DNA Notes_editd2.ppt

7/30/2019 DNA Notes_editd2.ppt

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WARM-UP #7


2/20

DNA

(Deoxyribonucleic Acid)


3/20

Genetic material of cells

GENES units of genetic material thatCODES FOR A SPECIFIC TRAIT

Called NUCLEIC ACIDS

DNA is made up of repeating moleculescalled NUCLEOTIDES


4/20

DNA Nucleotide

O

O=P-OO

PhosphateGroup

N

Nitrogenous base(A, G, C, or T)

CH2

O

C1C4

C3 C2

5

Sugar(deoxyribose)


5/20

A HISTORY OF DNA

Discovery of the DNA double helixA. ___________ Discovers that afactor in diseased bacteria can transformharmless bacteria into deadly bacteria

(1928)B. Avery, et al- Determine thetransforming factor is__________

(1944)

C. Hershey & Chase- tagged_________ & __________ of virusescalled ___________ and determined thatDNA controls _______________.

(1952)


6/20

A HISTORY OF DNA

Discovery of the DNA double helix

D. ___________ Discovers that a factor indiseased bacteria can transform harmlessbacteria into deadly bacteria (1928)

E. _________________- X-ray photo ofDNA.

(1952)

F. _______________- described theDNA molecule from Franklins X-ray.

(1953)


7/20

Chargaffs Rule

Number of Adenine =Thymine

Number of Guanine must pair with Cytosine

Their amounts in a given DNA molecule will beabout the same.

G CT A


8/20

Watson & Crick proposed

DNA had specific pairing between thenitrogen bases:

ADENINETHYMINE

CYTOSINE - GUANINE

DNA was made of 2 long stands of

nucleotides arranged in a specificway called the Complementary Rule


9/20

DNA Double Helix

NitrogenousBase (A,T,G or C)

Rungs of ladder

Legs of ladder

Phosphate &Sugar Backbone


10/20

DNA Double Helix

P

P

P

O

O

O

1

23

4

5

5

3

3

5

P

P

P

O

O

O

1

2 3

4

5

5

3

5

3

G C

T A


11/20

Nitrogenous Bases

PURINES

1. Adenine (A)

2. Guanine (G)

PYRIMIDINES

3. Thymine (T)

4. Cytosine (C) T or C

A or G


12/20

BASE-PAIRINGS

CG

H-bonds

T A


13/20

Genetic Diversity

Differentarrangements ofNUCLEOTIDES in anucleic acid (DNA)

provides the key toDIVERSITY amongliving organisms.


14/20

The Code of Life

The code of the chromosome is the

SPECIFIC ORDER that bases occur.

A T C G T A T G C G G


15/20

DNA is wrapped tightly around

________and coiled tightly to

form chromosomes


16/20

DNA Replication DNA must be copied

The DNA molecule produces 2IDENTICAL new complementarystrands following the rules ofbase pairing:

A-T, G-C

Each strand of theoriginal DNA serves asa template for the newstrand


17/20

DNA Replication

SemiconservativeModel:

1. Watson and Crick

showed: the two strandsof the parental moleculeseparate, and eachfunctions as a templatefor synthesis of a newcomplementary strand.

. Parental DNADNA Template

New DNA


18/20

1. Why is replication necessary?

2. When does replication occur?

3. Describe how replication works.

4. Use the complementary rule tocreate the complementary

strand:

A---?

G---?C---?T---?A---?

G---?A---?G---?C---?A---?G---?T---?

Replication Quiz


19/20

AMAZING DNA FACTS

DNA from a single humancell extends in a singlethread for almost 2 meters

long!!!

It contains informationequal to some 600,000printed pages of 500 wordseach!!!

(a library of about 1,000 books)


20/20

LETS REVIEW DNA

1. List the conclusions Griffith & Avery,Hershey & Chase drew from their

experiments.2. Summarize the relationship between

genes & DNA.

3. Describe the overall structure of theDNA molecule.

4. What are the 4 kinds of bases?

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DNA Notes_editd2.ppt