AP Biology Difficult Topic Review

What is the ligand of a GPCR?

It could be a wide variety of things; hormones, steroids, pheromones, etc.

What happens to the alpha subunit once the receptor is activated in a GPCR?

TIt stops holding GDP and starts holding GTP. Then, it breaks away from the beta-gamma dimer.

What is the end result of one cell undergoing meiosis?

4 haploid gametes

What is the end result of one cell undergoing mitosis?

2 diploid daughter cells

What is the difference between the alignment of genetic material in mitosis metaphase vs. meiosis metaphase 1?

In mitosis metaphase, chromosomes align individually at the cell's equatorial plane, while in meiosis metaphase 1, homologous chromosome pairs align together side by side.

What is the difference between mitosis and meiosis prophase?

Mitosis prophase involves the condensation of chromatin into individual chromosomes, with the spindle apparatus beginning to form. In contrast, meiosis prophase I includes homologous chromosomes pairing up to form tetrads and crossing over may occur, increasing genetic diversity.

What happens to the nucleus in mitosis and meiosis?

The nucleus breaks and reappears. The nucleus breaks because it stops the spindles from attaching from either end and eventually pulling the chromatids apart.

Saturated vs unsaturated lipid

Saturated lipids contain no double bonds between carbon atoms, making them solid at room temperature, while unsaturated lipids have one or more double bonds, resulting in a liquid state at room temperature. Unsaturated lipids pack together less tightly than saturated lipids.

How do nucleotides bond with each other? hydrogen or covalent bond?

Nucleotides bond with each other through covalent bonds, specifically phosphodiester bonds, which link the phosphate group of one nucleotide to the sugar of the next, forming the backbone of nucleic acid strands.

In which direction does RNA polymerase work?

RNA polymerase synthesizes RNA in the 5' to 3' direction, adding nucleotides to the growing strand.

In what form is genetic material during interphase?

Genetic material is in the form of chromatin during interphase, which is less condensed than chromosomes, allowing for transcription and replication.

Law of Segregation

States that during the formation of gametes, the two alleles for a trait separate from each other so that each gamete carries only one allele for each gene.

Law of Independent Assortment

States that the alleles for different traits are distributed to gametes independently of one another during meiosis, leading to genetic variation.

Law of Dominance

States that when two different alleles for a trait are present, one allele can mask the expression of the other, leading to a dominant phenotype.

Lamarck’s Theory

Posits that organisms can pass on traits acquired during their lifetime to their offspring, suggesting evolution occurs through adaptation to the environment.

Bottleneck Effect

A genetic phenomenon in which a population's size is significantly reduced for at least one generation, resulting in a loss of genetic diversity and alteration of allele frequencies.

Founder Effect

A genetic phenomenon that occurs when a small group of individuals establishes a new population, leading to a reduction in genetic diversity and different allele frequencies compared to the original population.

Heterozygous Advantage, and why does it occur?

A situation where individuals with two different alleles for a given gene (heterozygotes) have a higher fitness than those with two identical alleles (homozygotes). This phenomenon often occurs in environments where heterozygotes can better tolerate stressors such as disease or environmental changes. This advantage can maintain genetic diversity within a population, as seen in cases like sickle cell anemia resistance to malaria.

Allopatric vs sympatric speciation

Allopatric speciation occurs when populations are geographically isolated, leading to reproductive isolation and divergence, while sympatric speciation occurs without geographic barriers, often through mechanisms like polyploidy or behavioral differences.