DNA and RNA

Section 5.1

DNA

• Stores information about an organism

Proteins

• Made up of chains of amino acids• 20 different amino acids combine to make

thousands of proteinslysozyme has

129 amino acidsdystrophin has

3685 amino acids

Proteins

• DNA stores the information (code) that tells the cell what amino acids to put together to make a specific protein

• Code – a set of rules and symbols used to carry information (computer uses ones and zeroes)

DNA Structure

• A double stranded spiral, twisted ladder• Four nucleotides make up the ladder

AdenineThymineCytosineGuanine

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Each of these connect to each other

DNA Structure

• The order of the bases determine the code for what protein is to be made

• The genetic code is a triplet of bases – Each triplet codes for 1 amino acid• (T-C-T codes for arginine)

DNA Structure

Gene – the entire sequence of the bases that codes for all the amino acids in a protein

Each gene is made up of a sequence of bases at a particular location on the DNA

Replication

• Process where DNA is copied

• Occurs before a cell divides into two

Replication Process

• Step 1– Two strands of DNA separate

Replication Process

• Step 2– Nucleotides in area match up to nucleotides on

DNA strands

Replication Process

• Step 3– At completion, there are 2 identical molecules of

DNA. Each has one old strand and one new strand.

RNA

• Ribonucleic acid• Carries the information from DNA to a

ribosome where the amino acids are brought together to make a protein

• 3 types – Messenger (mRNA)– Ribosomal (rRNA)– Transfer (tRNA)

Transcription

• Process of transferring info from DNA to RNA

• Uses 4 nucleotide bases – Guanine– Cytosine– Adenine– Uracil

Transcription

• Only part of DNA opens up

• RNA bases match up to complimentary DNA basesA-UC-G

Transcription

• Only a single strand of RNA is produced

• When complete RNA is released so more can be made

• DNA closes when finished

Translation

• Three specific bases = 1 amino acid• To make proteins, cells must translate

nucleotide base “language” to amino acid “language”

• The actual assembly of bases is the translation

Translation

• 1) ribosome attaches to beginning end of mRNA• 2) tRNA matches up and joins mRNA• 3) ribosome attaches one amino acid to another

as it moves along the mRNA• 4) tRNA is released• 5) translation is finished at end of mRNA and

finished protein is released• VIDEO