Modern Genetics Notes DNA, RNA, PROTEIN SYNTHESIS

Concept: RNA Section: Notes

RNA Background THE STRUCTURE OF RNA. 1. RNA stands for: ____________ ___________ _________ How is this different than DNA?

2. DNA and RNA are both organic molecules called __________________acids. 3. RNA is made up of subunits called _____________________.

a) sugar = _____________ (what was the sugar in DNA? ________________)

b) Nitrogenous __________ c) _____________________ group 4. Differences between DNA and RNA:

a) different _____________ b) ONE different base! Instead of T (thymine), there’s a U (__________)

c) RNA is only a ____________________ strand! (NOT a double helix) The four _____________ bases bond together in a specific way in RNA also:

____________ bonds to ____________ ____________ bonds to ____________ THE FUNCTION OF RNA There are 3 types of RNA:

Types Full Name Function Where it is found in the cell

mRNA

tRNA

rRNA

Protein Synthesis Background THINGS YOU MAY ALREADY KNOW:

1. DNA is a code. The “code” (instructions) is found as a sequence of ________________. 2. The DNA code is really instructions for making ______________________.

3. A polypeptide is just another name for a _________________.

4. Proteins are made from long chains of __________ __________ (the building blocks).

5. Proteins make up many of the important parts of an organism. Name some below :

• • •

6. In a cell, proteins are made in the organelles called __________________. STEPS TO MAKING A PROTEIN.

1. DNA “lives” in the _____________________ of a cell. IT NEVER LEAVES! Here’s the problem. DNA needs to make a protein. It has the instructions for making it,

but it is not allowed to leave the nucleus! Since the instructions for a certain protein is just a few nucleotides on the DNA, what do you think happens?

2. A short section of the double helix _________________ and the 2 sides of the DNA “ladder” ________________ from each other.

3. A copy of the short section of DNA is made – just 1 side – so it is ______________ stranded.

This copy is called _________________RNA (mRNA).

The copy is not exactly like the DNA strand. Instead of the nucleotide Thymine, RNA has the nucleotide ____________. (A – U and G – C)

4. How is mRNA different from DNA? mRNA is _________________ -stranded mRNA is allowed to leave the _____________________. (it is MOBILE!) mRNA has the nucleotides A, C, G, but not ________! It uses _______.

So, now that we have a single-stranded, short copy of the information needed to make our protein, it ’s t ime to travel and build it!!!!!

Modern Genetics Notes Cont’d Concept: Prot Syn Section: Notes

5. The mRNA takes the code to a _______________________ in the cell. 6. Ribosomes are wonderful, but they can only read ____ letters of code at a time. They start

reading the mRNA code strip in groups of 3 letters called ___________. 7. Each time the ribosome reads 3 letters on the mRNA, it calls for another molecule called a

_________, which carries an amino acid. (tRNA stands for ________________ RNA)

tRNA is like a dump truck. It picks up the amino acid that is needed and brings it to the ribosome where it dumps it off.

There are hundreds of different tRNAs floating around a cell. So, if the codon on the

mRNA is GGG then the ribosome calls for a tRNA with the opposite code _______. Since this tRNA code is the exact opposite of the mRNA codon, it is called the _________________.

8. Now, remember we’re trying to make a PROTEIN, so each time a tRNA brings an _____________ _________ to the ribosome, the amino acids link together!

And PRESTO --- we have a protein (polypeptide)!!!!