(3) THE CELL AND ITS STRUCTURE Flashcards
Father of Microscopy, coined the term cells
Robert Hooke (1665)
Book by Robert Hooke w/ description of images using a compound microscope (molds, rust, fleas, lice, fossilized plants and animals, and sections of cork)
Micrographia
Reminded Robert Hooke of the bare rooms of the monastery
Cells
Concluded that all plants and animals were composed of cells
Mathia Schleiden and Theodore Schwann (1838-1839)
States that all plants and animals are composed of cells
The Cell Theory (Mathias Schleiden and Theodore Schwann)
Proposed the theory of biogenesis
Rudolf Virchow (1858)
States that life can only arise from pre-existing life
Theory of Biogenesis (Rudolf Virchow)
Means “All Cells come from Cells” or “Every Cell is born of a previous Cell”
Omnis Cellula E Cellula (Theory of Biogenesis)
- Fundamental living unit
- Exhibits basic characteristics of life
- Can mutate or change genetically
Cells
Cells obtains nutrients from the ______ to produce energy for metabolism
Environment
- Refers to all the chemical reactions that occur within a cell
- Enables ability to grow and reproduce
- Responds to stimuli in environment
Metabolism
Result of accidental changes to a cells genetic material or DNA
Mutation
Known as the study of cells
Cytology
- Cells with no true nucleus
- First inhabitans of the earth
- Includes bacteria and archeans
Prokaryotic Cells
Means “pre-nucleus”
Prokaryotes
- Cells with true nucleus
- Make up plants and animals
- Includes fungi, protozoa, and algae
Eukaryotic Cells
- Complex type of unicellular oganisms due to variations
- Means “true nucleus”
- Precursors of multi-cellular animals including humans
Eucaryotes (eu- true; k/caryo-nucleus)
Average size of Eucaryotes
10-100Mm in diameter
Eukaryotes that have simple cell walls made of cellulose
Plant Cell
Eukaryotes that don’t have cells walls nor cellulose and have smaller vacuoles
Animal Cells
Sub-type of animal cells that can engulf other structures
Phagocytic Cell
- Outermost boundary of most eukaryotic cells
- Supported by either cell wall or cell membrane
Glycocalyx
Functions of the Glycocalyx
(1) ______
(2) ______
(3) ______
(1) Protection from dehydration
(2) Adherence
(3) Reception of chemical signals
The glycocalyx is usually composed of a gelatinous subtstance of ________
Polysaccharide, polypeptide, or both
The glycocalyx appears as a (1) ______, (2) ______ , or a (3) ______
(1) network of fibers
(2) slime layer (loosely attached)
(3) capsule (strongly attached)
The layer beneath the glycocalyx for fungi and most algae is a ______
Thick and rigid cell wall
The layer beneath the glycocalyx for protozoa and animal cells have _______
no cell wall
Referred to as the cell membrane, plasma membrane, or the cell sac
Cytoplasmic Membrane
- Beneath cell wall
- Composed of a bilayer phospholipids w/ embedded protein molecules
Cytoplasmic Membrane
Contained in the cytoplasmic membrane that gives stability and important in cells without a cell walls
Sterols
Characterisitic of the cytoplasmic membrane that allows for transport of selected solutes
Selectively permeable
For ______ the cytoplasmic membrane is the site for the electron transport chain and ATP production (especially for prokaryotic cells w/o mitochondria)
aerobic organisms
The cytoplasmic membrane contains
(1) ______
(2) ______
(3) ______
(1) enzymes for biosyntheis of DNA
(2) cell wall components
(3) protein synthesis
- Command / control center for eukaryotes
- Distinguishing charasteric between eukaryotic and prokaryotic cells
- Controls the entire cell
Nucleus
The three components of the nuclues are:
(1) ________ - gelatinous matrix / base material and contains the chromosomes [embedded or suspended]
(2) ________ - largest nuclear organelle, primary site for ribosome subunit biogenesis
(3) ________ - skin around the nucleus w/ nucleur pores where large molecules can enter and exit
(1) Nucleoplasm
(2) Nucleolus
(3) Nuclear Membrane
- Consists of linear DNA molecules and proteins (histones and nonhistones)
- Genes located along DNA molecules
Chromosomes
Referred to as the “beads on a string”
Genes
- Consists of rRNA and CHON (protein)
- Primarily for protein syntheis
Ribosomes
Each eukaryotic ribosome (80S) ribosome consists of:
(1) ______
(2) ______
that are transported to the cytoplasm
