Chapter 10DNA, RNA, and Protein Synthesis

The first experiments

• Fredrick Griffth• Studied bacterium Streptococcus pneumoniae

and was trying to develop a vaccine for the bacteria

• Discovered transformation• The transfer of genetic material from one cell to

another cell, or from organism to organism.

Hey girl, I like your dna• DNA is a nucleic acid made of two long chains of

repeating subunits called nucleotides

• DNA is responsible for storing an organism’s genetic information and controlling the production of proteins• Also called the biochemistry of an organism

• Nucleotides consist of three parts:• A five-carbon sugar• A phosphate group• A nitrogenous base

• The five carbon sugar in DNA is called dioxyribose

• The nitrogenous base contains nitrogen atoms, carbon atoms and is a base (that means it accepts hydrogen)

Science can be sexy

The nitrogenous bases

• You have 4 nitrogenous bases in your DNA

• Form hydrogen bonds in the double helix

• Can be purines ( double ringed) or pyrimidines (single ringed)

Compliments are nice

• Base pairing rules determine that the bases will pair with only one compliment.

• These compliments are called complementary base pairs

• Adenine with Thymine

• Guanine with Cytosine

• The order of these repeating base pairs in DNA is called base sequence

DNA Replication

• DNA replication is the process by which DNA is copied in a cell before a cell divides by mitosis, meiosis, or binary fission

• The two strands separate and each acts as a template of synthesis of a complementary strand

Making dna 101• Steps of replication

1. Enzyme helicase separates the DNA strands1. This creates a replication fork

2. Enzymes called DNA polymerases add complimentary nucleotides

3. DNA polymerases finish adding bases

4. DNA ligase acts like a glue to close any gaps and seal the new strand together

What about the prokaryotes or the Eukaryotes?

• Prokaryotes

What about the prokaryotes or the Eukaryotes?

• Eukaryotes• Because eukaryotic chromosomes are long and

not circular, a fast method had to arise

Dna errors

• DNA replication usually occurs with great accuracy• 1 error for every billion paired nucleotide added

• When a mistake does happen this causes a mutation• A change in the nucleotide sequence of a DNA

molecule

• Some errors can escape repair by the body, or can be the result of chemicals and UV light

Protein is good

• Know that a gene is a segment of DNA that is located on a chromosome and that codes for a hereditaty character• Hair color, eye color,

• These genes code for nucleic acids called RNA, or ribonucleic acid

How do we make it?

• Transcription- the DNA acts as a template for the synthesis of RNA

• Translation RNA directs the assembly of proteins

• Protein synthesis the forming of proteins based on information in DNA

• DNARNAProtein

RNA structure

• Much like DNA but different in 4 ways• RNA contains the sugar

ribose, not dioxyribose• RNA contains the

nitrogenous base Uracile, not thymine

• RNA is single stranded, not double stranded

• RNA is much shorter in length, usually only containing one gene, while DNA contains thousands of genes

The types of rna

• Did you know there are 3 types or RNA?

• Messenger RNA a single stranded RNA molecule that carries the instructions from a single gene to make a protein

• Ribosomal RNA part of the structure of ribosomes

• Transfer RNA which transfers amino acids to the ribosome to make protein

Structure yo

Transcription

• 3 step process occurring in the nucleus

1. RNA polymerase• An enzyme that binds to a promoter, or a specific

nucleotide sequence of DNA that initiates transcription

2. RNA polymerase adds free RNA nucleotides that are complementary to the nucleotides on the DNA strands

3. RNA polymerase reaches a termination signal, a specific sequence of nucleotides that marks the end of a gene

Transcription

The genetic code

• Genetic code-term for the rules that relate how a sequence of nitrogenous bases in nucleotides corresponds to a particular amino acid

• Codon is the name for the 3 nucleotide sequence in mRNA that encodes for a particular amino acid

Translation

• Translation-the making of a protein

• Proteins are made of one or more polypeptides• Chains of amino acids linked by peptide bonds

• There are 20 different amino acids• Can make up chains of hundreds or thousands

• Amino acid sequence will determine the structure of the polypeptide

• Protein shape is critical to function!!!!!!!!

Steps of translation

• There are 5 main steps to translate genetic information to form a polypeptide

This all occurs in the cytoplasm of the cell!!!

1. 2 ribosomal subunits tRNA and mRNA join together

1. tRNA contains anitcodon-the 3 nucleotides that are complementary to the codon sequence on the mRNA

2. The polypeptide chain is put together and grows in length

3. No joke, the third step is that it just keeps growing

Steps of translation

4. A polypeptide chain continues to grow until a stop codon is reached. This causes the newly formed polypeptide to detach

5. The components of translation disassemble 4. The components can either start coding a

new mRNA or translate the same strand.

Translation

The Human genome

• The entire gene sequence of the human genome, the complete genetic content, is know

• Scientists know the order of the 3.2 billion base pairs in the 23 human chromosomes

• Bioinformatics is when scientists use computers to help interpret different DNA sequences