Patterns Of Inheritance Flashcards
What is continuous variation
- polygenic / controlled by environment
Wheee the individuals vary within a range: no distinct categories
Data = quantitative e.g. height
What is discontinuous variation
- monogenic & little environmental influence
2 or more distinct categories (& u only fall into one)
E.g. type A, B, AB, O
Examples of factors influenced by genetic & environmental factors (therefore continuous?)
- diet
- chlorosis
- etiolation
What is chlorosis (yellowed leaves due to less chlorophyll production) due to
- lack of light,therefore low chlorophyll production to conserve resources
- mineral deficiencies e.g. iron needed as enzyme cofactor to make chlorophyll
- virus infections
How can animal diet be linked to mass and obesity etc
Obesity can be due to genes e.g. mutations on chromosomes = altered fat deposition
Bit mainly due to environmental factors e.g. how much u eat, workout, disease
What is etiolation
When plants are grown in the dark and may develop long stems with small, curled leaves even though genetically, should grow normally
How sexual reproduction can lead to genetic variation
5 diff types of genetic diagrams
- monogenic inheritance
- dihybrid inheritance
- multiple alleles
- sex linkage
- co-dominance
What’s monogenic inheritance
Dihybrid inheritance (of two genes) diagram
Multiple Alleles diagram
Multiple Alleles diagram
Genetic diagram for sex linkage
Codominance diagram
Difference between Co-dominance & Incomplete dominance
Co-dominance = both alleles have the effect so e.g. a red and a white coat come together to give a pink coat
Incomplete dominance = a mixture of the alleles in the genotype e.g. than the pink coat, it would be red or white stripes or spots on the coat
How are phenotypic ratios important
What is autosomal linkage
If 2 genes are found on the same (nonsex chromosome)
- the closer the two genes are, the likelier they both are of being inherited as one unit
Occurs differently depending on the gene loci / location as they affect that the two genes / alleles & how they may be inherited
What is epistasis
What are the factors that affect the evolution of a species
- founder effect
- genetic drift
- genetic bottleneck
- selection pressures
What are the 2 types of selection pressures
Directional selection
Stabilising selection
What is stabilising selection
Natural selection that keeps alleles frequencies = constant (unless a change in environment)
What is directional selection
Natural selection that produces a gradual change in allele frequencies over several generations
- usually happens when there are changes in environmental & therefore change in selection pressures, or a new allele has appeared in the population that’s advantages
Example of directional selection:
-> process of steps using fish size as an example, as climate change selects for a smaller body size
- Warmer size = metabolism increases, more need for O2, and O2 decreases in warmer seas
- Large fish = disadvantaged is greater metabolic needs
- Organisms sensitive to temp changes, due to enzyme activities, therefore smaller fish = fitter = better adapted
- So smaller fish more likely to reproduce & their alleles for smaller size down
- Over time, inc freq of alleles for a small body size
What is genetic drift
-> when chance (not environmental selection pressures) affects which individuals in a population survive therefore breed & pass on their alleles