Who was Gregor Mendel and what did he discover?

How many chromosomes are found in the nucleus of each human body cell?

During cell division, your cells DNA is replicated during which part of the cell cycle? G1 (Growth Phase S (synthesis) G2

After Mendel’s work, scientists wondered what are genes made of?

Through experimentation of scientists **Griffith, Hershey, & Chase**, scientists became convinced that genes were made of DNA

One question then arose….

What is the structure of DNA?

I can – describe the structure of DNA

DNA Structure

Knowing the structure of DNA was important because it clarified how DNA could serve as genetic material

Scientists **Watson & Crick** pieced together a model of the structure of DNA

DNA Structure

Double helix- 2 strands twisted around each other (winding staircase)

Each strand was made of nucleotides. (subunits of DNA)

Each nucleotide is made of 3 parts.◦A phosphate group◦A five carbon sugar -

deoxyribose◦A nitrogen containing base Adenine (A) Guanine (G) Thymine (T) Cytosine (C)

◦Draw & label the three parts of a nucleotide in the box your notes

DNA resembles a ladder twisted like a spiral staircase. The bases represent the ladder’s rungs

The bases are bonded together by weak hydrogen bonds

The sugar and phosphate group are the “backbone” for DNA

Adenine & Guanine are considered “Purines”

Cytosine & Thymine are “Pyrimidines”

The double helix is held together by weak hydrogen bonds between the pair of bases.

Base pairing rules- Adenine pairs with Thymine (A-T) Cytosine pairs with Guanine (C-G)

The sequence of bases on one strand determines the sequence of bases on the other strand.

If the sequence on one strand of DNA can determine sequence of other strand then….

One strand of DNA contains nitrogen bases in this order..

A T G A C C

What will the complementary DNA strand look like?

If the sequence on one strand of DNA can determine sequence of other strand then….

The second strand will look like this.. A T T A G C A T C G C G

What type of bonds hold these strands of bases (the ladder’s rungs) together?

If the sequence on one strand of DNA can determine sequence of other strand then….

The second strand will look like this.. T G C G A T

What will the complementary strand look like?

If the sequence on one strand of DNA can determine sequence of other strand then….

The second strand will look like this.. T A G C C G G C A T T A

Create one strand of DNA with 8 nitrogen bases. Have your partner complete the complementary strand

T A G C C G G C A T T A

Describe the 3 parts of a DNA nucleotide

Name the bonds that hold together the nitrogen bases in a DNA strand

List the abbreviations for the four nitrogen bases of DNA

I can – explain the three steps in DNA replication

I can – create two replicated strands of DNA

Replication of DNA

**Remember – DNA is replicated during the “S” (synthesis)phase in cell division

DNA Replication: making a copy of DNA

Replication of DNA

In DNA Replication, one strand of DNA serves as the “template” to build the second strand of DNA

The replicated strand would look like this

Replication of DNA

There are 3 steps in the replication of DNA

In your group, assign a step to each member

Use pages 198 – 199 to describe your step in your own words

Each member will also describe how DNA “checks for errors”

Share each step in order once the whole group is finished

Result: 2 new DNA double helixes created (identical to each other and original DNA)

What two enzymes play an important role in DNA replication?

What is the purpose of DNA polymerase in the “proofreading” role?

What is the result of DNA replication?

What occurs in the first step of DNA replication?

Gene Scene DNA Workshop The Geee! In Genome Putting DNA to work Kids Genetics: DNA Hershey and Chase Experiment Animation DNA Replication Animation Another DNA Replication Animation