Name one scientist who was involved in the discovery of the structure of the DNA molecule.

DNA replication

Before a cell can go through mitosis or meiosis, it’s DNA first must be copied.

Replication

• The process of copying DNA. Occurs during late interphase (during the S phase)

Replication• Step 1: DNA molecule separates into two strands - enzymes called helicase “unzip” molecule of DNA by breaking hydrogen bonds

DNA replication• Step 2:• Nucleotides are added to separated strands

of DNA.• -The enzyme DNA polymerase joins individual

nucleotides to produce a new strand of DNA.

New nucleotides are added to separated strand by following base pairing rules.

Nucleotides with nitrogen base A, pair with base T base C pairs with base G

DNA replication

• Step 3: As replication continues, the new strands twist into their helical form.

DNA replication enzymesDNA helicase an enzyme that unwinds and separates the two strands of the DNA double helix.

• DNA polymerase• Two functions:• 1. Attaches nucleotides to DNA strand• 2. Proofreads each new DNA strand

Prokaryotic DNA replication

• Prokaryotic DNA is found in the cytoplasm. Most have a single, circular DNA molecule

• Replication in most prokaryotic cells starts from a single point and proceeds in two directions until the entire chromosome is copied

Eukaryotic DNA replication

• Replication may begin at dozens or even hundreds of places on the DNA molecule, proceeding in both directions until each chromosome is completely copied.

https://www.youtube.com/watch?feature=player_detailpage&v=HBwyNrkYnp0

https://www.youtube.com/watch?feature=player_detailpage&v=zdDkiRw1PdU

Telomeres

• The tips of chromosomes that make it less likely that important genes will be lost during replication.

Telomeres

• The tips of chromosomes that make it less likely important genes will be lost during replication.

What is the name of the enzyme that adds new nucleotides to the

separated DNA strand?

• DNA polymerase

1. What is the name of the process in which DNA makes a copy of itself?

2. What type of bond forms between two nitrogenous bases?