- the basic structural, functional, and biological unit of known organisms -the smallest unit of life or the "building blocks of life"
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Cytology
- study of cells
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surface area to volume ratio
- as a cell's size increases, its volume increases much more rapidly than its surface area - when this happens, the cell must divide into smaller cells with favorable ratios - the reason why cells are small
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Robert Hooke(1665)
- named the basic structure of all living things as a cell and observed cork cells & cells walls under a microscope - he named them "cells" as they reminded him of the cells or rooms in monasteries
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Anton van Leeuwenheok
- discovered "bacteria" from looking at dental scrapings on his teeth using hi own microscope - named bacteria "Animalcules" because they looked like little animals
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light micoscope (LM)
- visible light is passed through the specimen, through glass lenses, and is bent through the lens allowing you to see a magnified image of a specimen
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Bright-field microscope
- illumination light is transmitted through the sample and the contrast is generated by the absorption of light in dense areas of the specimen. - light then gets transmitted through the specimen and appears against an illuminated background. - best used by fixed stained specimens to improve contrast
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dark-field microscope
- Light is directed at an angle toward the specimen -A microscope that only shows light that was reflected off the sample due to a condenser lens. - ideally used to illuminate unstained samples causing them to appear brightly lit against a dark background
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phase-contrast microscope
- its components bring light waves out of phases and produces differences in image contrast and brightness when the light waves recombine. - internal details and organelles of live, unstained organisms can be seen and called phase objects
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differential-interference-contrast microscope
- splits polarized light into to beams that have slightly different paths through the sample. - combining these two beams produces greater contrast, producing a pseudo 3D-effect
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fluorescence microscope
- its stains absorb light at one wavelength, then emit it at another. - It filters only the emitted light - used to image specific features of small specimens such us the genetic material within a cell
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confocal microscope
- designed to reject background from matter outside the focal plane and therefore allowing images of different sections of a specimen to be obtained. - produces a point source of light and rejects out of focus light, providing 3D reconstructions of imaged samples
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Electron Microscope(1950)
- rather than focusing light, focuses a beam of electrons through the specimen or onto its surface
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scanning electron microscope (SEM)
- focuses a beam of electrons onto the surface of a specimen, providing images that look 3D
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transmission electron microscope
- focuses a beam of electrons through a specimen
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Cell Fractionation
- takes cells apart and separates the major organelles from one another - enable scientist to determine the functions of organelles
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Ultracentrifuge
- fractionate cells into their component parts
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Prokaryotes
- simplest organisms - most of its genetic material lies in a single circular molecule of DNA that resides in the NUCLEOID, but the area is not segregated from the rest of the cell's interior
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Eukaryotes
- complex organisms - its DNA is contained in the NUCLEUS surrounded by a double-membrane structure called the Nuclear Envelope
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Cytoplasm
- a common feature among all types of cells - a semifluid matrix that fills the interior of the cell - contains all of the sugars, amino acids, and proteins the cell uses to carry out its everyday activities. -contains the organelles and cytosol
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Organelle
- any discrete macromolecular structure the cytoplasm specialized for a particular function
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Cytosol
- part of the cytoplasm that contains organic molecules and ions in solution to distinguish it from larger organelles suspended in its fluid
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Plasma membrane
- a common feature among all types of cells - encloses a cell and separates its contents from its surroundings - it is a PHOSPHOLIPID BILAYER about 5 to 10 nm thick, with proteins embedded in it.
