2 Prokaryotic and Eukaryotic Cells Structure and Function Flashcards
– No Nucleus and No Organelles
– Cell Wall of peptidoglycan
– Binary Fission
– 1 circular chromosome
-Do not have membrane surrounding their DNA
-Lack various internal structures bound with phospholipid membranes
-Are small, ~1.0 µm in diameter
-Have a simple structure
-Composed of bacteria and archaea
prokaryotes
– has Nucleus and Organelles
– If cell wall, Cellulose or chitin
– Mitosis
– Linear chromosomes
- Have membrane surrounding their DNA
-Have internal membrane-bound organelles
-Are larger, 10-100 µm in diameter
-Have more complex structure
-Composed of algae, protozoa, fungi, animals and plants
eukaryotes
a coating or layer of molecules external to the cell wall. it serves protective, adhesive and receptor functions
– Gelatinous, sticky substance surrounding the outside of the cell
– Composed of polysaccharides, polypeptides, or both
*In Eukaryotic Cells
– Never as organized as prokaryotic capsules
– Help anchor animal cells to each other
– Strengthen cell surface
– Provide protection against dehydration
– Function in cell-to-cell recognition and communication
Glycocalyx or Glycocalyces
the site where the large DNA molecule is condensed into a packet. DNA is the code that directs all genetics and heredity of the cell
-is an irregularly shaped region that contains the cell’s chromosome and numerous proteins
* Bacterial cells contain ONE chromosome
* Circular in structure
* Just DNA, no associated proteins
* Bacterial chromosomes are longer than the length of the cell.
* Some cells contain PLASMIDS
Bacterial chromosome or Nucleoid
-an elongate, hollow appendage used in transfers of DNA to other cells and in cell adhesion
– Tubules composed of pilin
– Also known as conjugation pili
– Longer than fimbriae but shorter than flagella
– Bacteria typically only have one or two per cell
– Mediate the transfer of DNA from one cell to another
Pilus or Pili
an extension of the cell membrane that folds into the cytoplasm and increases surface area
- invagination of the plasma membrane that increases the surfaces area of the plasma membrane during binary fission
-also serves as a site for the attachment and distribution of genetic material during binary fission.
-considered analogous to the cristae in mitochondria of eukaryotic cells, enhancing the surface area for metabolic activities
Mesosomes
specialized appendage attached to the cell by a basal body that holds a long rotating filament. the movement pushes the cell forward and provides motility
– Are responsible for movement
– Have long structures that extend beyond cell surface
– Are not present on all prokaryotes
- Rotation propels bacterium through environment
- Rotation reversible, can be clockwise or counterclockwise
- Bacteria move in response to stimuli (taxis)
– Runs
– Tumbles
*In Eukaryotic Cells
-Do not rotate, but undulate rhythmically. move like a
whip
Flagellum or Flagella
-fine, hair like bristles from the cell surface that help in adhesion to other cells and surfaces
Hollow tubes that protrude from some bacteria
Compose of protein – fimbrin
- Sticky, bristlelike projections
- Used by bacteria to adhere to one another, to hosts, and to substances in environment
- Shorter than flagella
- May be hundreds per cell
- Serve an important function in biofilms
- Virulence factor
Fimbriae
stored nutrients such as fat, phosphate, or glycogen deposited in dense crystals or particles that can be tapped into when needed
inclusion or granule
a semirigid casing that provides structural support and shape for the cell
cell wall
a thin sheet of lipid and protein that surrounds the cytoplasm and controls the flow of materials into and out of the cell pool
cell membrane
-tiny particles composed of protein and RNA that are the sites of protein synthesis
-are the site of protein synthesis, and large numbers of them are found in nearly all cells.
Ribosomes
External covering outside the cytoplasm
The Cell Envelope
The Cell Envelope is Composed of two basic layers that Maintains cell integrity:
cell wall
cell membrane
- Two generally different groups of bacteria
demonstrated by Gram stain:
Gram-positive bacteria
Gram-negative bacteria
- macromolecule composed of a repeating framework of long glycan chains cross-linked by short peptide fragments
- provides strong, flexible support to keep bacteria from bursting or collapsing because of
changes in osmotic pressure
peptidoglycan (cell wall) aka murein
- The backbone of the
peptidoglycan layer is
made of alternating sugar
molecules:
N-acetylglucosamine (NAG/ GlcNAc) and N-acetylmu ramic acid (NAM/ MurNAc).
