RNA (ribonucleic acid)– single stranded nucleotide chain– ribose sugar– G-C and A-U – Uracil instead of Thymine

– Different types:– mRNA, tRNA, rRNA

Types of RNAThe three types of RNA are:

o Ribosomal or rRNA: combines with proteins to make ribosomes.

o Messenger or mRNA: Carries instructions for protein synthesis from nucleus to ribosomes in the cytoplasm

oTransfer or tRNA: Carries amino acids to the ribosome and matches them to the coded mRNA message.

DNA Only RNA OnlyBoth

-Uses Thymine

-Double stranded

-Cannot leave the nucleus

-Uses deoxyribose sugar

-Acts as blueprint for protein production

-Uses Uracil

-Single stranded

-Can leave the nucleus

-Uses ribose sugar

-Works in actual protein production

-Uses A, G, C

-type of

nucleic acid

-stores info

-made of nucleotides

Proteins are large molecules that are made building blocks called amino acids.

Hundreds of amino acids linked together by peptide bonds and fold into a specific shape to make up a protein.

There are 20 different types of amino acids.

Different order of amino acids = different protein!

Functions of Proteins

Most structurally & functionally diverse group of biomolecules! Function - involved in almost EVERYTHING!1. Metabolism – enzymes: biological catalysts!2. Structure – hair, skin, nails (keratin, collagen)3. Transport (cell membrane channels & pumps, hemoglobin –transports oxygen in blood)4. Defense (immune system – antibodies)5. Regulation- hormones (insulin, HGH, cell cycle )6. Motion - muscle fibers (actin & myosin)7. Communication – protein receptors in cellmembrane send and receive chemical signals (nerve cells)

THE CENTRAL DOGMAProtein synthesis occurs in two major parts transcription and translation.

1. Transcription: Process in which DNA serves as a template to produce complementary mRNA

2. Translation: Process in which mRNA is used to link amino acids together to synthesize proteins.

DNA mRNA Protein transcription translation

mRNA

From gene to protein

DNAtranscription

nucleus cytoplasm

aa

aa

aa

aa

aa

aa

aa

aa

aa

aa

aa

proteintranslation

ribosome

trait

Transcription• Making mRNA from DNA• Occurs in the nucleus

– transcribed DNA strand = template strand– Enzyme is RNA polymerase

template strandrewinding

mRNARNA polymerase

unwinding

DNAC C

C

C

C

C

C

C

C CC

G

GG

G

G G

G G

G

G

GAA

AA A

A

A

A

A

A A

A

AT

T T

T

T

T

T

T

T T

T

T

U U

5

35

3

3

5

build RNA

GENE = region of DNA that codes for a protein!

• Eukaryotic genes are not continuous– exons = the real gene

• expressed / coding DNA– introns = do NOT contain code for proteins

• inbetween sequence

eukaryotic DNA

exon = coding (expressed) sequence

intron = noncoding (inbetween) sequence

intronscome out!

mRNA Splicing• Occurs after Transcription• Introns are removed and exons are spliced

together to make the mature mRNA transcript

eukaryotic DNA

exon = coding (expressed) sequence

intron = noncoding (inbetween) sequence

primary mRNAtranscript

mature mRNAtranscript

pre-mRNA

spliced mRNA

~10,000 bases

~1,000 bases

The code of life• Code for ALL life!• Code is redundant

– several codons for each amino acid

Start codon AUG

Stop codons UGA, UAA, UAG

Part 2: Translation

1.Takes place in the cytoplasm.

2. mRNA finds a ribosome that is floating in the cytoplasm or attached to the rough ER.

3. Ribosomes are the site of translation.

4. A sequence of three mRNA nucleotides is called a codon.

5. One codon codes for one amino acid.

6. tRNA molecules enter the ribosome carrying the correct amino acid. The tRNA has an anticodon that matches the codon on the mRNA. 7. Amino acids are linked together to form a protein!

The types of proteins an organism possesses depend upon the sequence of nucleotides