unit 2 - cell structure and function

plasma membrane

double layered structure with phospholipids and proteins

semi permeable

only small, hydrophobic molecules like O2 and CO2 can pass through without help

integral proteins

firmly bound to plasma membrane

transmembrane proteins

intregral proteins that extend all the way through the membrane

fluid mosaic model

each layer of phospholipids is flexible

adhesion proteins

form junctions between adjacent cells

receptor proteins (hormones)

docking sites for things that arrive at the cell

transport proteins

make pumps to actively transport solutes across the membrane with ATP

channel proteins

make channels that selectively allow for the passage of certain ions/molecules

cell-surface markers (glycoproteins)

exposed on surface -- cell recognition and adhesion

carb side chains

on the surface of some proteins; stabilize fluidity of membranes in animal cells (cholesterol)

nucleus

directs what happens in the cell and is responsible for the cell’s reproduction ability

what is the largest organelle

nucleus

chromosomes

what DNA is organized into

nucleolus

where rRNA is made and where ribosomes are assembled

ribosomes

carry out protein synthesis

what are ribosomes made out of?

rRNA and protiens

where are ribosomes located?

free floating in the cell or attached to the ER

rough endoplasmic reticulum

proteins made here are trafficked to/across membrane, used to build golgi bodies. lysosomes, or ER, compartmentalize

where is the rough endoplasmic reticulum located?

attached to nucleus and has ribosomes attached

smooth endoplasmic reticulum

makes lipids, hormones, steroids, detoxification of waste

golgi bodies

helps process pollutants by modifying/processing/sorting products after RER synthesizes them; packaging/distribution for stuff meant to be discarded from the cell; produce lysosomes

vesicles

carry products to the plasma membrane

mitochondria

convert energy from organic molecules into energy for the cell (ATP)

where does most ATP production happen?

cristae

lysosomes

have digestive enzymes to break down unwanted/dead/old stuff in the cell, intracellular digestion

hydrolytic enzymes

found inside lysosomes; only work at a certain pH -- essential during apoptosis

centrioles

make microtubules to pull replicated chromosomes to opposite ends of the cell during cell division

vacuoles

fluid-filled sacs that store water, food, wastes, salts, pigments

peroxisomes

detoxify stuff to make H2O2 via enzymes

what makes up the cytoskeleton

microtubules and microfilaments

microtubules

made up of protein tubulin; help control cellular division and movement

microfilaments

help with movement; made from protein actin that can be joined together and broken down to help microfilaments grow and shrink

cilia and flagella

help with movement in single-celled organisms

cellulose

makes up cell wall

what are cell walls found in

plant cells, protists, fungi, bacteria

chloroplasts

have chlorophyll and make plants green :)

central vacuole

large vacuole that takes up much of a plant’s cytoplasm

what does a full vacuole indicate about a plant?

it’s not dehydrated

what does a not full vacuole indicate about a plant?

it’s dehydrated

what charge of things can cross the lipid bilayer

hydrophobic

facilitated transport

uses protein channels as tunnels through membranes

aquaporins

a type of facilitated diffusion for water; water can’t cross without it

passive transport/diffusion

high → concentration

simple diffusion

small, polar molecules can go right through without assistance

facilitated diffusion

when assistance from a channel-type protein is required

passive trasnport

when soemthing is moving by diffusion; no energy needed

osmosis

when the molecule that’s diffusing is water

what happens if a cell membrane loses H2O in a plant cell?

shrinks away from the wall

what happens if a cell membrane takes in H2O in a plant cell?

expands and goes against it

hypertonic

more dissolved solutes/less solvent

hypotonic

fewer dissolved solutes/more solvent

water potential

measures potential energy in water; how much potential it has to diffuse -- how eager it is to go from low to high

in what direction does water potential go?

high to low ALWAYS.

what is water potential affected by

pressure potential and solute potential

how does adding a solute affect water potential?

water potential is lowered; water is less likely to leave the solution and more likely to enter

active transport

movement against natural flow (low → high)

sodium-potassium pump

pushes out 3 Na+ ions and brings in 2 K+ ions across the membrane

secondary active transport

something is actively transported using energy from movement of another substance going down its concentration gradient

endocytosis

when larger pieces want to enter the cell, a piece of the membrane engulfs it, forms a pocket, and makes a vacuole/vesicle

pinocytosis

cell ingests liquids

phagocytosis

cell igests solids

receptor mediated endocytosis

when a ligand bonds to a receptor, it’s brought into the cell by folding in the membrane, making a vesicle around the ligand

bulk flow

fluids moving in one direction due to pressure

exocytosis

large particles transported out of the cell

why are cells small?

moving things in and out is harder the larger the cell

what leads to a more efficient cell?

a higher ratio of SA:V (12/1 is higher than 6/1)

what happens as cells increase in volume?

relative SA decreases and the demand for internal resources increases → more complex structures needed to sustain the cell

when do phospholipids form a bi-layer in an aqueous environment?

spontaneously

embedded proteins

hydrophilic or hydrophobic, loosely bound to membrane surface

what happens when embedded proteins are hydrophilic?

charged and polar side groups

what are the purposes of embedded proteins?

transport, cell-cell recognition, enzymatic activity, signal transduction, enzymatic activity, signal transduction, intercellular joining, attachment for extracellular matrix or cytoskeleton

how is cholesterol distributed in the bilayer?

randomly between phospholipids

what does cholesterol do for the bilayer?

regulates fluidity under different environmental conditions

plasmodesmata

small holes between plant cells that allows the transfer of nutrients, waste, plants

what complex carbs do plants have?

cellulose

what complex carb do fungi have?

chitin

what complex carb do prokaryotes have>

peptidoglycan

what does exocytosis require energy for?

to move large molecules out of the cell

what does active transport do?

establishes and maintains concentration gradients

cotransport

uses energy from an electrochemical gradient to transport two different ions across the membrane through a protein

symport

two different ions are transported in the same direction

antiport

two different ions are transported in opposite directions

electrochemical gradient

relies on an electrochemiccal difference across a membrane (membrane potential)

osmolarity

total solute concentration in a solution

solute

substance being dissolved

solvent

a substance that dissolves

how are water concentration and solute concentration related?

inversely

environmental hypertonicity

less cellular solute and more cellular water (water leaves); plasmolysis

environmental hypotonicity

more cellular solute and less cellular water (water enters); turgid

what does osmoregulation allow for in animal cells

maintains water balance and allows control of internal solute composition/water potential

what do plasma membranes allow cells to do

establish and maintain different internal and external envrionments

what do cellular compartments allow for

various metabolic processes and specific enzymatic reactions to occur simultaneously, increasing cell efficiency

what do prokaryotic cells have in terms of compartmentalization

internal region, nucleoid region with genetic material

what do eukaryotic cells have in terms of compartmentalization

additional inner membranes and membrane bound orgnalles

endosymbiosis

a free living anaerobic prokaryote was engulfed and didn’t get digested → over time, lost some functionality and became mitochondria