DNA Notes

Central Dogma DNA RNA Protein

Structure and function Nucleic acids (DNA and RNA) are made of smaller subunits called nucleotides. The components of DNA nucleotide are a simple sugar, called deoxyribose, a phosphate group and a nitrogen base.

Structure and function The 4 nitrogen bases are: adenine, guanine, cytosine and thymine. Adenine pairs with Thymine Cytosine pairs with Guanine

Structure and function In DNA, nucleotides combine to form 2 long chains, producing 1 large molecule. The 2 chains are joined by a hydrogen bond.

The importance of sequences DNA in each organism is different because of the sequencing of the nitrogen base.

Replication In autosomal cells, mitosis is the process by which organisms copy their DNA in the cell to prepare to pass it on to new cells. In sex cells, meiosis is the process by which organisms copy their DNA in the cell to prepare to pass it on to new cells.

Replication Every time a cell reproduces it needs to make a copy of the directions for life for it’s offspring.

Replication Replication begins with an enzyme “unzipping” the hydrogen bond between the nitrogen bases. After the bond is broken, free nucleotides in the nucleus bond with the unpaired nucleotides.

Replication After this pairing, another enzyme bonds them together with a hydrogen bond. Each new strand is a perfect copy of the parent.

The DNA code The sequence of nitrogen bases along one of the DNA strands is a code to make protein.

RNA and DNA RNA and DNA differ structurally in three ways: RNA is a single strand Different sugar (ribose) Has uracil instead of thymine

RNA RNA is the form in which information moves from the nucleus to the ribosome. Enzymes make a copy of DNA through a process called transcription, the result is RNA.

mRNA is the copy of DNA that is taken out into the cytoplasm of the cell.

Proteins Proteins are made in ribosomes in the cytoplasm of the cell, but DNA is only found in the nucleus.

Proteins Proteins are built from smaller molecules called amino acids. There are 20 different kinds of Amino acids. But there are only 4 types of bases in DNA…

Codons Each set of three bases that codes for an amino acid and is known as a codon, also known as a triplet code.

RNA Translation is the process of converting the information in a sequence of nitrogen bases into amino acids that make up proteins. This occurs on ribosomes and involves tRNA

tRNA codes the mRNA and brings the correct amino acid to the ribosome to make it a protein. rRNA is a type of RNA that is in the ribosome and helps to guide translation

Mutations A mutation is any mistake or change in the DNA sequence.

Point Mutation: One nucleotide is substituted for another ACGCTTGCA  ACACTTGCA Frameshift Mutation: One nucleotide is inserted or deleted causing a shift in the reading frame ACGCTTGCA  ACCTTGCA

Causes of mutations Errors in DNA can result from exposure to X-rays, ultraviolet light, radioactivity and other chemicals.

Causes of mutations DNA mutations cause the changes necessary for survival of a species. But they can cause birth defects and can lead to cancer.