(1) Large subunit (60S subunit)
(2) Small subunit (40S subunit)
The large and small subunits are joined together by the _______ to initiatie protein synthesis
mRNA molecule
CHON released from the endoplasmic reticulum are mostly ______
immature
The CHON must mature in the _________ before they can do their functions within and outside the cell
Golgi Apparatus
- External structures
- Provides rigidity, shape, and protection for the cell
Cell Wall
Cell walls may contain the following:
(1) ________ as in plant cells
(2) ________ as in fungi with thick inner layer of polysaccharide fibers
(3) ________ as in algae
(1) cellulose, pectin, and lignin
(2) chitin/cellulose and thin outer layer of mixed glycans
(3) mineral salts
Cellulose can also be found in ______
algae
Chitin can also be found in the exoskeletons of _______
beetles and crabs
Varied in chemical composition which can contain cellulose, pectin, mannans, and mineral salts (silicon dioxide and calcium carbonate)
Algae
- Energy-producing organelle
- Membrane-bound and contains numerous photosynthetic pigments (site of photosynthesis)
Plastids
Sample of plastid that contains chlorophyll which is a green photosynthetic pigment
Chloroplast
Process by which light energy is used to convert carbon dioxide and water into carbohydrates and oxygen
Phosynthesis
Collectively called the locomotor organs used by cells to move themselves or their food
Flagella and Cilia
Long, thin, and whip-like structure that serves as organelles of locomotion (whipping motion to “swim”)
Flagella (eukaryotes)
Term for protozoa that have flagella
Flagellates
Hair-like structures that are shorter, thinner, and abundant than flagella that also serves for locomotion (coordinated and rhythmic movement)
Cilia
Term for protozoa that have cilia
Ciliates
A prokaryote can be distinguished from the other type of cell (a eukaryote) because of certain characteristics it possesses:
(1) The way its _____ is packaged
(2) The makeup of its ______
(3) Its _____
(1) DNA
(2) cell wall
(3) internal structures
- Considered as cell extensions and accessory structures on the surface of bacteria
- Common but not present in all species
- Can provide motility (flagella, axial filaments)
- Can be used for attachment and mating (fimbriae, pili)
Appendages (prokaryotes)
- Threadlike, protein appendages
- Long filamentous appendages
- Propels bacteria
- Functions for chemotaxis and motility/self-propulsion
Flagella (prokaryotes)
Ability of flagella in prokaryotes to detect and move in response to chemical signals
Chemotaxis
Movement of chemotaxis that goes to a favorable chemical stimulus (nutrients)
Positive chemotaxis
Movement of chemotaxis that moves away from a stimulus that is potentially harmful
Negative chemotaxis
Parts of the flagella (prokaryotes):
(1) _______ - long outermost region containing flagellin that are intertwined chains that form a helix
(2) _______ - enables 360 degree rotation
(3) _______ - stack of rings which anchors the flagellum to the cell wall and plasma membrane
(1) Filament
(2) Hook
(3) Basal Body
Flagella Arrangement - Polar Arrangement (prokaryotes):
(1) ________ - single flagellum
(2) ________ - flagella at both poles of the cells
(3) ________ - small brances/tufts of flagella emerging from same site
(1) Monotrichous
(2) Amphitrichous
(3) Lophotrichous
Flagella Arrangement - _________ Arrangement (prokaryotes): the flagella is dispersed randomly throughout the cell
Peritrichous
- A.K.A. periplasmic flagella or endoflagella
- Found in spirochetes
- Bundles of fibrils (enclosed between cell wall and cell membrane)
- Rotaion causes cell to move
- Corkscrew movement
Axial Filaments (prokaryotes)
Corkscrew shaped organisms that move in a wriggly motion due to axial filaments
Spirochetes (prokaryotes)
- Hair-like appendages seen in gram (-) bacteria
- Offer adhesion rather than locomotion
- Small and bristle-like fibers
- Most contain protein found either in the poles of bacterial cells or evenly distributed throughout the surface
- Tend to stick to each other and to surfaces
Fimbriae (prokaryotes)
Fimbriae are mostly responsible for the _______ in inanimate objects (rock or glass) because of their mutual clinging
Microbial colonization
- Elongated, rigid, and tubular structure
- Made of protein called pilin
