Cellular Processes Week 4: DNA and DNA Replication

DNA Video

I Can… I can describe the structure of DNA.

DNA If you were to unravel a chromosome, you would find 1 long strand of DNA. With around cells in the human body, all of the DNA in a human, lined up end to end, would stretch to about 1000 times the distance from the Earth to the Sun.

Vocabulary DNA (de-oxy-ribo-nu-cle-ic acid) Double Helix Deoxyribose (a type of sugar molecule) Phosphate Group (a type of molecule) Nitrogen Base (a type of molecule) Adenine Guanine Thymine Cytosine Nucleotide

DNA Deoxyribonucleic Acid, or DNA, is the genetic material that carries information about an organism and is passed from parent to offspring.

The Structure of DNA The strands of a DNA molecule look like a twisted ladder. We call this shape a “double helix”.

The Structure of DNA The 2 sides of the DNA “ladder” or the “backbone” are made up of molecules of sugar called DEOXYRIBOSE, alternating with molecules known as PHOSPHATES.

The Structure of DNA Each “rung” of the ladder is made up of a pair of molecules called NITROGEN BASES.

Nitrogen Base Pairs DNA has four kinds of nitrogen bases: –ADENINE=A –THYMINE=T –GUANINE=G –CYTOSINE=C

Nitrogen Base Pairs The bases on one side of the ladder pair with bases on the other side of the ladder. ADENINE ONLY pairs with THYMINE GUANINE ONLY pairs with CYTOSINE. AT GC

Nucleotide DNA is made up of interconnected molecules called NUCLEOTIDES (like beads on a string). Each nucleotide has three parts: 1.A sugar molecule: deoxyribose 2.A phosphate molecule 3.A nitrogen base (A, T, G, or C).

BrainPOP and Bill Nye DNA and Genes (11 min)

Exit Quiz 1. What are the “parts” of a nucleotide? 2. What is the backbone of DNA made of? 3. What are the “rungs” of DNA made of? 4. What do we call the shape of DNA? 5. Which nitrogen base always pairs with Adenine? 1.1 molecule of deoxyribose 2.1 phosphate group 3.1 nitrogen base (A, T, G or C) Deoxyribose and Phosphate Groups Nitrogen Bases A Double Helix. Thymine

I Can… I can describe the process of DNA replication that occurs during interphase.

DNA Replication The process by which the cell makes an EXACT copy of the DNA in its nucleus.

But how does the cell make an exact copy of its DNA? The key is DNA’s pairing pattern (A-T or G-C). DNA replication begins when the two sides of the DNA molecule unwind and unzip like a zipper.

But how does the cell make an exact copy of its DNA?

Next, nitrogen bases that are floating in the nucleus pair up with the bases on each half of the DNA molecule. This creates two exact copies of the parent DNA (because each side is like a pattern telling us what to add to the other side).

Exit Quiz 1. How do the nitrogen bases pair? 2. What happens in DNA replication?