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Mind Map by pau.leal10, updated more than 1 year ago
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Created by pau.leal10
over 8 years ago
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Genetic Regulation
- DNA: Desoxirribonucleic Acid
- Polymere of Nucleotides
- Watson & Crick's Model
- Double Helix Structure
- Back Bone (outside): Sugar + Phosphate
- (inside) Paired Bases
- Double Ring: Purine Bases
- Adenine (A)
- Guanine (G)
- Adenine (A)
- Single Ring: Pyrimidine Bases
- Thymine (T)
- Cytosine (C)
- Chargaff's Rules
- 1. the amount of A, T, G, C in DNA varies
from specie to specie
- 2. in each species the amount of A=T
and the amount of G=C
- Structure
- COMPLEMENTARY PAIRING: A is always bonded to
T & G is always bonded to C by a hydrogen bond
- A purine (wide) is always paired to a
pyrimidine (narrow) to complement sizes
- Strands with ANTI PARALLEL ARRANGEMENT
- Every nucleotide has a phosphate
group at the 5' position of the sugar
& they bind together by linking this 5'
phosphate to the free hydroxyl (--OH)
at the 3' position of the other
nucleotide's sugar (giving it it's
direction)
- DOGMA OF MOLECULAR BIOLOGY
- Replication: Copying a DNA molecule
- DNA replication is termed
semi-conservative replication because
each daughter DNA double helix contains
an old strand from the parental DNA
double helix and a new strand
- STEPS:
- 1. Unwinding: an enzyme called helicase breaks
the hydrogen bond between the paired bases (creating a replication fork)
- 2. Complementary Base Pairing: New complementary nucleotides, always present in
the nucleus, are positioned in place (by an enzyme complex called DNA polymerase)
- 3. Joining: new strands are crated so each daughter DNA molecule contains
an old and a new strand (by an enzyme complex called DNA polymerase)
- DNA ligase, joins the fragments, but there is
no way for DNA polymerase to replicate the
5' ends of both new strands after RNA
primers are removed. So DNA molecules get
shorter as one replication follows another.
- DNA ligase, joins the fragments, but there is
no way for DNA polymerase to replicate the
5' ends of both new strands after RNA
primers are removed. So DNA molecules get
shorter as one replication follows another.
- the leading new strand continues it's
normal process, the lagging strand is
discontinuous, the segments are known
as Okazaki Fragments. as the RNA
primers are replaced by the nucleotides.
- A DNA polymerase is very
accurate and makes a mistake
approximately once per
100,000 base pairs at most.
- 3. Joining: new strands are crated so each daughter DNA molecule contains
an old and a new strand (by an enzyme complex called DNA polymerase)
- 2. Complementary Base Pairing: New complementary nucleotides, always present in
the nucleus, are positioned in place (by an enzyme complex called DNA polymerase)
- Differences
between...
- Eukaryotes
- Telomeres (special
nucleotide sequence at the
end of the DNA) do not code
for proteins, instead creates
repeats of a short nucleotide
sequence, such as TTAGGG.
- replication may begin at numerous origins
- the process can take
hours because of the
amount of info replicated
- Telomeres (special
nucleotide sequence at the
end of the DNA) do not code
for proteins, instead creates
repeats of a short nucleotide
sequence, such as TTAGGG.
- Prokaryotes
- Bacteria have a single
circular loop of DNA,
replication moves around
the DNA molecule in one
direction only.
- it requires 40 min. to
replicate & can do so
every 20 min.
- it is possible for a
new round of DNA
replication to begin
even before the
previous round is
complete.
- Bacteria have a single
circular loop of DNA,
replication moves around
the DNA molecule in one
direction only.
- Eukaryotes
- 1. Unwinding: an enzyme called helicase breaks
the hydrogen bond between the paired bases (creating a replication fork)
- DNA replication is termed
semi-conservative replication because
each daughter DNA double helix contains
an old strand from the parental DNA
double helix and a new strand
- Transcription
- 1st step in syntetization of a protein: DNA
serves as a template for RNA formation.
