Glossary S-Z

Question 1

screening

Answer 1

Term given to act of assaying recombinants for a particular sequence of traits.

Can take many forms, depending upon the methodologies available.

Question 2

semiconservative replication

Answer 2

term refering to the retention of one parental strand along with one nascent strand during DNA replication

Question 3

Sequence homology

Answer 3

Similarities in nucleic acid sequence and organization, and in their encoded products, that are sufficiently great as to imply common ancestral origins

Question 4

Sequence similarity

Answer 4

Similarity in nucleic acid or polypeptide sequences, particularly in shorter segments, that may not be sufficient to imply common ancestral origins

Question 5

sex-linked

Answer 5

a trait transmitted by one of the chromosomes determining sex of an individual

Question 6

short arm (p)

Answer 6

One of the two prominent segments of a chromosome

the long or “q” arm is the other

the arms of a given chromosome join at its centromere

Question 7

Shuttle vector

Answer 7

A type of cloning vector that contains sequences enabling it to be propagated and maintained in more than one type of host (e.r. E. coli and mammalian cells)

Question 8

single recognition particle (SRP)

Answer 8

a chaperonin complex responsible for arresting polypeptides synthesis and facilitating the docking of a ribosome to the endoplasmic reticulum membrane.

normally, on ribosomes translating polypeptides destined for insertion into or across the endoplasmic reticulum membrane become associated with SRP

Question 9

siRNA

Answer 9

refers to “small interfering RNAs” that are formed from the nucleolytic processing of larger double stranded RNA regions into 21 nt molecules, one of which associates with the RISC complex and provides specificity to the cleavage of other related RNAs

Question 10

snRNA

Answer 10

refers to the small nuclear RNAs that are or become part of spiceosomal complexes.

Question 11

somatic

Answer 11

refers to non-germline cells

Somatic cells may become terminally differentiated with alterations in their overall genetic complement, because they are NOT responsible for passing along the organism’s genetic material to the offspring

Question 12

Somatic hypermutation

Answer 12

A very high frequency of the mutational events that occur in specific loci, such as the variable segments of expressed immunoglobulin genes

in immunoglobulin genes this occurs after all rearrangements how occurred and provide additional potential for a variation in immunoglobulin structure

Question 13

Southern blot

Answer 13

The transfer of size-separated DNA fragments to a synthetic membrane for further studies

initially described by E.N. Southern

Question 14

Splice sequence

Answer 14

a sequence within an mRNA molecule that is the site at which splicing occurs

Question 15

Spliceosome

Answer 15

A ribonucleoprotein structure responsible for splicing of primary transcripts

Question 16

Sporadic

Answer 16

Not familial

Question 17

Start codon

Answer 17

The codon at which translation of an mRNA molecule begins

in eukaryotes and most prokaryotes this is always AUG (encoding methionine)

in prokaryotes N-formyl-methionine is used to initiate polypeptide synthesis

Question 18

stop codon

Answer 18

The codon at which translation of an mRNA molecule into a polypeptide is terminated

in the Universal Code this may be: UGA, UAG, or UAA

Question 19

Stringency

Answer 19

A measure of the rigorousness of an attempt to separate two components

Often applied to nucleic acid hybridization conditions to indicate the likely degree of sequence homology between probe and target sequences

Question 20

synteny

Answer 20

The conservation of gene groupings and organization on the chromosomes of different species of organisms

Question 21

Telomerase

Answer 21

a ribonucleoprotein complex that maintains the repeat structures at the telomeric ends of chromosomes

Question 22

telomere

Answer 22

The natural distal end of a chromosome

Contains some form of simple repeating sequence, usually with a Single stranded distal end that may form a hairpin

Question 23

Template

Answer 23

an original form from which a copy is made using information present in the original

Question 24

Termination sequence

Answer 24

The point in a DNA sequence at which transcription of a gene into RNA ceases

Question 25

TFIID | transcription factor IID

Answer 25

Also know as "TATA factor" Necessary for the assembly of RNA polymerase for transcription of essentially all eukaryotic mRNAs

Question 26

thymine

Answer 26

one of the pyrimidine bases found in DNA 2,4-dihydroxy-5-methylpyrimidine

Question 27

topoisomerase

Answer 27

An enzymatic activity responsible for relieving excessive supercoiling in DNA

Question 28

Trans-

Answer 28

located on two physically dis-contiguous DNA molecules

Question 29

transcribe

Answer 29

to copy DNA into RNA

Question 30

transcription

Answer 30

the process wherein DNA is copies into RNA (often mRNA)

