DNADNAthe Blue Print of Lifethe Blue Print of Life

DNADNAthe Blue Print of Lifethe Blue Print of Life

Biology 10Biology 10

Understand that DNA is the Blue Print or Code that Controls

all activities in living creatures

1. Growth

2. Repair

3. Hormones

4. Enzymes

5. Eye color

6. Behavior

7. Hair color

……..

You Probably know DNA like this

DNA Developed you from this

Head

Spine

To This

Into this - Yikes

But How did they ever discover DNA?

The story begins with a curious experiment conducted by Dr. Griffiths

with white mice…….

What was killing these Mice?

Hershey-Chase Experiment

Researchers had to determine if DNA was genetic material and not protein

1. Was it DNA or proteins that was the genetic material?

2. Bacteriophages - viruses useda. protein coatb. nucleic acid interior (DNA

core)

3. Radioactive labeling of protein & DNA

4. Results showed that DNA directed the formation of new viruses, not the protein coat

Discovery of DNA Structure

Components of DNA 1. DNA consists of a sugar,

base and phosphate group

2. One of 4 possible bases:

adenine (A)cytosine (C)guanine (G)thymine (T)

DNA Structure – The Twisted Ladder

The Nucleotide:

1. Sugar

2. Phosphate Group

3. Nitrogenous Base

Ribose Sugar

Phosp

hate

Base

Experiments – 1949

1. the amount of A = amount of T

2. the amount of C = amount of G

3. ratios vary by species

X-Ray experiments

1. Used X-rays to examine structure of DNA

2. Observed thata. DNA is helicalb. DNA exists in long

strandsc. DNA is highly repetitive

Watson-Crick Analysis of DNA 1. Constructed a model of DNA

structure 2. Phosphate groups from backbone3. Double-stranded molecule4. Base=pairing of A-T and G-C5. Helical shape

DNA Replication & Repair

A. Replication 1. replication is semi-conservative2. major molecules

a. unwinds DNA strandsb. DNA polymerase - copies DNAc. molecular glues seal newly

formed DNA strands

B. DNA Repair

1. DNA polymerase “proofreads” the new strands

2. Glues help to repair mismatched bases

DNA OrganizationA. Chromosome structure

1. DNA is organized into long molecules called chromosomes

2. Chromosome are stabilized by proteins called histones

3. Histones organize the DNA

DNA has been Mapped – E. Coli DNA

Plants have been able to Clone themselves and their DNA

forever

Scientists Did this with Sheep

The Human Genome Project

Science Fiction?Science Fiction?