Proteins

Types of proteins Structural Storage Immunoglobulins These protein types serve as essential components to your body's construction. Keratin and collagen are the most common structural proteins. Storage These proteins house critical elements that your cells need. Hemoglobin is a vital protein that stores oxygen in your red blood cells. Immunoglobulins Immunoglobulins protect your body from invaders and other foreign substances. They act as antibodies.

Types of Proteins Hormonal Enzymes These proteins act as chemical messengers. They carry signals through a complex communication process known as your endocrine and exocrine system. Your pancreas excretes the hormone insulin, which is released in response to your blood sugar levels, for example. Enzymes Enzymes serve as biological catalysts needed for chemical reactions. Digestive enzymes help your body digest food, for instance.

Protein Structure Protein structure begins with the sequence of amino acids that is made during translation. Following translation the protein folds into a very specific shape. The structure of a protein determines its function.

Enzymes One of the many types of proteins in the body is enzymes. We will focus our discussion of proteins on enzymes from here on out. Remember – enzymes are just one type of proteins. Enzymes are protein catalysts. They speed up chemical reactions by reducing the amount of energy needed to get the reaction started. (they lower activation energy)

Enzymes Enzymes are specific – meaning each enzyme speeds up its own reaction. What reaction an enzyme speeds up (catalyzes) depends on its 3-D shape. Enzyme is like a lock and the reactants (substrates) are like the keys. Only certain substrates fit into an enzyme like only certain keys fit into a lock.

THE CATALYTIC CYCLE OF AN ENZYME 1 Enzyme available with empty active site Active site Substrate (sucrose) 2 Substrate binds to enzyme with induced fit Enzyme (sucrase) Glucose Fructose H2O 4 Products are released 3 Substrate is converted to products

There are many factors that affect enzyme activity. Factors that effect speed Concentration of substrate & its surface area Concentration of enzyme Factors that effect speed & function Temperature Salinity pH Enzymes are very important but also very fragile. When an enzyme’s structure is damaged and it no longer functions we say the enzyme has been denatured. video

Mutations

A mutation is a permanent change in the DNA sequence of a gene.

There are two ways in which DNA can become mutated: Mutations can be inherited. Passed from parent to child through meiosis (creation of gametes). Will be present in every cell of the child. Mutations can be acquired. This happens when environmental agents damage DNA, or when mistakes occur when a cell copies its DNA prior to cell division. Passed from cell to cell through mitosis. Will only be present in some cells of the body. Most likely will not be passed on to children.

Protein synthesis is based on transcription and translation. If the DNA sequence is changed then the mRNA sequence WILL be changed during transcription. If the mRNA is changed then the amino acid sequence MAY be changed during translation.

Point Mutations Point mutations are single nucleotide base changes in a gene's DNA sequence. You can change a single nucleotide by substituting, inserting or deleting.

Substitutions

Insertions and Deletions

Insertions and Deletions

  Insertion mutations and deletion mutations add or remove one or more DNA bases. Insertion and deletion mutations cause frameshift mutations, which change the grouping of nucleotide bases into codons. This results in a shift of "reading frame" during protein translation.

These types of mutations can change the gene's protein product in the following ways: Missense mutations are point mutations that result in a single amino acid change within the protein. Nonsense mutations are point mutations that create a premature "translation stop signal" (or "stop" codon), causing the protein to be shortened. Silent mutations are point mutations that do not cause amino acid changes within the protein.

Practice: Translate the ‘normal’ mRNA: AUG CCA GAC AAU AUU AAG UGA Translate the ‘mutated’ mRNA: AUG CCA GAC GAA UAU UAA GUGA What type of mutation is this? (two answers)

Chromosome Mutations Chromosome mutations are changes in the chromosome number or structure. Chromosome mutations will impact many genes (and therefore proteins). There are 4 major types of chromosomal mutations:

Key Points Key Points to keep in mind about mutations Mutations are not always bad – they can have no effect (like a silent mutation) or be good for you! They are the source of variety in a given population. Mutations can be broken down into two main groups: Point Mutations – effect 1 gene Substitution, Insertion, Deletion Chromosome Mutations – effect groups of genes Insertion, Deletion, Inversion and Translocation

Vocabulary Point Mutation Chromosome Mutation Substitution Insertion Deletion Missense Nonsense Silent Chromosome Mutation Deletion Duplication Inversion Translocation