10/24: DNA Structure

Quick intro:

What is the
monomer of
nucleic acid?

A. DNA

B. RNA

C. Nucleotide

D. Ribose sugar

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Talk to your partner about the answer

Unit 4:
DNA & Protein Synthesis

Learning target

•Use mathematical and computational thinking
to examine the structure of DNA and RNA
using the rules of base pairing.

Task #1:
What do you see?

What do you think?

What do you wonder?

Task #1:
Think-see-wonder

– %A ≈ %T

– %C ≈ %G
- not all organisms
have the same amounts

Task #2: Calculate DNA %

You’ll need a
calculator!

First count all As, then Ts, Cs and Gs. Find total #. Plug into formula with calculatur & convert to %.

Task #3: DNA Puzzle

Put the fitting pieces together (5 min)

What do you notice? (2 min)

What does your partner notice? (2 min)

​DO NOT LOSE ANY PIECES!!!

​KEY - what do you recognize here?
What do you notice about A, T, C and G?

Task #4:
Class notes

Fill in what we discuss!

10/23/2024

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DNA

•DeoxyriboNucleic Acid

•DNA is a nucleic acid

–Monomer?

• nucleotide

–Polymer?

• DNA & RNA

This Photo by Unknown Author is licensed under CC BY-SA

nucleotide

4 different
Nitrogen bases:
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)

Deoxyribose and
phosphate make up
DNA “backbone”

Nitrogen base

Deoxyribose sugar

Phosphate

P

DNA structure

• Double-stranded helix

• Sugar-phosphate backbone faces outside

• Nitrogen bases (A, T, C & G) face
inside & are paired together to
form “rungs” of DNA ladder

Base pairing rules

A pairs with T & C pairs with G always!!

Why?

• Because A will only fit next to T

• C will only fit next to G

• Together they are called
“complementary” = go together

Chargaff’s Rule

• Erwin Chargaff discovered that in DNA, nitrogen bases A and
T were in equal amounts, and so were C and G.

Task #4: fill in blanks
& table (8 min)

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10/23/2024

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Review together

Exit ticket:

if Thymine = 30% of the DNA strand,
how much Guanine is there?

Work it out like a math problem!
Use calculator as needed!