RNARNARibonucleic AcidRibonucleic Acid

QuestionQuestion1.1. Use the following diagram to locate the Use the following diagram to locate the

nucleus and ribosomes on the cell.nucleus and ribosomes on the cell.

Key TermsKey Terms

RiboseRibose: sugar molecule of every RNA : sugar molecule of every RNA nucleotidenucleotide

TranscriptionTranscription: process by which genetic : process by which genetic information is copied from DNA to RNAinformation is copied from DNA to RNA

The structure of RNAThe structure of RNA

Like DNA, RNA is Like DNA, RNA is a nucleic acid a nucleic acid made of repeating made of repeating nucleotides.nucleotides.

3 Differences Between RNA and 3 Differences Between RNA and DNADNA

1.1. The sugar molecule The sugar molecule of RNA nucleotides of RNA nucleotides is ribose.is ribose.

2.2. UracilUracil usually usually replaces thymine in replaces thymine in RNA. U- replaces TRNA. U- replaces T

3.3. RNA is single strandRNA is single strand

3 Types of RNA3 Types of RNA

Messenger RNA (mRNA): mRNA carries Messenger RNA (mRNA): mRNA carries genetic info. from DNA in the nucleus to genetic info. from DNA in the nucleus to the cytosol inside the cell.the cytosol inside the cell.

Transfer RNA (tRNA): binds to amino Transfer RNA (tRNA): binds to amino acidsacids

3 Types Continued…3 Types Continued…

Ribosomal RNA (rRNA): most abundant Ribosomal RNA (rRNA): most abundant form of RNA, RNA makes up ribosomes form of RNA, RNA makes up ribosomes where proteins are made.where proteins are made.

TranscriptionTranscription

Transcription is Transcription is the formation of the formation of RNA from a DNA templateRNA from a DNA template. .

The RNA formed may be rRNA, The RNA formed may be rRNA, tRNA, or mRNA.tRNA, or mRNA.

Steps of TranscriptionSteps of Transcription

Inside the nucleus, an enzyme, Inside the nucleus, an enzyme, RNA RNA polymerasepolymerase, binds to bases on the DNA , binds to bases on the DNA of the gene to be expressed. of the gene to be expressed. This starting sequence is the This starting sequence is the promotorpromotor. .

Steps of TranscriptionSteps of Transcription

1.1. The DNA begins to unwind and the The DNA begins to unwind and the strands begin to separate. strands begin to separate.

2.2. The RNA polymerase begins to move The RNA polymerase begins to move along one strand of the exposed DNA, along one strand of the exposed DNA, linking ribonucleotides together in order linking ribonucleotides together in order specified by the sequence of bases on specified by the sequence of bases on the DNA.the DNA.

3. Transcription (literally "rewriting") 3. Transcription (literally "rewriting") continues until the continues until the RNA polymeraseRNA polymerase reaches a "stop" message on the DNA (a reaches a "stop" message on the DNA (a termination signaltermination signal). ).

4. The unzipped DNA closes back up and 4. The unzipped DNA closes back up and the mRNA is released into the nucleus the mRNA is released into the nucleus prior to the next stage in the production prior to the next stage in the production of a protein.of a protein.

Products of TranscriptionProducts of Transcription

The RNA formed may be rRNA (ribosomal The RNA formed may be rRNA (ribosomal RNA), tRNA (transfer RNA) or mRNA RNA), tRNA (transfer RNA) or mRNA (messenger RNA). (messenger RNA).

1. What would the complementary RNA 1. What would the complementary RNA strand be for these DNA sequences?strand be for these DNA sequences? TACGTACG

ATTAGTCATTAGTC

GATTACAGATTACA

What would the complementary RNA strand What would the complementary RNA strand be for these DNA sequences?be for these DNA sequences? TACGTACG AUGCAUGC

ATTAGTCATTAGTC UAAUCAGUAAUCAG

GATTACAGATTACA CUAAUGUCUAAUGU

Protein SynthesisProtein Synthesis(translation)(translation)

Making proteinsMaking proteinsThe mRNA now takes the message from The mRNA now takes the message from DNA to the ribosome to make proteinsDNA to the ribosome to make proteins

What’s the big Deal about What’s the big Deal about proteins????proteins????

Proteins run our show. Proteins run our show. Muscles, organs, hair, bone, and skin either Muscles, organs, hair, bone, and skin either contain or are made of proteins. contain or are made of proteins. They are a major component in all of our cells.They are a major component in all of our cells.Enzymes that run the chemical reactions in our Enzymes that run the chemical reactions in our bodies are proteins. bodies are proteins. Proteins help us move, send messages Proteins help us move, send messages (hormones and nerve receptors), fight off (hormones and nerve receptors), fight off disease (antibodies), and transport other disease (antibodies), and transport other molecules and atoms around our bodies. molecules and atoms around our bodies.

Proteins

Like DNA and RNA, proteins are polymers.Proteins are made up of one or more polypeptides, each of which consists of a specific sequence of amino acids. There are 20 different amino acidsThe function of a protein depends how it binds with other molecules in the cell.

Cracking the codeCracking the code

The code for proteins is held in the RNA The code for proteins is held in the RNA (originally from the DNA)(originally from the DNA)

3 base pairs on mRNA makes up a codon3 base pairs on mRNA makes up a codon

A codon chart is used to tell what 3 base A codon chart is used to tell what 3 base pairs codes for what amino acids.pairs codes for what amino acids.

TranslationTranslation

Translation is the process of reading the Translation is the process of reading the mRNA code and using the code to mRNA code and using the code to assemble amino acids to make proteins.assemble amino acids to make proteins.

Start and StopStart and Stop

Start codons tell translation to beginStart codons tell translation to begin AUG = start, also codes for the amino acid AUG = start, also codes for the amino acid

methioninemethionine

Stop codons tell translation to stopStop codons tell translation to stop There are three stop codonsThere are three stop codons These do not code for an amino acid These do not code for an amino acid UAA, UAG, UGAUAA, UAG, UGA

tRNAtRNA

tRNA contains 3 base pairs that tRNA contains 3 base pairs that compliment the mRNA codons.compliment the mRNA codons.

The 3 base pairs of tRNA are called anti The 3 base pairs of tRNA are called anti codons.codons.

tRNA links the Amino Acids together with tRNA links the Amino Acids together with the help of the ribosome to form proteins.the help of the ribosome to form proteins.

tRNAtRNA

Role of the RibosomeRole of the Ribosome

Ribosome are composed of rRNA and Ribosome are composed of rRNA and proteins.proteins.Membrane proteins and proteins to be Membrane proteins and proteins to be shipped out of the cell made by ribosome shipped out of the cell made by ribosome on rough ER.on rough ER.

Ribosome

Ribosome have three binding sites One for mRNA Two for holding matching tRNAs

Several ribosome can work on a single mRNA transcript

Completion of a Protein

After the primary structure is complete a protein will fold to form secondary and tertiary structures. It is at this time you have a completed functional protein.