bio unit 2

what are the three types of cells

archea, bacteria, and eukaryotes

what are archea

eveolved in harsh early earth environments

what do all cells have

1. plasma membrane that seperates cell from its environment

2. cytoplasm containing jelly-like cytosol inside cell

3. ribosomes that synthesise proteins

4. DNA to store and transmit hereditary info

prokaryotes may also have a cell wall that acts as extra layer of protection against environment

what are prokaryotes

• they do not have a nuclei

• dna exists as singular circular chromosome in center of cell called nucleiod

• some bacterial cells have circular DNA plasmids that often cary genes for resistance to antibiotics

what other things can prokaryotes have

• pili: exchange genetic info

• cell wall that protects, keeps shape, and stops dehydration

• flagella used for motion

are prokaryotes big or small + why

• smaller than eukaryotic

• allows ions and organic molecules that enter to quickly diffuse to other parts of cell

• waste can quiskly diffuse out

what happens to volume of prokaryotic cell as it increases

• increasess faster than surcace area

• surface are to volume ratio decreases

• becomes less efficient

  • divide or stretch to fix this

what is the plasma membrane

a phospholipid bilayer with embedded protiens that seperates cell from environment

what does plasma membrane control

• passage of organic molecules, ions, water, and oxygen in and out of cell

• lets waste out of cell

what part of the plasma membrane helps with absorption + where is it found

• called microvili and folds into fingerlike shape

• usually found in small intestine

• ppl with celiac have reactions to gluten that damages microvili so they cant absorb nutrience which causes pain

what is the cytoplasm

the entire region between plasma membrane and nuclear envelope

what is cytoplasm made up of

• organelles suspended in gel-like cytosol, cytoskeleton, and chemicals

• 70-80% water

what causes consitensy of cytoplasm to be semisolid

proteins in it and sugar, polysaccharises, amino acids, nucleic acids, fatty acids, Na, K, Ca ions and elements that are also disolved in it

what happens in cytoplasm

metabolic reactions such as protein synthesis

what is the nucleus

• houses cells DNA and directs synthesis or ribosomes and protiens

• combines rRna with proteins to make ribosome parts that are transported out pores in envelope to cytoplasm

what is nuclear envelope

• double membrane structure that makes up outermost part of nucleus

• inner and outer membranes are phospholipid bilayers

• broken up by pores that control passage of ions, molecules, and RNA btwn nucleoplasm and cytoplasm

what is chromatin

when cell is in growth.maintinence, proteins attatch to chromosomes and resemble unwound, jumbled bunch of threads

what are chromosomes

• structures withing nucleus made up of DNA

• linear in prokaryotes

• each species has speficic # of chromosomes in nucleus

• only visable when cell is getting ready to divide

what are ribosomes

• cellular structures responsible for protein synthesis

• either attatched to plasma membrane or endoplasmic recticulum

• large complexes of protein and RNA

  • recieve orders for synth from nucleus where DNA —> mRNA

• found in practically every cell

what is mitochondria

responsible for making ATP which is energy carrying molecule

what is ATP and how is it made

• short term stored energy of cell

• made via cellular respiration using energy from glucose

  • uses oxygen and produces CO2

what cells have high concentration of mitochondria

• muscle cells because they need lots of energy

• low 02 means low ATP so its made without oxygen and is accompanied with lactic acid

what is a peroxisome

small round organelle enclosed by single membranes

• carry out oxidation reactions that break down fatty and amino acids

• detoxify poisons that enter body

• glyoxysomes (plants) convert stored fats into sugars

what are vesticles and vacuoles (larger)

• membrane bound sacs that function in storage and transports

  • membrane of vesticles can fuse with plasma membrane or other membrane systems within cell

  • enzymes wihtin vacuoles brak down macromolecules

    • doesnt fuse with membranes

animal cells vs plant cells characteristics

• animal: centrosome and lysosomes

• plant: cell wall, chloroplasts and plastids, and central vacuole

• both: microtube organizing centers (MTOC)

what is centrosome

MTOC found near nuclei containing pair of centrioles perpendicular to each other

• centrosome replicates itself before cell divides

• centriole pulls duplicated chromosome to opposite ends of dividing cell

what is lysosome

cell’s garbage dispolas

• enzymees aid breakdown of protein, polysaccarides, lipids,nucliec acids, etc

  • lower pH than cytoplasm

what is cell wall

rigid covering that protects cell, provides structural support, and gives shape

• chief component = peptidoglycan

• major organic molecule = cellulose

what r chloroplasts

have their own DNA and ribosomes and carry out photosynthesis

• have outer and inner membranes

  • space enclosed by inner is sets of interconnected, stacked fluid-filled sacs called thylakoids

  • each stack is called granum

  • fluid enclosed that surrounds grana is stroma

• have green pigment called chlorophyll which captures light energy

what is center vacuole

regulates cells concentration of water in changing environmental conditions

• as water concentration in osil becomes lower than the plant’s, water moves out of central vacuoles

  • leaves cell walls unsupported → wilts

• supports expansion of cell

  • holds more water to make cell get larger

what is endoplasmic recticulum (ER)

• works to modify, package, and transport lipids and proteins

• includes nuclear envelope, lysosomes, vesticles, endoplasmic reticulum, and golgi apparatus

• series of interconnected membranous sacs and tubules that modify protiens and synthesize lipids

