Unit 4 Inheritance of Traits Part 2: How DNA codes for Proteins

DNA carries the info to make Proteins. How does it work? DNA RNA Proteins Starts with DNA….transcribed into mRNA…..translated into proteins by tRNA This process is known as: Central Dogma of Molecular Biology How does the DNA get made into RNA and that made into Protein???.

When DNA inside the nucleus is This strand then leaves the nucleus. Transcription When DNA inside the nucleus is TRANSCRIBED (re-written) Into mRNA. This strand then leaves the nucleus.

DNA Deoxiribonucleic acid 1.sugar=deoxyribose 2.bases = A, T, G, C 3.double strand 4.stays in nucleus RNA Ribonucleic acid 1.sugar = ribose 2.Bases=A, U, G,C 3.single strand 4.leaves nucleus

What are the three main differences between DNA and RNA?

There are three main differences between RNA and DNA: The Structure of RNA There are three main differences between RNA and DNA: The sugar in RNA is ribose instead of deoxyribose. RNA is a single-stranded polymer molecule RNA contains the base: uracil, in place of thymine. Copyright Pearson Prentice Hall

3 Types of RNA are made from DNA 1. mRNA  “messenger” made from DNA in nucleus…travels out of nucleus and finds a ribosome. 2. tRNA “transfer” brings amino acids to the ribosomes; found in cytoplasm 3. rRNA  “ribosomal” part of the ribosome; this is where proteins are made

Types of RNA The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA. Messenger RNA (mRNA) carries copies of instructions for assembling amino acids into proteins. Copyright Pearson Prentice Hall

Types of RNA Ribosome Ribosomal RNA The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA. Ribosomal RNA is combined with proteins to form ribosomes. Ribosomes are found in all Eukaryotic and Prokaryotic organisnms and are made up of proteins and ribosomal RNA (rRNA). Copyright Pearson Prentice Hall

Amino Acids are monomers (subunits) of proteins Types of RNA Amino acid Amino Acids are monomers (subunits) of proteins The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA. Transfer RNA During protein construction, transfer RNA (tRNA) transfers each amino acid to the ribosome. Copyright Pearson Prentice Hall

Lets watch: https://www.youtube.com/watch?v=JZXT2uOcD2w https://www.youtube.com/watch?v=ztPkv7wc3yU

Transcribe this…… TACAGTACCATAATC AUGUCAUGGUAUUAG

Is ALL the DNA transcribed into mRNA? NO!!! Only certain sections of the DNA (GENES) are made (transcribed) into message (mRNA)

Now…to make proteins from the mRNA This is called: Translation Translation is the decoding of an mRNA message into a an amino acid acid chain creating a (protein). The mRNA goes into the Ribosome and a tRNA molecule brings amino acids.

Codon A grouping of 3 mRNA bases This tells the TRNA what amino Acid to bring

Translation The ribosome binds new tRNA molecules and amino acids as it moves along the mRNA. Lysine Phenylalanine tRNA Methionine Ribosome During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process. mRNA Start codon Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Why do we need Proteins? 1. Proteins give certain traits and capabilities to organisms Ex: lots of the protein melanin leads to darker pigment EX: Production of insulin helps in glucose metabolism 2. Proteins act as enzymes to make reactions go faster, act as parts of muscle, skin, bone,& organs!! Proteins are hormones & cell signalers Organisms are dependent on proteins in order to function! Copyright Pearson Prentice Hall

Translation :Decoding the Message FOR REVIEW mRNA leave nucleus and enters ribosome mRNA codons read & tRNA brings matching amino acid to the ribosome Amino acids are strung together like beads on a necklace Amino Acids are held together by peptide bonds 1000 or more Amino Acids = protein

Lets watch! https://www.youtube.com/watch?v=5bLEDd-PSTQ https://www.youtube.com/watch?v=TfYf_rPWUdY

Use the RNA Codon Chart to decode RNA into amino acids. The Genetic Code Use the RNA Codon Chart to decode RNA into amino acids. The genetic code is the “language” of mRNA instructions. The code is written using four “letters” (the bases: A, U, C, and G). Copyright Pearson Prentice Hall

WHEN WE DECODE DNA Example: AUG= Methylamine (Start) Use the “Genetic Code”  Convert mRNA 3 letter groupings called codons Example: AUG= Methylamine (Start) The mRNA Code tells us what amino acid each codon codes for.

The Genetic Code The genetic code shows the amino acid to which each of the 64 possible codons corresponds. To decode a codon, start at the middle of the circle and move outward. Copyright Pearson Prentice Hall

Protein Synthesis Translation direction Translation Lysine tRNA mRNA During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process. mRNA Translation direction Ribosome Copyright Pearson Prentice Hall

The process continues until the ribosome reaches a stop codon. Translation The process continues until the ribosome reaches a stop codon. Polypeptide Ribosome tRNA During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process. mRNA Copyright Pearson Prentice Hall

REVIEW! Watch these: https://www.youtube.com/watch?v=gG7uCskUOrA https://www.youtube.com/watch?v=28mgfg8nRT4

Transcribe and Translate this DNA Strand without looking at your notes TACAGTACCATAATC NOW, Label the DNA, mRNA, amino acid, Which part is transcription Which is translation ?

DNA TACAGTACCATAATC mRNA AUGUCAUGGUAUUAG AA: MET-SER-TRP-TYR-STOP Codon Amino Acid