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Ribosomes
- a common feature among all types of cells - particles made of ribosomal RNA and protein - carry out protein synthesis - made up of different subunits
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Svedberg unit(S)
- sedimentation coefficient - not additive - determines how fast a particle/organelles pellet out during centrifugation
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- 5S RNA, 23S RNA, 16S RNA - 50S large subunit + 30S small subunit
Subunit of prokaryote
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- 5S RNA, 5.8S, 28S RNA, 18S RNA - 60S large subunit + 40S small subunit
Subunit of eukaryote
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Prokaryotic Cells
- cells without a nucleus or other membrane-bound organelles - -pro(before) + -karyon(nucleus) - consists of bacteria and archaea
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nucleoid/nuclear region
- part of a prokaryote - contains the DNA
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plasmid
- part of a prokaryote - the extrachromosomal source of DNA that can replicate independently
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plasma/cell membrane
- part of a prokaryote - made up of phospholipids and proteins, semi-permeable
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ribosomes
- part of a prokaryote -site of protein synthesis
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Cell wall
- part of a prokaryote - made of peptidoglycan, structural support
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Peptidoglycan
- A protein-carbohydrate compound that makes the cell walls of the prokaryotic cell
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Gram Staining method
- can use cell wall composition to classify bacteria into either Gram + (purple) or Gram - (pink)
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Flagellum
- part of a prokaryote - for locomotion
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Pilus
- part of a prokaryote - for conjugal(reproduction) exchange & locomotion
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Capsule
- part of a prokaryote - extra layer made of glycolipids for protection
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Endospore
- part of a prokaryote - dormant, tough, non-reproductive structure for protection against severe environment stresses
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Eukaryotic Cells
- cells that have a nucleus and other membrane-bound organelles - -eu(true) + -karyon(nucleus) -consists of plants, animals, fungi, and protists
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Nucleus
- part of a eukaryote - contains most of the cell's genes and is usually the most conspicuous organelle - the DNA and proteins inside it form a genetic material called CHROMATIN
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Nuclear membrane
- part of a eukaryote's nucleus - a double membrane each consists a lipid bilayer - its pores regulate the entry and exit of molecules from the nucleus
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nuclear lamina
- part of a eukaryote's nucleus - maintains the shape of the nucleus - composed of protein
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nucleolus
- part of a eukaryote's nucleus - located within the nucleus - is the site of ribosomal RNA(rRNA) synthesis
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Endomembrane System
- part of a eukaryote - has 6 components - its components are either continuous or connected via transfer by vesicles - modifies, packages, and transports lipids and proteins
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Nuclear envelope
- component of the endomembrane system - encloses the nucleus, separating it from the cytoplasm
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Endoplasmic Reticulum(ER)
- component of the endomembrane system - accounts for more than half of the total membrane in many eukaryotic cells - continuous with the nuclear envelope - has 2 distinct regions: smooth ER & rough ER
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Smooth ER
- component of the endomembrane system - lacks ribosomes - synthesizes lipids - metabolizes carbohydrates - detoxifies poison - stores calcium
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Rough ER
- component of the endomembrane system - has bound ribosomes which secrete GLYCOPROTEINS(protein covalently bonded to carbohydrates) - distributes transport vesicles, proteins surrounded by membranes - a membrane factory for the cell
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Golgi Apparatus
- component of the endomembrane system - consists of flattened membranous sacs call CISTERNAE - modifies products of the ER - manufactures certain macromolecules - sorts and packages materials intro transport vesicles
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Cisternae
- what the Golgi apparatus consists of - has two types: cis face" receiving" and transface "shipping"
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Lysosome
- component of the endomembrane system - membranous sac of hydrolytic enzymes that can digest macromolecules - its enzymes can hydrolyze proteins, fats, polysaccharides and nucleic acids
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Phagocytosis
- a process in which some types of cell can engulf another cell forming a food vacuole - the food vacuole created fuses with LYSOSOME and digests the molecules
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Autophagy
- a process in which lysosomes uses enzymes to recycle the cell's own organelles and macrimolecules
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Vacuole
- component of the endomembrane system - a eukaryotic cell may have one or several - help in the storage and disposal of various substances - has 3 kinds
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Food vacuole
- temporarily stores food - formed by phagocytosis
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contractile vacuole
- found in many freshwater protists - pump excess water out of cells
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central vacuole
- found in many mature plant cells - hold organic compounds and water
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plasma membrane
