DNA & Protein Synthesis

Vocabulary terms to learn:

gene messenger RNA (mRNA) ribosomal RNA (rRNA) transfer RNA (tRNA) transcription RNA polymerase

codon translation anticodon

DNA Replication

• Before a cell divides, it duplicates its DNA

1. Enzymes (DNA polymerase) “unzip” the DNA molecule, breaking the hydrogen bonds.

2. Each strand is now a template

3. New complimentary strands are produced.

DNA Replication

• Replicate the following strand of DNA:

• ATTAGCTACTGC

• TAATCGATGACG

DNADNA RNARNA

What is the difference?

What is RNA? DNA contains the

information for making proteins, but it does not make protein.

There are 3 forms of RNA that are responsible for using the information stored in DNA to make protein.

mRNArRNA

tRNA

DNADNA RNARNA

RNA & Protein Synthesis

• RNA – ribonucleic acid– Single polynucleotide chain– 5 carbon sugar – ribose– No thymine; replaced with Uracil (A-U)– Assembles amino acids into proteins.

DNA vs mRNA

DNA has deoxyribose,

mRNA has ribose;

DNA has 2 strands, mRNA has 1 strand;

DNA has thymine, mRNA has uracil.

mRNA

rRNA tRNA

messenger RNA ribosomal RNA transfer RNA

Protein Synthesis

• Transcription (DNA mRNA)– an RNA molecule is produced by copying part of the

nucleotide sequence of DNA

– Occurs in the nucleus

– RNA Polymerase

• Translation (RNA Protein) – Decoding of mRNA message

– Occurs in cytoplasm

– Uses all 3 forms of RNA

The Genetic Code

• Proteins are formed by joining amino acids into long chains. – There are 20 different amino acids

– the order in which they are arranged determines the property of the protein.

• Codon – 3 consecutive nucleotides in RNA that specifies for a specific amino acid. – there are 64 possible codons

– Some amino acids are specified by more than one codon.

Types of RNA1. Messenger RNA (mRNA)

• Carries message from DNA (instructions for the assembly of amino acids) from DNA to rRNA in cytoplasm.

• Every 3 N-bases = codon 2. Transfer RNA (tRNA)”

• also known as anticodon (3 N-bases) complementary to mRNA codons

• Translates the message carried on mRNA codons into amino acids. Fig.12-17 pg.303

• Carries/transfers amino acids to ribosomes. 3. Ribosomal RNA (rRNA)

• Makes up most of the ribosome• Site of protein synthesis- mRNA and tRNA come

together here

• RNA Sequence: UCGCACGGU

• Codons: – UCG CAC GGU

• Amino Acids: – Serine – Histidine –

Glycine

Transcribe & Translate the following:

• TACCCTCAAGTAATT

• Transcribe: DNA RNA – AUGGGAGUUCAUUAA

• Translate: RNA Protein – Meth – Glyc-Val-Hist-STOP

DNA Translation

Translation assures that the right amino acids are joined together by peptides to form the correct protein.

The cell uses information from mRNA to produce proteins.

Transfer RNA (tRNA) The Amino Acid Suppliers

Transfer RNA is part of the process of translation. It brings the amino acid coded for by mRNA, and these amino acids are joined together to form proteins.

Messenger RNA (mRNA): The Genetic Blueprint

Messenger RNA is a copy of the genetic information that was transcribed from the cell’s DNA.

It is like a ‘blueprint’ of the genetic information and is brought to the ribosome and translated into protein with the help of tRNA.

Ribosomal RNA (rRNA) The Protein Factories

Most of the RNA in cells is associated with small cellular structures known as ribosomes, the protein factories of the cells.

Ribosomes are the site of Translation, where mRNA arrives with genetic instructions for building proteins from amino acid monomers brought by tRNA.