Download DNA - Edmonds

DNA:
A paper model,
transcription, and translation
(Honors)
Warmup
• Working with your neighbor, find answers to
these questions; be ready to share (verbal).
• 1) What are the three main components of DNA? How are
they arranged? What is a nucleotide?
• 2) What are the base pair names, and how do they bond?
(Chargaff’s rules, late 1940s)
• 3) Describe the bonds between bases.
• 4) What did Rosalind Franklin show in the early 1950s?
• 5) What did Watson and Crick write about in 1953?
• 6) How can you remove DNA from animal cells? Explain
salt, soap, and ethanol.
Update your notes!
• Add to your Cornell notes
– Drawings on the board
– Clarifying comments/information, etc…
Review 291 - 294
• What are the three main components of DNA?
How are they arranged? What is a nucleotide?
• Nitrogenous base
– Adenine
– Thymine
– Guanine
– Cytosine
• Deoxyribose
sugar
• Phosphate
• Mr. Welman will show you some models…
Review 291 - 294
• What are the base pair names, and how
do they bond? (Chargaff’s rules)
• Describe the bonds between bases.
• What did Franklin show?
• What did Watson and Crick show?
• How can you remove DNA from animal
cells? Explain salt, soap, and ethanol.
• Any questions about 291-294?
Simple DNA Model - Activity
• Goal: build a simple model of DNA to use as we learn
how DNA is transcribed into mRNA and translated into
proteins
– DNA  mRNA  Proteins  Characteristics
• Work with your lab partner at your desk
– Complete the “DNA model” instructions
• One partner gets materials; other reads instructions
– Make sure you mark the first nucleotide “beginning”
and the last nucleotide “end”.
• The order is very important later!
• When done, place your model in a LABELED Ziploc
bag (your names). Place the bags on the tray in back.
DNA– Record # and bases.
(Single strand of DNA)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
ATAGGCAACGTACGA
AAAGGCAAGGTACGT
TGCTAGGTTCGGAAT
CGTACGTACGTAATT
TTTAACCGGATGGGG
CTTAAAGGCATAAAC
AGGCGATATACCGAT
TACCCATATAGCCGA
CATTAGGACCAGAAA
TTTACACACGGCTTA
CGATTACCGTAGCAA
CGGGTACCGGATTAC
GGCAATGGTTACCCC
TACCCTAAGGATTTA
AAGGCATTACGGTAC
TGGCACCGTTACCGT
Replication - reminder
• Reminder: Replication occurs so cells can make
more DNA for mitosis (copies DNA)
– Replication does NOT create proteins
• How would you use the model to show replication?
• DNA transcription mRNA translation  proteins
Replication
More DNA
Reading DNA - Transcription
• Where is DNA stored?
– Nucleus
• What makes proteins (which organelle)?
– Ribosome
• Does DNA leave the nucleus during usual cell functions?
– No! Never! (only in mitosis…)
• So, how does “DNA” get to the ribosome?
– We need a messenger!
– Transcription: creation of a “messenger”
– Messenger RNA (mRNA).
• Note:
– Replication = creating more DNA (double-stranded)
– Transcription = creating mRNA (single-stranded)
• mRNA is NEVER attached to DNA! (Leaves nucleus…)
Reading DNA - Transcription
• Transcription: creation of a complimentary
single stranded molecule from DNA
– DNA molecule opened in nucleus
– Single stranded molecule of RNA created using
base pair rules*
• *Uracil replaces thymine in RNA
• Ex) Adenine in a DNA strand would be transcribed to
form a Uracil in RNA
• Ex) Thymine in a DNA strand would be transcribed to
form an Adenine in RNA.
Reading DNA - Transcription
• Protein synthesis “Big Picture”
• DNA  mRNA  Proteins  Characteristics
• Today: RNA Model - Transcription
• Read and complete all the “RNA Model - Transcription”
instructions carefully.
• The goal is to try this hands on to help you learn it.
• One person gets materials, partner reads ahead (at regular seat)
– IMPORTANT! Please transcribe the original sequence of DNA
(start from the beginning of your original DNA strand
– Label your new mRNA strand with a “beginning” and “end”
– Ask me for more tape if you run out!
• Place your DNA and your mRNA back in the Ziploc and tray. Make
sure you have answered all questions.
Review
• What is DNA replication?
– Be prepared to explain what it is and how it
works.
• What is transcription?
– Be prepared to explain what it is and how it
works.
Reading DNA – Translation
• Goal: translate the mRNA into a short section of protein
– DNA  mRNA  Proteins  Characteristics
• Materials needed:
– 5 tRNA paper pieces
• With your partner, carefully complete “RNA Model – Translation”
– READ DIRECTIONS!
– Start at the beginning!
– Write the name of each amino acid on a separate tRNA
molecule.
– Proofread your double-stranded DNA molecule, your mRNA,
and your protein.
– Place the final protein strand in the wire basket. Record your
and your partner’s name and number on the back.
– Keep the remaining DNA/mRNA model for reference.
– Ziplocs returned to box in the back