- pre-mRNA if formed (by
RNA Polymerase when it
ataches to a DNA promoter)
- RNA (Ribonucleic Acid)
carries the information
- Polymere composed of nucleotides:
sugar ribose & bases.
- Structure: single
stranded, NO double helix
- typically has a poly a tail (has many adenine
nucleotides at one end & a cap at the other end)
- typically has a poly a tail (has many adenine
nucleotides at one end & a cap at the other end)
- Adenine (A), Guanine (G),
Uracil (U), Cytosine (C)
- Types of RNA
- Messenger RNA (mRNA) takes a
message from DNA in the nucleus to
the ribosomes in the cytoplasm.
- Transfer RNA (tRNA) transfers
amino acids to the ribosomes
- Ribosomal RNA (rRNA), along with ribosomal
proteins, makes up the ribosomes, where
polypeptides are synthesized.
- Messenger RNA (mRNA) takes a
message from DNA in the nucleus to
the ribosomes in the cytoplasm.
- Structure: single
stranded, NO double helix
- Codon (triplet code):
3 nucleotide bases
- properties
- 1. The genetic code is
degenerate. most amino
acids have more than one
codon; (leucine, serine,
and arginine have six
different codons)
- The degeneracy of the code
protects against potentially
harmful effects of mutations.
- The degeneracy of the code
protects against potentially
harmful effects of mutations.
- 2. The genetic code is unambiguous.
Each triplet codon has only one meaning.
- 3. The code has 1 start
and 3 stop signals.
- 1. The genetic code is
degenerate. most amino
acids have more than one
codon; (leucine, serine,
and arginine have six
different codons)
- properties
- Polymere composed of nucleotides:
sugar ribose & bases.
- elongation of the mRNA
continues until DNA reaches
a stop point & the mRNA is
liberated = mRNA Transcript
- made up of nucleotides & regions
called: exons and introns
- splicing: introns are removed (forming
an mRNA: template to form proteins)
- m RNA will leave the nucleus
through the nuclear pore into the
cell's cytoplasm
- Prokatyotes have
self-spllicing: the
intron itself has
the capability of
enzymatically
splicing itself out
of a premRNA.
- Another type of RNA
called small nucleolar
RNA (snoRNA) is present
in the nucleolus, where it
helps process rRNA and
tRNA molecules.
- Another type of RNA
called small nucleolar
RNA (snoRNA) is present
in the nucleolus, where it
helps process rRNA and
tRNA molecules.
- Eukaryotes: splicing is
done by spliceosomes,
which contain small
nuclear RNAs (snRNAs:
are capable of identifying
the introns to be
removed) A spliceosome
utilizes a ribozyme when
it removes the introns.
- m RNA will leave the nucleus
through the nuclear pore into the
cell's cytoplasm
- splicing: introns are removed (forming
an mRNA: template to form proteins)
- made up of nucleotides & regions
called: exons and introns
- RNA (Ribonucleic Acid)
carries the information
- REGULATION OF GENE ACTIVITY
- Prokaryote Regulation
- Operon Model
- Promoter: signals where
transcription is to begin.
- Operator: controls transcription of
structural genes.
- active repressor
binds to the
operator, RNA
polymerase
cannot attach to
the promoter, and
transcription
cannot occur
- active repressor
binds to the
operator, RNA
polymerase
cannot attach to
the promoter, and
transcription
cannot occur
- Structural Genes: instructions to primary
structure of enzymes in a metabolic pathway
- Regulator Gene: codes for a repressor that
controls whether the operon is active or not.
