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Cell Bio > Unit 3 Vocab > Flashcards

Unit 3 Vocab Flashcards

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Biology 101 flashcards
1
Q

3’ end

A

terminates at the hydroxyl group of the third carbon in the sugar-ring

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2
Q

3’ poly-A tail

A

polydenylation provides a newly transcribed mRNA by trimming the mRNA and adding adenine

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3
Q

5’ end

A

the replication fork is asymmetrical

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4
Q

5’ G-cap

A

RNA capping modifies the RNA by attaching guanine

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5
Q

A site

A

(A for aminoacyl) the binding site of a ribosome for charged t-RNA molecules during protein synthesis

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6
Q

activator

A

A protein that binds to a specific regulatory region of DNA to permit transcription of an adjacent gene.

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7
Q

adenine

A

shares two hydrogen with thymine

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8
Q

aminoacyl-tRNA synthetase

A

an enzyme that joins each amino acid to the appropriate tRNA

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9
Q

anticodon

A

set of three consecutive nucleotides in a tRNA molecule that recognizes, through base-pairing, the three-nucleotide codon on a mRNA molecule

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10
Q

AUG

A

start codon

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11
Q

base pairs

A

two complementary nucleotides in an RNA or a DNA molecule that are held together by hydrogen bonds, normally G with C, and A with T or U

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12
Q

centromere

A

specialized DNA sequence that allows duplicated chromosomes to be separated during M phase; can be seen as the constricted region of a mitotic chromosome

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13
Q

charged tRNA

A

is capable of binding tightly to the P site in the absence of the large ribosomal unit

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14
Q

chromatin

A

complex of DNA and protein (condensed) that makes up the chromosomes in a eukaryotic cell

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15
Q

chromosomes

A

long, threadlike structure composed of DNA and proteins that carries the genetic information of an organism; becomes visible as a distinct entity when a plant or animal cell prepares to divide

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16
Q

codon

A

group of three consecutive nucleotides that specifies a particular amino acid or that starts or stops protein synthesis; applies to the nucleotides in an mRNA or in a coding sequence of DNA

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17
Q

continuous DNA replication

A

DNA polymerase can only add to the 3’ end, so the 5’ end of the primer remains unaltered. synthesis proceeds immediately only along the so-called leading strand. the immediate replication is known as continuous replication

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18
Q

cytosine

A

a compound found in living tissue as a constituent base of nucleic acids. It is paired with guanine in double-stranded DNA.

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19
Q

discontinuous DNA replication

A

replication along the lagging strand ( in the 5’ direction from the primer)

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20
Q

DNA (deoxyribonucleic acid)

A

a complex molecule containing the genetic information that makes up the chromosomes.

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21
Q

DNA polymerase

A

enzyme that catalyzes the synthesis of a DNA molecule from a DNA template using deoxyribonucleoside triphosphate precursors

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22
Q

DNA replication

A

the process by which a copy of DNA molecule is made

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23
Q

E site

A

the third and final binding site for t-RNA in the ribosome during translation (e stands for exit)

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24
Q

elongation

A

(translation elongation) the ribosome ratchets along its mRNA template, incorporating each new amino acid and translocating from one codon to the next

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25
Q

enhancers

A

the DNA sites to which eukaryotic gene activators bond

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26
Q

error rate of DNA replication

A

1 per every 100,000 nucleotides

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27
Q

euchromatin

A

chromatin that exist in a more de-condensed state which allows access for proteins involved in transcription

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28
Q

exons

A

segment of a eukaryotic gene that is transcribed into RNA and dictates the amino acid sequence of part of a protein

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29
Q

gene expression

A

the process by which the nucleotide sequence of a gene is transcribed into the nucleotide sequence of an RNA molecule, which is then translated into the amino acid sequence of a protein.

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30
Q

guanine

A

shares three hydrogen with cytosine; The base that pairs with Cytosine in DNA

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31
Q

gyrase

A

supercoils DNA

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32
Q

helicase

A

an enzyme that untwists the double helix of DNA at the replication forks, separating the two parental strands and making them available as template strands

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33
Q

heterochromatin

A

the most highly condensed form of interphase chromatin; generally gene-poor and transcriptionally inactive (turned off)

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34
Q

histones

A

abundant proteins which DNA wraps to form nucleosomes; represents the most fundamental level of chromosome packing

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35
Q

histone tail modification

A

some chromatin become so highly condensed that its genes cannot be expressed to produce RNA; such condensation occurs on all chromosomes during mitosis and in the heterochromatin of interphase chromatin

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36
Q

inducer

A

a molecule that regulates gene expression

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37
Q

inducible

A

(inducible operon) is one whose expression increases quantitatively in response to an enhancer, an inducer, or a positive regulator

38
Q

initiation

A

the beginning of transcription; occurs when the enzyme RNA polymerase binds to a region of a gene called the promoter, which signals the DNA to unwind so the enzyme can “read” the bases in one of the DNA strands

39
Q

initiator proteins

A

bind to specific DNA sequences called replication origins and locally open up the double helix, it attracts proteins that carry out DNA replication

40
Q

initiator tRNA

A

special tRNA that initiates the translation of an mRNA in a ribosome. It always carries the amino acid methionine

41
Q

introns

A

noncoding sequence within a eukaryotic gene that is transcribed into an RNA molecule but is then excised by RNA splicing to produce an mRNA