the sugars of peptidoglycan are linked together
through;
β-(1,4)-glycosidic bonds
4 Groups Based on Cell Wall
Composition
- Gram positive cells
- Gram negative cells
- Bacteria without cell walls
- Bacteria with chemically unique cell walls
FOUR DIVISIONS OF BACTERIA
Division Gracilicutes – gram negative
Division Firmicutes - gram positive
Division Tenericutes - without cell wall
Division Mendosicutes - lack peptidoglycan in their cell wall and are similar to Archaea/archaebacteria
- Consists of
– a thick, homogenous sheath of peptidoglycan 20-80 nm thick
– tightly bound acidic polysaccharides - including teichoic acid and lipoteichoic acid
– cell membrane - Retain crystal violet and stain purple
Gram Positive Cell Wall
- Consists of
– an outer membrane containing lipopolysaccharide (LPS)
– thin shell of peptidoglycan
– periplasmic space
– inner membrane - Lose crystal violet and stain red from safranin counterstain
- Protective structure while providing some flexibility and sensitivity to lysis
Gram Negative Cell Wall
– endotoxin that may become toxic when released during infections
– may function as receptors and blocking immune response
– contains porin proteins in upper layer
* Regulates molecules entering and leaving cell
lipopolysaccharide (LPS)
– Referred to as phospholipid bilayer; composed of lipids and associated proteins
– Approximately half composed of proteins that act as recognition proteins, enzymes, receptors, carriers, or channels
* Integral proteins
* Peripheral proteins
* Glycoproteins
– Fluid mosaic model describes current understanding of membrane structure
Prokaryotic Cell Membrane
Cell Membranes contain a ____ and ____ side
Composed of many different types of proteins
Proteins in the lipid bilayer move ____ within the membrane
hydrophilic and hydrophobic
freely
functions of the cell membrane (5)
- Regulates nutrient and water intake
- Regulates waste removal
- Site of prokaryotic respiration
- Site of prokaryotic flagella attachment
- Involved in the distribution of genetic material during binary fission
what are the 2 types of the glycocalyx
capsule
slime layer
*Type of Glycocalyx
- Composed of organized repeating units of organic chemicals - polysaccharides or polypeptides in composition.
- Firmly attached to cell surface
- Functions:
- Protection from phagocytosis - May prevent bacteria from being recognized and destroyed by host
- Osmotic barrier
- Protects cells from drying out
- Reservoir for nutrients
- Virulence factor
Capsule
*Type of Glycocalyx
- Loosely attached to cell surface - consist of polysaccharide fibers that extend form the bacterial surface
- Water soluble
- Functions:
- Protects cells from drying out
- Attachment - Sticky layer that allows prokaryotes to attach to surfaces
- Associated with biofilms
Slime layer
what are the 3 parts of the flagella
filament - long, thin, helical structure composed of proteins
hook - curved sheath
basal body - stack of rings firmly anchored in cell wall
*structure of flagella
● ____, a protein (filament) deposited in a helix at the lengthening tip
● Base of filament inserts into Hook
● Basal body anchors filament and hook to cell wall by a rod and a series of either two or four rings of ____
● Filament capable of rotating 360 degrees
Flagellin
integral proteins
5 Arrangements of Flagella
MONOTRICHOUS
LOPHOTRICHOUS
AMPHITRICHOUS
PERITRICHOUS
ATRICHOUS
*Which Arrangement of Flagella
multiple
flagella arising from one or both
ends
LOPHOTRICHOUS
*Which Arrangement of Flagella
– a single
flagellum arises from each
end
AMPHITRICHOUS
*Which Arrangement of Flagella
flagella are
randomly dispersed over the cell
surface
PERITRICHOUS
*Which Arrangement of Flagella
a single
flagellum at one end
MONOTRICHOUS
*Which Arrangement of Flagella
- No flagella
present
ATRICHOUS
✔Originates in the cell membrane and transverses the length of the cell in the periplasmic space.
✔As this rotates to move the cell the characteristic shape is formed
✔are associated with spirochetes.
-Attached to the plasma membrane and transverses the entire cell.
-Responsible for the spirochete morphology.
Axial filament (aka endoflagella)
Transfer of plasmid DNA from a donor to a recipient.
Process strengthens the bacterial cell and allows for survival in a competitive environment
Bacterial Conjugation
are common in all cells and are formed by the aggregation of substances that may be either organic or inorganic.
Inclusions
*Bacterial Inclusion Bodies
stores lipids for use in plasma membrane
- carbon and energy reserve
POLY-BETA-HYDROXYBUTYRIC ACID (PHB)
*Bacterial Inclusion Bodies
stores starch like polymer of sugar for
energy production
GLYCOGEN
*Bacterial Inclusion Bodies
- storage for
phosphates for plasma membrane and the formation of
ATP from ADP.
POLYPHOSPHATE GRANULES (METACHROMATIC GRANULES)
*Bacterial Inclusion Bodies
stores sulfur which is
necessary for the metabolic reactions in biosynthesis.
SULFUR GRANULES
*Bacterial Inclusion Bodies
storage of metabolic gases
such as methane or hydrogen gas. This helps in the buoyancy of the cell and aids
in its motility
GAS VACUOLES -
*Bacterial Inclusion Bodies
present in many
cyanobacteria and other C02-fixing bacteria
stores; serves as a site for C02 fixation.
