chapter 6 bio1101

Genome

is an organism’s complete complement of DNA containing all of its genetic instructions

Homologous Chromosomes

are matched pairs in a diploid cell that are equal in length and carry genes for the same traits at identical loci

Interphase

is the long preparatory phase of the cell cycle where a cell grows, performs normal biochemical functions, and replicates its DNA across G1, S, and G2 stages

G1 Phase:

is the initial interphase stage where the cell increases in size and accumulates the necessary energy and building blocks for DNA replication

S Phase

is the synthesis stage of interphase during which genomic DNA is replicated, forming two identical sister chromatids joined at the centromere

G2 Phase

is the final interphase stage where the cell replenishes energy stores, synthesizes proteins required for division, and completes preparations for nuclear division

Mitosis

is the process of eukaryotic nuclear division that segregates duplicated chromosomes into two genetically identical daughter nuclei through prophase, prometaphase, metaphase, anaphase, and telophase

Cytokinesis

is the physical separation of the cytoplasm following mitosis, dividing the cell via an actin cleavage furrow in animal cells or a cell plate in plant cells

G0 Phase

is an inactive, quiescent stage outside the active cell cycle where non-dividing cells reside temporarily or permanently

G1 Checkpoint:

assesses cell size, energy reserves, and genomic DNA integrity before irreversibly committing the cell to division

G2 Checkpoint

verifies that all chromosomes have been fully and accurately replicated without DNA damage prior to entering mitosis

M Checkpoint

(spindle checkpoint) monitors whether all sister chromatids are properly attached to spindle microtubules via kinetochores before allowing entry into anaphase

Proto-oncogenes & Oncogenes

____are normal genes that promote positive cell cycle regulation, but when mutated, become cancer-causing_____that accelerate cell division

Tumor Suppressor Genes:

encode negative cell cycle regulators that halt cell division when errors or damage occur to prevent uncontrolled growth.

Binary Fission

is the rapid, simple form of asexual cell division in prokaryotes where a single circular chromosome replicates and divides using an FtsZ protein ring and septum

Meiosis

is a specialized two-stage nuclear division process that reduces a diploid cell's chromosome sets by half to create four genetically unique haploid gametes

Red Queen Hypothesis

suggests that organisms must continually evolve and maintain genetic variation through sexual reproduction simply to survive alongside coevolving competing species

Synapsis & Crossing Over

During Prophase I of meiosis,_pairs homologous chromosomes tightly so non-sister chromatids can perform_exchanging DNA segments to create unique recombinant chromosome

Independent Assortment

is the random alignment of homologous chromosome pairs along the metaphase plate in Metaphase I, creating millions of possible maternal and paternal gene combinations

Nondisjunction

is the failure of homologous chromosomes or sister chromatids to separate during meiosis, resulting in gametes with abnormal chromosome numbers

X Inactivation

is a developmental process in female mammalian embryos where one X chromosome randomly condenses into an inactive Barr body to balance gene dosage

Phenotype

An organism's ___ consists of its observable physical traits,

Genotype

is its underlying combination of inherited alleles

Law of Segregation

states that paired copies of genes separate equally into gametes during meiosis, ensuring offspring have an equal probability of inheriting either allele

Law of Independent Assortment

states that alleles for different genes sort into gametes independently of one another during meiosis

Incomplete Dominance

is a pattern of inheritance where a heterozygous individual expresses a blended, intermediate phenotype between the two homozygous parents.

Codominance:

occurs when a heterozygous individual simultaneously expresses both alleles fully in its phenotype

Sex-Linked Traits

__are controlled by genes on the X chromosome, causing recessive conditions to be expressed far more frequently in hemizygous males

Gene Linkage

occurs when genes located close together on the same chromosome are inherited as a unit unless separated by recombination

Epistasis

is a gene interaction in which the expression of one gene masks or interferes with the phenotypic expression of a completely different gene