GETTING TO KNOW DNA
WHAT DO YOU ALREADY KNOW?
PART 1: KNOWING YOUR NUCLEOTIDES
DNA is the code that makes you who you are.
The code has ONLY 4 LETTERS!!!
A = Adenine T = Thymine C = Cytosine G = Guanine
PART 1: KNOWING YOUR NUCLEOTIDES
A, T, C, & G are nucleotides.
Nucleotides: The building blocks of DNA that match up to form the double helix shape
A + T bond C + G bond
PART 1: KNOWING YOUR NUCLEOTIDES Nucleotides all have the
same general structure.
1. Phosphate Group is the backbone
2. Sugar is the link
3. Nitrogen Base is the code: A, T, C, G
The green base can change, but yellow and pink stay the same
PART 1: KNOWING YOUR NUCLEOTIDES DNA is the code to
make RNA. RNA is the code to
make proteins! RNA replaces the
deoxyribose sugar link of DNA with just a ribose sugar link
RNA also replaces the T nucleotide for a U
U = Uracil A + U bonds
DNA HISTORY: ERWIN CHARGAFF (1950)
Erwin did the experiments to prove that A matches with T and that C matches with G in a 1 to 1 ratio.
DNA HISTORY: ROSALIND FRANKLIN (1951)
Rosalind took the first clear photo of DNA
DNA HISTORY: MARTHA CHASE & ALFRED HERSHEY (1952)
First to absolutely prove that DNA is the molecule that is the code for all genes
CURRENT APPLICATION: (JUST FOR FUN)
DNA HISTORY: FRANCIS CRICK & JAMES WATSON (1953)
Determined the “double-helix” shape of DNA from Rosalind’s photo.
Some say Rosalind got it first!
CHECK FOR UNDERSTANDING
1. What is a NUCLEOTIDE?2. What are the 3 parts of a nucleotide?3. Which nucleotide bonds with “A”?4. Which nucleotide bonds with “C”?5. Which nucleotide is replaced with
“U” for RNA?6. Which nucleotide bonds with “U”?
PART 2: DNA REPLICATION
We need to pass on our genes to new cells (by Mitosis) and to our offspring (by Meiosis).
DNA Replication is the process by which perfect copies of our DNA are made!
PART 2: DNA REPLICATION
Think of DNA as a zipper, two sides that are held together by matching base pairs.
The enzyme helicase unwinds the helix and forces the zipper to open!
The Chainsaw!!!
PART 2: DNA REPLICATION
Opening the DNA causes “bubbles” to form
Replication can only happen when these single strands of DNA are exposed!
PART 2: DNA REPLICATION
Replication is “semi-conservative” because the original (parent) strands stay the same, while new matching (daughter) strands are added on.
PART 2: DNA REPLICATION The nucleus is
filled with a pool of extra nucleotides, waiting to make new DNA.
DNA Polymerase is like a train that rides along the rail of DNA and attaches matching base pairs.
CHECK FOR UNDERSTANDING
1. Why do the DNA strands need to be “unzipped” before they can be copied?
2. What is “semi-conservative” DNA replication?
3. In replication, parents strands are matched with new nucleotides to make a _________ strand.
CHECK FOR UNDERSTANDING
FIND THE MATCH!
C
G
A
T
PART 3: PROTEIN SYNTHESIS
Transcription: A process where a section of DNA code is copied into its matching RNA code.
Makes “messenger” mRNA
PART 3: PROTEIN SYNTHESIS
mRNA leaves the nucleus to find a ribosome in the cytoplasm.
PART 3: PROTEIN SYNTHESIS Translation: The
process of decoding the mRNA code
Every 3 letter code of mRNA (codon) = amino acid
Transfer RNA bring amino acids to match the codes of mRNA
Amino acids build the protein
PART 3: PROTEIN SYNTHESIS mRNA codes
for 20 different amino acids that have almost infinite combinations for making needed proteins.
AAA F CAA V GAA L UAA I
AAC L CAC V GAC L UAC M
AAG F CAG V GAG L UAG I
AAU L CAU V GAU L UAU I
ACA C CCA G GCA R UCA S
ACC W CCC G GCC R UCC R
ACG C CCG G GCG R UCG S
ACU - CCU G GCU R UCU R
AGA S CGA A GGA P UGA T
AGC S CGC A GGC P UGC T
AGG S CGG A GGG P UGG T
AGU S CGU A GGU P UGU T
AUA Y CUA D GUA H UUA N
AUC - CUC E GUC Q UUC K
AUG Y CUG D GUG H UUG N
AUU - CUU E GUU Q UUU K
COMPARING TO BUILDING A BUILDING
Architect's Office = Nucleus
The Master Plan by the architect = DNA
The location of the land to build the building = cytoplasm
The Blue Prints that communicate the Master Plan = mRNA
COMPARING TO BUILDING A BUILDING
The Supervisor at the site of construction = Ribosome
The concrete and lumber to build the building = amino acids
The trucks to bring the lumber = tRNA
The finished building = Complete Protein
CHECK FOR UNDERSTANDING
Now let’s compare building a protein to making a song.
The completed song = the completed protein
1. What is the recording studio?
2. What is the tape player?
3. What are the musical notes?
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