GETTING TO KNOW DNA:. As you may already know, DNA stands for…. DEOXYRIBONUCLEIC ACID

GETTING TO KNOW DNA:

As you may already know, DNA stands for….

DEOXYRIBONUCLEIC ACID

Functions of DNA

• Contains the code for making proteins

Types of Nucleic Acids

1. DNA (deoxyribonucleic acid):

*double-stranded

*deoxyribose sugar

2. RNA (ribonucleic acid):

*single-stranded

*ribose suger

Nucleic Acid Structure

• The monomer units of DNA are known as nucleotides

• All nucleotides have three “parts” in common: a. Phosphate

b. Pentose sugar a. (ribose or deoxyribose)

c. Nitrogen base

Deoxyribose Sugar (DNA)

• Has 5 carbons• Carbon atoms are numbered 1', 2', 3', 4',

and 5' • 5'-carbons link to the phosphate groups• 3'-carbons link to the hydroxyl groups

• Notice what’s attached to the 5’ end

And the 3’end

Antiparallel

• DNA is antiparallel because one strand runs upside down from the other. (If one strand ends with a phosphate (5’), the other strand will end with a sugar (3’))

Is DNA a monomer or polymer

8.33E-02

92%

1. Monomer

2. Polymer

Table

What does it mean to be a polymer???

What does it mean to be a monomer?

What type of reaction is being shown below?

Cova

lent

Oxi

datio

n

Hyd

roly

sis

Deh

ydra

tion S

ynth

esis

Poly

mer

izatio

n

0%4%

0%

17%

78%

1. Covalent2. Oxidation3. Hydrolysis4. Dehydration Synthesis5. Polymerization

O

O 0

Table

Response

Counter

The molecules marked “Y” and “W”:

86%

0%

0%

0%

14%

1. Polymers and monomers

2. Water and polymer

3. Water and monomer

4. Water and water

5. Monomers and polymers

Table

What two functional groups will be involved in joining nucleotides?

19%

76%

0%

4.76E-02

0%

1. Phosphate and amine

2. Phosphate and hydroxide

3. Amine and amine

4. Phosphate and phosphate

5. Amine and hydroxide

Table

The monomer units of DNA are known as….

NUCLEOTIDES

All nucleotides have three “parts” in common. They all contain….

Sugar= Deoxyribose

Phosphate Group

One of FOUR different NITROGEN BASES

PLEASE UNDERSTAND, A NUCLEOTIDE IS A VERY COMPLEX STRUCTURE. IF WE REPRESENTED ALL OF THE ATOMS, IT

WOULD LOOK LIKE THIS…

The four different Nitrogen Bases for DNA are abbreviated using the following letters….

Adenine

Thymine

Guanine

Cytosine

A

T

G

C

Let’s Practice How to Form DNA!

We will use our hands to represent a nucleotide.

SUGAR

PHOSPHATE NITROGEN BASE

Using your two hands, please show how you think two nucleotides will/should bond together.

Did you put your hands like this???

Time to find out why this is wrong!!!

Adenine and Guanine are larger molecules known as…

PURINES

LOOK! TWO RINGS!!!

b. Purines: combination of a pentagon shaped ring and a hexagon shaped ring

1. Adenine

2. Guanine

THYMINE and CYTOSINE are smaller molecules known as…

PYRIMIDINES

LOOK! Only one ring!!

Nitrogen Base Pairing

• Adenine and Thymine must form two hydrogen bonds to be stable while Guanine and Cytosine must form three– Makes the base pairing system an extremely

simple: the A-T and C-G pairs are the only ones physically possible

Now, when using our hands to represent the nucleotides, we must modify the nitrogen base in order to represent these PURINES and PYRIMIDINES.

How would you represent a large PURINE?

How would you represent a small PYRIMIDINE?

Full Finger

Half Finger

In DNA, a PURINE always bonds with a PYRIMIDINE when forming a “rung” of the DNA ladder.

LOOK! A long finger pairs with a short finger! In other words, a purine pairs with a pyrimidine.

In DNA, Adenine always pairs with Thymine (using two

hydrogen bonds.)

A T

A AND T AT THE ATOMIC LEVEL

In DNA GUANINE always pairs with CYTOSINE (using three hydrogen bonds.)

G C

G AND C AT THE ATOMIC LEVEL

THE

ENTIRE

MOLECULE

AT THE

ATOMIC

LEVEL

Time to use your brain and hands in order to review nucleotide structure and type.

USING YOUR HAND, SHOW ME THYMINE

USING YOUR HAND SHOW ME ADENINE

SHOW ME CYTOSINE

SHOW ME HOW CYTOSINE AND THYMINE BOND TO FORM A RUNG ON THE LADDER

THEY DON’T

OK

Now that you recognize nucleotide type and structure, it’s time to start building the polymer

from these monomers.

In order to make a molecule of DNA, you would need to create many rungs to the DNA ladder.

Look. Many Rungs.

Etc…

What part of the nucleotide alternates to form the sides of the DNA ladder?

Etc…

Sugar, Phosphate.

Sugar, Phosphate.

Sugar, Phosphate.

Etc…

What makes up the “RUNGS” of the ladder?

The Nitrogen Bases

Go Ahead!Stack you hand on top of your partners hands building two rungs of the DNA ladder.

Why is this WRONG????

