Mutations acquired by a cell that can be passed to future cells arising from the mutated cell in the course of cell division. A mutation that changes the structure of an individual chromosome, leading to imbalance involving only a part of a chromosome, such as duplication, deletion, or translocation. A genetic mutation caused by a deletion or insertion in a DNA sequence that shifts the way the sequence is read.
The specific location in DNA where a set of codons will code for a certain protein. The reading frame begins with the start codon AUG. A class of biological molecule consisting of linked monomers of amino acids and which are the most versatile macromolecules in living systems and serve crucial functions in essentially all biological processes. A group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body.
A cycle of growth and division that cells go through. It includes interphase G1, S, and G2 and the mitotic phase. The process by which DNA is copied transcribed to mRNA in order transfer the information needed for protein synthesis. Mutant Cosplay You probably recognize these costumed comic fans in Figure 5. What Are Mutations? Most people have multiple mutations in their DNA without ill effects.
Mutations are the ultimate source of all new genetic variation in any species. Mutations may happen spontaneously during DNA replication or transcription. Other mutations are caused by environmental factors called mutagens. Mutagens include radiation, certain chemicals, and some infectious agents. Germline mutations occur in gametes and may be passed onto offspring. Every cell in the offspring will then have the mutation.
Somatic mutations occur in cells other than gametes and are confined to just one cell and its daughter cells. These mutations cannot be passed on to offspring. Chromosomal alterations are mutations that change chromosome structure and usually affect the organism in multiple ways. Charcot-Marie-Tooth disease type 1 is an example of a chromosomal alteration in humans. Point mutations are changes in a single nucleotide.
The effects of point mutations depend on how they change the genetic code and may range from no effects to very serious effects. Frameshift mutations change the reading frame of the genetic code and are likely to have a drastic effect on the encoded protein. Many mutations are neutral and have no effect on the organism in which they occur. Some mutations are beneficial and improve fitness. An example is a mutation that confers antibiotic resistance in bacteria.
Other mutations are harmful and decrease fitness, such as the mutations that cause genetic disorders or cancers.
Define mutation. Identify causes of mutation. Compare and contrast germline and somatic mutations. Describe chromosomal alterations, point mutations, and frameshift mutations. Identify the potential effects of each type of mutation. Why do many mutations have neutral effects?
Give one example of a beneficial mutation and one example of a harmful mutation. Separate images are all in public domain or CC licensed:. An alteration in the nucleotide sequence of the genome of an organism. A population of similar organisms able to breed with one another. A physical or chemical agent that changes the genetic material, usually DNA, of an organism.
A mutation that only affects a single nucleotide of nucleic acid. Amino acids are organic compounds that combine to form proteins. Each gene must have the correct instructions for making its protein. This allows the protein to perform the correct function for the cell. All cancers begin when one or more genes in a cell mutate. A mutation is a change. It creates an abnormal protein. An abnormal protein provides different information than a normal protein.
This can cause cells to multiply uncontrollably and become cancerous. Acquired mutations. These are the most common cause of cancer. For example, this could be a breast cell or a colon cell, which then goes on to divide many times and form a tumor.
A tumor is an abnormal mass. Cancer that occurs because of acquired mutations is called sporadic cancer. Acquired mutations are not found in every cell in the body and they are not passed from parent to child.
Germline mutations. These are less common. A germline mutation occurs in a sperm cell or egg cell. It passes directly from a parent to a child at the time of conception. As the embryo grows into a baby, the mutation from the initial sperm or egg cell is copied into every cell within the body. Because the mutation affects reproductive cells, it can pass from generation to generation. Cancer caused by germline mutations is called inherited cancer.
Mutations happen often. A mutation may be beneficial, harmful, or neutral. This depends where in the gene the change occurs. Typically, the body corrects most mutations. A single mutation will likely not cause cancer. Usually, cancer occurs from multiple mutations over a lifetime.
That is why cancer occurs more often in older people. The result of a mutation, a change in the DNA sequence. The effects of mutations can vary widely, from being beneficial, to having no effect, to having lethal consequences, and every possibility in between.
The majority of mutations have neither negative nor positive effects on the organism in which they occur. These mutations are called neutral mutations. Examples include silent point mutations. They are neutral because they do not change the amino acids in the proteins they encode. Many other mutations have no effect on the organism because they are repaired before protein synthesis occurs. Cells have multiple repair mechanisms to fix mutations in DNA.
One way DNA can be repaired is illustrated in Figure below. DNA Repair Pathway. This flow chart shows one way that damaged DNA is repaired in E. Some mutations have a positive effect on the organism in which they occur. They are called beneficial mutations. They lead to new versions of proteins that help organisms adapt to changes in their environment. Beneficial mutations are essential for evolution to occur. There are several well-known examples of beneficial mutations. Here are just two:.
Imagine making a random change in a complicated machine such as a car engine. The chance that the random change would improve the functioning of the car is very small. The change is far more likely to result in a car that does not run well or perhaps does not run at all.
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