cell structure and function

what are the characteristics of living things?

1. cellularity

2. growth

3. responsiveness

4. reproduction

5. metabolism

cellularity

refers to having membrane bound structures

growth

increase in size via assimilation (using nutrients and compounds to make

responsiveness

• ability to of the cell to make changes in response to an external environment

• long and short term changes

reproduce

ability to increase the number of cells

metabolism

ability of the cell to take nutrients and compounds to synthesize energy and new structures

cell theory

1. cells arise from cells

2. cells are the basic living units of life

3. all living things have one or more cells

response to short term changes

1. transport

2. taxis

3. enzyme concentrations

response to long term change

adaptation and evolution

what is natural selection

• process in which organisms adapt to their environment.

• those who are well adapted are more likely to pass on their genes to the next generation

how does natural selections lead to change in a species?

organisms that are more well adapted to their environment will be able to pass on their genes, causing shift one characteristics to appear more often than others. that shift in charactersitics causes changes in a species

compare size of eukaryotic and prokaryotic cells

proks are smaller than euks

compare nuclei of eukaryotic and prokaryotic cells

euks have nuclei while proks do not

compare organelles of eukaryotic and prokaryotic cells

euks have organelles while proks do not

compare cell wall chemistry of eukaryotic and prokaryotic cells

euks → only SOME have cells walls (fungi, alage, plant cells) that are composed of either cellulose, chitin, carrageenan

proks → bacteria cell walls are made up of peptidoglycan while archaeal cell walls are made up of polysaccharides, proteins, or both

compare ribosomes of eukaryotic and prokaryotic cells

euks have ribosomes that are larger (80s) than proks (70s)

compare external structures of eukaryotic and prokaryotic cells

euks → less organized glycocalyx (not all have them); has flagella and cilia; does not have fimbriae, pili, or hami; has a phospholipid bilayer but not all of cell walls

proks → more complicated glycocalyx; has flagella, fimbriae, pili, and/or hami; does not have cilia; has a phospholipid bilayer and cell wall

compare DNA of eukaryotic and prokaryotic cells

euk → DNA is wound around histones (nucleosome) and condensed into a chromosome

prok → one singular and circular chromosome in bacteria, nucleosome in archaea

compare/contrast eukaryotes and prokaryotes flagellum structures

euks → complex tubulin arrangement that creates hollow tubes known was microtubules. has basal body (9+0 arrangement in triplets) and filament (9+2 arrangement)

proks → made up of flagellin, has basal body, hook, and filament. endoflagella form axial filaments that cause spirochetes to corkscrew into a medium since it rotates around the body of the cell

how does bacterial flagella move?

• run and tumble

• run → rotates 360 CCW in one direction and the tufts are bundled

• tumble → rotates 360 CW in random direction and the tufts unbundle

monotrichous

flagellum at one end of the cell

peritrichous

multiple flagella surrounding the cell

taxis

movement in response to an external stimulus

chemotaxis

movement in response to a chemical stim

positive taxis

• movement towards the stimulus

• increase in runs

negative taxis

• movement away from a stimulus

• increase in tumbles

magnetotaxis

movement in response to magnetic fields

phototaxis

movement in response to light

geotaxis

movement in response to gravity

lophitrichous

multiple flagella at one end of the cell

amphitrichous

one or more flagella at both ends of the cell

polar flagella

refers to flagella arrangements in which there is one or more flagella at one or both ends of the cell

what are the polar flagella arrangements

• monotrichous, amphitrichous, lophotrichous

• not peritrichous

chemo, photo, geo, magneto taxis all require what

cell surface receptors (integral/peripheral membrane proteins)

describe the structure of biological membrane

• a phospholipid bilayer containing integral or peripheral proteins.

• euks have cholesterol on theirs

what cannot cross the phospholipid bilayer?

• large molecules

• strongly charged molecules

what can cross the phospholipid bilayer?

