© Amy Brown Science
Lesson 3.02 DNA Replication
Unit 3…Genetics!!
3.01 - Cell Division (Mitosis)
3.01A - Binary Fission / Asexual Reproduction
3.02 - DNA Replication
3.03 - Protein Synthesis
3.04 - Mutations
3.05 - Meiosis (Sexual Reproduction)
3.06 - Mendel
3.07 - Hereditary Patterns
3.08 - Biotechnology
3.09 - DBA (Exempted if you completed 1 or 2)
Module 3 Enhanced Assignment
3.10 - Segment 1 Exam!!!
Make sure you are taking notes (Don’t be like Dipper)
3.02 DNA Replication
(EOC Practice)
3.02 DNA Replication
Let’s Quickly Recap!!!
1.02 Macromolecules - What are the 4 types?
3.01 Cell Cycle - What are the 3 stages of Interphase?
Let’s Quickly Recap!!!
1.02 Macromolecules - What are the 4 types?
3.01 Cell Cycle - What are the 3 stages of Interphase?
3.02 and 3.03: DNA Replication
and Protein Synthesis
Phosphate + sugar + nitrogen base = 1 nucleotide
Phosphate
Deoxyribose Sugar
Nitrogen Base
The four nucleotides that make up DNA differ by the type of nitrogenous base they contain: adenine, guanine, cytosine, and thymine.
a) Adenine – A
b) Guanine – G
NOTE: The nitrogen base uracil is only found in RNA. We will discuss uracil later.
Purines are double ring structures.
c) Thymine – T
d) Cytosine – C
The four nitrogen bases found in DNA are:
Guanine
Adenine
Cytosine
Thymine
Uracil
Pyrimidines are single ring structures.
Purines
Pyrimidines
Model of DNA
A double helix looks like a ____________.
twisted ladder
The sides of the ladder are formed from alternating sugar and phosphate groups.
The rungs of the ladder are formed by …
… two nitrogen bases that pair together across the center of the helix.
Alternating sugar and phosphate groups
Two nitrogen bases paired across the center of the helix.
The two strands are joined by weak _________ bonds.
hydrogen
These hydrogen bonds form only between certain base pairs.
Adenine is always bonded to thymine
and guanine is always bonded to cytosine.
Model of DNA
Hydrogen bonds
Hydrogen bonds
This is called the “base pairing rules”.
Every _______ in the DNA molecule is bonded to a _______.
(A-T)
Every ________ in the DNA molecule is bonded to a _______.
These are called complementary base pairs.
Model of DNA
adenine
thymine
cytosine
guanine
(C-G)
The two sides of the ladder are made up of alternating sugar and phosphate molecules.
The rungs of the ladder are formed by the nitrogenous bases.
Two bases form each rung.
The bases are covalently bonded to a sugar-phosphate unit.
The paired bases meet across the helix and are joined together by hydrogen bonds.
sugar
sugar
sugar
sugar
phosphate
phosphate
phosphate
phosphate
nitrogen bases
nitrogen bases
Covalent
bond
hydrogen
bond
© Amy Brown Science
DNA as a Carrier of Information
A necessary property of genetic material is that it be able to carry information.
The DNA molecule is able to do this.
The information is carried in the ________________________ and any sequence of bases is possible.
sequence of nitrogen bases
Since the number of paired bases ranges from about 5,000 for the simplest virus to 6 billion in human chromosomes, the variations are infinite.
DNA as a Carrier of Information
If the DNA from a single human
cell were stretched out, it would
reach about 6 feet. It would carry
information equivalent to 1,200
books! And yet all of this information
can be copied in just a few hours with
very few errors.
Replication of DNA – An Overview
The structure of DNA allows it to be easily copied or replicated.
Each strand of the double helix has all the information needed to construct the other half by the mechanism of base pairing.
Because each strand can be used to make the other strand, the strands are said to be complementary.
Replication of DNA – An Overview
During DNA replication, the molecules separate into two strands.
Each strand serves as a template for producing a new strand.
Two new complementary strands are produced according to the base pairing rules.
Steps in Replication
1. The parent molecule has ________________________ of DNA.
Each base is paired to its specific partner by _______________.
Adenine always pairs with _______.
Cytosine always pairs with _______.
two complementary strands
hydrogen bonding
thymine
guanine
Steps in DNA Replication
1: Separation: DNA unzips into 2 strands, breaking the Hydrogen bonds. Each parent strand now serves as a template.
2: DNA polymerase helps to organize the complementary nucleotides pairing up with their partner (G-C, T-A) along both sides.
3: Sugar-phosphate units re-form & connect the “rungs” of the ladder.
Where there was one double-stranded DNA molecule at the beginning of the process, there are now two.
Each is an exact replica of the parent molecule.
Question 1: If the template strand has the bases ACTGCA, what new complementary strand would be produced?
2. If the template strand has the bases TGACTTAC, what new complementary strand would be produced?
Question 1: If the template strand has the bases ACTGCA, what new complementary strand would be produced?
Answer: TGACGT
2. If the template strand has the bases TGACTTAC, what new complementary strand would be produced?
Bio Flash Back!
Bio Flash Back!
Lesson 2.03 & 3.01: Inside the nucleus, the cell's DNA and some proteins are packed together into chromosomes.
Lesson 2.03: Ribosomes are where proteins are made. They are also known as the "factory" of the cell
Lesson 1.02: Proteins are large biological macromolecules that are made up of smaller molecules, called amino acids.
Questions?
Now What?
Complete the 3.02 DNA Replication Quiz in your gradebook.
GimKit Review