T.G.I.T. !!! 3/23/101. What are the What are the NAMESNAMES of the nucleotides?of the nucleotides?

2. How do they 2. How do they pair uppair up??

3. What are the 3. What are the 3 3 moleculesmolecules that make up a that make up a nucleotide of DNA??nucleotide of DNA??

Practice for you!! Practice for you!! Please answer on a new piece of paper!Please answer on a new piece of paper!

1.1. How many types of nucleotides are in DNA??How many types of nucleotides are in DNA??

2.2. How are they different?How are they different?

3.3. How are they the same?How are they the same?

4.4. What are the base pairing rules for DNA? What are the base pairing rules for DNA?

5.5. What is a double helix?What is a double helix?

6.6. What is DNA? What is DNA?

7.7. Where is DNA found??Where is DNA found??

8.8. What are the 3 molecules that make up a What are the 3 molecules that make up a nucleotide of DNA??nucleotide of DNA??

9.9. What sequence of bases would pair with the What sequence of bases would pair with the sequence: TGACTAsequence: TGACTA

10.10. A sample of DNA is 31.5% adenine (A). Predict A sample of DNA is 31.5% adenine (A). Predict the approximate %s of G, T, and C.the approximate %s of G, T, and C.

8.3 KEY CONCEPT DNA replication copies the genetic information of a cell!

What does replication mean????

•To COPY!!!!

Why does a cell need to replicate its DNA???

Why does a cell need to REPLICATE its DNA?

Replication copies genetic information

•Remember this stuff? Remember this stuff? •When does DNA When does DNA replication occur????replication occur????

Replication copies genetic information • DNA is replicated during theDNA is replicated during the

S (synthesis) S (synthesis) stage of thestage of thecell cycle!cell cycle!

• DNA needs a template, can’t DNA needs a template, can’t do it alone!!!do it alone!!!

• Base pairing rules Base pairing rules

complementary copy!!!complementary copy!!!• Each new cell gets a complete Each new cell gets a complete

set of identical DNA.set of identical DNA.

• Replication = process, DNA is copied during cell cycle (S phase of interphase)

• each new cell has its own full copy of DNA

Proteins carry out replication!• DNA serves only as a DNA serves only as a template! template! • Enzymes /proteins do the WORK of replication!Enzymes /proteins do the WORK of replication!

1. Enzymes 1. Enzymes unzipunzip the double helix. the double helix.

2. Free-floating nucleotides form 2. Free-floating nucleotides form H bonds H bonds with with template strand.template strand.

3. result: 2 identical double strands!!!3. result: 2 identical double strands!!!

nucleotide

The DNA molecule unzips in both directions.

Let’s see this in action...

• http://www.classzone.com/cz/books/bio_07/resources/htmls/animated_biology/unit3/bio_ch08_0237_ab_dnarep.html

p. 237: Label the STRUCTURE SIDE of the diagram! You can do it! You are You are amazingamazing!

Word BankWord Bank::

Newly Newly synthesized synthesized strand of DNAstrand of DNA

Nitrogen BasesNitrogen Bases

Sugar-Sugar-phosphate phosphate BackboneBackbone

DNA DNA polymerasepolymerase

Sugar-Sugar-phosphate phosphate backbonebackbone

Nitrogen Bases Nitrogen Bases (A,T,G,C)(A,T,G,C)

DNA DNA polymerase polymerase (enzyme)(enzyme)

Newly Newly synthesized synthesized strand of DNAstrand of DNA

(complementary)(complementary)

Enzymes unzip Enzymes unzip dbl helix in 2 dbl helix in 2 directions @ directions @ same timesame time

Nucleotides pair Nucleotides pair with exposed with exposed bases on bases on template strandtemplate strand

DNA DNA polymerase polymerase bonds new bonds new n’tides togethern’tides together

2 molec’s of DNA, 2 molec’s of DNA, identical to original; identical to original; each has 1 old & 1 each has 1 old & 1 new strandnew strand

– DNA polymerase enzymes DNA polymerase enzymes bond the bond the nucleotides togethernucleotides together to form the double to form the double helix.helix.

– What kind of bonds hold the bases What kind of bonds hold the bases together????together????

DNA polymerase

new strand nucleotide

• .

original strand new strand

Two molecules of DNA

• Two new molecules of DNA are formed, each with an original strand and a newly formed strand.

• DNA replication is semi-conservative!

Let’s try it!•We are going to extract DNA We are going to extract DNA

from Strawberries! from Strawberries! YUMYUM! ! •You mustYou must

– Follow directions, or it won’t workFollow directions, or it won’t work– Let’s see....40 points for Lab Let’s see....40 points for Lab Participation Participation

– Follow directions!!!Follow directions!!!– Puzzle Activity AfterPuzzle Activity After