DNA Replication

I. Nucleic Acids

• Built by repeating subunits called NUCLEOTIDES• Process of DEHYDRATION synthesis chains them

togetherDNA (deoxyribose nucleic acid)RNA (ribonucleic acid)

II. Nucleotides have 3 parts

(review from Bio-A!!)A. _PHOSPHATE groupB. 5 carbon SUGARC. _NITROGEN base

DRAW THIS& Label it!

Outside Inside Outside

Phosphate Nitrogen Base 5 Carbon Sugar

Hydrogen Bond

There are 4 Nitrogen Bases

a. Adenine (A)b. Thymine (T) –DNA, Uracil (U) – RNA c. Cytosine (C)d. Guanine (G)

Base Pairing Rule• The bases pair up in a particular way like

pieces in a puzzle

a. _A-T in DNA or A-U in RNAb. _C-G in both DNA and RNA

III. What is DNA?• DNA shape is a double

helix1. Deoxyribose sugar and

phosphate form the OUTSIDE backbone

2. Pairs of nitrogen bases form the rungs or INSIDE of helix

• Two strands connected by HYDROGEN bonds

• Functions:–Contains the hereditary instructions to

make proteins that organisms need to function

IV. DNA Replication

• The process of copying DNA in a cell

A. Once fertilization occurs and before cell division can occur, a cell must make a copy of its chromosomes so each new daughter cell gets a full set of DNA

B. How it works: When a cell begins to copy DNA during the S-phase

1. An enzyme separates and UNZIPS the two sides of DNA

2. The HYDROGEN bonds are BROKEN between the strands• DNA can be transcribed to

RNA when this happens

3. The DNA is read and each complimentary base makes BASE PAIRS

4. The REPLICATION process produces TWO new strands of DNA-each containing one strand from the original

Video