Download DNA Characteristics

DNA
Characteristics
Why is DNA important to
study?
What characteristics should
genetic material not have?
Should
Should Not
Review
DNA
Gene
Protein
Trait
Any brave volunteers to explain our “Big Picture” view?
DNA
Part 1: The basics
So far...
The Big Picture
DNA => Genes => Proteins => Traits
Physical traits come from heredity
Chargraff’s Data
Ratios of DNA molecule => A:T & G:C always
close to 1:1
Different percentages for different species
leading to different traits
What is DNA
DNA molecules are long chains linking
four subunits (smaller molecules),
whose sequence encodes genetic
information
Watson & Crick’s Model
What’s that DNA stuff Made
of?
DNA = deoxyribonucleic acid
The DNA chain is made of many nucleotides
joined together (a polymer).
Nucleotides (a monomer)= molecules with
1.a sugar portion (the “deoxy” form of ribose)
[same]
2.a phosphate group [same]
3.a nitrogen base [4 different]
O
Nucleotides
O -P O
One
deoxyribose
together
with
O
O its phosphate and base make a
O -P O
nucleotide.
O O
O -P O
Nitrogenous
O
O
base
Phosphate
C
C
C
ODeoxyribose
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One Strand of DNA
nucleotide
•
One strand of DNA is a
polymer (chain) of
nucleotides.
•
One strand of DNA has
many millions of
nucleotides
12
The 4 nitrogen bases of DNA
are...
Adenine
Thymine
Guanine
Cytosine
How do I remember?
“All Turtles Go Camping”
“All Teachers Get Cranky”
DNA Structure
Overall Structure
DNA forms into a “double helix,”
or a twisted ladder shape
The sugar-phosphate backbone
forms the “legs” of the ladder
The bases paired up between the
legs form the “rungs” of the
ladder/helix
The bonds between the sugar
and phosphate groups form the
twist of the helix
Ladder
The Double Helix
The 4 Nitrogen Bases of DNA
Are...
A always pairs with T
G always pairs with C
WHY??
Chargaff’s ratios
Practice Problem
If an organism has a 64% GC content, what
percent of A, T, C and G does it have?
A = 18
T = 18
G = 32
C = 32
Chromosomes
Chromosomes are tightly wound DNA…
Think of twisting a piece of string
21
Chromosomes
•
http://www.mhhe.com/socscience/anthropology/s
tein2003/stein.html
•
http://learn.genetics.utah.edu/content/begin/dna/
•
The human genome:
http://www.ornl.gov/sci/techresources/Human_G
enome/posters/chromosome/chooser.shtml
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DNA by the Numbers
•
Each cell has about 2 m
(6 feet) of DNA.
•
The average human has
30-50 trillion cells.
•
The average human has
enough DNA to go from
the earth to the sun more
The earth is 150 billion m
than 400 times.
•
DNA has a diameter of
only 0.000000002 m.
or 93 million miles from
the sun.
23
Create a concept map, connecting the
below ideas with lines. On each line,
write a 5+ word description of how the
2 ideas connect.
•
DNA structure
•
Phosphate
•
Deoxyribose sugar
•
Nitrogen bases
•
Chromosome
• Adenine
• Cytosine
• Thymine
• Guanine
• Nucleotide
• Double helix
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Make a strand…
•
Make one strand of DNA that is 36 base pairs
(bp) long
•
•
Write them in 3-bp groups
Write the corresponding bp’s under the original
strand
25
Quiz
1.
2.
3.
4.
What are the three parts of a nucleotide?
Which parts make up the backbone of a DNA strand?
List the two base pairs found in DNA.
If six bases on one strand of a DNA double helix are
AGTCGG, what are the six bases on the complementary
section of the other strand of DNA?
26
Karyotypes
•
A karyotype is a full set of an organism’s
chromosomes that can be used to determine if a
person has chromosomal abnormalities
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