From DNA to Proteins

Review (from BJ): What are proteins?

Proteins are made of Amino Acids.

Provide structure (nails, skin, hair…)

Function (enzymes-speeds up reactions)

Introduction

• DNA contains information that controls how cells function, grow and reproduce. It controls how you look like (traits) and how you function.

• Your DNA has pieces of DNA called genes that codes for proteins.

• These proteins determine your traits.

You are different from the people around you because you all have different proteins

Traits are characteristics. Example: Eye color

If genes change, then the protein changes and horrible things can happen to the organism.

But how can one little protein affect you?

• Melanin is a protein that gives your hair color. If the gene that makes melanin was destroyed, would you have black or brown hair? What color would your hair be?

• So, remember genes are pieces of DNA and they code for proteins that are necessary for structure and for our bodies to function in a particular way!

Like we’ve got to break this code , Scoob. Codes are a set of rules

and symbolsused to carry info.

DNA and RNA has many, many codes for proteins hidden within.

How do we go from DNA to protein?

DNA RNA Protein (Central Dogma)

When cells need to make proteins, they transcribe (copy) the information found in DNA into an RNA molecule and then the code in RNA is used to build proteins.

Going from DNA to RNA to Protein is called the Central Dogma.

Nucleus DNA

RNA Protein

Cytoplasm

From DNA to proteins:

Step 1: DNA is converted into RNA in a process called TRANSCRIPTION. This occurs in the nucleus.

Step 2: The RNA is released into the cytoplasm where RNA is read forming a chain of amino acids (Protein) . Going from RNA to protein is called TRANSLATION and this occurs in the cytoplasm.

DNA RNA Protein

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Remember, these proteins that are made determine your traits: hair color, eye color, and so on. They provide structure and function (enzymes).

There are 3 types of RNA! Type of RNA What it does Picture

mRNA Single RNA strand that carries a message or code

rRNA Is the place where mRNA and tRNA bind to make chains of amino acids.

tRNA Carries and transfers amino acids

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How do we go from DNA to mRNA?

• Transcription!! You are rewriting DNA’s message! Steps:

1 ) DNA unwinds (unzips), then RNA polymerase adds RNA nucleotides using a DNA strand. 2) RNA polymerase adds bases that include: A, C, G and U (Uracil)---NO thymine exists in RNA, only in DNA!3) Then you end up with a single mRNA strand.

* Paste your picture.

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DNA: G = C A = T Transcribe the following DNA strand. (DNA to mRNA)

A T G G C A T (DNA)

U A C C G U A (mRNA)

RNA: G = C A = U

Base Pair Rules

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DNA Replication (making more DNA):

A T C T G A A (old DNA strand)

T A G A C T T (new/complementary DNA strand)

Transcription: DNA mRNAA T C T G A A (old DNA Strand)

U A G A C U U (new/complementary RNA strand)

(pg103) Replicate the following Strand:

C A T A G (old DNA strand)__ __ __ __ __

Transcribe the following DNA strand:

G A T A G (old DNA strand)__ __ __ __ __ (single stranded mRNA)

RNARNA is a nucleic acid like DNA, but is different in 3 important ways:

DNA RNA

DNA Sugar is a Deoxyribose

RNA Sugar is a Ribose

DNA bases include A, C, G and T

RNA bases include A, C, G, and U (NO

T!!!)

DNA is double stranded

RNA is single stranded

Let’s go from RNA to Protein! Finally!!

• After mRNA leaves the nucleus, it encounters rRNA and tRNAs in the cytoplasm!

• As the strand of mRNA slides through a ribosomes (rRNA), it binds with tRNA bases, three nucleotides at a time.

• A group of 3 nucleotides is called a codon. Each codon codes for 1 Amino Acid

• 3 nucleotides = 1 codon= 1 Amino Acid! • As each tRNA binds to each codon on the

mRNA, it attaches an amino acid to a chain.

• The chain of amino acids that form is your protein.

This is how we translate codons into amino acids. • Look at the left

side, find the 1st letter in the codon.

• Then look at the top and find the 2nd letter of that codon

• Then look to the right and find the 3rd letter in the codon.

• Example: CGU is a codon that codes for Arginine (Arg)

• Try: (Find A. Acid)-UUA __________-AAG __________

From mRNA to Protein

To translate an mRNA strand to protein: 1) start at the far left2) Find your start codon (AUG) 3) divide the mRNA message into codons4) look the codons up in the genetic code chart.

Example: CCGCAUGCGAAAUAGA (mRNA) AUG | CGA | AAU | AGALook at genetic code to find Amino Acids: Methionine- Arginine-Asparagine-Arginine (Protein!)