DNA Structure.Protein Synthesis for website

What is DNA?

1. A molecule

2. A living thing

3. A type of cell

Where is DNA found?

1. In skin, hair, blood, sperm and egg cells

only.

2. In animal cells only.

3. In animal and plant cells only.

4. In all cells.

B. How is DNA related to

chromosomes and genes?

For glossary:

CHROMOSOME = DNA Molecule

(A gene is a section of a DNA molecule. We’ll define it more completely later…)

DNA Structure

• Study the DNA structure at

your lab station

• With your partner look for

patterns

C.

What are the themes

or patterns that occur

over and over again?

Be specific.

D.

What is the relationship between a

nucleotide

E. Based on your nucleotide kit and reading,

compare/contrast RNA & DNA nucleotides:

• DNA

• RNA

RECAP:

Each

Nucleotide

has 3 parts:

RNA

Ribose

PO4

Adenine = A

Uracil = U

Cytosine = C Guanine = G

Deoxyribose

PO4

Adenine = A

Thymine = T

Cytosine = C Guanine = G

sugar

1. SUGAR:

2. PHOSPHATE:

DNA

F.

1. 2 strands, like a ladder. 2. Sides (sugars and

phosphates) held together by

strong bonds.

3. “Rungs” (nitrogen bases) held together by weak bonds.

4. Whole ladder twisted into a “DOUBLE HELIX”.

STRONG bonds WEAK bonds

HOW DOES THE OVERALL STRUCTURE OF RNA DIFFER FROM THIS?

Some questions remain: What exactly does

DNA do – and how does it do it??? And

what does RNA have to do with anything?

We already know:

But what is a gene?

And how does DNA “determine traits”?

• Parents give offspring DNA

UNDERLYING CAUSES OF SOME GENETIC DISEASES

• Huntington's Disease: defect in gene for the protein huntingtin.

• _{PKU: defect in gene for the enzyme phenylalanine hydroxylase.} • _{Sickle Cell Anemia: defect in gene for the protein hemoglobin}

• _{Achondroplasia (dwarfism): defect in gene for the protein fibroblast growth factor.} • Marfan's disease: defect in the gene for protein fibrillin.

• _{Cystic fibrosis: defect in the gene for protein transmembrane conductance}

regulator.

• _{Tay Sachs disease: defect in the gene for the enzyme beta-hexosaminidase A} • _{Progeria: defect in the gene for the protein progerin.}

• Neurofibromatosis: defect in the gene for protein neurofibromin 1.

G.

Is there a pattern?

Based on this, what do you think a “gene” does? What kind of “information” must be in the DNA molecule?

GENE:

The section of a DNA molecule that

contains the instructions for one protein.

So now we know that DNA contains the

instructions for building proteins.

Those

C’

T

G

A

PROTE_IN RECIPE_S FOR O_NE HUMAN

Our DNA is like a giant recipe book for all the proteins our body needs, and it is those proteins that make each of us unique.

There are about 20,000-25,000 recipes, and every cell in our body has a complete set of them.

PROTEIN STRUCTURE: Quick Review

–

_{What do we know}

about the structure

of proteins?

• What are they

made of?

• How many different

amino acids are

What would we need to know if we wanted to build

a certain protein, for example

insulin

?

• How many amino acids

total are in the two chains

of insulin?

• The gene for insulin

contains

153 nucleotides.

• Let’s look at a couple of

other examples of proteins

and the genes that code for

them.

H.

Compare numbers. Any

similar patterns in

numbers of amino acids

and the nucleotides that

code for them?

I.

So…what hypothesis can

you make about how the

code works?

CODON: each 3-letter sequence in a DNA molecule codes for one of the 20 amino acids and is called a “codon”.

For glossary:

(FYI there are 64 different 3-letter combinations possible using A, T, C and G)

Scientists have figured out what amino acid

is specified by each

3

-letter sequence (or

“codon”).

This shows the same information organized

in a different way:

FACT: this code is identical for every single living thing.

•For example “TCA” means

“serine” to every living cell

whether human, pine tree, mushroom, bacteria… etc.

•What might be the significance of this?

Where in a cell is the DNA

found?

Always?? Can it ever leave?

Nucleus

Where in a cell are proteins made?

Where are ribosomes found?

Ribosomes

• Soooo…what’s the problem??

How do the ribosomes

know what to do?

How do the instructions get

from the DNA in the

nucleus to the ribosomes??

Instructions here (DNA in nucleus)

“Job site” here

(ribosomes)

An Analogy:

Building a

Sky Scraper

Where are the master plans (blueprints)

for the project kept?

Does the foreman ever

let the blueprints leave

the trailer?

WHY NOT??

So what if someone needs the plans to work on

part of the project – say, the restroom on the 3

Can you think of anything that can move

freely around a cell that could possibly

“copy” part of a DNA molecule and

carry the copy out to the ribosomes?

WORD BANK

• nucleus

• DNA molecule • Strong bonds • Weak bonds • Enzyme

• Unzip • Gene

• nucleotide pool

• Complementary RNA nucleotides • mRNA

• Copy of recipe

• nuclear membrane • cytoplasm

• ribosome

• Complementary tRNA • Specific amino acid • peptide bond

• Protein

1. Follow PROTEIN SYNTHESIS KIT directions to act out and narrate the steps of protein synthesis using all words in the word bank correctly. Put up RED cup when all members of group are ready to demonstrate.

2. When done or waiting to be tested:

• Make sure you can answer the following questions:

1) Compare and contrast the 2 types of RNA in terms of location, structure and function.

2) What is the minimum number of different tRNA’s a cell could have? Why?

3) What are the advantages of having RNA carry the instructions for proteins to the ribosomes instead of having the DNA molecule go there and do it directly?

• Help other groups.

• Read “MUTATIONS” and answer the summary questions.

Take your

OP sheet

with you to

lab table.

1. Follow PROTEIN SYNTHESIS KIT directions to act out and narrate the steps of protein synthesis using all words in the word bank correctly. Put up RED cup when all members of group are ready to demonstrate.

2. When done or waiting to be tested:

• Make sure you can answer the following questions (for a

possible future SRI ):

1) Compare and contrast the 2 types of RNA in terms of location, structure and function.

2) What is the minimum number of different tRNA’s a cell could have? Why? 3) What are the advantages of having RNA carry the instructions for

proteins to the ribosomes instead of having the DNA molecule go there and do it directly?

• Do a practice write of your explanation of protein synthesis.

(This will be an SRI in the next 3 days. You will have the word bank but will not be allowed to use notes.)

• Start on tonight’s HW.

Take your OP

sheet with you to

lab table.

P.S. What is the “SECRET WORD” from the Protein Synthesis Kit? Make sure you know! (Don’t tell – let others figure it out themselves!)

Write out your description of how protein synthesis

occurs in a cell. Use all of the terms correctly.

UNDERLINE the terms as you use them in your

explanation. (no credit for words not underlined)

• nucleus

• DNA molecule • Strong bonds • Weak bonds • Enzyme

• Unzip • Gene

• nucleotide pool

• Complementary RNA nucleotides

• mRNA

• Copy of recipe

• nuclear membrane

• cytoplasm

• ribosome

• Complementary tRNA

• Specific amino acid

• peptide bond