CARBOXYSOMES
*Bacterial Inclusion Bodies
Aquatic magnetotactic
bacteria use this to orient themselves
in Earth’s magnetic field.
MAGNETOSOMES
it is the cell division in prokaryotic cells
BINARY FISSION
- Bacterial cells contain ONE chromosome
- Circular in structure
- Just DNA, no associated proteins
- Some cells contain PLASMIDS
Nuclear area
- single, circular, double-stranded DNA molecule
- contains all the genetic information required by a cell
- DNA is tightly coiled around a protein
– dense area called the nucleoid
Chromosome
- small circular, double-stranded DNA
- self-replicating extrachromosomal DNA
- free or integrated into the chromosome
- duplicated and passed on to offspring
- not essential to bacterial growth & metabolism
- may encode antibiotic resistance, tolerance to toxic metals, enzymes & toxins
- used in genetic engineering- readily manipulated & transferred from cell to cell
- are separate from the main chromosome
- Also circular in structure, but smaller
- Contain only a few genes
- Often carry genes for antibiotic resistance
Plasmids
a survival mechanism of certain genera of bacteria such as Clostridium and Bacillus.
- resting, dormant cells
- produced by some G+ genera
– Clostridium, Bacillus & Sporosarcina - have a 2-phase life cycle
– vegetative cell
– endospore - withstand extremes in heat, drying, freezing, radiation & chemicals
- resistance linked to high levels of calcium & certain acids
- longevity verges on immortality
– 25 to 250 million years - pressurized steam at 121oC for 20-30 minutes will destroy endospores
ENDOSPORES
endospores are composed of a complex of ____ and ____
dipicolinc acid and calcium
formation of endospores
Sporulation
return to vegetative growth
Germination
____ have cell walls but no
glycocalyx
Fungi, algae, plants, and some
protozoa
Fungal cell walls composed of
cellulose, chitin, and/or glucomannan
Cellulose found in
plant cell walls
-Consist of a lipid bilayer and associated proteins.
-Contains high levels of sterols such as cholesterol.
-No respiratory enzymes located in the eukaryotic plasma membrane.
-Respiration occurs in the mitochondria.
Plasma Membrane/Cell Membrane
Algal cell walls are
composed of
cellulose, silicon, and calcium carbonate
*Eukaryotic Cells
-Similar to flagella both structurally and functionally but are much shorter and more numerous.
-are found peritrichously to the cell.
-Move in an undulating manner and motility by those organisms, is much more rapid than those with flagella.
Cilia
*Eukaryotic Cells
● Often largest organelle in cell
● Contains most of the cell’s DNA
● Semi-liquid portion called nucleoplasm
● One or more nucleoli present in nucleoplasm; RNA synthesized in nucleoli
● Nucleoplasm contains chromatin – masses of DNA associated with histones
● Surrounded by nuclear envelope
– double membrane composed of two phospholipid bilayers
● Nuclear envelope contains nuclear pores
-double membraned organelle that houses the genetic material of cell.
Nucleus
*Eukaryotic Cells
contains numerous
pores through which
proteins and RNA
can move.
Nuclear membrane
*Eukaryotic Cells
● Netlike arrangement of flattened, hollow tubules continuous with nuclear envelope
● Functions as transport system
- has Two forms
-network of cytoplasmic membranes where lipids and proteins are produced.
Endoplasmic reticulum
*Eukaryotic Cells
-synthesis of lipids
Smooth ER
*Eukaryotic Cells
ribosomes attached to its outer surface; transports proteins produced by ribosomoe
Rough ER
*Eukaryotic Cells
● Receives, processes, and packages large molecules for export from cell
● Packages molecules in secretory vesicles that fuse with cytoplasmic membrane
● Composed of flattened hollow sacs surrounded by phospholipid bilayer
● Not in all eukaryotic cells
Golgi body
*Eukaryotic Cells
-is associated with the ER.
-It modifies and packages the lipids and proteins manufactured by the ER and places them in vesicles for cellular use.
Golgi apparatus (dictyosome)
*Eukaryotic Cells
- Store and transfer chemicals
within cells - May store nutrients in cell
(4)
Lysosomes, peroxisomes,vacuoles, and vesicles
*Eukaryotic Cells
contain catabolic
enzymes
Lysosomes
*Eukaryotic Cells
contain enzymes
that degrade poisonous wastes
Peroxisomes
*Eukaryotic Cells
- Have two membranes composed of phospholipid bilayer
- Produce most of cell’s ATP
- Interior matrix contains 70S ribosomes and circular molecule of DNA
-involved in the production of chemical energy in the form of ATP.
-Consist of convoluted inner membrane and outer membrane. Invaginations are called cristae and contain enzymes used to synthesis ATP.
-All respiratory enzymes are located in the inner membrane of this shit
Mitochondria
*Eukaryotic Cells
- Light-harvesting structures found in photosynthetic eukaryotes
- Have two phospholipid bilayer membranes and DNA
- Have 70S ribosomes
Chloroplasts
