DNA NotesThe Genetic Code…

The genetic code is made up of __________. It’s functions are to:

◦ ______________________________in the form of a __________ ____________________code.◦ Pass information on from one ____________________to the next.

DNA Stands for: ________________________________________

◦ Say it… “deoxy” “ribo” “nu-clay-ic” “acid” It is located in the ____________________ of each cell. It ______________________________and

____________________

Structure of DNA DNA is a ____________________, which means it

is made of ____________________.◦ Called ____________________

Structure of a Nucleotide ◦ Each nucleotide contains:

◦ 5-carbon sugar (Deoxyribose)◦ Phosphate group◦ Nitrogenous base

◦ There are 4 possible Nitrogenous Bases ◦ Purines:

◦ ____________________ and ____________________◦ Pyrimidines:

◦ ____________________ and ____________________

Back to DNA… DNA is a ______________________________structure. It looks like a twisted ladder. It is made up of different combinations of the 4

nucleotides. ____________________ and ____________________ make up the

sides of the ladder-like structure. ______________________________make up the steps of the

ladder-like structure. Weak ______________________________ (like velcro) hold the

nitrogenous bases together from each side.

What does DNA store the information for??? The information stored in the DNA is used to make ____________________ Why proteins?

Proteins can directly make __________, ____________________, and ____________________ ____________________are proteins that act as catalysts to facilitate chemical reactions Proteins are important ______________________________of cells and are responsible for

cell movement (cilia and flagella)

How was DNA discovered??

There were several discoveries that happened that informed scientists that DNA existed BEFORE they actually discovered the structure.

All discoveries were related and helped scientists come to a full understanding later…

Experiments: 1. __________________________________________________

Griffith studied 2 types of ____________________ Type “R” Bacteria: harmless to mice Type “S” Bacteria (R): gave mice a __________ strain of

____________________ What happened??

The non-invasive bacteria R was__________________________ into an invasive/deadly form!

Descendents of the transformed bacteria carried the invasive characteristic.

◦ Conclusion: whatever transformation the bacteria made was ____________________and could be passed down to the next generation.

2. __________________________________________________

Avery studied Griffith’s work and wanted to know what this “transforming factor” was.. ◦ He knew several things:

Chromosomes function in ____________________ Chromosomes are made up of __________ and _________________

◦ So was this “transforming factor” in Griffith’s experiment DNA or Proteins? ◦ Avery treated Griffith’s “heat killed S cells/ living R cells” combination with a

“__________________________________________________” Result: The new colonies of bacteria still killed the mice.

◦ Avery treated Griffith’s “heat killed S cells/ living R cells” combination with a “__________________________________________________”

Result: The new colonies of bacteria did not kill the mice. ◦ What did this mean??

If the Proteins were destroyed… nothing changed. If the DNA was destroyed… the mice were now fine.

◦ Avery concluded that the lethal trait was being held in and passed on through ____________________

◦ __________________________________________________

3. __________________________________________________ ◦ Hershey and Chase studied ____________________◦ Structure of a virus:

Nucleic Acids (like DNA) wrapped in a protein coat. ____________________- virus that infects bacteria

◦ Viruses can only reproduce by infecting a living cell with its genetic material (nucleic acids) and making the cell copy it.

◦ By Hershey and Chase studying ____________________, there was a better understanding of how DNA is passed down through generations.

◦ Also, it concluded that viruses are definitely _________________________

The Discovery of the DNA structure…

Rosalind Franklin o She x-rayed DNA and saw its ______________________________

Erwin Chargaff o Noticed that the number of Adenine bases in a sample of DNA was equal to the

number of Thymine bases. o Also, the number of Guanine bases was equal to the number of Cytosine bases.o He came up with the base-pairing rule.

James Watson and Francis Crick o Used the work done by Franklin and Chargaff to build the first DNA model.o Won the Nobel Prizeo The structure is still accepted and used today.

DNA Replication

During DNA Replication, an ____________________ copy of DNA is made. Replication of DNA occurs during the

____________________of Interphase during the cell cycle.

Each strand of DNA holds specific information to create the other strand in the base-pairing pattern.

Replication occurs in segments, called ______________________________.

Each new strand consists of one old strand and one new strand, making it a ______________________________. (Conserves part of the old.

Enzymes involved in Replication 1. ____________________unzips and untwists the ______________________________.2. ______________________________adds nucleotides to the leading DNA strand in the 5’

to 3’ direction, which is continuous. 3. ____________________adds RNA primer to the lagging DNA strand in the 5’ to 3’

direction, which is discontinuous, making Okazaki fragments.4. A different ______________________________comes through and adds nucleotides to the

lagging strand fragments.5. ____________________binds the Okazaki fragments together.