• CO₂

• O₂

• water

• small nonpolar and lipid molecules

• steroids

cell membrane functions

1. barrier - separated extracellular matrix from intracellular

2. respiration - location of ETC to convert chemical energy to cellular energy in euks and some respiring proks

diffusion

movement of molecules across a membrane from high to low concentration

osmosis

movement of water from low solute concentration to high (follows the salt)

facilitated diffusion

movement of molecules across a membrane from high to low concentrations using transport proteins

active transport

molecular transport that requires ATP

passive transport

molecular transport that does not require ATP and follows a concentration gradient

group translocation

chemical is altered as it crosses a membrane via transport protein, causing it to be impermeable to the membrane

who does group location?

E.coli with glucose (most organisms do not do this)

what forms of cellular transport does not require energy

• osmosis

• diffusion

• facilitated diffusion

what forms of cellular transport requires energy

• pinocytosis

• phagocytosis

• exocytosis

• endocytosis

• group translocation

what are the types of facilitated diffusion?

• carrier protein (ex. permease)

• channel (pore ex. aquaporins = moves H₂O and ions) ← general transport

what are the external structures of bacteria?

• glycocalyx

• fimbria

• pilus

• cell membrane

• cell wall

• flagella

what are the internal structures of bacteria?

• nucleoid

• cytoskeleton

• cytoplasm

• cytosol

• inclusions

• ribosomes

• thylakoids

describe structure/function of glycocalyx in bacteria

• “sugar cup”

• composition = polysaccharides, proteins, or both

• function = protection and cell attachment

describe structure/function of flagellum in bacteria

• function = propels cell through environment

• composition = hollow flagellin shaft

• structure = basal body, hook, and filament

• powered by hydrogen ions

describe structure/function of fimbria in bacteria

• short bristle projections

• function = attachment (other surfaces, cells, pathogens)

• composition = protein

describe structure/function of pilus in bacteria

• cell projections longer than fimbriae but shorter than flagella

• hollow tube

• function = attachment to other cells

• "sex conjugation” → ability to share DNA with other cells

describe structure/function of cell wall in bacteria

• structure

• protect from osmotic forces

• attachment

• escapes microbial drugs

• composition = peptidoglycan (N acetylmuramic acid, N acetylglucosamine linked by tetrapeptides)

describe structure/function of cytoplasm in bacteria

• describes the materials, structures, and liquid in the cell

• provides internal organization of cell

describe structure/function of cytosol in bacteria

• liquid of cytoplasm

• contains H₂O, ions, carbs, proteins, lipis, and waster

describe structure/function of nucleoid in bacteria

• region of the cytosol containing DNA

describe structure/function of inclusions in bacteria

• storage deposits in cytosol

• varies with each species (diagnostic with pathogens)

• stores nutrients when resources are abundant and uses them when it is scarce

• stores lipids, magnetite (magnetotaxis), sulfur, starch, gasses (causes organism to float for photosynthesis)

• carbs and energy stored in lipid polymer POLYHYDROXYBUTYRATE biodegradable plastic

describe structure/function of ribosomes in bacteria

• protein synthesis

• 70s

• large subunit and small subunit

• composition = protein and rRNA

• some antibodies target bacterial ribosomes to alter/stop protein synthesis

describe structure/function of cytoskeleton in bacteria

• simple fiber networth beneath cell membrane

• provides shape to cell

describe structure/function of endospores in bacteria

• survival structures created during a period of starvation

• contains vegetative cell’s DNA

• can withstand extreme environments

describe structure/function of thylakoids in bacteria

• membrane sacs

• has ETC for photosynthesis

• infolding of cell membrane (more SA:V)

describe structure/function of DNA in bacteria

• genetic information

• singular and circular

compare/contrast gram-negative and gram-positive

gram negative → thin peptidoglycan layer, has outer membrane, channel proteins span bilayer, and contains lipopolysaccharides (LIPID A aka ENDOTOXIN)

gram-positive → thick peptidoglycan layers, has teichoic acids (for ion transport) and lipoteichoic acids (anchors cell wall to membrane)

what do endotoxins cause

when gram negative bacteria is killed in the body, can cause fever, blood clots, inflammation, vasodilation, and shock. antibiotics may worsen symptoms

what kind of bacteria has lipid A

gram-negative

what is the process of binary fission?

