Save
AP bio hard stuff
ap bio unit 6
Save
Share
Learn
Content
Leaderboard
Learn
Created by
Maggie Tu
Visit profile
Cards (43)
DNA is located in the
nucleoid
region in
prokaryotes
and are smaller and often circular
mRNA-
messenger
between DNA and the ribosomes
rRNA- structural components of
ribosomes
tRNA- bring
amino
acids
to ribosomes
miRNA and siRNA-
regulators
of genes
DNA replication is
semiconservative
, meaning that each strand in DNA acts as a template for the synthesis of a new,
complementary
strand
helicase- unwinds
the
DNA
at replication forks (breaking the hydrogen bonds between the nitrogenous base pairs)
single-strand binding
proteins- keep the
separated
strands from coming back together
in
E.
coli
, DNA polymerase
III
can only add nucleotides to the 3' end of an existing DNA strand (synthesizing the new strand in the
5
to
3
direction)
needs the enzyme called
primase
to make an
RNA
primer
that is
complementary
to the template
leading
vs. lagging strand:
leading is synthesized TOWARDS the replication fork, while lagging is synthesized
AWAY
from the replication fork
okazaki
fragments- new DNA is made in these fragments on the
lagging
strand
topoisomerase-
prevents the DNA double
helix
ahead of the replication fork from getting too tightly wound as the DNA is opened up by helicase
DNA polymerase I- RNA primers are removed and replaced by
DNA
the spaces that remain after the primers are replaced get sealed by DNA
ligase
chargaff's rules-
A
=
T
and
C
=
G
eukaryotic RNA modifications after transcription:
protection-
5'
cap and
poly-A
tail to protect the mRNA transcript from
attack
by enzymes in the cytoplasm called exonucleases
splicing-
remove
the
introns
(sequences of RNA that don't contain any information) from the mRNA transcript using
spliceosomes
transcription steps:
initiation-
RNA polymerase binds to the promoter of DNA (beginning of gene) and separates the DNA strands
elongation-
RNA polymerase reads DNA template strand and builds RNA strand of complementary nucleotides
termination-
terminator sequence signaling
transcription
-
nucleus
translation-
ribosome
alternative splicing- more than one mRNA can be made from the
same gene
translation:
initiation-
ribosome
assembles around mRNA,
tRNA
carrying
MET
matches
AUG
codon and is necessary to begin translation
elongation- amino acid chain gets
longer
termination-
stop
codon enters ribosomes, triggering events that separate chain from
tRNA
coding strand =
mRNA
eukaryotes
: transcription in nucleus,
translation
in ribosomes in cytosol
prokaryotes:
transcription
AND
translation
in cytosol
RNA
in retroviruses
lac operon (inducible)-
can be turned on by
allolactose
(inducer)
lac repressor originally blocks
RNA polymerase
from transcribing the
lac operon
when lactose is NOT AVAILABLE
when lactose IS
AVAILABLE
,
allolactose
(rearranged lactose) binds to the lac
repressor
, allowing it to change shape and not bind to the DNA
RNA polymerase
can now transcribe the
operon
in order to
BREAK
DOWN
LACTOSE
the lac operon turns ON when glucose is
UNAVAILABLE
and
lactose
is AVAILABLE
the
promoter
region is the binding site for
RNA
polymerase
the
operator
region is the binding site for a
repressor
protein
trp operon (repressible)-
can be turned off by tryptophan (
corepressor
) binding to the
trp
repressor
when tryptophan IS
AVAILABLE
, it is bound to the trp repressor and transcription is turned
OFF
when tryptophan is
NOT
AVAILABLE, the trp repressor is NOT BOUND and RNA polymerase can make
tryptophan
tryptophan is present = trp
repressor
bound, trp operon
NOT
TRANSCRIBED
tryptophan is NOT present = trp repressor
unbound
, trp operon is
TRANSCRIBED
to CREATE
TRYPTOPHAN
lac and
trp
operons are examples of gene regulation in
BACTERIA
eukaryotic
gene regulation:
growth
factors
growth factor binds to
receptor protein
triggers
chemical
events that activate
transcription
factors
transcription factors bind to
DNA
and cause
transcription
in prokaryotes,
RNA polymerase
attaches right to the DNA of the
promoter
, initiating transcription
in
eukaryotes
, transcription factors help RNA polymerase attach to the
promoter
bacteria reproduce by splitting in
two
via binary
fission
binary
fission makes
clones
genetic variation in prokaryotes:
transformation- a bacterium takes up a piece of DNA
floating
in its
environment
genetic variation in prokaryotes:
transduction- DNA is
accidentally
moved from one bacterium to another by a
virus
these viruses that infect bacteria are called
bacteriophages
genetic variation in prokaryotes:
conjugation- DNA is
transferred
from one
bacterium
to another through a pilus
DNA cloning- process of making multiple identical copies of DNA
restriction
enzyme:
DNA-cutting
enzyme that recognizes a specific target sequence and cuts DNA into two pieces at that site
joined together by
DNA ligase
bacterial transformation and selection in DNA cloning step 2-
plasmids and other DNA can be introduced into bacteria through
transformation
during transformation,
high
temperature encourages the bacteria to take up
foreign
DNA
a plasmid typically contains an
antibiotic resistance
gene, which allows bacteria to
survive
in the presence of a specific antibiotic
bacteria without a
plasmid
will die, while bacteria carrying a
plasmid
can live and reproduce
polymerase chain reaction (PCR): used to make many
copies
(millions) of a particular region of DNA
denaturation
: separate the DNA strands using heat
annealing
: primers can bind to their complementary sequences by cooling the reaction
extension
: raising the reaction temperatures for synthesis of new strands of DNA
gel electrophoresis: used to separate DNA fragments based on their
size
and
charge
DNA has a
negative
charge due to phosphate groups on backbone, so they start moving towards the
positive
pole
shorter
DNA travel
LONGER
DISTANCES
frederick griffith:
when the mice were exposed to an R strain (
non-virulent
) and a heat-killed S strain, they actually developed pneumonia and died
concluded that the R strain bacteria
transformed
and became a
virulent
strain
mRNA modifications:
5’
Guanine
cap
: signals the start of mRNA transcript for the ribosome to bind to; facilitates export from nucleus
Poly-A-tail
: inhibits degradation of hydrolytic enzymes in cytosol
Regulation of gene expression:
methylation-
stop
acetylation-
activate
signal transduction pathways are highly specific and regulated
one molecule can cause a
cascade effect
of thousands of molecules
these pathways evolved from a
COMMON ANCESTOR
lac operon is
INDUCIBLE
, trp operon is
REPRESSIBLE
the same
transcription factor
often regulates different
genes
See all 43 cards