cell bio 001

Bacteria, Archaea, and Eukarya

3 main domains of organisms

plasma membrane, cytosol, and ribosomes

• common to all cells

plasma membrane

• a double membrane that acts as a selective barrier, separating the inside of the cell from the rest of the environment

• rich in lipids and proteins

cell wall

• acts as a barrier to protect the plant cell

• more rigid, providing structure and strength

chitin

in fungi, the cell wall is made of?

mostly cellulose, along with lignin for structure

in plant cells, the cell wall consists of?

primary cell wall

• all plant cells have this, which is rigid but still allows for growth, repair, and metabolic processes

middle lamella

• gooey space connecting the primary walls of adjacent plant cells

pectin

• main substance that gives the middle lamella its plasticity

Ca²+ and hemicellulose

• makes the middle lamella more rigid

secondary cell wall

• some specialized plant cells can also grow this

• interior to the primary wall

to add more layers for strength, yet die at maturity

why are there secondary cell walls?

cytosol

• a gel-like substance inside the cell that everything else is suspended in, which allows molecules to travel across the cell

oligosaccharides

• saccharide polymer containing a small number of monosaccharides

disulfide bridges

• covalently links the sulfur atoms of two cysteine residues in close spatial proximity

cystoplasm

• a term that consists of the cytosol and all of the cell’s organelles

ribosomes

• tiny complexes scattered throughout the cell responsible for creating proteins from the genetic information of DNA

sedimentation coefficient (S), which is determined by how fast they move during a sedimentation assay

ribosomes are categorized depending on their?

a. Eukaryotes: 40S and 60S subunits

b. Prokaryotes: 30S and 50S subunits
- associate with each other when translation is initiated

two diff subunits of ribosomes:

if they contain a nucleus

how can a cell be determined as a prokaryote or eukaryote?

prokaryotes lack a nucleus, instead contain a nucleoid; lack any membrane-bound organelle

a eukaryote contains a nucleus

differentiate a prokaryote & eukaryote

nucleoid

• contains concentrated DNA

nucleus

• cell’s information center and contains DNA

• double membrane

nuclear pores

• lining the surface, allowing molecules to pass in and out

nuclear lamina

• directly interior to the nuclear pores

• net of intermediate filaments that maintains the shape of the nucleus

nucleolous

• a region that contains special DNA coding for ribosomal RNA (rRNA)

rRNA

• plays an important role in ribosomes

endomembrane system

• regulates protein transport and performs metabolic functions within the cell

• oversees the process of secreting proteins, metabolism and movement of lipids, and detoxification

nuclear envelope
endoplasmic reticulum
golgi apparatus
lysosomes
vesicles
plasma membrane

multiple membrane-bound organelles

endoplasmic reticulum

• an organelle containing an extensive amount of membranes

• contains numerous tubules and cisternae sacs

cisternae sacs

• store proteins and lipids for transport

lumen

• inside of the endoplasmic reticulum

continuous and attached to the nuclear envelope to allow 1. [__] and other molecules to pass freely through the 2. [__]

1. RNA

2. nuclear pores

1. Smooth ER

2. Rough ER

2 distinct connected regions of the ER

Smooth ER

• region of the ER that is responsible for synthesizing lipids, detoxification of poisons, and storage of calcium ions

Rough ER

• region of the ER that is studded with ribosomes on the outside; proteins are synthesized by ribosomes attached and are signalized to be secreted outside the cell; synthesizes membrane phospholipids

Golgi Apparatus

• shipping center of the cell, responsible for directing vesicles to the correct location

• travel through 1. [___] to the 2. [___]

once proteins/molecules leave the ER, they..

1. transport vesicles

2. golgi apparatus

1. cis face - vesicles from the ER enter through this face

2. trans face - vesicles then mature through numerous sacs and cisternae until they reach this face

two asymmetrical ends of the golgi

1. cisternal maturation model - cisternae are dynamic structures that move along with incoming vesicles

2. vesicular transport model - believes that cisternae are more stable, not newly made as often, and stay in place

scientists are debating on these two different models to explain how vesicle transport works in the golgi:

they can travel to the 1. [__] to be secreted, to a 2. [___], or directed to a 3. [___]

when vesicles finally reach the trans end of the golgi,

1. plasma membrane

2. lysosome

3. vacuole

1. copi - responsible for moving molecules retrograde (backwards)

2. copii - moving molecules from the ER to the golgi

3. clathrin - move molecules from the golgi to the plasma membrane

three transport vesicles of the cell

triskelion skeleton

• clathrin-coated vesicles are surrounded by this protein shell

lysosomes

• vesicles can then merge to this to be digested

• are found only in animal cells, and contain enzymes for degrading molecules

4.5

the acidic pH level of lysosomes

1. [__] structures that allows it to be the 2. [___] of the cell, breaking down 3. [___] for their parts

complete the lysosome’s ability:

