The gene pool Flashcards
Gene pool
A gene pool is the sum of alleles possessed by an entire population at one given time.
What causes/results in increased genetic diversity
The larger and more diverse gene pool will contain a greater variety of gene and alleles which results in increased genetic diveristy
Mutation
A Permanente change inthe DNA sequence
How can mutations be advantgeous
muatations can be advanteous by providing a selective advantage over other phenotypes
types of advatenouse mtuations are HIV resistnace and lactose tolereance
a mutation that is deleterious
a mutation that can cause disease
eg. mutation that causes sick cell anemia
a mutation that is neutral
A neutral mutation can have an effect on the amino acid sequence, but does not effect the functioning of a protein and are usually termed silent mutations
eg. silent mutation
Why is silent mutation, an example of a neutral mutation
A silent mutation is an example of a neutral mutation because it does not change the amino acid sequence of the protein that is produced.
Why is sickle cell anemia an example of a deleterious mutation
A single nucleotide change in the β-globin gene leads to abnormal hemoglobin, causing red blood cells to sickle. This impairs blood flow and results in health issues like pain and anemia.
why is the mutation for lactose intolerance and hiv resistance, an advantageous mutation
The lactose tolerance mutation allows adults to digest lactose by maintaining lactase enzyme production, while the CCR5-Δ32 mutation provides resistance to HIV by preventing the virus from entering immune cells.
causes of mutations
mutations can be caused by mutagens such as UV rays, X rays, chemicals or spontaneously
mutations can be inherited through mutations to th germline
what causes genetic variation between species
mutation
All genetic variation between species is a result
of a mutation
The evolutionary significance of mutations is
the ability to create new alleles, increasing genetic diversity in a population
Mutations can change the frequency of existing alleles by
by competing for space and resources for them
The effect of mutations on allele frequencies
Mutations introduce new alleles to a gene pool
Passing this down to offspring will increase the allele frequency and overtime may replace another allele if it is beneficial.
Point mutations
Changes to one nucleotide in a gene due to substitution, point mutations can be classified as silent, missense and nonsense
Silent mutations
One nucleotide is substituted for another. The gene still codes for the same amino acid sequence and no effect on the protein
Missense mutation
One nucleotide is substituted for another resulting in a difference sequence of amino acids. A different protein is produced
Nonsense
One nucleotide is substituted and now codes for STOP. Protein is not functional
compare the effect of substitution to a nucleotide of point mutations
Silent mutation-Substitution to a nucleotide that has no effect on the amino acid sequence. This is due to degeneracy of the genetic code.
Missense mutation-Substitution to a nucleotide that results in a difference amino acid. This results in an altered primary protein structure
Nonsense mutation-Substitution to a nucleotide that results prematurely ending translation due to a codon becoming the STOP codon. Protein is shorter than the regular protein. and protein is not functional
types of mutations
point mutation
silent mutation
block mutation
frame shift mutation
Involves the addition or deletion of one or two nucleotides. This results in a ‘shift’ in how the DNA strand is read
Amino acid sequence changes which also results in a change in protein.
frameshift mutations examples
Cystic fibrosis, Crohn’s disease and certain types of cancers are due to frameshift mutations
Crohn’s disease can be associated with frameshift mutations in the NOD2 gene, where insertions or deletions of nucleotides shift the reading frame of the gene, resulting in a nonfunctional protein that disrupts immune system regulation.
Cystic fibrosis is often caused by frameshift mutations in the CFTR gene, such as the ΔF508 deletion, which leads to a misfolded cystic fibrosis transmembrane conductance regulator protein and impairs chloride ion transport across cell membranes.
Frameshift mutation(insertion) vs frame shift mutation(deletion)
frameshift muttion insertion hasAddition of one or two nucleotides which alter the reading frame of the following nucleotides. Whereas, frameshift mutation deletion has Deletion of one or two nucleotides which alter the reading frame of the following nucleotides.
Block mutation
a mutation involving the altering of the structure of a chromosome by inserting, deleting or swapping a cluster of nucleotides during meiosis, hence block mutations can impact mutiple genes
What are examples of chromosomal abnormalties
Aneuploidy- occurs when an individidaul has an extra chromsome or one missing thier their karyotype
Polyploidy occurs when an individaul has more than 2 sets of chromsomes–when this occurs in humans, zygote is unable to survive, but when this occrus in plants the phenotype of the plant will be altered
allele what is it
pair of genes that occupy a specific location on a particular chromosome and control the same trait
mutagen
Anything that can cause a mutation
what are mutations caused by
Mutations can be caused by a mutagen like radiation or it can occur randomly,
how does a random mutation occur
changes in the nucleotide sequence of DNA that occur without pattern and introduce new variation into a population.
Do all mutations pass on
no some mutations do not pass on because some people cnanot have children
when will a mutation be heritable and when will a mutation be non heritable
a mutation can occur in both somatic cells nad germline cells but mutations can only occur in germline cells because germline cells are reporudctive cells hence mutatiosn can be passed onto offspring in only germline cells.
Degeneracy
Refers to the concept that Multiple codons code for the same amino acid.
unambiguous
one codon codes for only single amino acids and are specific
universal
refers to the concept that almost every organism uses the same codons to code for the same amino acid.
what happens when there is a change in the amino acid sequence
it can lead to a defective protein
What happens when a mutation occurs that DOESNT change the amino acid sequence
this will have a neutral effect, known as a silent mutation
Sickle cell anemia is problematic as the person affected by it will have less oxygen. However, when they are infected by malaria, this mutation can be helpful. Applying your knowledge of immunity, why do you think this mutation is helpful in those who are infected.
the sickle cell shape allows immunecells to identiyfthat the cell is infected quicker to laucnh an immune response
How does having heterozygous sickle cell anemia affect a person’s susceptibility to malaria compared to someone with normal red blood cells?
In heterozygous sickle cell anemia, both normal and sickle-shaped red blood cells are present. Sickle cells are more easily recognized and destroyed by immune cells when infected with malaria, offering some protection. In people with only normal red blood cells, the infected cells are harder for immune cells to detect and eliminate.
What happens to people with homozygous sickle cell anemia when they get malaria?
n homozygous, they only have sickle cells which means a lot of these cells are affected and thus most of them are killed by the immune system. however, they do not have normal red blood cells to supply oxygen and all the sickle cells are alos being killed so less oxygen -> more likely going to die regardless of whether they are infected or not
explain chromosomal insertion, inversion and translocation in BLOCK MUTATIONS
Chromosomal insertion: A segment of one chromosome is inserted into another chromosome or into a different location on the same chromosome (block mutation).
Inversion: A segment of a chromosome is reversed end to end (block mutation).
Translocation: A segment of one chromosome is transferred to another chromosome (block mutation).
