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8.4 Transcription
Classwork
• On pg. 94 of your notebooks
– Split page in ½
– Top ½- Draw fig 8.10 (pg.239)- color code
– Make a double-bubble map comparing and contrasting
DNA and RNA (239-240)
–
• On pg. 96 of your notebooks
– Draw and label figure 8.11 (pg 241) in book
– Needs to have color
•SetTranscription
up Cornell Notes on
8.4
pg. 95
•Topic: 8.4 Transcription
•Essential Question:
1. What is the central
dogma?
2. Why can an mRNA
strand made during
transcription be
thought of as a mirror
image of the DNA
strand from which it
was made?
•Don’t forget to add it to
8.4 Transcription
2.1 Atoms, Ions,
and Molecules
3.2 Cell Organelles
There are two types of endoplasmic reticulum.
– rough endoplasmic
reticulum
Have bumps called
ribosomes which
link amino acids together
to form
proteins
8.4 Transcription
Review: Replication
nucleotide
nucleotides
unzips
8.4 Transcription
2. DNA polymerase (poly-mer-ace)
enzymes bond the nucleotides together to
form the double helix.
complementary
new strand
nucleotide
DNA polymerase
8.4 Transcription
complementary
nucleotide
new strand
DNA polymerase
8.4 Transcription
3. Two
new molecules of DNA are formed,
each with an original strand and a
“complementary” newly formed strand.
complementary
original strand
new strand
Two molecules of DNA
Why do we call the new strand a complementary strand and not
an identical strand?
8.4 Transcription
Please complete the two DNA sequences below :
TACGTATGAAAC
TGGTTTAGAATT
8.4 Transcription
TACGTATGAAAC
ATGCATACTTTG
TGGTTTAGAATT
ACCAAATCTTAA
8.4 Transcription
Proteins are used for movement, eyesight,
and digestion.
8.4 Transcription
KEY CONCEPT
Transcription converts a gene into a single-stranded
RNA molecule.
RNA
DNA
8.4 Transcription
RNA carries DNA’s instructions.
• The central dogma
states that
information flows in
one direction from
DNA to
RNA to
proteins.
8.4 Transcription
•
The central dogma includes three processes.
1. Replication
2.Transcription
3.Translation
replication
transcription
• RNA is a link between
DNA and proteins.
translation
8.4 Transcription
• RNA differs from DNA in three major ways.
RNA
Ribose Sugar
Uracil (U)
Single-Stranded
DNA
Deoxyribose Sugar
Thymine (T)
Double-Stranded
8.4 Transcription
• Transcription copies genes from DNA to make a strand of
RNA.
8.4 Transcription
To transcribe is to make or translate a copy of DNA into RNA
8.4 Transcription
– RNA polymerase and other proteins recognize
the start of a gene and unwinds a segment of it.
transcription complex
start site
nucleotides
8.4 Transcription
Transcription Complex
transcription complex
START
start site
nucleotides
nucleotides
8.4 Transcription
– Nucleotides pair with one strand of the DNA.
– RNA polymerase bonds the nucleotides together.
– The DNA helix winds again as the gene is transcribed.
RNA
DNA
RNA polymerase
moves along the DNA
8.4 Transcription
Transcribe this DNA strand into a mRNA strand
DNA
AAA TAG GAT ATC GGA TAC AGT
RNA
UUU AUC CUA UAG CCU AUG UCA
8.4 Transcription
– The RNA strand detaches from the DNA once the gene
is transcribed.
RNA
8.4 Transcription
• Transcription makes three types of RNA.
– Messenger RNA (mRNA) carries the message that will
be translated to form a protein.
– Ribosomal RNA (rRNA) forms part of ribosomes where
proteins are made.
– Transfer RNA (tRNA) brings amino acids from the
cytoplasm to a ribosome.
8.4 Transcription
Replication vs. Transcription Double Bubble (pg.95)
• Transcription and replication are similar, but have different
end results.
– Replication copies
all the DNA;
transcription copies
a gene.
– Replication makes
one copy;
transcription can
make many copies.
one
gene
growing RNA strands
DNA