Download The Structure of DNA

What is DNA?
 DNA - the genetic material required for the
building, maintenance, and regulation of the
cells of all living organisms.
 Stands for deoxyribonucleic acid
 DNA can come in two forms in a cell
 Chromatin – unpackaged DNA
 Chromosomes – packaged DNA

Made of one unbroken DNA molecule coiled with
protein molecules
What is DNA?
What are Genes?
 Genes – are sequences of DNA that code for
proteins and thus determine traits.
 Each chromosome contains thousands of
genes.
 Each gene is a specific sequence of DNA
nucleotides.
 Trait – a specific characteristic of an
individual
 Can be physical or behavioral
What’s the relationship?
What is the relationship between:
DNA, CHROMOSOMES, GENES, AMINO ACIDS, PROTEINS, and TRAITS
Organized into
CHROMOSOMES
Determine
TRAITS
DNA
Sections are
GENES
Specific
instructions to
make a PROTEIN
Made of AMINO
ACIDS
What are the parts of DNA?
 Nucleotides
 3 component parts



Sugar molecule –
Deoxyribose
Phosphate Group
Nitrogen Base
 Label parts &circle
one nucleotide
 Label parts & circle
model in NB
What are the parts of DNA?
 DNA “Backbone”
 Sugar molecule –
Deoxyribose
 Phosphate Group
 Label and circle the
backbone
 Label your model
in NB
What are the parts of DNA?
 Nucleotide Types
 4 different types




Adenine – A
Guanine – G
Cytosine – C
Thymine - T
What are the base pair rules?
 Complementary
Base Pairing Rules
 Also known as
Chargaff’s Rule
 A with T

G with C
How are the parts connected?
 Connections
 Covalent bonds (CB)
for one strand
 Hydrogen bonds
(HB) to connect
complementary base


3 HB between G and C
2 HB between A and T
 Label, point to a HB &
CB; label model in NB
Record your answers in your notebook - #19; Record answer first in notebook and
then place answer on white board!
Question #1
What is the name
of the structure
the arrow is
pointing at?
Answer:
Phosphate
Group
Question #2
What is the name
of the structure
the arrow is
pointing at?
Answer:
Sugar
(deoxyribose)
Question #3
What is the name
of the structure
the arrow is
pointing at?
Answer:
Hydrogen bond
Question #4
What is the name
of the structure
the arrow is
pointing at?
Answer:
C (cytosine)
Question #5
What is the name
of the structure
the arrow is
pointing at?
Answer:
T (thymine)
Question #6
What is the name
of the structure
the arrow is
pointing at?
Answer:
Covalent bond
Question #7
 What is the complementary strand for the
following?
A
__
A
__
Answer:
T
T
A
__
G
__
A
__
C
__
C
__
T
__
T
__
T
C
T
G
G
A
A
Question #8
 What does DNA stand for?
 Answer: Deoxyribonucleic Acid
Question #9
 Describe the relationships among DNA,
chromosomes, genes, amino acids,
proteins, and traits. (you may use a flow
chart or diagram to show relationships)
Question #10
 Using words and/or diagrams, describe
the structure of DNA? Be sure to discuss:
(1) the three parts of a nucleotide
(2) the four types of nucleotides and their
base-pairing
(3) the arrangement of the nucleotides in
DNA (How are the nucleotides in one strand
connected? How are the two strands
connected?)
(4) two other key features or characteristics
How is DNA copied?
 Replication is aided by the enzyme DNA
polymerase.
 Steps to replication:
DNA strands are separated
2. Each strand is a template and new nucleotides
are added one at a time according to base
pairing rules
3. Two new DNA strands form hydrogen bonds
with the template strands
1.
Why is DNA copied?
 DNA is replicated for two reasons:
 To go into gametes (sex cells – egg and sperm) - Meiosis
 To go into new cells for growth and maintenance - Mitosis
Mitosis