3 - CELL STRUCTURE AND TAXONOMY

Eukaryotes

are so named because they have a true nucleus, in that their DNA is enclosed by a nuclear membrane.

eu

true

caryo

refers to a nut or nucleus

Cell Membrane

separates the inside of the cell from its environment

Cytoplasm

jelly-like fluid substance

DNA

cell’s genetic material

Eukaryotic and prokaryotic cells

2 categories of cell

eukaryotic cells

plants and animal cells with a nucleus and membrane-enclosed organelles

prokaryotic cells

unicellular organisms without a nucleus or membrane enclosed organelles

cell membrane, cytoplasm and genetic material

al cells have

bacteria

classified as prokaryotic

organelles

“little organ”

specialized parts of the cell that have unique jobs to perform

nucleus

control center of the cell

contains DNA or genetic material

also contains nucleolus

DNA

dictates what the cell is going to do and how its going to do it

chromatin

the tangled, spread out form of DNA found inside the nuclear membrane

chromosomes

it is when a cell is ready to divide, DNA condenses into structures known as _______________

nucleolus

a structure where ribosomes are made

rough endoplasmic reticulum and smooth endoplasmic reticulum

two types of Endoplasmic reticulum

rough ER

has ribosomes attached to it

smooth ER

does not have ribosomes attached to it

Endoplasmic reticulum

membrane enclosed passageway for transporting materials such as protein synthesized by ribosomes

ribosomes

where protein synthesis occur

golgi apparatus

the packaging

vesicle

a shape that encloses protein synthesized

vacuoles

sac-like structures that store different materials

lysosomes

garbage collectors that take in damaged or worn out cell parts

filled with enzymes that break down this cellular debris

mitochondrion

powerhouse of the cell

makes ATP

ATP

provide energy for all cells activities

cytoskeleton

reason why the cell maintains its shape

includes thread-like microfilaments which are made of protein and microtubules which are thin hollow tubes

photoautotrophic

captures sunlight for energy

chloroplast

where photosynthesis happens

chlorophyll

green pigment of plants

plant cells

have cell wall outside their cell membrane that shape, support and protects it

only cell that have chloroplast

animal cells

do not have cell wall and chloroplast

mitochondria

both plant and animals cells have

cilia

microscopic hair-like projections that can move in waves; this feature helps trap inhaled particles in the air and expels them when you cough

respiratory tract

in human, the __________________ is lined with cells that have cilia

flagella

some bacteria have these

a little tail that can help a cell move or propel itself

sperm cell

only human cell that has a flagellum

Eukaryotes

Most animal and plant cells are 10 to 30 um in diameter, about 10 times larger than most procaryotic cells

bacteria

prokaryotic cells that has an important role in human disease and health

they can cause disease but are also a part on our human microbiota

less complex

nucleus, mitochondria, endoplasmic reticulum, and golgi complexes

prokaryotic cells do not have

cell envelope

bacterial cells are often surrounded by several layers called

cell wall

capsule

plasma membrane

called the cell envelope

cell wall

found on the outer surface of the cell membrane and its most important role is to protect the bacteria

consists of peptidoglycan

helps maintain the shape

peptidoglycan

helps differentiate whether bacteria are Gram positive or Gram negative

Gram positive

have a single thick layer of peptidoglycan above the plasma membrane which allows them retain the staining dye

color is pink or purple

Gram negative

have a thinner layer of peptidoglycan sandwiched between the surface membrane and the plasma membrane

can’t retain the dye

color is red

cocci

round shaped bacteria

bacilli

rod-shaped bacteria

spirilla

spiral shaped bacteria

pleomorphic

multiple forms of bacteria

capsule

helps shield the bacteria against phagocytosis and helps the bacteria adhere to surfaces

plasma membrane

most important layer because it encloses the cytoplasm

semi permeable barriers

acquires nutrients, eliminates waste and maintains constant, organized state

nucleoid

irregularly shaped region that contains the cells chromosomes

chromosomes

single circle double stranded DNA; contains the genes

plasmids

extra chromosomal DNA molecules; small ds DNA molecule

few genes

contains genes that confer a selective advantage to the bacterium such as resistance to antibiotics

pili

hair like structures that allows them to attach to other cells

fimbriae

when its shorter then pili, helps attach to surfaces

flagella

long whip like structures that allows them to move

Prokaryotes

about 10 times smaller than eucaryotic cells

Escherichia coli

about 1 um wide and 2 to 3 um long

binary fission

Reproduction of procaryotic cells is by ________________

it is the the simple division of one cell into two cells

taxonomy

the science of naming, describing and classifying organisms

classification, nomenclature and identification

Taxonomy consists of three separate but interrelated areas:

classification

arrangement of organisms into taxonomic groups (known as taxa [sing., taxon]) on the basis of similarities or relationships

Taxa (taxon)

include kingdoms or domains, divisions or phyla, classes, orders, families, genera, and species.

Kingdom, Phylum, Class, Order, Family, Genus, Species

taxa includes

nomenclature

the assignment of names to the various taxa according to international rules.

identification

the process of determining whether an isolate belongs to one of the established, named taxa or represents a previously unidentified species.

genotype or genome.

An organism’s complete collection of genes

phenotype.

organism’s complete collection of physical characteristics

Microbial classification

In the binomial system of nomenclature, the first name (e.g., Escherichia) is the genus, and the second name (e.g., coli) is the specific epithet.

genus

in microbial classification the first name is the

specific epithet

in microbial classification, the second name is the

species

When used together, the first and second names (e.g., Escherichia coli) are referred to as a

Hans Christian Gram

developed a staining technique (1884) that classifies most bacteria into two large groups that are referred to eponymously, as Gram-positive and Gram-negative bacteria

Robert H. Whittaker (1969)

proposed a Five- Kingdom System of Classification, in which all organisms are placed into five kingdoms

Five Kingdom System

• Kingdom Prokaryote or Monera (bacteria and archaea)

• Algae and protozoa are in the Kingdom

  Protista (organisms in this kingdom are

  referred to as protists)

• Fungi are in the Kingdom Fungi

• Plants are in the Kingdom Plantae

• Animals are in the Kingdom Animalia

Kingdom Monera, Kingdom Protista, Kingdom Animalia, Kingdom Fungi, Kingdom Plantae

5 kingdom system

viruses

are not included in the Five-Kingdom System of Classification because they are not living cells; they are acellular.

Three-Domain System

Archaea, Bacteria and Eukarya

Archaea, Bacteria and Eukarya

Three-Domain System. Note that the domain names are italicized.

Archaea

comes from archae, meaning “ancient.

archae

meaning “ancient.