Biology: Reproduction and Cell Division

Study Notes

Asexual reproduction requires only one parent, while sexual reproduction requires two parents.
Offspring produced via asexual reproduction are genetically identical to their parents.
Offspring produced by sexual reproduction are genetically unique, with a mix of traits from both parents.

Budding: a new individual grows from a parent cell, eventually separating from the parent.
Fragmentation: a parent cell breaks into multiple fragments, each developing into a new individual.
Binary fission: a parent cell divides into two identical daughter cells.

Internal fertilization: fertilization occurs within an organism's body, e.g., in humans.
External fertilization: fertilization occurs outside an organism's body, e.g., in fish.

Steps of mitosis:
- Interphase: cell growth and DNA replication.
- Prophase: chromatin condenses, and the nuclear envelope breaks down.
- Metaphase: chromosomes align at the center of the cell.
- Anaphase: sister chromatids separate.
- Telophase: nuclear envelope reforms, and chromosomes uncoil.
- Cytokinesis: cytoplasm divides, and cell splits.
Mitosis produces two identical daughter cells, each with the same number and type of chromosomes as the parent cell.

Cancer occurs when cell division becomes uncontrolled, leading to abnormal cell growth and tumor formation.

Fertilization occurs when a sperm cell fuses with an egg cell, resulting in a zygote.

Purpose of meiosis: to produce gametes with unique genetic combinations.
Process of meiosis:
- Meiosis I: reduction division, resulting in two haploid cells.
- Meiosis II: equational division, resulting in four haploid gametes.
In females, meiosis produces one egg cell and three polar bodies.
In males, meiosis produces four sperm cells.

Crossing over: the exchange of genetic material between homologous chromosomes during meiosis.
Genetic variation: the difference in genetic traits between individuals, resulting from meiosis and crossing over.

Types of mutations:
- Gene mutations: changes in a single gene.
- Chromosomal mutations: changes in chromosome structure or number.

Codominance: when both alleles of a gene have an equal effect on the phenotype.
Incomplete dominance: when one allele does not completely mask the effect of another allele.
Sex-linked traits: traits carried on sex chromosomes.

Punnett squares: diagrams used to predict the probability of offspring genotypes and phenotypes.
Pedigrees: diagrams used to track the inheritance of traits in a family.

Relative dating: determining the age of a fossil or rock layer relative to others.
Stratification: the layering of rock formations, with older layers at the bottom.
Homologous structures: similar structures in different organisms, e.g., forelimbs.
Analogous structures: similar structures in different organisms, with different functions.
Vestigial structures: structures that have lost their original function.
Convergent evolution: the development of similar traits in different organisms.
Divergent evolution: the development of different traits in different organisms.

Charles Darwin: credited with developing the theory of evolution.
Heritable trait: a characteristic that can be passed from parent to offspring.
Fitness: an organism's ability to survive and reproduce.
Adaptation: a trait that enhances an organism's fitness.
Natural selection: the process by which better-adapted organisms are more likely to survive and reproduce.
Speciation: the formation of new species from a single ancestral species.

Binomial nomenclature: the system of naming species using a genus and species name.
Taxonomic levels: domain, kingdom, phylum, class, order, family, genus, species.
Cladogram: a diagram used to show the relationships between organisms.
Cladogram reading: organisms that share a common ancestor are grouped together.