RNA

RNA= Ribonucleic Acid RNA is a nucleic acid, like DNA, but has different features that make it important. Functions of RNA

◦ Acts a messenger between DNA (which is in the ____________________and the __________ ____________________ (which are in the cytoplasm)

◦ Why does the information need to get to the ribosome? __________________________________________________

◦ Therefore, RNA helps carry out ________________________________________ Structure of RNA

◦ The structure of RNA is very similar to DNA, except… RNA is ____________________stranded RNA is composed of Nucleotides that have a ____________________ sugar

instead of Deoxyribose (still has a phosphare group and a base…) The bases are Adenine, Cytosine, Guanine, and ____________________ (there is

no Thymine!) 3 types of RNA:

◦ mRNA: ______________________________

Carries the DNA code from the ____________________ to the ____________________

◦ tRNA: ______________________________

Recognizes codons on mRNA and brings specific amino acids to the _________________

◦ rRNA: ______________________________

Found in the ribosome Interacts with mRNA and

tRNA to ensure proteins are made correctly

Protein SynthesisThe whole point of all of this is to make ____________________.

DNAà RNAà amino acid sequenceà Protein *****Why are proteins so important??*****

Protein synthesis happens in the __________________________ (Located in the cytoplasm OR on the rough ER)

Transcription: DNAà RNA DNA is trapped in the ____________________.

The cell does not want the DNA to leave the nucleus because then it will not be ____________________.

Proteins are made in the ______________________. Somehow, the code from the DNA needs to get to the ribosomes so that the correct _______________ are made.

Nucleotides are arranged into triplets, called ____________________.

◦ Example: AAC CGT TACTTG GCA ATG

◦ Each codon specifies (codes for) a particular ____________________________.

◦ The sequence of the ____________________ in the DNA will be transferred to the RNA, which will then determine the sequence of amino acids.

What kind of RNA is DNA translated directly into?◦ ____________________

◦ Why?◦ Because mRNA can ________________________________________

Steps for Transcription (DNA being transcribed into RNA)1. A portion of the ____________________ untwists and unzips (Helicase)2. ______________________________adds the __________ nucleotides with the

corresponding base sequence of the transcribing strand3. __________________________occurs. Regions with introns and exons signal start and

stop areas4. The __________ moves away from the DNA molecule and goes into the

____________________ 5. The DNA zips back up and twists into its normal ______________________________.

When RNA is being synthesized by enzymes, they pair the bases just like they would during DNA

replication. There is one big difference, though.

RNA does not have the base Thymine. Instead, if the enzymes come across an Adenine base, they pair it with

____________________. Can you transcribe the following DNA strand?

DNA: ATC GGA TAC GGG CCA RNA: ____________________________________

Let’s remember the goal here… Proteins! Proteins! Proteins!

Now the we have our mRNA with the DNA code, the mRNA can leave the nucleus and head to the ribosome!

Translation: mRNAàtRNAàa.a. sequence During translation, the codons are translated into an _________________________ tRNA is structure to carry specific amino acids to the ribosome. mRNA has the code for tRNA tRNA has 3 exposed bases called the _______________________

◦ What does that remind you of? ______________________________

◦ What was a codon? ______________________________

What do you think the anticodon does?◦ ________________________________________________________________________________

________________________________________________________________________________Steps to Translation (mRNAàtRNAàa.a. sequence)

1. The ribosome attaches to the __________ strand2. The tRNA (carrying an amino acid) with the matching ____________________pairs with

the mRNA strand.3. The ribosome moves down the strand and complimentary tRNA’s line up the

_________________ in the order specified by the bases.4. The amino acids are then bonded together by a _____________________, forming a

polypeptide.5. The polypeptide is then folded in a specific way according to the amino acids and

their structures- forming a functional ____________________!

Using the Codon chart… Let’s Practice.

Mutations ______________________________: Any change in the nucleotide sequence of a DNA strand. Point Mutations

◦ ________________________________________ 1 base (nucleotide) is ____________________with another

A base substitution can be a ____________________mutation, meaning that it does not cause any change in the amino acid sequence.

How is this possible? Because more than 1 codon can

code for the same amino acid. Remember, there are 64 possible codons, and only 20 possible amino acids.

Example: GAA and GAG both code for Glucine!

Frame shift Mutations ◦ ______________________________

An extra nucleotide is ____________________

This alters the rest of the sequence because each codon downstream is ________________

This usually results in a ________________________________________

◦ ______________________________ A nucleotide is

____________________ This also alters the rest of the

sequence because each codon downstream is ____________

This usually results in a _______________________________

What causes mutations? ◦ ______________________________: any chemical or physical agent that causes a

mutation Examples: ____________________________________________________________

Most mutations are harmful…

◦ ______________________________ Caused by 1 base substitution on a gene with 438 bases!

◦ ______________________________ Caused by several types of mutations

Some mutations are actually beneficial… ◦ There is a mutation that occurs in monarch butterflies that changes a protein that

determines color. ◦ This results in the butterfly being bright orange instead of dull orange or brown.◦ Why might this be beneficial?