Genes Determine the characteristics of individuals. Found in the nucleus of the cell Located on chromosomes Aka DNA

Structure of DNA DNA is made of two long chains of nucleotides. Each chain of nucleotides is formed by the sugar of one nucleotide connecting to the phosphate group of another nucleotide. P S N P S N

The bases from one chain complement the bases on the other chain (Complement = they fit together like a lock and key.) Adenine (A) complements Thymine (T) Cytosine (C) complements Guanine (G) A T C G

Double strand showing complements

Because of the configuration of the nucleotides the DNA is in the form of a double helix. A helix is shaped like a spring

DNA Replication When a new cell is created the DNA is replicated. Each of the 2 original strands are copied (thus each cell has the same complete genome with one strand being the original DNA and the other a copy.). A T G G C C T G G A one strand of the original DNA T A C C G G A C C T copied strand of the original DNA

THE CENTRAL DOGMA OF BIOLOGY DNA RNA PROTEIN TRANSCRIPTION TRANSLATION

Protein Synthesis RNA makes a copy of DNA in the nucleus (DNA is to large to fit through the nucleus) this is sent to the ribosome for protein synthesis.

(RNA is a single strand of nucleotides)

The DNA acts as a template for the RNA to copy. The RNA is actually going to be the opposite of the original DNA strand Example: instead of a “C” on the strand there will be a “G”. Also there is no thymine (T) in RNA instead there is uracil (U) So if there is an “A” in the strand of DNA then the RNA will have a “U” in its copied strand. (Think of a template like a rubber stamp)

Messenger RNA The RNA that copies the DNA is called messenger RNA or mRNA because it sends the message to the ribosome to make the protein.

If the original DNA looks like this: A-C-C-G-T-A The mRNA will look like this: U-G-G-C-A-U

What will the mRNA look like if the DNA is: T-T-G-C-A-G-A-T-C The mRNA will be: A-A-C-G-U-C-U-A-G

The mRNA is read at the ribosome by the transfer RNA (tRNA) Acceptor Arm The mRNA is read at the ribosome by the transfer RNA (tRNA) The anticodon complements the mRNA (codon) The acceptor arm is where the amino acid attaches to the tRNA. Anticodon

As the tRNA’s attach to the complementary part of the mRNA the amino acids attach to each other with peptide bonds The resulting long strand of polypeptides is then formed into a protein

Overview DNA double strand

The majority of genes are expressed as the proteins they encode The majority of genes are expressed as the proteins they encode. The process occurs in two steps: Transcription = DNA → RNA Translation = RNA → protein

Transcription Translation