DNA What is it? DNA A chemical molecule that has all the information to run and build a living organism. Contains instructions for genes (inherited traits)

DNA

What is it?

DNA

• A chemical molecule that has all the information to run and build a living organism.

• Contains instructions for genes (inherited traits) and for proteins (structures and functions – like enzymes)

Types of proteins

DNA MODEL (deoxyribonucleic acid)

• Double stranded molecule with 2 sides called a helix

• Looks like a twisted ladder structure• Rungs (steps) are called bases or nucleotides.

(abbreviated as A, C, T, G)

• Sides are made of sugar & phosphate molecules alternating

• The sugar is deoxyribose• Found in every living cell in structures called

chromosomes, inside the nucleus.

nucleotide

Base pairs are: A with TC with Galways

Phosphate molecules

Deoxyribose (sugar) molecules

Nitrogen

bases

Hydrogen

bonds

Sugar phosphate (backbone)

http://biology.about.com/library/weekly/aa051701a.htm

Notice base pairings:

A with T &C with G

DNA replication (copying itself)

Required during growth or repair of cells.The weak hydrogen bonds are unzipped by an enzyme called

DNA helicase. Free floating nucleotides from in the nucleus attach themselves

to the exposed DNA strands. DNA the new bases are “glued” or fused together with DNA polymerase and the 2 new molecules of DNA are formed.

DNA replication (copying itself)

ACG ATGCAC

___ ___ ___

GTA CGT

___ ___

___ ___

CAT GCA

UNZIPPED BY HELICASE

2 NEW DNA STRANDS

COPIES OF EACH OTHER!

TGC TAC GTG

Glued BY polymerase

CAT GCA

GTA CGT

who contributed to the discovery of the DNA model

Timeline in text pg 292-293

DNA is also responsible in making RNA in a process called transcription.

RNA will function as a template to help make proteins for the body.

Remember that proteins can be structural (muscles, hair, fingernails, etc) but can also be functional in the body systems like enzymes or hormones.

RNA differs from DNA in 4 main ways:

•Single stranded

•Ribose sugar

•Uracil base instead of thymine

•Moves out of nucleus to be functional.

bases

pairingsSugar phosphate backbones

RNA DNARibonucleic acid deoxyribonucleic acid

8

9

AddAs 11B

3 forms of RNAmRNA messenger- comes out of nucleus to be the carrier of the code to make proteins. The code is read 3 bases at a time called the codon.

tRNA transfer – transfers the amino acids to the

growing protein or peptide chain- attaches to the

mRNA with an anticodon base pairing with the codon.

rRNA ribosomal- helps the ribosomes read the code on the mRNA, so the correct amino acids are delivered in the correct order.

11

DNA MAKES RNA IN A PROCESS CALLED TRANSCRIPTION.

An enzyme, RNA polymerase, separates the strands of DNA.

The free floating bases in the nucleus are attracted to the bases on the DNA strand. They assemble the same as in replication except URACIL bonds with ADENINE.

ACG ATG CAC

___ ___ ___

GTA CGT

___ ___

___ ___TGC TAC GTG

CAT GCA

THE NEW FORMING mRNA strand

CAU GCA

A protein is made by a process called translation.

Text pages 304-306

Know parts and how to read the circle (mRNA & inside out)For what amino acids are part of new protein.