Cell Junctions, Cell Cycle, Mitosis & Meiosis – Vocabulary

A comprehensive set of vocabulary flashcards covering key terms related to cell junctions, the cell cycle, mitosis, meiosis, checkpoints, apoptosis, genetic disorders, and spindle formation discussed in the lecture.

Cell Cycle

Ordered sequence of growth, DNA replication, and division that produces two daughter cells.

Interphase

Non-dividing portion of the cell cycle (G1, S, G2) in which the cell grows and duplicates DNA and organelles.

G1 Phase

First gap of interphase; cell grows, makes proteins, and prepares for DNA synthesis.

S Phase

Interphase stage in which the entire genome is replicated.

G2 Phase

Second gap of interphase; cell prepares for mitosis by producing proteins and checking DNA.

G0 Phase

Resting state in which highly differentiated cells leave the cycle and perform normal functions without dividing.

Cell Division

General term for the separation of one parent cell into daughter cells by mitosis or meiosis.

Mitosis

Nuclear division that produces two genetically identical diploid daughter cells for growth and repair.

Meiosis

Two consecutive nuclear divisions that yield four genetically unique haploid gametes, introducing variation.

Cell Cycle Checkpoint

Surveillance point that stops the cycle until critical conditions are met, preventing mutations.

G1 Checkpoint

Restriction point verifying cell size, nutrients, DNA integrity before DNA replication.

S Checkpoint

Mid-S-phase control that ensures accurate and complete DNA replication.

G2 Checkpoint

Pre-mitotic gate confirming DNA replication completion and lack of damage before M phase.

M Checkpoint

Spindle checkpoint during metaphase that verifies chromosome attachment before anaphase.

Cyclins

Regulatory proteins whose concentrations oscillate and activate Cdks to drive cell-cycle transitions.

Cyclin-Dependent Kinases (Cdks)

Protein kinases activated by cyclins that phosphorylate targets to advance the cell cycle.

p53

Tumor-suppressor protein that halts the cycle or triggers apoptosis in response to DNA damage.

ATM

Protein kinase that senses double-strand DNA breaks and initiates checkpoint signaling.

ATR

Kinase that responds to replication stress or single-strand breaks, activating repair pathways.

Chk1

Checkpoint kinase that inhibits Cdk activity to delay the cycle when DNA is damaged.

Chk2

Kinase working with p53 to enforce cell-cycle arrest after DNA damage.

Mad Proteins

Spindle-checkpoint sensors that detect unattached kinetochores and block anaphase onset.

Bub Proteins

Checkpoint proteins cooperating with Mad family to ensure proper spindle attachment.

Apoptosis

Programmed cell death that safely eliminates damaged, dangerous, or unneeded cells.

Caspases

Family of proteases that, once activated, dismantle the cell during apoptosis.

Intrinsic Pathway (Apoptosis)

Mitochondria-initiated death route triggered by internal stress such as DNA damage.

Extrinsic Pathway (Apoptosis)

Death-receptor pathway activated by external ligands like Fas on the cell surface.

Chromosome

Highly condensed DNA-protein structure carrying genetic information visible during division.

Chromatin

DNA-protein complex that forms chromosomes; relatively loose during interphase.

Chromatid

One of two identical DNA strands of a replicated chromosome.

Sister Chromatids

Paired identical chromatids joined at a centromere after DNA replication.

Centromere

Constricted region where sister chromatids are most closely attached and where kinetochores form.

Kinetochores

Protein complexes on centromeres that attach chromosomes to spindle microtubules.

Mitotic Spindle

Bipolar structure of microtubules that separates chromosomes during mitosis and meiosis.

Spindle Fiber

Individual microtubule filament contributing to the mitotic spindle.

Microtubule Organizing Center (MTOC)

Region in which microtubules nucleate; plant cells use dispersed MTOCs to form spindles.

Centrosome

Animal-cell MTOC containing a pair of centrioles that organizes spindle microtubules.