- Longer than fimbriae
- 1 to 2 found in cell
- Used in conjugation - sex pilus (mating process between compatibale cells)
- Observed in gram (-) bacteria
Pili (prokaryotes)
- Sugar coat of prokaryotes in cell wall (viscous, slimy, and gelatinous polymer produced by cell membrane)
- Composed repeating polysaccharide units, polypeptide, or both
- Protects the cell and helps adhere to environment
Glycocalyx (prokaryotes)
The glycocalyx differs in bacteria in terms of thickness, organization, and chemical composition:
(1) _______ - unorganized and loose, protects some bacteria from loss of water and nutrients and is easily detached
(2) _______ - neatly organized, bound more tightly and is denser and thicker; protection from phagocytosis
(1) slime layer
(2) capsule
Degree of pathogenicity
Bacterial Virulence
- Contained in the glycocalyx that allows cells to attach on various surfaces for their survival
- Highly adherent; allows for persistent colonization
Extracellular Polysaccharide (EPS)
- Found in majority of bacteria
- Lies outside of the cytoplasm
Cell Envelope
The cell envelope is composed of two or three basic layers:
(1) _______
(2) _______
(3) _______
they are tightly bounded and act as a single protective unit
(1) cell wall
(2) cell membrane
(3) outer membrane (some bacteria)
The difference between gram-positive and gram-negative bacteria lie in the ______
cell envelope
- Open-faced sandwhich
- 2 layers
- Thick cell wall and cytoplasmic membrane and peptidoglycan
Gram-Positive Cell Envelope
- Complete sandwhich
- 3 layers
- Outer membrane, thin cell wall, and cytoplasmic membrane
Gram-Negative Cell Envelope
- Complex and semi-rigid maintains shape
- Made of peptidoglycan (murein), NAM, NAG
- Prevents osmotic lysis (rupture or bursting)
- Anchorage for flagella
- Contributes to pathogenicity
- Site of action in antibiotics
Cell Wall
- Thick layer of peptidoglycan (60-100% murein)
- Contain lipoteichoic and teichoic acids (contributes to acidic charge and antigentic specificity - identification of bacteria)
Gram-Positive Cell Wall
- Thin layer of peptidoglycan (10-20% murein)
- More susceptible to mechanical breakage
- Periplasmic space surround peptidoglycan
- Site for large and varied pool of substances that enter and leave the cell
Gram-Negative Cell Wall
- Aren’t characterized as either gram-positive or gram-negative
- Some don’t have a cell wall at all
- Mycobacterium and Nocardia (unique types of lipids; still contains peptidoglycan that can stain and appear as gram-positive)
Nontypical Cell Walls
- Similar to cell membrane, except it contains specialized polysaccharides and proteins
- Uppermost layer: lipopolysaccharides (LPS)
- Inner most layer: phospholipid layer anchored by lipoproteins to the peptidoglycan layer below
Gram-Negative Outer Membrane
- Uppermost layer of gram-negative outer membrane
- Polysaccharide portion that act as antigens and receptors
- Useful in distinguishing certain gram-negative bacteria
O polysaccharides
- Uppermost layer of gram-negative bacteria
- Endotoxin
- Causes fever and shock reactions such as meningitis and typhoid fever
- The negative charge produced is vital
Lipid A
- Also known as the cytoplasmic / inner membrane
- Thin structure in cell wall
- Very thin (5-10nm)
- Contain primarily 60-70% proteins (DNA replication and segregation) and 30-40% phospholipids (two parallel rows)
Plasma (Cell) Membrane
Functions of Plasma (Cell) Membrance:
(1) Provides a site for functions such as _________
(2) Regulates _______ (semi-permiability; most important function)
(3) Secretion of _______ into extracellular environment
(1) energy reaction, nutrient processing, and synthesis
(2) transport
(3) metabolic product
- Site for metabolic activities, enzymes of respiration, and ATP Synthesis
- This is due to the lack of mitochondira of prokaryotes
- Enzyme structures synthesize structural macromolecules
Plasma Membrane (prokaryotes)
Excreted by the plasma membrance in the extracellular environment (outside of cell)
Enzymes and Toxins
- Extra barrier in gram-negative bacteria
- Makes them impervious (impermeable) to some antimicrobial chemicals (alcohol-based compounds - dissolve lipids in outer membrane)
- Makes it more difficult to kill or inhibit gram-negative bacteria
Outer Membrane
