Variation Flashcards
What is variation?
Members of different species look different and are rarely identical
What are the types of variation?
Intraspecific and interspecific
What is intraspecific variation?
Variation within a species
What is interspecific variation?
Variation between different species
What are the way variation be caused?
Genetic variation or between individuals due to environmental factors
What determines the phenotype of an organism?
Genes and environment
What is a phenotype?
The observable characteristics of an organism due to both genetic and environmental influence
What is a genotype?
The genetic makeup (all of the DNA) which refers to the combination of alleles of an organism that contributes to its traits
What are alleles?
Different version of genes
Where do alleles come from?
Each individual inherits 2, one from their mum and one from their dad
What is genetic variation?
A difference in DNA between an individual and another
What causes genetic variation?
Sexual reproduction and mutation
How does sexual reproduction cause genetic variation?
Random mating, random fusion of gametes, independent assortment andd crossing over
What is mutation?
Deletion, substitution and insertion cause different proteins to fold up differently due to amino acids
What do changes in DNA sequence cause?
They give rise to different alleles which could lead to differences at the protein level
What are the types of gamete mutations?
Somatic and germ-line
What is the effect of somatic and germ-line mutations?
Somatic are not passed onto offspring and germ-line are
How does meiosis cause genetic variation?
Independant assortment and crossing over gives rise to variation amongst offspring by mixing alleles
How does sexual reproduction cause genetic variation?
Two gametes fuse so half genetic material of one parent and offspring will always differ from parents
How does chance cause genetic variation?
Which individuals will mate and which gametes will fuse
What are environmental factors?
Water availability, temperature and food availability
What is the importance of variation?
If there is genetic variation, if one organism is susceptible to a disease, the whole population will be and could be wiped out, and it is the basis for evolution through natural selection
What is variation in microorganisms?
Microorganisms have different shapes and sizes, some with flagella, some not and some that can be stained with ram positive and others that can’t
How can bacteria and viruses mutate?
To become more resistance to drugs
What are types of data?
Continuous or discontinuous
What is continuous data?
It is quantitative, such as height or body mass
What is continuous variation?
A full range of intermediate phenotypes between the extremes with a wide range of phenotypic difference in one trait within the population
How is continuous data categorised?
It can take any numerical value within a range in distinct categories
How is continuous data recorded?
In a line graph
What controls continuous traits?
A number of genes, which each add a component to the phenotype
What influences continuous traits?
The environment, so they are multi factorial
What is the effect of different alleles?
They have a mall effect on the phenotype and may have a combined effect on the phenotype
What is discontinuous data?
It is qualitative, such as blood type or eye colour
What is discontinuous variation?
Seperate groups of phenotypes with no in between bars
How is discontinuous data organised?
Into clearly distinguishable phenotypic categories in distinct groups with no intermediate values
How is discontinuous data recorded?
A bar chart
What controls continuous variation?
One only genes and different alleles at a single gene locus have a large effect on the phenotype
What is special about alleles?
The inherited combination is unique
What does a normal distribution curve look like?
A bell-shaped curve
Where is the mean, median and mode of a bell shaped curve?
They are all the same in the centre
Where are the values on a normal distribution curve?
50% are above and 50% are below the mean, with most being close to the mean and the number of individuals at extremes low
What is an example of normal distribution?
Height in humans or mass in plants and animals
