Biology - Structures and Functions of Cells

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Cell

  • 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

<ul><li><p>cells without a nucleus or other membrane-bound organelles</p></li><li><p>-pro(before) + -karyon(nucleus)</p></li><li><p>consists of bacteria and archaea</p></li></ul>
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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

<ul><li><p>part of a prokaryote</p></li><li><p>the extrachromosomal source of DNA that can replicate independently</p></li></ul>
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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

<ul><li><p>part of a prokaryote</p></li><li><p>for conjugal(reproduction) exchange &amp; locomotion</p></li></ul>
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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

<ul><li><p>cells that have a nucleus and other membrane-bound organelles</p></li><li><p>-eu(true) + -karyon(nucleus) -consists of plants, animals, fungi, and protists</p></li></ul>
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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

<ul><li><p>part of a eukaryote</p></li><li><p>contains most of the cell&apos;s genes and is usually the most conspicuous organelle</p></li><li><p>the DNA and proteins inside it form a genetic material called CHROMATIN</p></li></ul>
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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

<ul><li><p>component of the endomembrane system</p></li><li><p>consists of flattened membranous sacs call CISTERNAE</p></li><li><p>modifies products of the ER</p></li><li><p>manufactures certain macromolecules</p></li><li><p>sorts and packages materials intro transport vesicles</p></li></ul>
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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

<ul><li><p>found in many freshwater protists</p></li><li><p>pump excess water out of cells</p></li></ul>
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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

<ul><li><p>nearly in all eukaryotic cells</p></li><li><p>have a smooth outer membrane and an inner membrane folded in CRISTAE</p></li></ul>
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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

<ul><li><p>in animal cells, the centrosome has a pair of ________, each with nine triplets of microtubules arranged in a ring</p></li></ul>
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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

<ul><li><p>is microfilaments that function in cellular motility that contain the protein MYOSIN in addition to ACTIN</p></li><li><p>in muscle cells, thousands of actin filaments are arranged parallel to one another</p></li><li><p>thicker filaments composed of myosin interdigitate(interlock) with the thinner actin fibers</p></li></ul>
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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

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(1) Primary cell wall (2) Middle lamella (3) Secondary cell wall

  • 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

<ul><li><p>the three layers of Plant cell walls</p></li><li><p>(1) relatively thin and flexible</p></li><li><p>(2) thin layer between primary walls of adjacent cells</p></li><li><p>(3) in some cells; added between the plasma membrane and the primary cell wall</p></li></ul>
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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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