SC STANDARD B-4
STUDENTS WILL DEMONSTRATE AN UNDERSTANDING
OF THE MOLECULAR BASIS OF HEREDITY
 EQ: HOW WOULD YOU COMPARE
TRANSCRIPTION &TRANSLATION?
 Notebook: page 98
 are coded DNA
instructions that
control the production
of proteins within a
cell.
 single stranded nucleic





acid
5-carbon sugar is
ribose
1 phosphate group
1 of 4 nitrogenous
bases:
1. adenine 2. guanine
3. cytosine 4. uracil
 1. Messenger
RNA (mRNA)
 carries copies of
instructions for
assembling
proteins from the
gene (in nucleus)
 ribosomes
 single strand of
nucleotides
 read in groups of 3
called codons
 look at the 2 codons
on this slide: What
sequence of
nucleotides on DNA
did this segment of
mRNA come from?
 with proteins make
up ribosomes
 ribosomes made of
2 subunits: 30S and
50S
 transfers each of
the amino acids to
the ribosome as is
specified by the
code in mRNA
 one end has the
anticodon
 other end the a.a.
 anticodon: group
of 3 bases that are
complimentary to
the codon on
mRNA
TRANSCRIPTION
TRANSLATION
 INVOLVES
 INVOLVES
TRANSCRIBING
(copying) THE
CODE IN DNA
MAKING mRNA
TRANSLATING the
CODE into AMINO
ACIDS 
POLYPEPTIDE
CHAINS 
PROTEINS
 mRNA, tRNA, rRNA
 mRNA molecules
are made by
copying part of a
nucleotide
sequence of DNA
into a
complimentary
(C’) sequence in
mRNA
 Steps:
 1. RNA Polymerase
opens DNA
 2.RNA Polymerase
uses 1 of the DNA
strands as
template
 uses C’ base pair
rules
 RNA Polymerase binds to DNA at certain
points called “promoters”
 after unwinding a short portion of the
double helix, RNA Polymerase moves
along 1 of the DNA strands making a
strand of RNA using base-pair rules
except there is no T in RNA: A is paired
with U (Uracil)
 RNA Polymerase moves along the DNA
until it hits a signal to stop.
 this strand of RNA is called pre-mRNA
 portions of DNA called introns do not
code for proteins
 DNA portions that code for proteins
called exons.
 introns get cut out of pre-mRNA and the
exons get spliced together
 http://www.dnalc.org/view/16938-3DAnimation-of-RNA-Splicing.html

 http://www.johnkyrk.com/DNAtranscription.html
 is the “language” of the
mRNA instructions
 written in a language
that only has 4
“letters”:
 G, C, A, & U
 must code for 20
amino acids
 is read 3 letters at
a time
 every 3
consecutive letters
codes for 1 of the
20 a.a., a start
signal, or a stop
 codon: is a “word”
in the code
 consists of 3
consecutive
nucleotides that
specify an a.a., a
stop, or a start
 Page of Notebook:
page 105
 “Crack the Code”
 Quick Lab from page
303 of textbook
 cell uses
information from
mRNA to produce
proteins
Step 1
Step 2
 mRNA attaches to
 tRNA with
ribosome
 1st codon codes for
methionine
anticodon
complimentary to
codon in mRNA
attaches to
ribosome,
delivering correct
a.a.
Step 3
Step 4
 peptide bond
 ribosome only
forms between a.a
brought to
ribosome by 1st &
2nd tRNA
holds 2 tRNA so 1st
one leaves
ribosome as 3rd
one “docks”
 Process repeated
until “stop” codon
Animations
Step 5
 http://www.wisc-
 polypeptide chain
online.com/Objects/Vie
wObject.aspx?ID=AP130
2
https://www.youtube.co
m/watch?v=Ikq9AcBcoh
A
 http://www.dnalc.org/re
sources/3d/TranslationB
asic_withFX0.html
falls off ribosome
 Ribosome free to
start another
peptide chain
TRANSCRIPTION
TRANSLATION
 DNA  mRNA
 mRNA 
 nucleus
cytoplasm or RER
 mRNA + ribosome
+ tRNA  protein
http://www.wiley.com/college/boyer/
0470003790/animations/translation/t
ranslation.htm
http://highered.mheducation.com/olcweb/c
gi/pluginpop.cgi?it=swf::535::535::/sites/dl/fr
ee/0072437316/120077/micro06.swf::Protein
+Synthesis
http://www.yourgenome.org/vi
deo/from-dna-to-protein-flash
http://sepuplhs.org/high/sgi
/teachers/genetics_act16_si
m.html
 Handout: Genetic Code for Keratin
 Page of Notebook: 99
 Answer questions 1-4