4c. Know how mutations in the DNA sequence of a gene may or may not affect the expression of the gene or the sequence of amino acids in the encoded proteins.

12—4: Mutations—Genetic Changes What are mutations? ______________: any change (Δ) or random error in a DNA sequence Affect _________ of nucleotides w/in a gene in a sperm or egg cells Impair the functions in body cells Gamma Radiation exposure

Gamma Radiation  Dr. Bruce Banner

Point Mutation Mutation in a DNA sequence; occurs from a Δ in a single base pair This mistake might affect the structure of the entire molecule Analogy: THE DOG BIT THE CAT. THE DOG BIT THE CAG.

Frameshift Mutations Mutation that occurs when a single base is added or deleted from DNA; causes a shift in the reading of codons by the one base Analogy: THE DOG BIT THE CAT Delete the G in “DOG” THE DOB ITT HEC AT

Kinds of Mutations The effects of ___________ or ___________ are more dramatic. The addition or deletion of a nucleotide causes a shift in the grouping of codons. Changes like these are called ____________ ___________.

Kinds of Mutations Frameshift mutations may change every _______________ __________ that follows the point of the mutation. Frameshift mutations can alter a ________ so much that it is unable to perform its normal functions.

Kinds of Mutations Gene Mutations Gene mutations involving a change in one or a few nucleotides are known as __________ _________________ because they occur at a single point in the DNA sequence. Point mutations include substitutions, insertions, and deletions.

Kinds of Mutations Substitutions usually affect no more than a single _________ _________. Gene mutations result from changes in a single gene. In a substitution, one base replaces another.

Kinds of Mutations In an insertion, an ________ base is inserted into a base sequence. Gene mutations result from changes in a single gene. In an insertion, an extra base is inserted into a base sequence.

Kinds of Mutations In a deletion, the ___________ of a single base is deleted and the reading frame is shifted. Gene mutations result from changes in a single gene. The loss of a single letter in a sentence models the effects of the deletion of one base in a DNA sequence.

Chromosomal Mutations Mutation that occurs at the chromosome level resulting in ’s in the gene distribution to gametes during meiosis; caused when parts of chromosomes break off or rejoin incorrectly Nondisjuntion Monosomy Trisomy Polyploidy How can we fix mutations? _______________

Causes of Mutations Mutagen: any agent that can cause a  in DNA High energy radiation X-rays, UV light, nuclear radiation Chemicals Benzene, asbestos, cyanide High temps

12-4 Mutations Mutations are __________ in the genetic material.

Kinds of Mutations Kinds of Mutations Mutations that produce changes in a ___________ gene are known as ___________ mutations. Mutations that produce changes in whole chromosomes are known as chromosomal mutations.

Kinds of Mutations Gene Mutations Gene mutations involving a change in one or a few nucleotides are known as __________ _________________ because they occur at a single point in the DNA sequence. Point mutations include substitutions, insertions, and deletions.

Kinds of Mutations Chromosomal Mutations Chromosomal mutations involve changes in the number or _____________ of chromosomes. Chromosomal mutations include deletions, duplications, inversions, and translocations.

Kinds of Mutations Deletions involve the loss of all or part of a ____________. Chromosomal mutations involve changes in whole chromosomes.

Kinds of Mutations Duplications produce extra copies of parts of a chromosome. Chromosomal mutations involve changes in whole chromosomes.

Kinds of Mutations Inversions _________ the direction of parts of chromosomes. Chromosomal mutations involve changes in whole chromosomes.

Kinds of Mutations ________________ occurs when part of one chromosome breaks off and attaches to another. Chromosomal mutations involve changes in whole chromosomes.

Significance of Mutations Many mutations have little or no effect on gene expression. Some mutations are the cause of _____________ disorders.

Significance of Mutations Beneficial mutations may produce proteins with new or altered activities that can be useful. _______________ is the condition in which an organism has extra sets of chromosomes.

Mutations Wrap-Up Mutations are permanent changes in the sequence of nitrogen-containing bases in DNA. Mutations occur when base pairs are incorrectly matched [(A—C) instead of (A—T)], improve the product coded by the gene. Inserting or deleting base pairs in an existing gene can cause a mutation by changing the codon reading frame by the ribosome.

Mutations Wrap-Up Mutations that occur in somatic cells (non-sex cells) are often not detected because they cannot be passed on to offspring. They may, however give rise to cancer or other undesirable cellular changes. Mutations in sex cells can produce functionally different proteins that cause such genetic diseases as Tay-Sachs, sickle cell anemia & Duchenne muscular dystrophy.

Mutations Wrap-Up Mutations are permanent changes in the sequence of nitrogen-containing bases in DNA. Mutations occur when base pairs are incorrectly matched [(______) instead of (_______)], improve the product coded by the gene. Inserting or deleting base pairs in an existing gene can cause a mutation by changing the __________ reading frame by the ribosome.

4d. Know specialization of cells in multicellular organisms is usually due to different patterns of gene expression rather than to differences of the genes themselves.

Gene Regulation: An Example Many genes are regulated by ___________________ proteins. Some genes use proteins that speed transcription. Sometimes regulation occurs at the level of _____________ _____________.

Eukaryotic Gene Regulation Genes are regulated in a variety of ways by ______________ sequences. Many proteins can bind to different enhancer sequences. Some ______-binding proteins enhance transcription by: opening up tightly packed chromatin helping to attract RNA polymerase blocking access to genes.

Development and Differentiation As cells grow and divide, they undergo ________________, meaning they become specialized in structure and function.

Wrap—Up Gene expression is a process in which a gene codes for a product, usually a ____________, through transcription & translation. Nearly all cells in an organism contain the same _______, but each cell transcribes only that portion of ______ containing the genetic information for proteins required at that specific time by that specific cell.

Wrap—Up The remainder of the DNA is not ___________. Specific types of ________ may produce specific proteins unique to that type of cell.