Download DNA Synthesis

Structure of RNA
Single strand of
nucleotides bonded into a
chain
– Each nucleotide contains
• Ribose, sugar
• Phosphate
• Nitrogen base: adenine,
guanine, cytosine or
uracil
• Adenine pairs with
Uracil/ Cytosine pairs
with Guanine
RNA Types
• Messenger RNA- carries the code for making
proteins
• Ribosomal RNA- combine with a ribosome
• Transfer RNA- brings the amino acid to the
ribosome
TRANSCRIPTION
• When DNA gives RNA the code with the help of
enzymes!!
Section 12-3
Transcription
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
RNA
polymerase
DNA
RNA
Go to
Section:
• The sugar in RNA is _______, the sugar in
DNA is ________.
a. deoxyribose, ribose
b. ribose, deoxyribose
c. ribose, phosphate
d. ribose, uracil
Once transcription is complete, DNA is not
necessary for protein synthesis
A. True
B. False
RNA is synthesized on a DNA template in a process
called ____, which utilizes the enzyme____.
A.
B.
C.
D.
translation, RNA polymerase
transcription, RNA polymerase
transcription, DNA polymerase
replication , DNA polymerase
• Given the following DNA strand, which of
the following is its complementary mRNA?
GGACTGATT
a. CCTGACTAA
b. TTAGTCAGG
c. GGACTGATT d. CCUGACUAA
• Which of the following takes the genetic
code to the cytoplasm:
a. DNA
c. tRNA
b. mRNA
d. deoxiribose
TRANSLATION
• Process of assembling proteins from the
information encoded in RNA
• mRNA leaves the nucleus and goes to the
ribosome
– the codon ( 3 bases in sequence on the mRNA)
• tRNA, transfer RNA leaves the nucleus and
picks up an amino acid
– the anticodon is the compliment to the codon on
mRNA
Section 12-3
Translation
Nucleus
Messenger RNA
Messenger RNA is transcribed in the nucleus.
Phenylalanine
tRNA
The mRNA then enters the cytoplasm and
attaches to a ribosome. Translation begins at
AUG, the start codon. Each transfer RNA has
an anticodon whose bases are complementary
to a codon on the mRNA strand. The ribosome
positions the start codon to attract its
anticodon, which is part of the tRNA that binds
methionine. The ribosome also binds the next
codon and its anticodon.
Ribosome
Go to
Section:
mRNA
Transfer RNA
Methionine
mRNA
Lysine
Start codon
Section 12-3
Translation (continued)
The Polypeptide “Assembly Line”
The ribosome joins the two amino acids—
methionine and phenylalanine—and breaks
the bond between methionine and its tRNA.
The tRNA floats away, allowing the ribosome
to bind to another tRNA. The ribosome moves
along the mRNA, binding new tRNA molecules
and amino acids.
Lysine
Growing polypeptide chain
Ribosome
tRNA
tRNA
mRNA
Completing the Polypeptide
mRNA
Ribosome
Go to
Section:
Translation direction
The process continues until the ribosome reaches
one of the three stop codons. The result is a
growing polypeptide chain.
http://www.courses.fas.harvard.e
du/~biotext/animations/TRANSL
ATE20b.swf
Show site above
• The three nucleotides sequence on MRNA
is called a:
• a. tRNA
b. gene
• c. triplet
d. codon
Which site of the tRNA molecule binds to the
mRNA molecule?
• a. anitcodon
• b. codon
• c. amino acid
• d. 5 prime end
• Translation occurs:
a. at the ribosome
b. in the nucleus
c. both
d. neither
START & STOP SIGNALS
• To start the protein synthesis the codon
AUG must be present
• To stop the protein synthesis there’s a stop
codon UAA, UGA, UUC
• Three nucleotides code for one amino acid
• Ex: UUG codes for Leucine
• There are only 20 Amino Acids that can
combine together to form proteins.
#ONLY 20 Amino ACIDS..WOW#
Practice
Use your book page 338
DNA
mRNA tRNA
Amino Acid
CAT
UGC
GTC
UAA
start
Practice Answers
DNA
mRNA tRNA
Amino Acid
CAT
GUA
CAU
valine
TGC
ACG
UGC
Threonine
GTC
CAG
GUC
glutamine
ATT
UAA
AUU
STOP
TAC
AUG
UAC
start