Download DNA - ScanlinMagnet

DNA: DEOXYRIBONUCLEIC ACID (DNA)
Heritable info
Can be passed from parent
to offspring
Codes for proteins
Hair, eye color, taste
DNA SHAPE
• Two strands stuck together
• Shaped like a twisted ladder
• “Double Helix”
• Each strand is stuck to a
matching strand
• A “complementary” strand
• Wow that scarf really
complements your hat
Complementary
strands
DNA STRUCTURE
•Made of parts
• Nucleotides
• Has 3 parts.
1.Phosphate group
2.Sugar (Deoxyribose)
3.Nitrogen base
NITROGEN BASES
4 types
1. Adenine (A)
2. Guanine (G)
3. Cytosine (C)
4. Thymine (T)
Do you notice anything about the shape of the
bases?
CYU
Label this
nucleotide
*Phosphate
*Sugar
* Base
NUCLEOTIDES FORM DNA
• Many nucleotides bond to form
DNA
• Stuck together by sugar &
phosphate
• “backbone” of DNA
• Bases face complement strand
• Each strand bonded together by
bases
• Hydrogen bonded
• VERY weak
• Easy to come apart
• Easy to stick together
IMPORTANCE OF BASES
• Bases are what is “read” in DNA
• Forms the code/gene in DNA
• How do enzymes “read” DNA bases if they cant see?
• The feel the inside
• How do they feel the inside of bases when each is stuck
to their complementary strand?
• Unzip weak hydrogen bonds
QUESTION
Can you describe anything about this picture.
Do you see any patterns?
CHARGAFF’S OR BASE PAIRING RULE
Adenine (A) bonds
with Thymine (T)
A=T
Guanine (G) bonds
with Cytosine (C)
G=C
CYU
According to “Chargaff’s Rules” what will the
complimentary strand of DNA be for the
molecule below?
T
REPLICATION
Replication
 Process in which DNA copies itself before cell division
Important so each new cell has a complete set of DNA molecules
Base pairing “Chargaff’s Rules” explains how DNA can be replicated
(copied)
A=T&G=C
Each strand has the information to reconstruct the other strand
ENZYMES ARE USED IN DNA REPLICATION
Helicase unwinds
double helix
Polymerase
binds new DNA strands
REPLICATION
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Overall direction
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PROOFREADING
DNA must be faithfully replicated…but mistakes occur
 Repair: ‘wrong’ inserted base can be removed. DNA may
be damaged by chemicals, radiation, etc. Mechanism to
cut out and replace with correct bases
DNA’S JOBS
DNA makes up genes
Must:
1)store
2)copy
3)transmit genetic information
STORING INFORMATION
DNA stores hereditary info
Instructions for development
Determines what an organism or cell will be
Info about traits
Eye color
Blood type
Flower color
TRANSMITTING INFORMATION
Genes transmitted from one generation to next
DNA passed along during cell division
 Loss of DNA means loss of genetic info
Next we will talk about mutations!!!