Question 31

Transcription factor

Answer 31

A protein whose function is to control the act of transcription

Question 32

Transcription start site

Answer 32

The point in a DNA sequence at which transcription of the gene into RNA begins

Question 33

Transcriptional control

Answer 33

gene control exerted at the level of transcription

Question 34

Transduction

Answer 34

The Incorporation of a cellular gene into a viral genome, that can then be introduced into other cells

Question 35

Transfection

Answer 35

The process of placing foreign DNA into mammalian cells also sometimes used to refer to insertion of foreign DNA into bacteria using bacteriophage

Question 36

Transformation

Answer 36

The cancerous alteration of mammalian cells also the act of putting foreign DNA into bacteria

Question 37

Transformed phenotype

Answer 37

Acquisition of the phenotype characteristic of oncogenetic transformation

Question 38

transgenic

Answer 38

an individual in which genetic modification has occurred in the germline tissues may be transmitted to subsequent generations

Question 39

Transition mutation

Answer 39

A point mutation involving the substitution of a purine for a purine, or a pyrimidine for a pyrimidine

Question 40

translation

Answer 40

The process of converting the nucleic acid language of the genetic code into the amino acid language of polypeptides, catalyzed by the ribosome and a host of soluble factors mRNA codons are recognized by tRNA anti-codons. Each tRNA translates a single codon into a single amino acid, resulting in synthesis of polypeptide wherein the amino acid sequence is dictated by and matches the order of the codons in the mRNA

Question 41

Translational control

Answer 41

Gene control exerted at the level of mRNA translation

Question 42

Translational frame shifting

Answer 42

A mechanism used by certain viruses and even higher organisms to change the reading frame used during translation of an mRNA molecule, in a controlled manner, so that the polypeptide product is the result of translation in more than one reading frame

Question 43

Transposable elements

Answer 43

Genetic elements characterized by their abilities to insert into withdraw from a given location within the genome, resulting in movement from site to site within the genome over a period of time may cause epigentic changes in phenotype

Question 44

transversion mutation

Answer 44

A point mutation involving the substitution of a purine for a pyrimidine, or vice versa

Question 45

trinucleotide repeat

Answer 45

a highly reiterative sequence comprised entirely of a single trinucleotide sequence Changes in the length of the repeat regions of many genes are associated with a number of genetic diseases

Question 46

tRNA | transfer RNA

Answer 46

special RNAs that are charge with amino acids and which carry anticodons for recognition of the codons in mRNA Responsible for translation from the language of nucleic acids into the language of polypeptides each tRNA can be charged with only one type of amino acid, although multiple tRNAs exist for many of the amino acids

Question 47

Tumor suppressor

Answer 47

A gene that prevents to tumor formation until deleted or mutated

Question 48

turnover

Answer 48

The balance between synthesis and degradation of the product The particular balance will affect the levels of accumulation of the product

Question 49

umber mutation

Answer 49

one wherein a codon has been modified, resulting in the formation of a UGA stop codon

Question 50

unifactorial

Answer 50

caused by mutations in a single, specific gene

Question 51

universal genetic code

Answer 51

the "standard" codon usage that is common to most organisms

Question 52

untranslated region

Answer 52

mRNA sequences that lie 5' and 3' to the sequences that are translated into polypeptide

Question 53

uracil

Answer 53

one of the pyrimidine bases found in RNA | 2,4-dihydroxypyrimidine

Question 54

vector

Answer 54

a construct use to propagate DNA in a host (bacteria, yeast, or cultured cells)

Question 55

virion

Answer 55

a replication-competent virus particle

Question 56

Western analysis

Answer 56

Reaction of specific immunoglobulin(s) with proteinaceous antigens separated by electrophoretic mean and transferred to membranous support used to identify those which carry epitopes recognized by the immunoglobulin(s) usually the proteins are first separated by size, so that information is gained about the approximate mass of recognized polypeptide(s)

Question 57

Yeast artificial chromosome (YAC)

Answer 57

a vector used in yeast that contains centromeric and telomeric sequences, and origins of replication so that is may be maintained and propagated Used as cloning vectors which can propagate very large fragments of foreign DNA