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IB Biology I: DNA Replication, Transcription, and Translation

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Morgan
showed that DNA is located on chromosomes
Griffith
studied bacteria (pathogenic versus nonpathogenic)
transformation
change in genotype and phenotype due to the assimilation of external DNA by a cell
Avery, McCarty, and MacLeod
showed the DNA is the transforming factor
bacteriophages/ phages
bacteria eaters
Hershey and Chase
grew bacteriophages on the radioisotopes of Phosphate and Sulfur
Meischer
discovered nucleic acids
Levene
DNA tetranucleotide hypothesis
Chargaff
% of DNA varies per organism
Wilkins and Franklin
made x-ray defraction of DNA
Watson and Crick
discovered that DNA is a double helix
A pairs with (on DNA)
T
G pairs with
C
A pairs with (on RNA)
U
semiconservative model
each of the two new double helices of DNA will have one new strand and one old strand of DNA
Meselson and Stahl
found that the semiconservative DNA model was correct
origins of replication
where the replication of DNA begins
replication fork
y-shaped region where the new strands of DNA are elongating
What are the bases of DNA?
Adenine, Thymine, Guanine, Cytosine
What are the bases of RNA?
Adenine, Uracil, Guanine, Cytosine
leading strand
the strand created by DNA polymerase III adding nucleotides to the complementary strand
DNA nucleotides are added from what end to what end?
5' prime to 3' prime
lagging strand
the direction that DNA is synthesized in
Okazaki Fragments
the segments of the lagging strand
DNA ligase
an enzyme that eventually joins the backbones of the Okazaki fragments
primer
the initial nucleotide chain
primase
starts RNA chain from scratch
helicase
enzyme that untwists the double helix at the replication fork, separating the two parental strands and making them available as template strands
topo-isomerase
helps the relive the strain ahead of the replication fork
single-strand binding protein
after the helicase separates the two parental DNA strands, this binds to the unpaired DNA strands, stabilizing themuntil they serve as templates
DNA polymerase I
removes the primer from the 5' end of the second fragment, replacing it with DNA nucleotides that it adds one by one to the 3' end of the third fragment
mismatch repair
cells use special enzymes to fix incorrectly paired nucleotides
nuclease
DNA cutting enzyme
nucleotide excision repair
when DNA is repaired through the usage of the enzymes DNA polymerase and ligase
telomeres
nucleotide sequences at the end of DNA molecules to prevent the genes from being damaged
telomerase
an enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells, thus restoring their original length
Which way is DNA read?
3' prime to 5' prime
Garrod
showed that genes act by influencing enzymes
Beadle and Ephrussi
examined fruit flies' eyes and saw that enzymes cause changes in eye color
Beadle and Tatum
looked at neospora (bread mold) and deduced the one gene- one enzyme hypothesis (now false)
What was the hypothesis that expanded the one gene- one enzyme hypothesis?
one gene- one polypeptide hypothesis
transcription
synthesis of RNA under the direction of DNA
Nirenberg
discovered poly- U (phenyalanine)
translation
synthesis of a polypeptide which occurs under mRNA in ribosomes
RNA processing
yields finished RNA
primary transcript
initial transcript
triplet code
genetic instructions for a polypeptide chain that are written on DNA in a series of 3 nucleotide words
template strand
provides template for ordering the sequence of nucleotides in RNA transcript
codons
mRNA's base triplets (read 5' to 3')
RNA polymerase
pries 2 DNA strands apart and hooks together the RNA nucleotides as they base pair along the DNA template
promoter
where RNA polymerase attaches/ initiates transcription
terminator
sequence that ends transcription
transcription unit
stretch of DNA that is transcribed into an RNA molecule
transcription factors
collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription
transcription initiation complex
assembly of transcription factors/ RNA polymerase II is bound to the promoter
TATA box
crucial promoter DNA sequence
5' cap
guanine after first 20-40 nucleotides
poly- A tail
at the 3' end consisting of 50-250 adenine nucleotides
RNA splicing
when a chunk of synthesized RNA is removed
introns
noncoding segments of nucleic acid that lie between coding regions
exons
other regions usually translated into amino acids
spliceosome
when several snRNPs join with other proteins to form an even larger assembly
ribozymes
RNA molecules that function as enzymes
alternative RNA splicing
a number of genes are known to give rise to 2 or more different polypeptides
domains
structural/ functional regions on proteins
anticodon
base pair of reflected codons on mRNA
aminoacyl- tRNA synthase
each amino acid is joined to a correct enzyme
wobble
relaxation of base pairing rules
P site
holds tRNA carrying the growing polypeptide chain
A site
holds tRNA carrying the next amino acid to be added to the chain
E site
tRNA leaves the ribosome here
polyribosomes/ polysomes
strings of ribosomes
post- translational modifications
additional steps after folding
signal peptide
targets proteins to the endoplasmic reticulum
signal recognition particle
emerges from the ribosome by this protein- RNA complex
messenger RNA (mRNA)
carries information specifying amino acid sequences of proteins from DNA to the ribosomes
transfer RNA (tRNA)
adapter molecule in protein synthesis/ translates mRNA codons to amino acids
ribosomal RNA (rRNA)
plays catalytic (ribozyme) roles and structured roles in spliceosomes
signal recognition particle RNA (SRP RNA)
component of signal recognition particle, the protein- RNA complex that recognizes the signal peptides of polypeptides to the endoplasmic reticulum
small nuclear RNA (snoRNA)
aids in processing of pre-RNA transcripts for ribosome subunit formation in the nucleolous
siRNA/ miRNA
regulation of gene expression
mutations
changes in the genetic information of a cell
point mutations
chemical mutations in the one base pair of a gene
base pair substitution
replacement of one nucleotide and its partner with another pair of nucleotides
missense mutation
substitution mutation
nonsense mutation
codon changes into a STOP codon
frameshift mutation
alters the reading frame of the genetic code
mutagens
physical/ chemical agents that interact with DNA in ways that cause mutations
Muller
showed that x-rays cause genetic changes in fruit flies
gene
region of DNA whose final product is either a polypeptide or an RNA molecule
What is the start codon?
AUG/ methionine
What is an example of a stop codon for RNA?
UAA, UAG, UGA