뒤로General Biology Exam 3 Study Guide
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Cell-cell contact-dependent, paracrine, synaptic, and endocrine/hormonal signaling differ by how signals are transmitted and the distance they travel.
RTKs are receptors that dimerize and autophosphorylate upon ligand binding, initiating a signaling cascade.
GPCRs activate G proteins by exchanging GDP for GTP, which then regulate downstream effectors.
These receptors open or close ion channels in response to ligand binding, altering ion flow across membranes.
Kinases add phosphate groups to proteins; phosphatases remove phosphate groups.
A cell is a target cell if it has the specific receptor to detect and respond to a particular signaling molecule.
cAMP is synthesized from ATP by the enzyme adenylyl cyclase after receptor activation.
Ca2+ ions flow from the ER to the cytosol through channels opened by second messengers like IP3.
IP3 is produced from PIP2 by phospholipase C and triggers Ca2+ release from the ER.
Programmed cell death in C. elegans is controlled by conserved genes regulating cell survival and death.
Diploid (2n) cells have two sets of chromosomes; haploid (n) cells have one set.
Diploid cells have two sets of chromosomes; haploid cells have one set. Total chromosomes = sets × chromosomes per set.
The cell cycle phases are G1, S (DNA replication), G2, and M (mitosis).
DNA replication occurs during the S phase of the cell cycle.
After replication, chromosome number stays the same, but each chromosome has two sister chromatids.
Microtubules form the mitotic spindle, separating chromosomes during mitosis and meiosis.
Actin filaments form the contractile ring that pinches the cell during cytokinesis.
The formation of a cleavage furrow marks the start of cytokinesis in animal cells.
A cell plate forms between daughter nuclei, initiating cytokinesis in plant cells.
G1 checks for cell size and DNA damage, G2 checks DNA replication completeness, M checks chromosome attachment to spindle.
Cancer cells often bypass or ignore cell cycle checkpoints, leading to uncontrolled division.
Homologous chromosomes are chromosome pairs from each parent; sister chromatids are identical copies joined after replication.
A karyotype is an organized profile of an individual's chromosomes arranged by size and shape.
Mitosis produces two genetically identical diploid daughter cells for growth and repair.
Meiosis I separates homologous chromosomes; Meiosis II separates sister chromatids, producing haploid cells.
Meiosis includes synapsis and crossing over during prophase I, which do not occur in mitosis.
During metaphase I of meiosis, homologous chromosomes assort independently, increasing genetic variation.
Dominant traits are expressed when present; recessive traits are expressed only when both alleles are recessive.
Homozygotes have two identical alleles; heterozygotes have two different alleles for a gene.
A monohybrid cross of heterozygotes typically yields a 3:1 dominant to recessive phenotypic ratio.
A dihybrid cross of heterozygotes typically yields a 9:3:3:1 phenotypic ratio for two traits.
Punnett squares predict genotypic and phenotypic ratios by combining parental alleles.
Alleles of different genes assort independently during gamete formation, creating genetic diversity.
The multiplication rule calculates the probability of independent events occurring together; the addition rule calculates the probability of one event or another occurring.