Centrioles

Cylindrical microtubule pairs within centrosomes that aid spindle formation in animal cells.

Metaphase Plate

Imaginary plane equidistant from spindle poles where chromosomes align during metaphase.

Cleavage Furrow

Contractile ring indentation that pinches animal cells in two during cytokinesis.

Cell Plate

New partition of cell wall material that separates daughter plant cells during cytokinesis.

Prophase

First stage of mitosis; chromatin condenses, nucleolus disappears, spindle begins forming.

Metaphase

Mitosis stage where duplicated chromosomes align at the metaphase plate.

Anaphase

Stage in which centromeres split and sister chromatids move to opposite poles.

Telophase

Final mitotic stage; chromosomes decondense and nuclear envelopes re-form around two nuclei.

Cytokinesis

Division of the cytoplasm producing two separate daughter cells after nuclear division.

Leptotene

First substage of prophase I; chromosomes start condensing and become visible.

Zygotene

Prophase I substage when homologous chromosomes pair by synapsis to form bivalents.

Pachytene

Substage of prophase I in which crossing over occurs between non-sister chromatids.

Diplotene

Prophase I stage where homologs begin to separate and chiasmata become visible.

Diakinesis

Final prophase I stage with fully condensed tetrads ready for spindle attachment.

Synapsis

Tight pairing of homologous chromosomes during prophase I of meiosis.

Tetrad

Group of four chromatids (two homologous chromosomes, each with two sister chromatids) seen in meiosis I.

Crossing Over

Reciprocal exchange of DNA between non-sister chromatids during pachytene, creating recombination.

Independent Assortment

Random orientation of homologous pairs at metaphase I leading to varied gamete combinations.

Homologous Chromosomes

Chromosome pair of same length and gene loci, one inherited from each parent.

Aneuploidy

Condition of having an abnormal number of chromosomes (2n ± 1, etc.).

Polyploidy

State of possessing more than two complete chromosome sets (3n, 4n…).

Nondisjunction

Failure of homologous chromosomes or sister chromatids to separate, leading to aneuploidy.

Spermatogenesis

Meiotic process in males that produces haploid sperm cells.

Oogenesis

Meiotic process in females that produces haploid ova (egg cells).

Haploid

Having one complete set of chromosomes (n); characteristic of gametes.

Diploid

Having two sets of chromosomes (2n); typical of somatic cells.

Trisomy

Presence of an extra chromosome in a diploid set (2n + 1).

Monosomy

Missing one chromosome from the diploid set (2n − 1).

Down Syndrome

Trisomy 21 disorder causing intellectual disability, characteristic facial features, and hypotonia.

Edward Syndrome

Trisomy 18 disorder marked by clenched fists, heart defects, and severe developmental delay.

Patau Syndrome

Trisomy 13 disorder featuring cleft palate, polydactyly, and severe organ defects.

Turner Syndrome

Monosomy X in females (45,X) leading to short stature, webbed neck, and infertility.

Klinefelter Syndrome

XXY trisomy in males causing small testes, infertility, and some feminization.

Triple X Syndrome

XXX trisomy in females; often tall with possible learning difficulties but usually fertile.

Cancer

Group of diseases characterized by uncontrolled, abnormal cell division.

Benign Tumor

Localized mass of abnormal cells that does not invade or spread to other tissues.

Malignant Tumor

Cancerous mass whose cells invade neighboring tissues and may spread systemically.

Metastasis

Migration of malignant cells to distant sites, forming secondary tumors.

Deletion (Chromosomal)

Loss of a chromosome segment, often causing genetic disorders.

Duplication (Chromosomal)

Repetition of a chromosome segment, increasing gene copy number.

Translocation

Transfer of a chromosome segment to a non-homologous chromosome.

Inversion

Reversal of a chromosome segment orientation within the same chromosome.

Cri-du-chat Syndrome

Genetic disorder from deletion on chromosome 5p, causing cat-like cry and intellectual disability.