Mutation and Genetic variation
Mutations can occur spontaneously during DNA replication or be induced by environmental factors such as radiation or chemicals.
Genotype is the gentic makeup of individual
Differnt from the gene are allets, and they correspind of different DNA sequences
– The combination of alleles at a specific gene make up the genotype.
– Individuals with two copies of the same allele for a gene are homozygous.
– Individuals with two different alleles of the same gene are heterozygous.
Polymorphisms refer to any genetic difference among individuals in the population.
Phenotype is the expression of the genotype.
Mutation are the change in the DNA sequence that can lead to genetic variation, potentially affecting an individual's phenotype by altering gene function or regulation.
Any heritable change in the gentic materia
- Mutations are changes in the DNA sequence that can lead to genetic variation, potentially affecting an individual's phenotype by altering gene function or regulation. A mutation is defined as any heritable change in the genetic material. When discussing genes or alleles, we often distinguish between the functional version (also known as the wild-type, which performs its intended biological role) and the mutated version (which contains a change in its DNA sequence that may alter or abolish its function).
Question: A population of mosquitoes is exposed to the pesticide DDT for several generations. At the end of that time, most individuals in the population are resistant to DDT. The most likely
reason is that:
A. DDT caused the mutations that led to resistance.
B. some individuals in the original population had the mutations that led to resistance.
C. by chance, new mutations that led to DDT resistance arose after DDT was used.
D. somatic mutations in the original population were passed on to subsequent generations.
E. random mutations in each generation made mosquitoes resistant to DDT.
The answer is this is because
Answer: Somatic mutations statement is wrong because somatic mutations are not passed on from generation to generation = not possible
Random mutations are not possible either because DDT iS lethal a> no chance
The only way is (B) some individuals in the original population had the mutations that led to resistance= over time, these populations will increase
Whyis the deletion more prober? the deletion allows for a more significant change in gene function, potentially disrupting important biological processes and leading to a phenotypic advantage in certain environments.
Gene duplication is a process where a segment of DNA is copied, creating new genes. This duplication is often random. Over time, mutations can occur in these duplicated genes, which may lead to new functions or traits in the organism.
Gene deletion is a type of mutation in which a segment of DNA is lost or removed from a chromosome. This can involve:
A single nucleotide (small deletion)
One or more genes (large deletion)
Effects of gene deletion:
If the deleted gene is essential, it can cause diseases or developmental problems.
If the deleted gene is non-essential, it might have little or no effect.
Large deletions can alter chromosome structure and sometimes affect multiple genes at once.
The mutation can in orccer in the somatic cells, the cells of the body, higher mutation rate, and the germ cells, reproductive cells, less likely to mutate through can happen age dependent
During sperm formation (a process called spermatogenesis), germ cells divide and develop into mature sperm. Mutations in these germ cells can occur due to errors in DNA replication, environmental factors (like radiation or chemicals), or age-related changes in the DNA repair mechanisms.
Here’s why these mutations matter:
Transmission to offspring – Unlike mutations in somatic cells (which only affect the individual), mutations in germ cells are heritable. That means any changes in the DNA can be passed to the child.
New traits or disorders – Some mutations might be neutral, some might confer new traits (beneficial changes), and some could lead to genetic disorders if they disrupt important genes.
Cumulative effect with age – In males, the older the germ cells, the more times DNA replication has occurred, increasing the chance of mutations in sperm. This is why paternal age can influence the likelihood of certain genetic conditions in children.
Evolutionary role – Over long timescales, these heritable mutations provide raw material for evolution, allowing populations to adapt to changing environments.
not every sperm will get affected.
Somatic mutation and cancer
Somatic mutations are changes in the DNA that occur in somatic cells (the non-reproductive cells of the body). These mutations are not passed on to offspring.
Connection to cancer:
Accumulation of mutations – Somatic mutations can accumulate in genes that control cell growth, division, and death.
Oncogenes and tumor suppressor genes – Mutations that activate oncogenes or inactivate tumor suppressor genes can cause cells to grow uncontrollably.
Cancer development – Over time, these mutations can lead to the formation of a tumor and, in some cases, metastasis (spread to other parts of the body).
Environmental factors – Somatic mutations leading to cancer can be caused by radiation, chemicals, viruses, or random DNA replication errors.
Key point: Somatic mutations are the main cause of most cancers, but they cannot be inherited by children.
Transposable elements are DNA sequences that can move from one location in the genome to another, either within the same chromosome or to a different chromosome. This “jumping” ability can create genetic diversity and contribute to the evolution of certain traits within a population.
If a transposable element inserts into the middle of a functional gene, it can disrupt normal gene expression or function, potentially leading to new phenotypic variations that may be advantageous or detrimental to the organism.
Transposable elements can move around throughout the genome, and approximately 15% of human DNA is made up of these elements, highlighting their significant role in shaping genetic variation and driving evolutionary processes.
Types of excision repair
1.) Corrects damage related to the removal of an amine group from a base (ex. C to U transition), and oxidation
2.) Base is removed first, then the baseless sugar
3.) Repairs made by polymerase and
ligase
Mismatch repair (this is done when the pair mis match, we use differnt type of enzyme.) The key is we will cut down and up.
Due to UV light we going to link the damage enxzyme and subsequently remove the damaged DNA segment before the polymerase synthesizes the correct sequence.