Week One Biochem Review

Flashcard maker : Sam Arent
Our genetic code is made up of DNA and are expressed in the phenotype as a __________.
What are the four characteristics of our DNA?
Universal, unambiguous, redundant, non-overlapping & commaless
The genetic code consists of bases, these bases comprise _________.
The four bases are:
A (adenine), T (thymine), C (cytosine), and G (guanine)
Since there are four bases, there are ____ possible codons
DNA molecule is a double-helix- __________ _________.
Rosalind Franklin
Meselson and Stahl experiment showed replication of DNA to be ________________.
___________ unwinds the strand.
_____________ ___________ sets up for the RNA primer
RNA primase
_______ ___________ _________adds nucleotides to the 3’ end of the RNA primer and elongates the DNA strand
DNA polymerase III
_________ __________ ___ removes the old RNA primer and replaces it with DNA
DNA polymerase I
________ _________ catalyzes the formation of the phosphodiester bond linking the Okazaki fragments
DNA ligase
___________ __________ action causes the newly forming leading strandto grow in the 5’-to-3’ direction
DNA polymerase
________ uses DNA polymerases to repeatedly replicate DNA in the test tube.
PCR (polymerase chain reaction)
RNA differs from DNA in 3 ways:
1)it is single-stranded
2) its sugar molecule is ribose rather than deoxyribose
3) its fourth base is uracil rather than thymine
Messenger RNA =
mRNA is the message or direction on how to make a protein
Transfer RNA =
tRNA it matches up amino acids with the RNA message
Ribosomal RNA=
rRNA used to bind the mRNA message
recognition sequence: one or two recognition sequences of 50 – 70bp form what?
the TATA box
TATA box (rich in thymine & adinine): ___ base pairs upstream from the_____ ______ for transcription
25; initiation site
_________ __________ _________ ___ needs transcription factors to initiate transcription
Eukaryotic RNA polymerase II
The protein ______ binds to the TATA box
Finally _____ ______________ ____ binds to the site
RNA polymerase II
_____ is transcribed from the DNA template after the ________ __ ____ are exposed by unwinding of the double helix.
RNA;bases of DNA
RNA polymerase reads the DNA template strand from __ to __ and produces the RNA transcript from __ to __.
3’ to 5’ ; 5′ to 3′
Nucleotides are added at the __ end of the growing RNA
One mRNA codon _____ indicates the starting point of translation, also codes for _____________.
AUG; methionine
Three stop codons indicate the end of _________.
translation – UAA, UAG and UGA
The other 60 codons code only for __________ ________ _________.
particular amino acids.
_____ binds the correct amino acid; has an _______ complementary to the mRNA codon.
tRNA ; anticodon
The _____________, a family of activating enzymes, attach specific amino acids to their appropriate tRNA’s, forming ________ tRNA’s.
aminoacyl-tRNA synthetases; charged
The ribosome is composed of two units:
large subunit that consists of _____ different molecules of rRNA and ___ different ________ ________ .
small subunit of one ___ ________ and ___ different protein molecules
3; 45; protein molecules;rRNA molecule; 33
An initiation complex consisting of an _______ _________ __________ _________ and a small ribosomal subunit bound to mRNA triggers the beginning of ____________.
amino acid-charged tRNA; translation
On the large subunit of the ribosome there are ___ sites to which tRNA binds.
T (transfer) site: where ___________.
tRNA first lands
A (amino acid) site is where the tRNA anticodon binds to ___________.
binds to mRNA codon
P (polypeptide) site is where the tRNA __________.
adds its amino acid to the growing poly peptide chain
E (exit) site is where tRNA, without its ______ _______, resides before leaving the________ and going back to the cytosol to pick up another ________ _________.
amino acid; ribosome; amino acid
Polypeptides grow from the __ terminus toward the __ terminus. The ribosome moves along the mRNA ___ codon at a time.
