DNA & Genetics

Biblical Reference Children are a heritage from the Lord, offspring a reward from him. Psalm 127:3

The Structure of DNA Chromosomes are made of proteins and deoxyribonucleic acid, or DNA—an organism’s genetic material.DNA A gene is a segment of DNA on a chromosome. animation

The Double Helix DNA is comprised of nucleotides and is shaped like a twisted ladder, which is referred to as a double helix. A nucleotide is a molecule made of a nitrogen base, a sugar, and a phosphate group.nucleotide –The sugar phosphate groups make up the sides of the ladder.

The Nitrogen Bases The nitrogen bases are: –Adenine (A) –Cytosine (C) –Thymine (T) –Guanine (G) These bases bond and form the rungs of the ladder. –A and T always bond together, and C and G always bonds together.

The Double Helix

Replication Replication is the process of copying a DNA molecule to make another DNA molecule.Replication

Making Proteins The DNA of each cell carries the complete set of genes that provide instructions for making all the proteins a cell requires. Proteins are made with the help of ribonucleic acid (RNA) - a type of nucleic acid that carries the code for making proteins from the nucleus to the cytoplasm.RNA

RNA is made of nucleotides. It is single-stranded. RNA has the nitrogen base uracil (U) instead of thymine (T), which is found in DNA.

Making a Protein: Step 1 Transcription - the process of making RNA from DNA.Transcription

Translation The process of making a protein from RNA is called translation.translation animation

Mutation A change in the nucleotide sequence of a gene is called a mutation.mutation The word, mutation, comes from the Latin word, mutare, which means “to change”. The 46 human chromosomes contain between 20,000 and 25,000 genes that are copied during replication.

Causes & Types of Mutations Mutations can be triggered by exposure to X-rays, ultraviolet light, radioactive materials, and some kinds of chemicals. There are three types of mutations: –Substitutions –Insertions –Deletions

Substitution In a substitution mutation, one nitrogen base is replaced by a different nitrogen base.

Insertion In an insertion mutation, one or more nitrogen bases is added to the DNA.

Deletion In a deletion mutation, one or more nitrogen base is left out of the DNA sequence.

Mutations The effects of a mutation depend on where in the DNA sequence the mutation happens and the type of mutation. Some mutations in human DNA cause genetic disorders. animation

Genetics Interactive

What is created through transcription? Pop Quiz A.DNA B.mutations C.mRNA D.protein

In DNA, which of the following is paired with guanine? Pop Quiz A.adenine B.cytosine C.thymine D.uracil

Which of the following describes the mutation that occurs when three base pairs are added? Pop Quiz A.insertion B.substitution C.transgression D.deletion