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Cell Bio > Unit 3 Vocab > Flashcards

Unit 3 Vocab Flashcards

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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
enhancers
the DNA sites to which eukaryotic gene activators bond
26
error rate of DNA replication
1 per every 100,000 nucleotides
27
euchromatin
chromatin that exist in a more de-condensed state which allows access for proteins involved in transcription
28
exons
segment of a eukaryotic gene that is transcribed into RNA and dictates the amino acid sequence of part of a protein
29
gene expression
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.
30
guanine
shares three hydrogen with cytosine; The base that pairs with Cytosine in DNA
31
gyrase
supercoils DNA
32
helicase
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
33
heterochromatin
the most highly condensed form of interphase chromatin; generally gene-poor and transcriptionally inactive (turned off)
34
histones
abundant proteins which DNA wraps to form nucleosomes; represents the most fundamental level of chromosome packing
35
histone tail modification
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
36
inducer
a molecule that regulates gene expression
37
inducible
(inducible operon) is one whose expression increases quantitatively in response to an enhancer, an inducer, or a positive regulator
38
initiation
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
initiator proteins
bind to specific DNA sequences called replication origins and locally open up the double helix, it attracts proteins that carry out DNA replication
40
initiator tRNA
special tRNA that initiates the translation of an mRNA in a ribosome. It always carries the amino acid methionine
41
introns
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
lac operon
encodes proteins required to import and digest the disaccharide lactose
43
lagging strand
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
leading strand
at a replication fork, the DNA strand that is made by continuous synthesis in the 5'-to3' direction
45
ligase
An enzyme that connects two fragments of DNA to make a single fragment
46
mediators
serves as a link the distantly bound transcription regulators to these proteins at the promoter
47
miRNA
regulate gene expression
48
moderator
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
mRNA
code for proteins
50
nucleoside triphosphates
a building block and energy source for replicating DNA
51
nucleosides
-a 5 carbon sugar (pentose) linked to a nitrogenous base through a 1' glycosidic bond
52
nucleotides
basic building block of the nucleic acids; DNA and RNA; a nucleoside linked to phosphate
53
Okazaki fragments
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
operator
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
origin
(replication origin) nucleotide sequence at which DNA replication is initiated
56
P site
the second binding site for the tRNA in the ribosome (p for peptidyl)
57
peptidyl-amino transferase
an enzyme that catalyzes the addition of an amino acid residue in order to grow the polypeptide chain in protein synthesis
58
polymerase
an enzyme that brings about the formation of a particular polymer, especially DNA or RNA
59
post-transcriptional RNA modifications
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
primase
an RNA polymerase that uses DNA as a template to produce an RNA fragment that serves as a primer for DNA synthesis
61
primer
RNA serves as this for DNA synthesis on lagging strand
62
promoter
DNA sequence that initiates gene transcription; includes sequences recognized by RNA polymerase and its accessory proteins
63
proofreading
the process by which DNA polymerase corrects its own errors as it moves along DNA
64
purine nucleotides
adenine & guanine
65
pyrimidine nucleotides
cytosine & thymine
66
regulator
used to switch genes on and off
67
repressible operon
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
repressor
protein that binds to the operator in an operon to switch off transcription
69
ribosomes
large macromolecular complex, composed of RNAs and proteins, that translates a mRNA into a polypeptide chain
70
RNA polymerase
enzyme that catalyzes the synthesis of an RNA molecule from a DNA template using ribonucleoside triphosphate precursors
71
RNA primer
only needed to start replication at the origin
72
RNA splicing
process in which intron sequences are excised from RNA molecules in the nucleus during the formation of a mature mRNA
73
rRNA
form the core of the ribosome's structure and catalyze protein synthesis
74
semiconservative
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
sigma-factor
primarily responsible for recognizing the promoter sequence on the DNA
76
sister chromatids
copy of a chromosome, produced by DNA replication, that remains bound to the other copy
77
small subunit
(of a ribosome) responsible for decoding the genetic information; matches the tRNAs to the codons of the mRNA
78
stabilizer
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
start codon
codon that signals to ribosomes to begin translation; codes for the first amino acid in a protein
80
stop codon
codon that signals to ribosomes to stop translation
81
TATA-box
key component of many promoters used by RNA polymerase II and is typically located 25 nucleotides upstream from the transcription start site
82
telomeres
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
template strand
an exact complementary strand to its partner strand; used to accurately copy DNA
84
termination
occurs when two replication forks meet on the same stretch of DNA
85
terminator
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
topoisomerase
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
tRNA
serves as adaptors between mRNA and amino acids during protein synthesis
88
trp-operon
tryptophan binds to the repressor protein and enables it to repress gene transcription
89
UAA
stop codon
90
UAG
stop codon
91
UGA
stop codon

Cell Bio (3 decks)

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