The sides of the DNA ladder “run” in opposite directions. One side is actually flipped and the nucleotides are upside down!

TRY IT!!!

Because the sides of the DNA “run” in opposite directions, DNA is said to be ANTIPARALLEL.

In this DNA molecule, the THUMB part or better known as the PHOSPHATE GROUP, is said to be the 5 prime (5’) end.

5 prime

5 prime

The “hand” or sugar part of the DNA molecule makes up the 3 prime (3’) end of the DNA ladder.

3 Prime

3 Prime

• Direction of the nucleotides in one strand is opposite to their direction in the other strand: the strands are antiparallel.

• Asymmetric ends of DNA strands are called the 5′ (five prime) and 3′ (three prime) ends– 5' end having a

terminal phosphate group– 3' end having a terminal

hydroxyl group

If you link enough nucleotides together, the DNA molecule begins to take on the characteristic shape known as the

Double Helix

Let’s make a candy version of our DNA

You Need…• Two Pipe cleaners

• Two red twizzlers

• One black twizzlers

• Many toothpicks

• Four different colored marshmallows

The marshmallows represent the nitrogen bases. Let’s decide as a class what colors will represent the following nitrogen bases.

ADENINE=

THYMINE=

CYTOSINE=

GUANINE=

Cut the black twizzlers into 1.5 cm pieces.

These will represent the phosphate groups

Cut the red twizzlers into 3 cm pieces.

These will represent the sugars.

Person One

Person Two

Add the twizzlers to the pipe cleaners.

Remember, you need to alternate SUGAR (red) AND PHOSPHATE GROUPS (black).

When you are finished, your strand should not end in the same color you started with!

Did you and your partner make the same number of nucleotides

on the sides of your ladder?

If not, FIX IT!!!

Time to put together the two sides.

Using the toothpicks and marshmallows, you are to add the nitrogen bases to the sides of the ladder. Remember, the nitrogen bases “come off” the sugar part of the nucleotide. As a result, they should be coming off of the red twizzler.

Please use two of the same color marshmallows to represent one ADENINE and GUANINE. The BIG purines.

Please use only one marshmallow to represent THYMINE and CYTOSINE. The small pyrimidines.

Following your teachers directions, let’s build one

long strand of DNA

A Particular strand of DNA contains 10 adenine molecules. How many thymine will

it contain:

0%

0%

0%

0%

1. 5

2. 10

3. 20

4. Not enough information

Table

A strand of DNA is 20% Guanine molecules. What is the percent of thymine in the strand

of DNA?

0%

0%

0%

0%

0%

1. 10

2. 20

3. 30

4. 40

5. Not enough information

Table

A particular strand of DNA is 40% guanine. What is the percent of adenine in the same

strand?0%

0%

0%

0%

1. 10

2. 20

3. 30

4. 40

Table

The molecule at the location identified by the arrow:

0%

0%

0%

0%

0%

1. Adenine

2. Guanine

3. Sugar

4. Phosphate

5. thymine

Table

The molecule at the location identified by the arrow:

0%

0%

0%

0%

0%

1. Adenine

2. Guanine

3. Sugar

4. Phosphate

5. thymine

Table

The molecule at the location identified by the arrow:

0%

0%

0%

0%

0%

1. Adenine

2. Guanine

3. Sugar

4. Phosphate

5. thymine

Table

The end of the molecule identified by the blue arrows:

0%

0%

1. Five prime

2. Three prime

Table

The end of the molecule identified by the red arrows:

0%

0%

1. Five prime

2. Three prime

Table

Because the sides of the DNA ladder run in opposite directions, DNA is said to be…

0%

0%

0%

0%

1. Parallel

2. Nonparallel

3. Antiparallel

4. proparallel

Table

What do you notice about all the DNA molecules in the room?

• They are all different!

If your DNA ladder contains 28 red segments of licorice, how many nucleotides

would your DNA ladder contain?

1 14 28 42 56

0% 0% 0%0%0%

1. 1

2. 14

3. 28

4. 42

5. 56

Table

What name is given to the reaction that was used to create this candy molecule?

Hyd

roly

sis

Fer

tiliza

tion

Deh

ydra

tion S

ynth

esis

Cro

ssin

g ove

r

0% 0%0%0%

1. Hydrolysis

2. Fertilization

3. Dehydration Synthesis

4. Crossing over

Table

In the diagram below, how will these two molecules join together?

OH HO

If you were making our candy molecule in a cell where would you be found?

Cyt

oplasm

Endop

lasm

ic R

etic

ulum

Golg

i Body

Nucl

eus

Vac

uole

0% 0% 0%0%0%

1. Cytoplasm

2. Endoplasmic Reticulum

3. Golgi Body

4. Nucleus

5. VacuoleTable

Looking around the room you noticed that a particular strand of DNA contains 20% adenine

marshmallows. What percentage of Thymine can be expected in that piece of DNA?

1% 10%

20%

40%

80%

0% 0% 0%0%0%

1. 1%

2. 10%

3. 20%

4. 40%

5. 80%Table

If a DNA molecule contains 30% Guanine, then you would expect it

to have how much Adenine?

15%

20%

30%

40%

60%

0% 0% 0%0%0%

1. 15%

2. 20%

3. 30%

4. 40%

5. 60%Table

What is a GENE?