Genetic Mutations Flashcards
What is a genetic mutation?
Changes in DNA can arise spontaneously during replication and any change in the base sequence or quantity of DNA
What are the 2 keys types of mutations?
1-substitution: this is when one nucleotide in the DNA sequence is replaced by another. The effect of the change in an amino acid depends on the role of the original amino acids in the overall shape and function of the protein. A substitution may not always be harmful as the code is degenerate
2-deletion event is when a nucleotide in the DNA sequence is lost. The loss of a single nucleotide can have a significant impact as it leads to a frame shift, resulting in completely different amino acids being coded for.
What the 2 types of mutations on chromosomes?
1-Polyploidy
changes can occur in the whole set of chromosomes so that an individual has three of more sets of chromosomes instead of two. This is common in plants, with many modern wheats arising to be polyploidy.
2.Non-disjunction
non-disjunction occurs when chromosomes fail to separate correctly in meiosis. As a result the gametes and any zygotes formed will have one more or one less chromosome than they should. Down’s syndrome is the result of non-disjunction where individuals have an extra chromosome 21.
What is a gamete and zygote?
Gamete:a reproduction cell of an animal or cell
Zygote:a fertilised eukaryotic cell that turns after union of gamete cells
What is meosis?main role and what is diploid?
Meiosis is a form of cell division that gives rise to four daughter cells that are all genetically different and have half the number of chromosomes found in the parent cell (haploid)
Main role is to produce haploid gametes
Diploid:2 sets of chromosomes (1 chromosome)
Stages of meiosis:
1:Prophase I: Chromosomes condense, homologous chromosomes pair up (synapsis), crossing over
Metaphase I: Homologous chromosome pairs line up at the metaphase plate, attached to spindle fibers.
Anaphase I: Homologous chromosomes separate and move toward opposite poles of the cell.
Telophase I: Chromosomes arrive at the poles of the cell, nuclear membrane reforms, and the cell undergoes cytokinesis, resulting in two haploid daughter cells.
2:
Prophase II: Chromosomes condense again, nuclear envelope breaks down if reformed.
Metaphase II: Chromosomes line up at the metaphase plate, attached to spindle fibers.
Anaphase II: Sister chromatids separate and move toward opposite poles of the cell.
Telophase II: Chromosomes arrive at the poles of the cell, nuclear envelope reforms, and the cell undergoes cytokinesis again, resulting in four haploid daughter cells, each genetically distinct from the parent cell and each other.
What is necessary to maintain the stable number of chromosomes in meosis?
-homologous pairing and in meosis ii ensuring the each daughter cell has 1 set of chromosomes
-separation of sister chromatids
Standards deviation,what is it??
is a measure of how dispersed the data is in relation to the mean.
How is the process of meiosis creates genetically different cells,
-Independent assortment of chromosomes:homologous pairs line up in arrangement is random this the division into daughter cell is random
-crossing over:when Pairs of chromosomes line up they exchange some of their genetic material,swapping places with the same part of its homologous pair this have a different combination of alleles on the gene
What is a niche of a species?
-it’s role within the environment
What is natural selection and the process?and what is evolution?
Natural selection is the mechanism of evolution
Is the process where fitter individuals who are better adapted to environment will survive and pass on the advantageous genes to futures generations,then the frequency of the alleles in the gene pool changes over time and it increases
How does evolution happens via natural selection?
-There’s a variety of different phenotypes within a population.
-An environmental change occurs and as a result of that the selection pressure changes.
-Some individuals possess advantageous alleles which give them a selective advantage and allow them to survive and reproduce.
-The advantageous alleles are passed on to their offspring.
-Over time, the frequency of alleles in a population changes and this leads to evolution.
How is the the genetic diversity within a species to be determined?
comparing the frequency of
1-measurable or observable characteristics
2-the base sequence of DNA and mRNA
3-the amino acid sequence of the proteins encoded by DNA and mRNA.
What are the limitations of using observable characteristics to measure genetic diversity?
-The characteristics could be coded for by more than one gene.
- The same characteristics could have arisen separately.
- The characteristics could be influenced by the environment and not the genes
How do we now classify species in a accurate way?
-scientist now use gene technology to read the base sequences of organisms. The genetic diversity of a species can be measured by sampling DNA or mRNA from different individuals.