42
Q

lac operon

A

encodes proteins required to import and digest the disaccharide lactose

43
Q

lagging strand

A

at a replication fork, the DNA strand that is made discontinuously in short fragments that are later joined together to form one continuous new strand

44
Q

leading strand

A

at a replication fork, the DNA strand that is made by continuous synthesis in the 5’-to3’ direction

45
Q

ligase

A

An enzyme that connects two fragments of DNA to make a single fragment

46
Q

mediators

A

serves as a link the distantly bound transcription regulators to these proteins at the promoter

47
Q

miRNA

A

regulate gene expression

48
Q

moderator

A

used to moderate or slow down fast fission neutrons from relatively high (kinetic) energies to thermal (ambient temperature) energy levels in a thermal reactor

49
Q

mRNA

A

code for proteins

50
Q

nucleoside triphosphates

A

a building block and energy source for replicating DNA

51
Q

nucleosides

A

-a 5 carbon sugar (pentose) linked to a nitrogenous base through a 1’ glycosidic bond

52
Q

nucleotides

A

basic building block of the nucleic acids; DNA and RNA; a nucleoside linked to phosphate

53
Q

Okazaki fragments

A

short length of DNA, including an RNA primer, produced on the lagging stand during DNA replication. following primer removal, adjacent fragments are rapidly joined together by DNA ligase to form a continuous DNA strand

54
Q

operator

A

a special DNA sequence located between the promoter sequence and the structural genes that enables repression of the entire lac operon, following binding by the inhibitor (lac i) protein

55
Q

origin

A

(replication origin) nucleotide sequence at which DNA replication is initiated

56
Q

P site

A

the second binding site for the tRNA in the ribosome (p for peptidyl)

57
Q

peptidyl-amino transferase

A

an enzyme that catalyzes the addition of an amino acid residue in order to grow the polypeptide chain in protein synthesis

58
Q

polymerase

A

an enzyme that brings about the formation of a particular polymer, especially DNA or RNA

59
Q

post-transcriptional RNA modifications

A

include covalent modification, the binding of small molecule cofactors, or association with other protein subunits, which are often needed for a newly synthesized protein to become fully functional

60
Q

primase

A

an RNA polymerase that uses DNA as a template to produce an RNA fragment that serves as a primer for DNA synthesis

61
Q

primer

A

RNA serves as this for DNA synthesis on lagging strand

62
Q

promoter

A

DNA sequence that initiates gene transcription; includes sequences recognized by RNA polymerase and its accessory proteins

63
Q

proofreading

A

the process by which DNA polymerase corrects its own errors as it moves along DNA

64
Q

purine nucleotides

A

adenine & guanine

65
Q

pyrimidine nucleotides

A

cytosine & thymine

66
Q

regulator

A

used to switch genes on and off

67
Q

repressible operon

A

type of operon in which the transcription of the gene is repressed by the presence of a particular substance; regulated by a co-repressor i.e. mainly the end product of the metabolic pathway

68
Q

repressor

A

protein that binds to the operator in an operon to switch off transcription

69
Q

ribosomes

A

large macromolecular complex, composed of RNAs and proteins, that translates a mRNA into a polypeptide chain

70
Q

RNA polymerase

A

enzyme that catalyzes the synthesis of an RNA molecule from a DNA template using ribonucleoside triphosphate precursors

71
Q

RNA primer

A

only needed to start replication at the origin

72
Q

RNA splicing

A

process in which intron sequences are excised from RNA molecules in the nucleus during the formation of a mature mRNA

73
Q

rRNA

A

form the core of the ribosome’s structure and catalyze protein synthesis

74
Q

semiconservative

A

the two original DNA strands separate during replication; each strand then serves as a template for a new DNA strand; each newly synthesized double helix is a combination of one original and one new DNA strand

75
Q

sigma-factor

A

primarily responsible for recognizing the promoter sequence on the DNA

76
Q

sister chromatids

A

copy of a chromosome, produced by DNA replication, that remains bound to the other copy

77
Q

small subunit

A

(of a ribosome) responsible for decoding the genetic information; matches the tRNAs to the codons of the mRNA

78
Q

stabilizer

A

a single-stranded DNA-binding protein: binds to the DNA as a tetramer and stabilizes the single-stranded structure that is generated by the action of the helicases

79
Q

start codon

A

codon that signals to ribosomes to begin translation; codes for the first amino acid in a protein

80
Q

stop codon

A

codon that signals to ribosomes to stop translation

81
Q

TATA-box

A

key component of many promoters used by RNA polymerase II and is typically located 25 nucleotides upstream from the transcription start site

82
Q

telomeres

A

repetitive nucleotide sequence that caps the ends of linear chromosomes; counteracts the tendency of the chromosome otherwise to shorten with each round of replication

83
Q

template strand

A

an exact complementary strand to its partner strand; used to accurately copy DNA

84
Q

termination

A

occurs when two replication forks meet on the same stretch of DNA

85
Q

terminator

A

where the polymerase halts and releases both the DNA template and the newly made RNA transcript; transcribed into the 3’ end of new RNA

86
Q

topoisomerase

A

an enzyme that cuts one or both strands of DNA to relieve the excess tension caused by the unwinding of the helix by helicase during replication

87
Q

tRNA

A

serves as adaptors between mRNA and amino acids during protein synthesis

88
Q

trp-operon

A

tryptophan binds to the repressor protein and enables it to repress gene transcription

89
Q

UAA

A

stop codon

90
Q

UAG

A

stop codon

91
Q

UGA

A

stop codon

Cell Bio (3 decks)

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