BIO120 CH3

what is cell theory

• All organisms are made up of cells

• The cell is the fundamental unit of life

• Cells come from preexisting cells

do organisms have many or one cell?

Unicellular and multicellular

what is the smallest independent unit of life

the cell is the smallest independent unit of life

what characteristics do cells demonstrate

Cells demonstrate characteristics such as evolution, reproduction, use energy, response to environment, and homeostasis.

how do cells reproduce

divide from parent cells to produce daughter cells through processes like mitosis and meiosis.

structure is closely related to what in a cell?

function

what allows a cell to perform its function?

shape

what are the two different types of cells

prokaryotes and eukaryotes 

where do prokaryotic cells store genetic info

nucleoid

what maintains the structure of prokaryotes?

cell walls

which is bigger, prokaryotes or eukaryotes

Eukaryotes

which type of cell has internal membranes?

eukaryotes 

membranes define compartments containing

cell organelles

where do eukaryotes store DNA

Nucleus

what is the shape of chromosomes in prokaryotes

circular

what is the shape of chromosomes in eukaryotes

antiparallel strands (straight)

process of transcription and translation in eukaryotes speed:

transcription and processing of RNA happens in nucleus, then in cytoplasm translation occurs LATER

features of both eukaryotes and prokaryotes

have dna

are cells

transcription and translation

has cell wall

independent unit of life

cells are defined by:

membranes

what do membranes do

membranes act as physical barriers to distinguish exterior and interior of cells and their components

what is the main component of cell membranes

lipids

what components (3) can be found in cell membrane

lipids (main) carbs proteins

how many layers of lipids in cell membranes

2

what is made of glycerol backbone

phospholipids

what are phosopholipids

made of glycerol backbone attached to a phosphate group and 2 fatty acids

what part of lipid bilayer contains glycerol and phosphate group

hydrophilic head

what part of lipid bilayer contains fatty acids

hydrophobic tail

what is amphipathic

molecules that are both hydrophobic and hydrophilic

what part of bilayer interacts more with environment

head

are fatty acid tails polar or nonpolar

nonpolar

is water polar or nonpolar

polar

how do phospholipids arrange their polar heads in aqueous environments

to the outside to interact with water

how do phospholipids arrange their nonpolar tails in aqueous environments

on inside away from water

phospholipids are all arranged the same way(T or F)

False, phospholipids form different structures based on shape

what do phospholipids form when placed in water at neutral pH

liposomes

what is a liposome

spherical bilayer formed when phospholipids are placed in water at neutral pH

what shape are liposomes

sphere

what does the water pH need to be for liposomes to form

neutral pH

what structure can capture other molecules inside (spherical)

liposomes

what do liposomes do

break and filter (with semi-permeable membrane) some molecules

what type of membrane do liposomes have

semipermeable

liposomes can ______ and _______ in some environments

break, reform

what types of molecules do liposomes capture

nucleic acids and other molecules

early membranes were semi-permeable (T or F)

false, they were likely not semipermeable

why do lipids interact so often

due to extensive Van Der Waals forces

what are van Der Waals forces

temporary polarization because of electron presence around atoms

Van Der Waals forces are easily _______ and ________

broken, reform

what allows lipids to move more rapidly thru a cell

van der waals forces

what part of the cell is dynamic and constantly changing and moving thru the cells life

cell membrane

membranes are _______

fluid

what particle is able to move freely within cell membranes

liipids

what features affect membrane fluidity

number of C=C double bonds

length of fatty acid tails

how does # of C=C double bonds impact membrane fluidity

Less double bonds = less movement in membrane

how does length of fatty acid tails impact membrane fluidity

Longer tails = more surface area for Van der Waals forces =  less lateral movement in membrane

cell membranes only contain one type of lipid (T or F)

false, cell membranes have multiple types of lipids

what substance has one region that is hydrophobic and one hydrophilic

cholesterol

what is a major component of animal cell membranes

amphipathic

at makes up 30% of membrane lipids

Cholesterol

cholesterol makes of ______% of cell membranes

30%

hydrophilic head is what type of molecule

hydroxyl group (-OH)

how does temp affect membrane fluidity

• High temperatures = low membrane fluidity

• Low temperature = high membrane fluidity

how does cholesterol at high temps impact membrane fluidity? (what does it do to phospholipids)

• Ring structure interacts with fatty acid tails, reducing phospholipid mobility

• Increases rigidity in high temps

how does cholesterol at low temps impact membrane fluidity? (what does it do to phospholipids)

• The cholesterol keeps phospholipid molecules from packing too close together in cold temps

  • Cholesterol regulates fluidity

what is the function of transporter proteins

• move ions or molecules across the membrane (like a tunnel)

what is the function of receptor proteins

allow the cell to receive signals from the environment, creating a response inside the cell

what is the function of anchor proteins

attach to other proteins and help maintain cell structure and shape

what is the fluid mosaic model

lipids proteins and carbs coexist in the cell membrane and are able to move within it

what is a structure that allows molecules to move laterally

lipid bilayer (membrane fluidity)

what is a crucial component of all cells

cell membranesd

are cell environments stagnant or always changing

always changing

how do cell membranes control molecules coming in and out

mitigate molecular traffic and sustain the intracellular conditions

how do cells maintain homeostasis

thru selectively permeable membrane

how does movement of molecules across cell membrane occur

when there is a concentration gradient

how does diffusion work

high concentration → low concentration

what is passive transport

movement across cell membrane via diffusion

how do oxygen and carbon move thru the cell

thru passive transport

what is facilitated diffusion

passive transport occurring with the help of protein transporters

what are the two types of membrane transporters

channel proteins and carrier proteins

what are channel proteins

create an opening between inside and outside of membrane to allow movement of molecules

what are carrier proteins

bind to molecules in order to transport them across the membrane

how does water move across cell membrane

passive transport

how are water molecules able to travel thru phospholipid bilayer

The size of water molecules enables some transport through the phospholipid bilayer, despite hydrophobic tails

what is the main way water comes thru membrane

via channel proteins called aquaporins

what is osmosis

net movement of a solvent (dissolve other substances) across semipermeable membrane

how does water move via osmosis?

high concentration of solute to lower concentration

water concentration ________ as solute concentration _________

decreases, increases

what is osmotic pressure

the tendency of a solution to draw water in by osmosis

_______ solute concentration = __________ osmotic pressure of the solution

higher, higher

what is active transport

movement of substances against a concentration gradient (uphill)

what type of transport requires energy

active transport

how is active transport possible? (what performs function)

transport proteins in the membrane that act as pumps

what needs to be moved against a concentration gradient

sodium and potassium

what is primary active transport

movement of ions thru membrane (needs ATP)

what is electrochemical gradient

gradient with both electrical and chemical componenets

how do you calculate electrochemical gradient

Sum of the chemical gradient (solute concentration difference) and electrical gradient (charge difference)

what drives the movement of other molecules in active transport

movement of protons

how do cells maintain their size (what type of transport)

Active transport

what is hypertonic

when cell rejects water bc concentration greater outside cell

what is hypotonic

when cell takes in water bc concentration great inside cellw

what is isotonic

water is coming in and out of cell evenly