Cell: The Unit of Life - Flashcards

Flashcards based on Chapter 8: Cell - The Unit of Life

Cell

Fundamental structural and functional unit of all living organisms.

Cell Theory

Formulated by Matthias Schleiden and Theodore Schwann, modified by Rudolf Virchow; states that all living organisms are composed of cells and products of cells, and all cells arise from pre-existing cells.

Eukaryotic

Cells with membrane-bound nuclei.

Prokaryotic

Cells lacking a membrane-bound nucleus.

Cytoplasm

Semi-fluid matrix occupying the volume of the cell.

Prokaryotic Cells

Represented by bacteria, blue-green algae, mycoplasma, and PPLO.

Bacillus

Rod shaped bacteria.

Coccus

Spherical bacteria.

Vibrio

Comma shaped bacteria

Spirillum

Spiral shaped bacteria

Glycocalyx

Outermost layer of the cell envelope, can be a slime layer or capsule.

Mesosomes

Extensions of the plasma membrane into the cell, involved in cell wall formation, DNA replication, respiration, and secretion.

Flagella

Composed of filament, hook, and basal body, they help in motility of bacteria.

Pili and Fimbriae

Elongated tubular structures made of pilin, and fimbriae are small bristles, both help bacteria attach to host or other substances.

70 S Ribosome

Prokaryotic ribosome type; site of protein synthesis.

Inclusion Bodies

Reserve food material stored in the cytoplasm.

Cell Membrane Composition

Lipids and protein arranged in a bilayer, with polar heads outwards and hydrophobic tails inwards.

Fluid Mosaic Model

Proposed by Singer and Nicholson (1972); describes the membrane as a quasi-fluid structure for lateral protein movement.

Cell Wall

Non-living rigid structure that gives shape and protects the cell.

Plasmodesmata

Connects the cytoplasm of neighboring cells.

Endo-membrane System

Includes endoplasmic reticulum, golgi complex, lysosomes, and vacuoles.

Endoplasmic Reticulum (ER)

Network of tubular structures in the cytoplasm, divides intracellular space into luminal and extra luminal compartments.

Rough Endoplasmic Reticulum (RER)

ER with ribosomes on the surface, involved in protein synthesis and secretion.

Smooth Endoplasmic Reticulum (SER)

ER lacking ribosomes, major site for lipid synthesis.

Golgi Apparatus

Observed by Camillo Golgi in 1898; performs packaging and transportation of materials.

Lysosomes

Membrane-bound structures formed by packaging in the Golgi apparatus, rich in hydrolytic enzymes for digestion.

Vacuoles

Membrane-bound space containing water, sap, excretory products; bound by tonoplast.

Mitochondria

Double membrane bound structure, site of aerobic respiration, produces ATP (power house of the cell).

Plastids

Classified into chloroplasts, chromoplasts, and leucoplasts based on pigments.

Chloroplasts

Contain chlorophyll and carotenoid pigments for photosynthesis.

Chromoplasts

Contain fat soluble carotenoid pigments.

Leucoplasts

Colourless plastids that store food.

Ribosomes

Non-membranous cell organelles made of RNA and proteins, site of protein synthesis.

Cytoskeleton

Elaborate network of filamentous proteinaceous structures in the cytoplasm, involved in support, motility, and shape maintenance.

Cilia and Flagella

Hair-like outgrowths of the cell membrane for movement, with axoneme core.

Centrosome

Organelle containing two centrioles.

Centrioles

Cylindrical structures made of tubulin, form basal bodies and spindle fibres.

Nucleus

Cell organelle described by Robert Brown in 1831, contains DNA.

Nuclear Matrix/Nucleoplasm

Contains nucleolus and chromatin.

Nucleolus

Site of ribosomal RNA synthesis.

Chromatin

Contains DNA, histones, non-histone proteins, and RNA.

Chromosome Types

Classified as metacentric, sub-metacentric, acrocentric, and telocentric based on centromere position.

Microbodies

Minute membrane bound vesicles containing various enzymes.