Unit 1 | Structures and Functions of the Cell

Zacharias Janssen

invented the first compound microscope

Anton van Leeuwenhoek

Made his own tiny paddle-like lens microscope. Discovered 'bacteria' which he called as animacules from dental scrapings or the gunk on his teeth

Robert Hooke

coined the term "cell" from the cork he examined

cella

latin term which means small room

Matthias Schleiden

botanist who concluded that all plants are made of cells

Theodor Schwann

zoologist who concluded that all animals are made of cells

Matthias Schleiden

Proposed free cell formation

Free Cell Formation

cells just crystallized into existence

Theodor Schwann

believed that cells came from pre-existing cells

Rudolf Virchow

presented a study that establish the idea of cells coming from pre-existing cells

Robert Remack

his study about the cell was plagiarized by Virchow

first postulate of cell theory

All organisms are composed of one or more cells

second postulate of cell theory

The cell is the basic unit of structure and organization in organisms

third postulate of cell theory

All cells came from pre-existing cells

unicellular organisms

single celled organisms

cell biology

study of function and behavior of cells

cytology

study of the cell structure

Why are cells so small?

A larger surface area and volume ratio is preferred. The cell radius should be small to be optimal.

Common cell features

plasma membrane, cytoplasm, DNA, ribosomes

Nucleoid

A non-membrane-enclosed region in a prokaryotic cell where its chromosome is located.

single circular molecule of DNA

where most of the genetic material of prokaryotes lies

deoxyribonucleic acid (DNA)

every cell contains ________________

Nucleus

where DNA of eukaryotes is contained

nuclear envelope

A double membrane that surrounds the nucleus in the cell

cytoplasm

semifluid matrix that fills the interior of the cell. everything inside the cell except nucleus

organelle

discrete macromolecular structure in the cytoplasm specialized for a specific function

cytosol

contains organic molecules and ions in solution. "the fluid"

plasma membrane

semi-permeable phospholipid bilayer that encloses a cell. amphipatic

phospholipid bilayer

Plasma membrane layers composed of phospholipid molecules arranged with polar heads facing the outside and nonpolar tails facing the inside.

phospholipid bilayer

about 5 to 10 nm thick, with proteins embedded in it

phosphate

hydrophilic, polar, negatively charge

lipid

non-polar, hydrophobic

amphipatic

both hydrophobic and hydrophilic

ribsomes

non-membrane-bounded organelles responsible for protein synthesis

ribosomes

made up of rRNA (ribosomal rna) and proteins

Subunits for prokaryotes

50S (large) and 30S (small)

Subunits for eukaryotes

60S and 40S

"S" in subunits

Svedberg unit for sedimentation coefficient that determines how fast organelles pellet out during centrifugation. Larger S are easier to pellet out

Prokaryotic Cells

do not have a nucleus or other membrane-bound organelles

prokaryotes

very first organisms (bacteria or archaea)

nuclear region (nucleoid)

Contains a circular chromosome of DNA

plasmid

Extrachromosomal source of DNA. Not all have one

plasmid

genes able to be passed around such as antibiotic resistance for more resistant pathogens

Cell Wall of prokaryotes

made of peptidoglycan, structural support

Gram staining method

classify bacteria using cell wall composition

Violet Crystal

make cells violet

Iodine

makes sure that stain sticks to cells

Ethanol 95%

remove excess crystal violet from gram - or cells with low amt of peptidoglycan

safranin

pink colored stain used to determine gram -

plasma/cell membrane

Semi-permeable outer structure of cell; controls what goes in/out of cell.

glycocalyx, flagella, fimbrae, pilus, endospore

structures found in some prokaryotes

Glycocalyx

outer coating used for protection because they are more resistant, can be capsule or slime layer

Flagella

locomotion organelle

fimbriae

attachment structures on the surface of some prokaryotes

pilus

conjugal exchange and locomotion

Plasmid replication/conjugal exchange

bacteria uses pilus to transfer plasmid from donor to recipient

Endospore

a tough, resistant, and non-reproductive structure for protection against severe environmental stresses

Monotrichous

polar, one flagellum

lophotrichous

multiple flagella at one end

amphitrichous

flagella at both ends

Peritrichous

flagella distributed over the entire cell

magnetosome

allows bacteria to feel gravity

Eukaryotic cells

have a nucleus and other membrane-bound organelles

Nucleus

contains most DNA

Nuclear lamina

maintain shape of nucleus

nuclear pores

regulate the entry and exit of molecules from the nucleus

chromatin

DNA + protein

chromosomes

formed from condensed chromatin

Nucleolus

site of rRNA synthesis

endomembrane system

A network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles.

Nuclear Envelope, Endoplasmic Reticulum, Golgi Apparatus, Lysosomes, Vacuoles, Plasma Membrane

Components of endomembrane system

Endoplasmic Reticulum

more than 50% of the total membrane in many eukaryotic cells. It is continuous with the nuclear envelope.

Smooth ER

lacks ribosomes, synthesizes lipids, metabolizes carbohydrates, detoxifies drugs and poisons, stores calcium ions

Rough ER

has ribosome, secrete glycoproteins, distributes transport vesicles and proteins surrounded by membranes

glycoproteins

proteins covalently bonded to carbohydrates

Rough ER

membrane factory of the cell

Golgi apparatus

modifies products of the ER, manufactures certain macromolecules, and sorts and packages materials into transport vesicles

Cisternae

flattened membranous sacs in the golgi apparatus

cis face

receiving side of GA and undegoes cisternal maturation

cisternal maturation

modification of proteins

trans face

shipping side of golgi apparatus

lysosome

membranous sac of hydrolytic enzymes that digest macromolecules

Phagocytosis

"Cell eating"; food material in engulfed by plasma membrane forming FOOD VACUOLE

phagolysosome

digestive vesicle formed by the fusion of lysosome and food vacuole

autophagy

"Self eating"; useless organelles are enveloped by vesicles that fuses w/ lysosomes and release enzymes to salvage or retrieve nutrients

vacuoles

stores materials

food vacuole

food material engulfed by plasma membrane

contractile vacuole

pump excess water out of cell, in freshwater protists

central vacuole

in mature plants, hold organic compounds and water

mitochondria

site of cellular respiration, metabolic process that generated ATP

Adenosine Triphosphate (ATP)

compound used by cells to store and release energy

intermembrane space

the fluid filled space between the inner and outer mitochondrial membranes

cristae

folds in the inner membrane of mitochondria

mitochondrial matrix

the fluid that is inside the inner membrane of a mitochondrion

Chloroplast

Site of photosynthesis, generate ATP

plastids

class of small organelles, such as chloroplasts, for storage

chlorophyll

A green pigment found in the chloroplasts of plants, algae, and some bacteria

Stroma

fluid portion of the chloroplast; outside of the thylakoids

Thylakoids

A flattened membrane sac inside the chloroplast, used to convert light energy to chemical energy.

granum

stack of thylakoids