Genetics and Inheritance (MISS ESTRUCH VIDEO)

Inheritance

Genotype: The genetic constitution of an organism
Phenotype: The expression of the genes, influenced by the environment
Homozygous: Having two identical alleles (forms) of a gene
Heterozygous: Having two different alleles of a gene
Recessive allele: Only expressed if there is no dominant allele present
Dominant allele: Always expressed if present
Codominant: Both alleles are equally expressed in the phenotype
Multiple alleles: More than two alleles for a single gene
Sex linkage: A gene located on the X chromosome
Autosomal linkage: Genes linked on the same chromosome (not sex chromosomes)
Epistasis: One gene modifies or masks the expression of another gene

Representing Genotypes

Monohybrid: Representing one gene (e.g., cystic fibrosis)
- Capital letter for dominant allele, lowercase for recessive
Codominant: Both alleles equally dominant (e.g., blood group)
- Base letter represents the gene, superscript letter represents the allele
Multiple alleles: More than two alleles for a single gene (e.g., blood group)
Sex linkage: Representing genes on the X chromosome
Autosomal linkage: Representing genes on the same chromosome (not sex chromosomes)

Genetic Crosses

Punnett square: A table to predict the outcome of a genetic cross
Monohybrid cross: Analyzing the inheritance of one gene
Dihybrid cross: Analyzing the inheritance of two genes
Epistasis: One gene affects the expression of another gene
Autosomal linkage: Genes linked on the same chromosome affect the outcome

Probability and Chi-Squared

Probability: The chance of an event occurring
Chi-squared: A statistical test to determine if there is a significant difference between expected and observed frequencies
Null hypothesis: There is no difference between the expected and observed frequencies
Degrees of freedom: The number of categories minus one

Hardy-Weinberg Principle

Gene pool: All alleles of all genes in a population
Population: All individuals of one species in one area
Allele frequency: The proportion of an allele in a gene pool
Hardy-Weinberg equation: Used to predict allele frequencies in a population
p and q: Representing the dominant and recessive alleles, respectively### Topic 7: Genetics, Variation, and Evolution

Genetics and Probability

To calculate the probability of a genotype or phenotype, divide the frequency by 100 to convert it to a decimal.
Rearrange the equation to make p (probability of dominant allele) or q (probability of recessive allele) the subject.
Calculate 2pq to find the proportion of carriers (heterozygous individuals).

Variation and Evolution

Genetic variation occurs due to mutations, random fertilization of gametes, and crossing over during meiosis.
Natural selection acts on this variation, favoring individuals with phenotypes that provide a selective advantage.
As a result, the allele frequency changes, leading to evolution.
Disruptive selection occurs when individuals with extreme traits are more likely to survive and pass on their alleles, leading to a loss of the middling trait and eventually, speciation.

Speciation

Speciation occurs when a population becomes reproductively isolated, resulting in the accumulation of differences in their gene pools.
Allopatric speciation occurs when a geographical barrier separates the population, while sympatric speciation occurs when reproductive mechanisms prevent interbreeding.

Population Genetics

Genetic drift is the change in allele frequency within a population between generations.
The smaller the population, the greater the impact of genetic drift on evolution.
Population genetics is the study of the allele frequency changes within a population over time.

Ecology

A population is a group of organisms of the same species living in the same habitat.
A community is all the populations of different species in the same area at the same time.
An ecosystem is a community and the non-living components of the environment (abiotic and biotic factors).
A niche is an organism's role within an ecosystem, including its position in the food web and habitats.

Abiotic and Biotic Factors

Abiotic factors are the non-living components of the ecosystem, such as temperature, oxygen, and carbon dioxide concentration.
Biotic factors are the living components of the ecosystem, including interactions between organisms.
Adaptations develop through natural selection in response to abiotic and biotic factors.

