Review 5 Flashcards
Sources of Mutations
- Inherited
- Spontaneous:
a. DNA replication errors
b. Environmental factors
c. Completely random
Mutations Effects on DNA
- Point mutation
2. Frameshift mutation (Insertion/Deletion)
Mutation Effects on Protein
- Missense Mutation (leads to change in amino acid)
2. Nonsense mutation leads to stop codon prematurely
Missense Mutation
- Silent mutation - Does not affect final amino acid
- Conservative mutation - New amino acid is the same type as the previous one e.g. acid for acid
- Non-conservative mutation - New amino acid of different type e.g. Serine for Phe
Causes of Point mutation
Point mutations are caused by BASE SUBSTITUTION
1. Transition i.e. A->G or C->T (Change one purine for another purine or pyrimidine for another pyrimidine
- Transversion i.e. A or G for C or T (Change purine for pyrimidine or vice-versa)
- Mispairing mismatching
Causes of Frame-shift Mutation
- Insertion
2. Deletion
Large Scale Mutations
- Crossing over of non-homologous chromosomes
- Inversion:
a. Do not always affect individual nucleotides
b. Affects mostly regulation of expression and what it codes for
c. Position depends on regulation
Mutagens and Classes
Chemical or Physical substance or event that can cause genetic mutations
a. Endogenous (internal) e.g : ROS (Cause breaks, or base modification)
b. Exogenous (External) e.g Intercalators and base analogues (e.g. Uracil -> 5-Bromouracil)
5-Bromouracil
- Ketoform - Binds adenine 9good)
2. Enol form - Binds Guanine (:-(
Carcinogen
- Can be mutagen or not.
- Increase rate of cancer
3, Can cause mutation or increase a protein rate
e.g: Tobacco, asbestos
Complete Dominance
AB - A completely dominant over B
Incomplete Dominance
A MIXTURE of the alleles in the GENOTYPE is seen in the Phenotype
Co-Dominance
Both ALLELES in the genotype are seen in th ephenotype
Hardy-Weinberg Principle
- No selection
- No mutation
- Large Population
- Net migration = 0
- Random Mating
Hardy-Weinberg Equation
p + q = 1
p^2 + 2pq + q^2 = 1
Hersey-Chase
Sulphur and Phosphorous to determine DNA
Genetic Recombination 1
- Joining of homologous pair and form tetrad called synapsis
- Product formed is the synaptomenal complex
- Joined at the Chiasma and the result is crossing-over and recombination of genetic recombination
Genetic Recombination 2
Know the following:
Single Crossing over
2 strand single crossver
3 strand double crossover, etc
Pseudoautosomal region
These are regions on the X and Y where crossing over occurs but beyond those points, crossing over does not happen
Gene Mapping
Higher the distances, the greater the recombination frequency
Centimorgan
Distance between genes for which one product of meiosis in 100 is recombinant
E.g. 1 centimorgan = 1 %
Extranuclear Inheritance
- Chloroplast and Mitochondria
2. Maternal Inheritance (Mito. and chloroplast) does not follow Mendelian Inheritance. (Does not involve sperm and egg)
Evolution
- Small changes to POPULATION and NOT INDIVIDUALS over a long period of time
Agents of Evolution
- Natural Selection
2. Genetic Drift
Natural Selection
- Nature selects it.
- Applies only to heritable traits and not teachable ones like saying hunting or fishing.
- The basis that the better trait will survive longer and then pass it down.
- Survival UNTIL reproduction
Fitness
- Refers to the organism’s total ability to pass on traits to offsprings
- Combination of ability to survive to the age of reproduction and actually be able to reproduce when it gets there.
Fecundity
- Refers to a description of how well a person can actually reproduce
- How easy or often a person can reproduce or produce offspring
- Direcrtly related to natual selection
Alternatives to Natural Selection
- Group Selection
2. Artificial Selection
Group Selection
- Survival AFTER reproduction
- Genetic traits that benefit the group as a whole will be naturally selected for even though they do not benefit the individual with the trait.
Artifical Selection
Outside individual NOT nature can literally choose which traits will be passed on instead of it occurring naturally.
Genetic Drift
- Not the traits most necessarily fit that survive or are selected.
- Random changes
- CHanges in Heritable traits
- More likely to happen to small populations
Types of Genetic Drift that lead to extreme reduction in population
- Bottleneck effect
2. Founder effect
Bottleneck Effect
- Significant reduction in population
2. Major disaster or event kills off population
Founder Effect
- Significant reduction in population
2. Due to loss in variation in population (some go off somewhere and find a new population)
Importance of Large Gene Pools
Good for a population because it allows to adapt to any changes in the environment
Inbreeding
- Groups of people will selectively have offspring with a smaller group within that population.
E.g: distant relatives, etc.
Concerns with Inbreeding
- Some inbred population are more likely to have carriers or diseased people with diseases than the general population
- Mostly concern with autosomal recessive because they go unnoticed than autosomal dominant
How are species divided
By reproductive isolation
Reproductive Isolation
- Pre-zygotic
2. Post-zygotic
Pre-zygotic Definition
All the different forces that prevent two organisms from having offspring together that occurs prior to formation of zygote
Post-zygotic Definition
All the different forces that arise after zygote forms
Pre-zygotic Forms
- Temporal or Habitat (Ecological) isolation
- Behavioral isolation
- Mechanical Isolation
- Gametic Isolation
Temporal/Habitat Isolation
- Not all organisms mate at the same time
a. Some at night/day or summer/winter
b. If they do not find at the same time, they are temporarily isolated - Refers to place for reproduction and if not found, it could be isolated
Behavioral Isolation
- Mate selection; attract mates in different ways
2. e.g. bird singing, dancing
Mechanical Isolation
- Mating is NOT possible e.g elephant and mouse
Gametic Isolation
If they do mate, fusion of gamete to form zygotes is NOT possible
Post-zygotic Forms
- Post-zygotic mortality
- Hybrid inviability
- Hybrid sterility
Post-zygotic mortality
- Gametes fuse but zygote will still die and cannot develop to mature offspring
Hybrid invariability
Zygote forms, grows to an offspring but cannot mature to an adult but dies off
Hybrid sterility
Gamete fuses, zygote forms, develops into offspring and adult but cannot mate and form or reproduce on its own
Species classification
If 2 sexually reproducing organisms are not isolated by any of these barriers, we say that they are the same species. Think ABOUT IT NOT JUST IMPOTENT PEOPLE BUT IF IT APPLIES TO ALL GROUPS
