RNA And PROTEIN SYNTHESIS

What DNA is for…… Making Proteins Why is this important?

Proteins Serve as… Enzymes that catalyze biochemical reactions (catalyst  speeds up chem. Rx)

Proteins Serve as… Enzymes that catalyze biochemical reactions Structural or mechanical factors –actin and myosin in muscle

Proteins Serve as… Enzymes that catalyze biochemical reactions Structural or mechanical factors –actin and myosin in muscle –Makes up cytoskeleton

Proteins Serve as… Enzymes that catalyze biochemical reactions Structural or mechanical factors –actin and myosin in muscle –Makes up cytoskeleton –Cell signaling, immune responses, cell adhesion, cell cycle

Proteins Serve as… Enzymes that catalyze biochemical reactions Structural or mechanical factors –actin and myosin in muscle –Makes up cytoskeleton –Cell signaling, immune responses, cell adhesion, cell cycle –Necessity in animals' diets, Can’t synthesize (make) some amino acids, must eat

So How are Proteins Made? Remember, proteins are a chain of amino acids that are folded up into a particular shape.

So How are Proteins Made? DNA has all codes (GENES) for any protein that’s needed Humans: Abt. 25,000 genes in 23 pairs of chromosomes.

Ribonucleic Acid (RNA) Compared to DNA: –Similar, built as a chain of nucleotides –Unlike DNA: Has Uracil (U), not Thymine (T) (so it has A, U, G, C) 5 Carbon Sugar is Ribose, not Deoxyribose Is single stranded Is shorter

Comparing the nucleic acids… DNARNA Deoxyribose sugarRibose sugar Double-sidedSingle-sided Guanine, Cytosine, Adenine, & Thymine Guanine, Cytosine, Adenine, & Uracil Millions of base pairs long 100’s / 1000’s of bases long In nucleusIn nuc. and cyt.

Ribonucleic Acid (RNA) 3 types of RNA: –Messenger RNA (mRNA) It’s the message carrier –Transfer RNA (tRNA) It transfers amino acids to the ribosomes –Ribosomal RNA (rRNA) It makes up actual ribosomes

TRANSCRIPTION DNA never leaves nucleus: 1. DNA is opened / read by RNA Polymerase 2. Template side is copied (transcription) into mRNA 3. DNA closes back 4.mRNA leaves nucleus through pore Animation

How mRNA is made RNA Polymerase (an enzyme) opens DNA, assembles mRNA nucleotides floating around in nucleoplasm (5’ to 3’ direction)

How mRNA is made As mRNA strand is assembled, it lengthens until a stop signal cuts it off. RNA Polymerase then detaches, DNA closes.

How mRNA is made This process is Transcription (copying, rewriting) movie movie

RNA Polymerase producing (transcribing) mRNA

TRANSLATION 1.The mRNA moves to a ribosome; bases read in 3’s (triplets,or codons) 2.tRNA floating in cytoplasm match up their anticodons to mRNA codons, delivering one amino acid at a time… 3.Amino acids link together (chain) then fold to make protein. Animation Animation

mRNA connects to Ribosome Ribosome: assembly site for a.a. chains mRNA moves thru ribosome; bases read in triplets (codons) tRNA floating in cytoplasm match up their anticodons to mRNA codons, delivering one amino acid at a time… movie1 movie2 movie3 movie4 movie1movie2movie3movie4

Codons and their Amino Acids

A Codon Chart is very simple to use. For this circle type chart, go from the largest to smallest letters when reading your codon. For example, A-G-C codes for Serine

Transfer RNA (model)

Transfer RNA (mapped)

Transfer RNA (mapped & modeled)

A Protein Forms tRNAs deliver the proper a.a’s., forming chain. Each a.a. bonded together by peptide bond a.a. chains always –Begin with the A-U-G codon (methionine) –End with one of three STOP codons

mRNA Ribosome New polypeptide chain of a.a. : Protein A New Protein is Born

The Protein is Completed The a.a. chain folds into its proper shape, then sent to where it’s needed… movie movie How proteins may be used in different cells… xHow proteins may be used x

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