Sampling

Sampling is used to estimate population size, and there are three types of sampling:
- Random sampling: used for uniform distributions, involves using a random number generator to select coordinates.
- Line transect: used for non-uniform distributions, involves placing a tape measure at a right angle to the shoreline or other feature.
- Mark-release-recapture: used for moving animals, involves marking and releasing individuals, then recapturing and estimating the population size.

Succession

Succession is the change in an ecological community over time.
Primary succession starts with a pioneer species colonizing bare rock or sand, while secondary succession occurs when the succession is disrupted and the plants are destroyed.
As succession occurs, species richness and biodiversity increase over time, and larger plant species and animals colonize the area.

Conservation

Conservation of habitats involves controlling succession to maintain a greater variety of habitats and species.
Management involves balancing human needs with conservation goals to maintain sustainability.

Inheritance

Genotype refers to the genetic constitution of an organism.
Phenotype is the expression of the genes, influenced by the environment.
Homozygous individuals have two identical alleles of a gene, while heterozygous individuals have two different alleles.
Recessive alleles are only expressed if there is no dominant allele present, and dominant alleles are always expressed if present.
Codominant alleles are equally expressed in the phenotype, and multiple alleles refer to more than two alleles for a single gene.
Sex linkage occurs when a gene is located on the X chromosome, while autosomal linkage occurs when genes are linked on the same chromosome (not sex chromosomes).
Epistasis occurs when one gene modifies or masks the expression of another gene.

Representing Genotypes

A monohybrid represents one gene, with a capital letter for the dominant allele and a lowercase letter for the recessive allele.
Codominant alleles are represented by a base letter for the gene and a superscript letter for the allele.
Multiple alleles refer to more than two alleles for a single gene.
Sex linkage represents genes on the X chromosome, and autosomal linkage represents genes on the same chromosome (not sex chromosomes).

Genetic Crosses

A Punnett square is a table used to predict the outcome of a genetic cross.
A monohybrid cross analyzes the inheritance of one gene, while a dihybrid cross analyzes the inheritance of two genes.
Epistasis occurs when one gene affects the expression of another gene.
Autosomal linkage occurs when genes are linked on the same chromosome, affecting the outcome.

Probability and Chi-Squared

Probability is the chance of an event occurring.
The chi-squared test is a statistical test to determine if there is a significant difference between expected and observed frequencies.
The null hypothesis states that there is no difference between the expected and observed frequencies.
Degrees of freedom refer to the number of categories minus one.

Hardy-Weinberg Principle

A gene pool consists of all alleles of all genes in a population.
A population is all individuals of one species in one area.
Allele frequency is the proportion of an allele in a gene pool.
The Hardy-Weinberg equation is used to predict allele frequencies in a population.
p and q represent the dominant and recessive alleles, respectively.

Genetics and Probability

To calculate the probability of a genotype or phenotype, divide the frequency by 100 to convert it to a decimal.
Rearrange the equation to make p (probability of dominant allele) or q (probability of recessive allele) the subject.
Calculate 2pq to find the proportion of carriers (heterozygous individuals).

Variation and Evolution

Genetic variation occurs due to mutations, random fertilization of gametes, and crossing over during meiosis.
Natural selection acts on this variation, favoring individuals with phenotypes that provide a selective advantage.
As a result, the allele frequency changes, leading to evolution.
Disruptive selection occurs when individuals with extreme traits are more likely to survive and pass on their alleles, leading to a loss of the middling trait and eventually, speciation.

Speciation

Speciation occurs when a population becomes reproductively isolated, resulting in the accumulation of differences in their gene pools.
Allopatric speciation occurs when a geographical barrier separates the population, while sympatric speciation occurs when reproductive mechanisms prevent interbreeding.

Population Genetics

Genetic drift is the change in allele frequency within a population between generations.
The smaller the population, the greater the impact of genetic drift on evolution.
Population genetics is the study of the allele frequency changes within a population over time.

Ecology

A population is a group of organisms of the same species living in the same area.
Ecology studies the interactions between organisms and their environment.