N to C; one
The presence of a _____ ______ in the __ site of the ribosome causes translation to terminate
stop codon; A
Signals contained in the amino acid sequences of proteins direct them to___________ ____________.
cellular destinations.
Modifications of proteins after translation include:
proteolysis, glycosylation, and phosphorylation.
Cells must regulate how they synthesize molecules to suit their:
condition, environment, and needs
cells can control synthesis activity by
___________ or controlling the production
of _________.
regulating; enzymes
cells can control synthesis activity by blocking __________ of the gene that codes for a protein.
cells can control synthesis activity by _______ the ______ after it is made.
hydrolyze; mRNA
cells can control synthesis activity by ________ __________ of mRNA at the ribosome.
preventing translation
cells can control synthesis activity by __________ the protein after it was made
Point mutations result from alterations in______ ________ ________ of DNA.
single base pairs
What are some examples of point mutation?
silent, missense, nonsense, or frame-shift
Chromosomal mutations involve _______ regions of a chromosome.
What are some examples of chromosomal mutations>
deletions, duplications, inversions, or translocations
Point mutations result from the _______ or _______ of one base for another in the DNA and as a result in the RNA
addition or subtraction;
Some result in no change in amino acid because of the redundancy of the genetic code=
silent or synonymous mutation
A ____________ mutation results in an amino acid change
____________ mutation results in no protein being made at all, they are disruptive.
____________ mutation results in no protein being made at all, they are disruptive.
A _________-__________ mutation, is when single base pairs may be inserted or deleted from DNA
___________ remove part of the genetic material
___________ mutations are homologous chromosomes brake at different positions and then reconnect to the wrong partners
_________ mutations are removal of a segment and its reinsertion into the same location but flipped.
___________ mutation is when a segment of DNA breaks off and is inserted into a different chromosome
Spontaneous mutations occur because of instabilities in ______ or _____________.
DNA or chromosomes
Induced mutations occur when an ________ __________ damages ____.
outside agent; DNA
Some of these non-transcribed regions are ________, such as the telomeres; some regulate ______ ________; and some have no known use.
structural; gene expression
____________ are 5-50bps are repeated side by side up to a million times.
________ are 12-100 bps long & are repeated several thousand times. Can be used as ______ _______ for identifying an individual because their numbers can vary
Minisatellites; genetic markers
__________ are 1-5bps present in small clusters 10-50 copies. These have been used in sequencing the human genome
___________ are repetitive sequences at the ends of chromosomes
Chromosome _________ occurs after each round of replication. This leads to ____ __________.
shortening; cell death
The enzyme_____________ prevents the loss of telomeric ends
A ___ _______ is added to the 5’ end.
G cap, GTP
A _______ __ _______ is added to the 3’ end
poly A tail
_______ _____________ particle binds at the 5’ splice site and a second binds near the 3’ splice site
Small ribonucleoprotein (snRNP) particle
____________ elements move about the genome
a _____________ consists of two transposable elements flanking another gene or genes. The entire transposon is copied and inserted as a unit.
If the insertion takes place in a somatic cell, _________ may result
If a transposon replicates not just itself but also an adjacent gene, the result may be _____ _____________.
gene duplication
Transposons can result in:
cancer cells, gene duplication, genetic variability, new genes
___________ _______ are instructions that specify the primary structures of a protein molecule (those that get transcribed into mRNA)
structural genes
_________ are units of transcription; structural genes plus regulatory mechanisms.
__________ regions bind activator proteins that stimulate the transcription complex (promoter then binds RNA polymerase & transcription starts)
enhancer regions
_________ -when attached to an operon, transcription shuts down
__________ are negative regulatory regions; turn off transcription by binding to repressor
___________ blocks RNA polymerase from binding & transcribing the structural genes, preventing synthesis of tryptophan pathway enzymes
When glucose levels are high:
1. RNA polymerase cannot bind efficiently
2. Structural genes are not transcribed. This is adaptive when the cell does not require an alternative energy source

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