- Trp Operon
(repressible system)
- when the active repressor
binds to the operator
transcription is prevented
because RNA polymerase
can't bind to the promoter
- gene expression "on" by default the
corepressor can bind to the repressor
activating it causing expresion to go off
- only on/off
(negative gene
regulation)
- when the active repressor
binds to the operator
transcription is prevented
because RNA polymerase
can't bind to the promoter
- Lac Operon
(inducible systems)
- on/ off
(negative gene
regulation)
- gene expression "off" by
default corepressor binds to
repressor deactivating it and
turnig expresion "on" by
unbinding it form the operator
- by unbinding the repressor
from the promoter
expression is allowed
- gene expression "off" by
default corepressor binds to
repressor deactivating it and
turnig expresion "on" by
unbinding it form the operator
- up/ down
(positive gene
regulation)
- there are no
repressors,
just
activators
- there's
some level of
transcription
but we need
more
- cyclic amp
activates the
activator by
binding to it
and changing
it's form so it
can bind with
the promoter
and increase
transctription
- there are no
repressors,
just
activators
- on/ off
(negative gene
regulation)
- Promoter: signals where
transcription is to begin.
- Operon Model
- Eukaryote Regulation
- 1. Chromatin Structure
- core of 8 histone
proteins wraped around
by DNA
- the DNA packed
around the histone
can't be transcribed
- chromatin remodeling
complex can liberate the DNA
making it transcribable
- Heterochromatin:
strongly packed
histones
- Euchromatin:
loosely packed
histones
- Epigenetic inheritance: When
histones are methylated, sometimes
the DNA itself becomes methylated
as well = genetic imprinting,
expression depends if the gene is
inherited from the mother or father,
not the gene it self
- core of 8 histone
proteins wraped around
by DNA
- 2. Transcriptional Control
- transcription
factors: proteins
that help regulate
transcription
- transcription
activators are DNA
binding proteins that
speed transcription
dramatically.
- transcription factors bind to the
promoter and transcription
activators bind to an enhancer
when the loop is formed to allow
transcription to begin
- transcription factors bind to the
promoter and transcription
activators bind to an enhancer
when the loop is formed to allow
transcription to begin
- transcription
factors: proteins
that help regulate
transcription
- 3. Posttranscriptional Control
- occurs in the nucleus
and includes alternative
mRNA splicing and
controlling the speed
with which mRNA
leaves the nucleus.
- pre-mRNA has introns
and exons, introns stay in
the nucleus as exons exit
the nucleous = mRNA
- pre-mRNA has introns
and exons, introns stay in
the nucleus as exons exit
the nucleous = mRNA
- occurs in the nucleus
and includes alternative
mRNA splicing and
controlling the speed
with which mRNA
leaves the nucleus.
- 4. Translational Control
- mRNA strands after
splicing are too short
so they become...
- micro RNA's, they
are double stranded
and where turned
off, micro RNA can
lower the
expression of genes
- micro RNA's, they
are double stranded
and where turned
off, micro RNA can
lower the
expression of genes
- mRNA strands after
splicing are too short
so they become...
- 5. Posttranslational Control
- the last chance a cell
has for influencing
gene expression
- Some proteins are
not immediately
active after
synthesis.
- some proteins only
become active when it
is appropriate for them
to do so.
- some proteins only
become active when it
is appropriate for them
to do so.
- Some proteins are
not immediately
active after
synthesis.
- the last chance a cell
has for influencing
gene expression
- 1. Chromatin Structure
- Gene Mutations
- permanent change
in the sequence of
bases in DNA
- Causes
- Spontaneous mutations
- the movement of
transposons from
one chromosomal
location to another
can disrupt a gene
and lead to an
abnormal product.
- a base in DNA can undergo a chemical
change that leads to a miss pairing
during replication and may be carried
in future generations.
- they are extremely
rare, 1 billion
nucleotide pairs
replicated.
- the movement of
transposons from
one chromosomal
location to another
can disrupt a gene
and lead to an
abnormal product.