1. circular dna is replication and attached to cytoplasmic wall

2. attachment site grows, pushing chromosomes apart and the cell elongates

3. septum forms in the middle of the cell

4. daughter cells may or may not separate

who performs binary fission and why?

• prokaryotic cells

• grows cell population

• reproduces exact copies of dna

what are the steps of endospore formation?

1. vegetative cell dna replications

2. cytoplasm invainates to create forespore

3. cytoplasm grows, engulfing forespore into a second membrane. vegetative cell DNA disintegrates

4. peptidoglycan cortex is deposited between the two membranes. dipicolinic acid and calcium ions accumulate in endospore

5. spore coate forms around endospore

6. endospore matures, spore coat is completed, and increases resistance to heat and chemicals

7. endospore is released from the cell

who creates endospores and why?

• Bacillus and Clostridium

• defense mechanism when only one or two nutrients are available

• when nutrients available, endospore will germinate back into a vegetative cell

why do we care if endospores exist?

• tolerant of extreme environments (desiccation, heat, radiation, lethal chemicals)

• can resist treatments that inhibits other microbes

• can turn into pathogens

diplo-

pair, two

strepto-

chain of four or more cells

staphylo-

cluster of cells (cocci specifc)

coccus

spherical

bacillus

rod

spirillum

stiff curvy pattern

spirochete

flexible curvy pattern

vibrio

half turn curve (cheeto puff)

pleomorphic

cell takes on many shapes

monomorphic

cell only has one shape

describe the structure/function of glycocalyx in archaea

• composition = polysaccharides or proteins

• cell attachment (biofilms)

describe the structure/function of flagellum in archaea

• basal body, hook filament

• filament is not hollow

• propels archaea through environment

describe the structure/function of fimbriae in archaea

• nonmotile, sticky rod structures

• used for attachment

• composition = protein

describe the structure/function of pili in archaea

• used for attachment

describe the structure/function of hami in archaea

• used for attachment

• protein composition

• has a grappling hook and prickles

describe the structure/function of cell wall in archaea

• composition polysaccharides, proteins, or both

• structure varies with each species

describe the structure/function of cell membrane in archaea

• sometimes one layer or bilayer

• acts as a barrier

• different phospholipids

• fatty acids can branch

• ether bonds between fatty acids and glycerol

describe the structure/function of cytoplasm in archaea

• internal organization

• contains the liquid and structures

describe the structure/function of cytoskeleton in archaea

• simple fiber network

• provides shape and support to cell

describe the structure/function of nculeoid in archaea

region of cytoplasm containing DNA

describe the structure/function of ribosomes in archaea

• 70s

• different protein composition (closer to euks)

• large subunit and small subunit

describe the structure/function of DNA in archaea

• holds genetic information

• circular, singular

• nucleosome

compare/contrast archaea and bacteria glycocalyces

• similar in structure and function

compare/contrast archaea and bacteria flagella

• bacterial flagella is hollow, thicker, faster, and uses H ions as a source of power

• archaea flagella is not hollow, thinner, slower, and uses ATP

compare/contrast archaea and bacteria cell walls

• bacterial cell walls are composed of peptidoglycan

• archaea cells are composed of polysaccharides, proteins, or both

compare/contrast archaea and bacteria cytoskeletons

function and structure is the similar

compare/contrast archaea and bacteria ribosomes

• both 70s

• archaea uses proteins that are genetically more similar to euks

compare/contrast archaea and bacteria DNA

• both singular chromosome

• both circular

• archaea is wrapped around histones