Mutation Notes Here is a combination of your presentations and your standards that you need to be familiar with.

Overview of Meiosis (we will go into more detail later)

Genetic Combinations from Meiosis Two types Crossing Over Nondisjunction

Meiosis and Crossing Over Meiosis is a process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in the diploid cell. Crossing-Over The process in which homologous chromosomes exchange portions of their chromatids during meiosis.

Process Crossing over is the process in genetics when the two chromosomes of a homologous pair exchange equal segments. Each chromosome has replicated into two strands called sister chromatids. While the chromosomes are synapsed, breaks occur at the corresponding points in the two non-sister chromatids in one chromatid of each chromosomes. They contain corresponding genes The broken sections are then exchanged to form complete new units, and each new recombinant chromosome of the pair can go to a different daughter sex cell. Crossing over results in recombination of genes found on the same chromosome, called link genes, that would otherwise always be transmitted together.

Picture and video to help you…. https://www.brightstorm.com/science/biology/mendelian-genetics/chromosomes-crossing-over-linked-genes/

Nondisjunction What is the process of nondisjunction? Nondisjunction is an error in cell division resulting in reproductive cells with an abnormal number of chromosomes. A reproductive cell may accidentally gain or lose one copy of a chromosome. If one of these atypical reproductive cells contributes to the genetic makeup of a child, the child will have an extra or missing chromosome in each of the body’s cells. Nondisjunction is the failure of chromosome pairs to separate during meiosis 1 or 2. Is it heritable? Nondisjunction is not heritable although it is possible to inherit some types of chromosomal abnormalities, most chromosomal disorders are not passed from one generation to the next.

PICTURES: Example 2: This image shows how when a reproductive cell has too many chromosomes, you write n+1, and when a reproductive cell has too few chromosomes, you write n-1. Example 1: This image shows how in normal meiosis, each chromosome pair separates correctly. Underneath that, it shows how the purple chromosome separates, but the blue remains the same. One reproductive cell now has too few chromosomes, and the other has too many. This causes the cell unable to function normally.

PICTURES: Example 3: number 1 and 2 chromosomes have separated correctly, while one of the number 3 chromosomes has not seperated. Example 4: one cell gets too many chromosomes and the other doesn’t get enough.

Nondisjunction Video Link https://www.brightstorm.com/test-prep/ap-biology/ap-biology-videos/mutation-2/

Errors that occur during Replication 3 types Insertion Deletion Substiution

Insertion Mutations A permanent change in a DNA sequence caused by the addition of a nucleotide(s) As a result, the protein made by the gene may not function properly.

Picture and Video https://www.brightstorm.com/science/biology/molecular-biology/genetic-mutation/

Deletion Mutation a mistake in the DNA replication process which removes nucleotides from the genome Can remove a single nucleotide, or entire sequences of nucleotides Losing a single nucleotide can cause a frameshift mutation to occur

Pictures

Video You can watch the same video for insertion mutations :) it covers many concepts and topics within this powerpoint.

Substitution Mutations Mutation - a permanent change in the DNA sequence of a gene. Substitution Mutation is defined as a mutation in which there is an exchange in base pairings ( A, T, C, and G) which consequently leads to the change of an amino acids’ codon. This change in bases can affect the type of protein that DNA molecules are to produce.

Types and Processes of Substitution Mutation There are two different types of Substitution/Point mutations. There are Transition and Transversion Mutations. Transition- A transition mutation occurs when in a DNA sequence a purine is change into another purine,( A-->G) or a pyrimidine changes into another pyrimidine (T--->C). Transitions are much more common than Transversions. Transversion- Is the opposite of a Transition Mutation. A Transversion Mutation occurs when purine is substituted for a pyrimidine or vise versa.

Substitution Mutation: Transition

Substitution Mutation: Transversion

Pollution Know that pollutants in the atmosphere can cause mutations that are genetically passed down from parent to offspring. Below is a SHORT article that will give you an example of this: https://www.nature.com/news/2008/080113/full/news.2008.439.html

Mendelian Mutations Called mendelian because of Gregor Mendel's study of inheritance patterns on pea plants is a solid foundation for understanding these diseases. Mendelian diseases are inherited It is defined as diseases caused by mutations in one gene or modifications in a single gene and it usually has predictable inheritance patterns. Can be divided into three categories: autosomal recessive, autosomal dominant and x-linked.

Mendelian: Autosomal Recessive Autosomal recessive- where both parents have to the mutation in their gene for the offspring to get it. This is one of the reasons inbreeding is dangerous. There is a much larger chance both parents will have the same mutant recessive gene, giving the child a autosomal recessive disease.

Mendelian: Autosomal Dominant Autosomal dominant-only one parent needs to pass down a defective gene for the offspring to get it.

Mendelian: X-linked X-linked- results from mutation on the X chromosome Can be recessive or dominant More common in males because they only have one copy of the X chromosome so if a single copy in the X chromosome is mutated they don’t have another copy to back it up.

Viral Mutations Virus- A virus is an infecting agent that is only able to multiply within the cells of a host and is too small to be seen with the naked eye. Infection- An invasion and reproduction of microorganisms that are not usually in the body. This occurs when a virus infects and multiplies in an organism. A Disease occurs when the cells of the body are damaged as a result of the virus, and symptoms appear.

Types of Viruses Active Virus - A type of virus that infects a cell and it begins its functions quickly, reproducing quickly even as the cell reproduces. Hidden Virus - A type of virus that does not immediately become active and does not change the cell’s functions for a long period of time. https://www.youtube.com/watch?v=8FqlTslU22s