- Induced Mutations
- caused by mutagens,
environmental factors that can
alter the base composition of DNA
- Many mutagens
are also
carcinogens
(cancer-causing)
- industrial
chemicals, foods,
tabacco, radiation
- Many mutagens
are also
carcinogens
(cancer-causing)
- caused by mutagens,
environmental factors that can
alter the base composition of DNA
- Spontaneous mutations
- Effects
- on Protein Activity
- point mutation: e a change in a single
DNA nucleo - tide and, therefore, a
possible change in a specific amino acid.
- can range in effect,
depending on the
particular codon
change
- can range in effect,
depending on the
particular codon
change
- Frameshift mutation:
one or more nucleotides
are either inserted or
deleted from DNA.
- The result can be a completely new sequence
of codons and nonfunctional protein
- Non-Functional Proteins
- dramatic effect on the
phenotype, because
enzymes are often a part
of metabolic pathways.
- Mental retardation,
albinism, PKU, etc.
- Mental retardation,
albinism, PKU, etc.
- dramatic effect on the
phenotype, because
enzymes are often a part
of metabolic pathways.
- Non-Functional Proteins
- The result can be a completely new sequence
of codons and nonfunctional protein
- point mutation: e a change in a single
DNA nucleo - tide and, therefore, a
possible change in a specific amino acid.
- Cancer
- The development of
cancer involves a
series of accumulating
mutations that can be
different for each type
of cancer
- tumor suppressor
genes are inactive
and oncogenes are
active
- cell division occurs
uncontrollably because a cell
signaling pathway that reaches
from the plasma membrane to
the nucleus no longer
functions as it should
- cell division occurs
uncontrollably because a cell
signaling pathway that reaches
from the plasma membrane to
the nucleus no longer
functions as it should
- The development of
cancer involves a
series of accumulating
mutations that can be
different for each type
of cancer
- on Protein Activity
- permanent change
in the sequence of
bases in DNA
- Prokaryote Regulation
- 1st step in syntetization of a protein: DNA
serves as a template for RNA formation.
- Translation
- 2nd step in syntetization of a
protein: the mRNA transcript
directs the sequence of amino
acids in a polypeptide.
- cell changes a nucleotide
sequence into an amino acid
sequence. With the help of
the three types of RNA, a
gene (a segment of DNA)
specifies the sequence of
amino acids in a polypeptide
- cell changes a nucleotide
sequence into an amino acid
sequence. With the help of
the three types of RNA, a
gene (a segment of DNA)
specifies the sequence of
amino acids in a polypeptide
- A tRNA molecule is a single-stranded nucleic
acid that doubles back on itself to create
regions where complementary bases are
hydrogen-bonded to one another
- there's at least 1 for every
amino acid in the protein, it binds to the 3' end.
- on the 5' end, an anti codon (group of three
bases complementary to a specific mRNA codon
so that they pair in an antiparallel fashion)
- fewer tRNAs that
codos because of the
wobble hypothesis.
- the first two positions in a tRNA anticodon
pair obey the A–U/G–C configuration, but
the third position can be variable. This
helps ensure that despite changes in DNA
base sequences, the correct sequence of
amino acids will result in a protein
- the first two positions in a tRNA anticodon
pair obey the A–U/G–C configuration, but
the third position can be variable. This
helps ensure that despite changes in DNA
base sequences, the correct sequence of
amino acids will result in a protein
- fewer tRNAs that
codos because of the
wobble hypothesis.