(1) ______ can interact with human tissues and cause disease:
- Corynebacterium diptheriae (+)
- Streptococcus pyogenes (+)
- Mycobacterium species (-)
Proteins attached to outer portion of cell well has (2) _______
(1) Cell envelope
(2) toxic properties
The _____ present within the cell walls of mycobacterium species are harmful to humans because they are foreign to the human body
Lipids
- Semi-liquid and gelatinous substance (70-80% water - solvent for cell pool)
- Internal matrix (inside plasma membrane)
- Contains CHON enzymes, CHO, lipids, inorganic ions, ribosomes, and inclusions
Cytoplasm (prokaryotes)
Serves as the building block for cell synthesis or sources of energy located in the cytoplasm
Cell Pool
Major Structures of Cytoplasm:
(1) ______ - DNA
(2) ______ - sites for protein synthesis
(3) ______ - reserve deposits
(4) ______ - acts as cytoskeleton
(1) Nuclear Area
(2) Ribosomes
(3) Inclusion
(4) Actin Strands
- Contains a single long circular molecule of double stranded DNA called: Bacterial Chromosomes (attached to plasma membrane)
- There could also be plasmids (small, circular, and double-stranded DNA molecules)
- No histones and nuclear envelope
Nuclear Area (Nucleiod)
Transfer of plasmids from one bacterium to another
Conjugation
- CHON synthesis
- Gives granular appearance of cytoplasm
- in prokaryotes, they are smaller and less dense
- Some antibiotics work to inhibit protein synthesis like: Erythromycin Cholramphenicol
70S Ribosomes (prokaryotes)
Erythromycin Cholramphenicol attaches to the _______ and interfere with the bacterial protein synthesis of bacteria
50S subunit
- Reserve deposits
- Storehouse of excess nutrients
Bacterial Inclusions
- Known collectively as volutin
- Has reserve inorganic phosphate
- Found in algae, fungi, protozoa, and bacteria
Metachromatic Granules (Bacterial Inclusions)
- Bacterial inclusions that have glycogen and starch
- Enegry storage products
Polysaccharide Granules (Bacterial Inclusions)
- Lipid storage in bacteria
Lipid Inclusions (Bacterial Inclusions)
- Long polymers of actin
- Arranged in helical ribbons around the cell just under the cell membrane
- Contribute to cell shape
Actin Skeleton
- Usually found in gram-positive bacteria
- Specialized resting cells
- Capable of sporulation and germination
- Highly durable and dessicated cells with thick walls & additional layers
Endospores (prokaryotes)
Phase One - ________
- Metabolically active and growing entity
- Can be induced by the environment to undergo spore formation (sporulation/sporogenesis)
- Goes into an inert and resting condition (shows up prominently in a spore/gram stain)
Vegetative Cell
Phase Two - Endospore (6-8 hours)
- Stimulus for sporulation - the depletion of (1) ________
- Vegetative cell undergoes a conversion to a (2) _______
- Sporangium then transforms into an (3) _______
- Hardiest of all life forms
(1) nutrients (carbon/nitrogen source)
(2) sporangium
(3) endospore
- Heat resistance of endospores are due to the high content of ______ and ______
- Thick and impervious cortex and spore coat of protein
Calcium and Dipicolinic Acid
- Breaking of dormancy
- In the presence of water and a specific agent (amino acid and inorganic salt)
- Quite rapid (1 1/2 hours)
Germination
Agent stimulates the formation of hydrolytic enzymes, digest the cortex, and expose the core to water under a process called ______
Rehydration
- Not a means of reproduction in bacteria
- A vegitative cell produces a endospore which remains as one cell
Sporulation
- Endospores that inhabit soil and dust, germinate and grow to release ______
- Resists ordinary cleaning methods
potent toxins
- Means of reproduction in bacteria
- Produces two daughter cells from a parent cell
Binary Fission
The the gram-negative outer membrance serves as a ______ where only relatively small molecules can penetrate
partial chemical sieve
Form the special membrane channels that span the gram-negative outer membrance, altering in size to provide access or block certain molecules
Porin Proteins
The gram-negative outer membrance blocks the entrance of certain antibiotice such as (1) _______, digestive enzymes such as (2) _______, (3) _______, (4) _______, (5) _______, and (6) _______
(1) penicillin
(2) lysozome
(3) detergents
(4) heavy metals
(5) bile salts
(6) certain dyes
