

A

An enzyme that catalyzes the RNA dependent polymerization DNA.

This enzymatic activity is found in retroviruses.

48
Q

RFLP

A

Restriction fragment length polymorphism

Variation in the distance between restriction enzyme cleavage sites that exist within a population producing unique DNA fingerprint patterns

49
Q

ribosome

A

The large, multi-subunit ribonucleoprotein complex responsible for the translation of mRNA into polypeptide sequences

50
Q

ribosome binding site

ribosome entry site

A

Sequences contained in an mRNA that organize the assembly of a ribosome to initiate translation of the mRNA into polypeptide

51
Q

RNA

ribonucleic acid

A

single-strand nucleic acid found mainly int he nucleolus and ribosomes.

Contains ribose and uracil

52
Q

RNAi

RNA interference

A

refers to the mechanism controlling transcript abundance through the induced degradation of transcripts by small (20-25 nt), complementary RNA fragments.

53
Q

RNA polymerase

A

Enzymatic activity responsible for DNA dependent synthesis of RNA.

prokaryotes = 1 type of RNA Pol.
eukaryotes - 3 types of RNA Pol. each transcribes a different group of genes

54
Q

rRNA

ribosomal RNA

A

RNAs which make up the scaffold upon which the ribosomal proteins are assembled to create the ribosomal subunits

55
Q

RT-PCR

A

reverse-transcriptase-polymerase-chain-reaction

starts with RNA. Since RNA cannot be amplified by PCR it must first be reverse transcribed into cDNA in order to have an amplifiable target molecule.

May also be called real-time PCR and refers to time and cycle dependent PCR. (pay attention to context)

Molecular biology (Updated 2016) (15 decks)

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