- aminoacyl-tRNA synthetase
(enzyme found in the cytoplasm)
attaches a different type of aminoacid to the specific tRNA
- this process uses ATP
- amino acid–tRNA complex is formed
- travels to a ribosome
- formation in
eukaryotes: rRNA spliced to form
2 rRNA strtands, 1 small & 1 big
- produced from a DNA template in the nucleolus
of a nucleus, synthetised by RNA polymerase I
- they leave the nucleolus & fold to form a
small and large sub unit of the ribosome
= pre-ribosome (still inside the nucleus)
- they leave the
nucleous and the
ribosome can
either stay un the
cytoplasm or get
attatchd to the ER
- they leave the
nucleous and the
ribosome can
either stay un the
cytoplasm or get
attatchd to the ER
- produced from a DNA template in the nucleolus
of a nucleus, synthetised by RNA polymerase I
- the small and large sub units of the
ribosome attach to the cap of the mRNA
- Translation
begins
- STAGE 1 Initiation: Proteins (initiation factors)
assemble the small ribosomal subunit and the
large ribosomal subunit through the P site of the
ribosome, now occupied by the initiator tRNA (with
an attached peptide), to the cap of the mRNA
- In prokaryotes, a small ribosomal
subunit attaches to the mRNA in
the vicinity of the start codon
(AUG).The first or initiator tRNA
pairs with this codon. Then, a large
ribosomal subunit joins to the
small subunit
- STAGE 2 Elongation:
- 1 tRNA + amino acid
arrives at the A site.
- 2 ribosome verifies that
new tRNA matches the
codon and firmly places it
at the A site, peptide will
transfer to the new tRNA.
- 3 the peptide bond
formation is one amino
acid longer than it was
before. creating a protein.
(now attached to the new
tRNA at A site)
- 4 translocation occurs: The ribosome
moves forward, and the peptide-bearing
tRNA is now at the P site of the ribosome.
The spent tRNA is now at the E site, and it
exits. :A new codon is at the A site and is
ready to receive another tRNA. (this
process repeats until the end of mRNA
strand)
- STAGE 3 Termination: it occurs at
a stop codon (codon that don't
code for an amino acid), a protein
called a release factor, binded to a
stop codon, releases the tRNA at P
site and the polypeptide chain.
the ribosome separates into 2,
- 1 tRNA + amino acid
arrives at the A site.
- In prokaryotes, a small ribosomal
subunit attaches to the mRNA in
the vicinity of the start codon
(AUG).The first or initiator tRNA
pairs with this codon. Then, a large
ribosomal subunit joins to the
small subunit
- STAGE 1 Initiation: Proteins (initiation factors)
assemble the small ribosomal subunit and the
large ribosomal subunit through the P site of the
ribosome, now occupied by the initiator tRNA (with
an attached peptide), to the cap of the mRNA
- Translation
begins
- structure: ribosome
has three binding
sites for tRNAs.
- E (exit) site
- P (peptide) site
- A (amino acid) site
- E (exit) site
- formation in
eukaryotes: rRNA spliced to form
2 rRNA strtands, 1 small & 1 big
- travels to a ribosome
- this process uses ATP
- DNA synthesised by RNA polymerase III creates the tRNA
- there's at least 1 for every
amino acid in the protein, it binds to the 3' end.
- 2nd step in syntetization of a
protein: the mRNA transcript
directs the sequence of amino
acids in a polypeptide.
- The universal nature of the genetic
code provides strong evidence that
all living things share a common
evolutionary heritage
- . Since the same genetic code is used by
all living things, it is possible to transfer
genes from one organism to another.
- . Since the same genetic code is used by
all living things, it is possible to transfer
genes from one organism to another.
- Replication: Copying a DNA molecule
- Every nucleotide has a phosphate
group at the 5' position of the sugar
& they bind together by linking this 5'
phosphate to the free hydroxyl (--OH)
at the 3' position of the other
nucleotide's sugar (giving it it's
direction)
- COMPLEMENTARY PAIRING: A is always bonded to
T & G is always bonded to C by a hydrogen bond
- 1. the amount of A, T, G, C in DNA varies
from specie to specie
- Chargaff's Rules
- Thymine (T)
- Double Ring: Purine Bases
- Back Bone (outside): Sugar + Phosphate
- Double Helix Structure
- Polymere of Nucleotides
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