1. break down

2. recycling center

3. old organelles

peroxisomes

• vesicles can also fuse to this

• similar to lysosomes

catalase

• peroxisomes contain this enzyme to break down hydrogen peroxide into hydrogen and oxygen

glyoxysomes

• plant seeds contain this special type of peroxisome

• converts lipids to starch during germination

vacuoles

• large vesicles that have (lots) of important functions

food vacuoles

• responsible for storing food

• merge with lysosomes to digest the food inside the compartment

phagmolysosome

• term for food vacuoles that merge with lysosomes

contractile vacuoles

• found in many unicellular protists living in freshwater environments

• responsible for expelling excess water out of the cell to prevent freshwater protists from bursting

central vacuoles

• found in plant cells

• much larger than other vacuoles

• main storage center for inorganic ions and water

1. [__] vacuole, which is important in maintaining 2. [__]

plant cells contain only..?

vesicle fusion

• when membranes fuse together, they utilize SNARE proteins to make the process easier

SNARE proteins

• large protein family consisting of at least 24 members in yeasts and more than 60 members in mammalian and plant cells

• is to mediate the fusion of vesicles with the target membrane

V-SNARE

• vesicle contains this type of snare protein

vesicle

the “V” in V-SNARE protein stands for?

presence of arginine (responsible for producing proteins that are important to help your body function)

why are V-SNARES called R-SNARES now?

T-SNARE

• plasma membrane contains this type of SNARE protein

target, typically the plasma membrane

what does the “T” in T-SNARE stand for?

Q-SNARE due to the presence of glutamine

what are T-SNAREs called now?

V and T-SNARE proteins combine to make Cis-SNARE

when the membranes fuse together,

harvesting and using energy in the cell

both mitochondria and chloroplasts play an important role in..?

endosymbiosis theory

• complex traits gave scientists the reason to believe that the mitochondria and chloroplast were once organisms that were actually ingested by another organism and then kept alive because of their ability to generate ATP and food

mitochondria

• powerhouse of the cell

• location of cellular respiration and are responsible for breaking down large molecules that store energy into usable energy

intermembrane space

• space between the two membranes of the mitochondria

• important for generating ATP

cristae

• inner membrane consists of numerous tiny folds

• greatly increases the inner membrane’s surface area

• important for generating ATP

matrix

• space inside the inner membrane

chloroplasts

• found in plants and some protists, but not animal cells

• site of photosynthesis and are responsible for converting solar energy to chemical energy for the cell to use later

thylakoid stacks

• inside of the chloroplast are numerous tiny disc-like stacks

• important for photosynthesis

stroma

• fluid that surrounds the thylakoids

1. gerontoplast

2. chromoplastids

3. leucoplastids

4. proplastids

other types of plastids

gerontoplast

• during senescence in plants, the chloroplast is deconstructed, forming…?

chromoplastids

• only contain carotenoids

• may be formed when a chloroplast loses its chlorophyll

function is unknown, but they may help with ripening fruit

whats the assumed function of chromoplastids?

leucoplastids

• lack pigments entirely and are plastids that store food

a. amyloplast - stores starch

b. elaioplast - stores lipids

how can you determine a leucoplastids type?

proplastids

• small colorless precursors to plastids

etioplasts - turn into chlorophyll when exposed to light

an example of proplastids

diffusion

• molecules will diffuse from high concentration to low concentration

some molecules from the more concentrated side will move to the less concentrated side and vice versa

net movement → more concentration side has more molecules

explain the concept of concentration gradient

simple diffusion

• any molecule that can freely pass through the cell membrane will move into/out of the cell via…? going from high to low

hydrophobic interior

• the phospholipid bilayer that makes up the cell membrane has a..?

nonpolar and small molecules

what kind of molecules only use simple diffusion?

osmosis

• instead of solute diffusing, it is water that moves across the membrane

semi-permeable membrane

• a type of synthetic or biologic, polymeric membrane that allows certain molecules or ions to pass through it by osmosis

how much water it has

a cell’s size is largely determined by…?

water

whats the main component of the cytosol?

osmolarity

• the relative concentration of solutes

• changes how much water is inside a cell through osmosis

hypertonic

• environment is more concentrated than the interior of the cell

• water will flow out of the cell

hypotonic

• the environment is less concentrated than the interior of the cell

• water will flow into the cell

isotonic

• environment has the same concentration of solutes as the interior of the cell

• no movement of water

animal cells

what type of cells perform best in an isotonic environment?

exerts turgor pressure on the cell

plant cells, on the other hand, have a cell wall that

hypotonic environment

since the cell wall tries to squeeze water out of the cell, plant cells actually do best in a …?

flaccid or limp

• in an isotonic environment, there is not enough pressure on the cell wall… the cell becomes?

plasmolysis

• since the cell wall is rigid, it will not shrink

• ergo, the cell membrane peels away from the cell wall, which is known as?

1. facilitated division

2. primary active transport

3. secondary active transport

types of transport