Biology: Evolution Mechanisms

Study Notes

Definition: The process by which species change over time through the transmission of genetic information from one generation to the next.
Mechanisms:
- Natural Selection: The process by which individuals with favorable traits are more likely to survive and reproduce, passing those traits to their offspring.
- Genetic Drift: The random change in the frequency of a gene or genetic trait in a population over time.
- Mutation: A change in the DNA sequence of an individual.
- Gene Flow: The movement of genes from one population to another, leading to genetic changes.

Definition: The study of heredity and variation in organisms.
Key Concepts:
- Genotype: The genetic makeup of an individual.
- Phenotype: The physical and behavioral traits of an individual.
- Dominant and Recessive alleles: Dominant alleles will be expressed if an individual has one copy of the allele, while recessive alleles will only be expressed if an individual has two copies.

Definition: Thread-like structures made up of DNA and proteins that carry genetic information in the nucleus of eukaryotic cells.
Number of Chromosomes:
- Humans: 23 pairs (46 total) of chromosomes.
- Other Organisms: The number of chromosomes varies, but is typically diploid (two sets).
Chromosomal Structure:
- Centromere: The region where the sister chromatids are joined.
- Telomeres: The protective caps on the ends of chromosomes.

Definition: A double-stranded molecule that contains the genetic instructions for an organism.
Structure:
- Double Helix: Two complementary strands twisted together.
- Nucleotides: The building blocks of DNA, consisting of a sugar molecule, a phosphate group, and a nitrogenous base (A, C, G, or T).
Replication: The process by which DNA is copied, ensuring that each new cell receives a complete set of genetic instructions.

Definition: A diagram used to predict the outcomes of cross-breeding experiments, illustrating the possible genotypes and phenotypes of offspring.
Components:
- Parents: The two individuals being crossed.
- Alleles: The different forms of a gene.
- Punnett Square: A grid displaying all possible combinations of alleles from the parents.
Predicting Offspring Traits: By analyzing the Punnett Square, we can determine the probability of different genotypes and phenotypes in the offspring.

Evolution is the process by which species change over time through genetic transmission.
Natural selection favors individuals with favorable traits, increasing their survival and reproduction rates.
Genetic drift is a random change in gene frequency in a population over time.
Mutation is a change in an individual's DNA sequence.
Gene flow is the movement of genes between populations, leading to genetic changes.

Genetics is the study of heredity and variation in organisms.
Genotype is an individual's genetic makeup, while phenotype is their physical and behavioral traits.
Dominant alleles are expressed with one copy, while recessive alleles require two copies.

Chromosomes are thread-like structures made up of DNA and proteins carrying genetic information in eukaryotic cells.
Humans have 23 pairs (46 total) of chromosomes.
Other organisms have varying numbers of chromosomes, typically diploid (two sets).
Chromosomes have a centromere where sister chromatids join and telomeres at the ends.

DNA is a double-stranded molecule containing genetic instructions for an organism.
DNA has a double helix structure with two complementary strands.
Nucleotides are the building blocks of DNA, consisting of a sugar molecule, a phosphate group, and a nitrogenous base (A, C, G, or T).
DNA replication is the process of copying DNA to ensure each new cell receives a complete set of genetic instructions.

Punnett Squares are diagrams used to predict cross-breeding outcomes, illustrating possible genotypes and phenotypes of offspring.
Parents, alleles, and Punnett Squares are used to determine the probability of different genotypes and phenotypes in offspring.
Punnett Squares help predict the traits of offspring by analyzing the possible combinations of alleles from parents.