Cytology - Anatomy Lecture 5-19-26

Practice flashcards covering cytology, cell organelles, and the phases of the cell cycle based on the provided lecture notes.

Cytology

The scientific study of cells.

Robert Hooke

The scientist who, in the $1600s$, coined the term "cell" after viewing box-like structures through a microscope.

Eukaryotic cells

Human cells which possess a membrane-bound nucleus, numerous membrane-bound organelles, and several rod-shaped chromosomes.

Erythrocytes

Cells that transport gases throughout the body.

Fibroblasts

Cells that connect body parts.

Epithelial cells

Cells that form linings within the body.

Macrophage

A type of cell that fights disease.

Cytoplasm

The cellular region between the nuclear and plasma membranes, consisting of fluid cytosol, organelles, and inclusions.

Mitochondria

Rodlike, double-membrane structures where the inner membrane is folded into cristae; they are the site of ATP synthesis and known as the powerhouse of the cell.

Cristae

The projections formed by the folding of the inner mitochondrial membrane.

Ribosomes

Dense particles consisting of two subunits composed of ribosomal RNA and protein; they serve as the sites of protein synthesis.

Rough endoplasmic reticulum

A membranous system studded with ribosomes that attaches sugar groups to proteins and synthesizes phospholipids.

Smooth endoplasmic reticulum

A membranous system of sacs and tubules free of ribosomes; it is the site of lipid and steroid synthesis, lipid metabolism, and drug detoxification.

Golgi apparatus

A stack of flattened membranes and associated vesicles that packages, modifies, and segregates proteins for secretion, inclusion in lysosomes, or incorporation into the plasma membrane.

Peroxisomes

Membranous sacs of catalase and oxidase enzymes that detoxify toxic substances.

Catalase

The most important enzyme in peroxisomes, responsible for breaking down hydrogen peroxide.

Lysosomes

Membranous sacs containing acid hydrolases which serve as sites of intracellular digestion.

Microtubules

Cylindrical structures made of tubulin proteins ($25\,nm$ in diameter) that support the cell, give it shape, and form centrioles, cilia, and flagella.

Microfilaments

Fine filaments ($7\,nm$ in diameter) composed of the protein actin, involved in muscle contraction and other types of intracellular movement.

Intermediate filaments

Tough, insoluble protein fibers ($10\,nm$ in diameter) constructed like woven ropes; they are stable cytoskeletal elements that resist mechanical forces.

Centrioles

Paired cylindrical bodies, each composed of nine triplets of microtubules, that organize a microtubule network during mitosis to form the spindle and asters.

Inclusions

Varied storage materials such as lipid droplets, glycogen granules, protein crystals, and pigment granules.

Cilia

Short cell-surface projections composed of nine pairs of microtubules surrounding a central pair that create a unidirectional current to propel substances.

Flagellum

A long cellular extension used to propel the cell; in humans, the only example is the sperm tail.

Microvilli

Tubular extensions of the plasma membrane containing a bundle of actin filaments that increase surface area for absorption.

Nucleus

The largest organelle and control center of the cell, responsible for transmitting genetic information and providing instructions for protein synthesis.

Nuclear envelope

A double-membrane structure pierced by pores that separates the nucleoplasm from the cytoplasm and regulates the passage of substances.

Nucleolus

Dense spherical, non-membrane-bounded bodies composed of ribosomal RNA and proteins; the site of ribosome subunit manufacture.

Chromatin

Granular, threadlike material composed of DNA and histone proteins; the DNA constitutes the genes.

Zygote

A cell formed by the fusion of a sperm and an egg (gametes) that possesses a diploid number of chromosomes.

Cell cycle

The series of events a cell undergoes that ultimately produces a new cell.

Interphase

The stage where a cell spends $90\%$ of its time; it is subdivided into $G_1$, $S$, and $G_2$ phases.

S phase

The specific period during interphase when DNA is duplicated to provide a full complement of chromosomes for daughter cells.

Mitosis

The division of the nucleus, consisting of five stages: prophase, prometaphase, metaphase, anaphase, and telophase.

Cytokinesis

The division of the cytoplasm that follows mitosis.

Metaphase plate

The imaginary plane midway between the spindle poles where chromosomes line up during metaphase.

Anaphase

The phase of mitosis where sister chromatids (now called chromosomes) are pulled toward opposite poles.

Cleavage furrow

The contractile ring that forms in animal cells to separate the daughter cells during cytokinesis.