Variation Flashcards
What is genetic variation?
The diversity in the genetic makeup of a species
Variation may happen to _________ factors or _______.
Environment , genetics
What are the two types of variation?
Continuous and discontinuous
Define what discontinuous variation and give an example.
A characteristic of a species with only a limited number of values.
Blood type
Define what continuous variation and give an example.
There is no clear separation into distinctive categories as measurements are on a continuous scale.
Eg. Height, shoe size
Continuous variation is controlled by multiple genes / alleles having a smaller effect on the phenotype of an organism.
True or False
True
What are the mechanisms that genetic variation may occur through?
Mutation , meiosis , sexual reproduction
How does sexual reproduction being about genetic variation?
The combination of genetic material from two distinct sources created new genetic combinations.
How does mutation bring about genetic variation?
It creates new DNA sequence of a particular gene creating new alleles which creates diversity within the species.
What are mutation?
Mutation occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene.
Give ways that mutation may occur
- Errors in DNA replication
- Exposure to radiation/ chemical
- Infection by a virus
Mutations may be __________, _____________, and ____________.
Beneficial, neutral and detrimental.
What is point mutation?
Refers to changes in a single nucleotide.
Point mutation may be beneficial and devastating.
True or false?
False it may be neutral or devastating.
What are the ways that a point mutation may happen?
Insertion, substitution and deletion.
Describe what happen with in these forms of point mutation
Insertion
Substitution
Deletion
Insertion - this occurs when a extra nucleotide is incorporated into the DNA sequence during DNA replication.
Substitution- refers to the case in which nucleotide is incorrectly swapped during DNA replication for another nucleotide.
Deletion- occurs when a nucleotide is skipped or absent from the replication stand.
When do most point mutation happens?
During DNA replication
Which of the two types point mutation are detrimental and why?
Insertion/ deletion as the DNA sequences are read in threes so if base pairs are not a multiple of three it disrupts the reading frame.
Examples of gene mutation
Cystic fibrosis, hemophilia and sickle cell anaemia.
Explain how a point mutation caused sickle cell.
Caused by a point mutation specifically a substitution in the protein of hemoglobin the amino acid of glutamic acid is replaced with valine causing a change of structure of the protein causing red blood cells to be become distorted.
A mutation in chromosome number involves a change in _____________ ___________.
Chromosome number
When will a chromosome mutation occur?
When an abnormal gamete takes part in fertilization
What are the types of chromosome mutation?
Deletion
Inversion
Duplication
What is deletion in chromosome mutation and examples
Deletion involves the loss of an entire region of a chromosome and all genes contained within it.
Cri du Chat deletion of chromosome 5 causing behavioral issues and developmental delays
Define this type of chromosome mutation and give an example duplication
Involves the duplication of a region of chromosome resulting in double the number of genes.
Down’s syndrome duplication of chromosome 21 resulting in double the number of genes
What is non disjunction?
The failure of one or more chromosome pairs of homologous chromosome or sister chromatids to separate normally during nuclear division.
Examples of beneficial mutation
Our rich color vision
CCR5 - delta 32 causing a resistance to HIV
Examples of harmful mutation
Sickle cell anaemia
Cystic fibrosis- mutated gene causes the body to produce thick sticky mucus that clogs the lungs
What is natural selection?
The process by which organisms better adapted to their environment tend to survive and produce more offspring.
What is adaptation?
The process of adjusting or changing to become more suited to your environment
Explain how environmental factors acts as forces of natural selection.
In a population the natural selection will favor the individual with the highest fitness one that has the best chances of survival in a environment.
Individuals produce more offspring than their environment can support, and some die because of factors such as predation, food shortage or disease. These factors are known as environmental selection pressures and they determine which individuals will do best at surviving and reproducing.
Describe the following
- Directional selection
- Stabilizing selection
- Disruptive selection
- one extreme is favored
- intermediate is favored instead of extremes
- both extremes are favored simultaneously while indeterminate is selected against.
How are peppered moths an example of natural selection?
Previously before the industrial revolution the black and white moths were more prevalent and the black ones weren’t as common but after the industrial revolution the place became polluted and dirty there fore the darker moths were better suited to their environment and they were able to camouflage than the other moths so after time there was a shift in the population where as there were more dark moths and the spotted ones.
How is natural selection a mechanism of evolution?
Natural selection is a mechanism of evolution. Organisms that are more adapted to their environment are more likely to survive and pass on the genes that aided their success. This process causes species to change and diverge over time.
What does Darwin theory says
The individual within a population differ
The differences are at least in part passed from parents to offspring
Some individual are more successful at surviving than others
What is biological species concept ?
Is a group of organisms that can reproduce with one another in nature and produce fertile offspring.
Some limitations of the biological species concept are..
- not all species can interbreed such as asexual species
- fossil species that are no longer able to reproduce
- sexual organisms with open mating system
How does mutation brings about genetic variation?
Mutation brings about variation as mutation creates new DNA sequence of a particular gene creating a new allele
explain why heritable variation is important to selection.
Heritable variation is the basis of natural selection with no variation there will be no natural selection as all environmental pressures will be the same for all with no inheritance offspring will not resemble their parents send the rest of the population natural selection will not push the population in a specific direction.
Ashley attempt- Heritable variation is important to natural selection as natural selection is the process by which organisms better adapted to the their environment survive but if these traits alllows these organisms to be better suited are not heritable these successful traits will be loss and therefore causing the organism not being able to evolve
What is speciation?
The process by which species are formed .
What do you need to create a new species ?
Separate the original population must be separated into two or more population form in their own gene pool.
Must be kept reproductively isolated. 
What are some mechanisms of reproductive isolation?
Mechanical isolation - difference in size and shape and body structure
Geographical isolation - existence in different geographical locations that keep population physically isolated
Ecological isolation - exist in the same geographical are but in different habitat.
Behavioral isolation - mating behavior patterns ritual may be different.
Hybrid sterility -  Meeting may be possible unsuccessful hybrid marriage maturity but cannot produce gametes.
Temporal isolation - time of breeding may be different
What is reproduction isolation ?
Factors that prevent members of different species from producing offspring, or ensure that any offspring are sterile
Describe the the different types of speciation.
Allopatric speciation- Occurs when geographical isolation prevents gene flow between two selections of a population
Sympathic speciation - occurs in population when individuals live together but it’s a biological differences separates the group
Paradatric speciation - occurs when new species evolve in contiguous, yet spatially segregated habitats.
Phyletic speciation - Refers to the granual accumulation of lineage through time until a group was distinct enough to be considered and new species
Hybridization- when two distinct species successfully mate to produce hybrid offspring
What is evolution?
Change in gene frequency of a population over time.
What is the two kinds of evolution?
Macro and micro evolution.
What is micro evolution?
Change in gene frequency of a chromosome/ chromosome structure which can be noticed over a short time.
What is macro evolution?
Macroevolution refers to larger evolutionary changes that result in new species