- part of a endomembrane system - a double layer of lipids that separates the cell interior from the outside environment
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endosymbiotic theory
- a theory that eukaryotic cells formed from symbiosis among several different prokaryotic organisms
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Mitochondria
- nearly in all eukaryotic cells - have a smooth outer membrane and an inner membrane folded in CRISTAE
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mitchondrial matrix
- catalyzes some metabolic steps in cellular respiration - a compartment created by the inner membrane along with the intermembrane space
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Cristae
- present a large surface area for enzymes that synthesize ATP - folds the inner membrane of mitochondria
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Chloroplasts
- part of a eukaryote - a member of a family of organelles called PLASTIDS - contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis - found in leaves and other green organs and in algae
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Thyakoids
- structure of chloroplasts - membranous sacs stacked to form a GRANUM
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Stroma
- structure of chloroplasts - the internal fluid
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mitochondria & chloroplasts
- not part of the endomembrane system - a member of a family of organelles - the site of cellular respiration, a metabolic process that generates ATP - have a double membrane -have proteins made by free ribosomes - contain their own DNA
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Peroxisomes
- part of a eukaryote - specialized metabolic compartments bounded by a single membrane - produce hydrogen peroxide and convert it to water - uses oxygen to break down different types of molecules
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Cytoskeleton
- a network of fibers extending throughout the cytoplasm - organizes the cell's structures and activities, anchoring many organelles - helps support the cell and maintain its shape - interacts with MOTOR PROTEINS to produce motility - provides "monorails" that vesicles can travel along in the cell - may help regulate biochemical activities
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Microtubules
- a type of fiber that makes up the cytoskeleton - the thickest of the three components of the cytoskeleton - function for intracellular trasnport
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Microfilaments
- type of fiber that make up the cytoskeleton -also called actin filaments - the thinnest components
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Intermediate filaments
- type of fiber that make up the cytoskeleton - fibers with diameter in a middle range
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Centrosome
- where microtubules grow - a "microtubule-organizing center"
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centrioles
- in animal cells, the centrosome has a pair of ________, each with nine triplets of microtubules arranged in a ring
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Cilia and Flagella
- their beating is controlled by microtubules - locomotor appendages of some cells - compared to each other, they differ in beating patterns
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muscle contraction
- is microfilaments that function in cellular motility that contain the protein MYOSIN in addition to ACTIN - in muscle cells, thousands of actin filaments are arranged parallel to one another - thicker filaments composed of myosin interdigitate(interlock) with the thinner actin fibers
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Ctyoplasmic Streaming
- a circular flow of cytoplasm within cells - speeds distribution of materials within the cell - driven by actin-myosin interactions in plant cells
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Amoeboid movement (pseudopodia)
- localized contraction brought about by actin and myosin - Pseudopodia (cellular extensions) extend and contract through the reversible assembly and contraction of actin subunits into microfilaments - Actin flexibility allows the structural change in the pseudopods of Amoeba, allowing it to move.
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Cell Wall
- an extracellular structure that distinguishes plant cells from animals cells - plant cell walls are made of cellulose fibers embedded in other polysaccharides and protein - prokaryotes, fungi, and some protists also have them
- the three layers of Plant cell walls - (1) relatively thin and flexible - (2) thin layer between primary walls of adjacent cells - (3) in some cells; added between the plasma membrane and the primary cell wall
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extracellular matrix (ECM)
- its functions: support, adhesion, movement & regulation - what animal cells are covered by instead of cell walls
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collagen, proteoglycans and fibronectin
The ECM is made up of glycoproteins such as _______, _____________, and ______________.
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integrins
ECM proteins bind to receptor proteins in the plasma membrane called _________
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intercellular junctions
- facilitate the adherance, interaction communication through direct physical contact of neighboring cells in tissues, organs or organ systems
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Plasmodesmata
- a type of intercellular junction - channels between adjacent plant cells - through this, water and small solutes(and sometimes proteins and RNA) can pass from cell to cell
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Tight junctions
- a type of intercellular junction - membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid
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Desmosomes (anchoring junctions)
- a type of intercellular junction - fasten cells together into strong sheets
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Gap junctions (communicating junctions)
- a type of intercellular junction - provide cytoplasmic channels between adjacent cells