  • performed in rough er and smooth er seperately

• holly potion of ER tubules = lumen/cisternal space

• membrane of ER is phopholipid bilaryer embedded with proteins

  • continuous with nuclear envelope

What is rough ER

ribosomes transwer newly synthesized proteins into the lumen where they undergo structural modifications

• acquire side chains

• proteins incourporated into cell membranes or secreted

• makes phospholipids for cellular membranes

• proteins and phospholipids not meant for RER move via transport vesticles out of RER’s membrane

• abundant in cells that secrete proteins (like liver cells)

smooth ER

continuous with RER but has few-no ribosomes on surface

• synthesises carbs, lipids, steroid hormones

• detoxifies medications and poisons

• stores calcium ions

• sarcoplasmic reticulum (in muscle cells) stores calcium ions needed to coordinate contractions of muscle cells

golgi apparatus definition

sorting, tagging, packaging, and distribution of lipids and protiens takes place here

• series of flattened membranes

• recieving end is called cis face (ooposite is trans face)

golgi apparatus cis face and trans face movement

• vesticles formed from ER travel to cis face, fuse, and empty contents into lumen

• traveling proteins and lipids go through modifications to be sorted

  • gain short chains of sugar

• then get tagged with phosphate groups or toher molecules to be routed to destination

• get packaged into secretory vesticles on trans side

  • deposited in cell or releasted out of cells

which cells have abudance of golgi

• cells that have lots of secretory activity like salivary glands or immune system

what does golgi do in plants

synthesize polysaccharides used for cell wall or other parts of cell

what is phagocytosis

• section of plasma membrane engulfs pathogen and becomes vesticle

• vesticle fuses with lysosome

• hydrolytic enzemes destroy pathogen

• exits cell

microfillament def

• narrowest fiber in cytoskeleton and function in cellular movement

• made of 2 intertwinded trands of gobular protein called actin

  • powered by ATP to assemble this form

    • serves as track for movement of myosin (motor protein)

      • allows actin to engage in motion events like cell division

  • actin and myosin are in muscle cells and cause muscle to contract

• provide shape to cell and can depolymerize and reform quickly to allow cell to change shape and move

what is cytoskeleton

• within cytoplasm there is network of protein fibers

  • shape cell, secure organelle’s positions, and allow movement of things in cell

  • 3 types of fibers: microfillaments, intermediate fillaments, and microtubules

what is intermediate fillament

• several strands of fiberous preoteins would tog

• bear tension and maintain shape of cell

• anchor nucleus and other organelles in place

  • ex: keratin which strengthens hair, nails, skin

what are microtubules

• small hollow tubes that help cell resist compression, provide track for vesticles to move through cell, and pull replicated chromosomes to opposite ends of dividing cell

  • can dissasemble and reform quickly

  • structural elements of flagella, cilia, and centroles

flagella definition

• long hairlike structures that move whole cell

• one or a few per cell

cilia definition

• short hairlike strucutres that move cell or substances

• cell would have many

what is extracellular matrix of animal cells

cells relase proteins such as collagen into extracellular space

• collagen fibers are interwoven with carb containing proteins called proteglycon

• holds cells together to form tissue

• allows cells within tissue to communicate with each other

  • matrix bond with receptors on plasma membrane and change confirmation of microfillament

    • tells nucleus to turn on/off specific sections of DNA

what is plasmodesmata

• channesl that pass btwn walls of adjacent plant cells and connect their cytoplasms

• enable materials to be transported cell to cell throughout plant

tight junction def

• watertight seal btwn 2 adjacent animal cells

• held tighlty by proteins

• prevent materials from leaking btwn cells

  • line organs, cavities, skin

desmosomes def

• created in animal cells when short proteins called cadherins connect intermediate fillaments

  • join cells together in organs and tissues that stretch (heart muscles skin)

what are gap junctions

channels btwn adjacent cells that allows for transport of ions, nutrience, and otehr substances in animals

• important for cardiac muscle (electrical signal for contractions is passed through junctions)

carbs on membrane

• always found on exterior and are bound to proteins (glycoproteins) or lipids (glycolipids)

• allow cells to recognize each other because of unique patterns

  • allows differentiation btwn body cells and foregin cells

• called glycocalyx and is hydrophillic so it attracts H2O

what is membrane fluidity

• membrane is fairly ridgid and can burst if penetrated or if it takes too much water

  • the more unsatureated fatty acids, the less ridgid because there are kinks and bonds that create “elbow room”

  • choleestorl dampens effect of temp on membrane

    • makes sure fludiity doesnt get too high or low

what is passive transport

• substances move from area of higher concentration to lower

  • requires no enegry from cell

what is concentration gradient

• physcal space with range of concentration of one substance

what is selective permiability

because membrane is amiphiphilic (has hydrophobic and phillic parts) some materials can go through, some cant

• lipid soluable material can easily pass through membrane

• moleucles without a charge can pass through with diffusion

• polar substances cannot readily pass through

• charged ions and simple sugras and amino acids need help

what is diffusion

substance moves from high to low concentrated area until it is equal. each substance has its own rate of diffusion

what is facilitated transport

• materials diffuse across plasma membrane with help of membrane proteins

  • materials are polar so theyre repelled by membrane

    • proteins sheild them so they can diffuse

what are channels

specific for substance being transported

• allows polar compounds to avoid nonpolar layer of membrane

• ex: aquaporins: channel proteins that allow water to pass through at high rate

• either open at all times or gated by ion or other substance

  • opening and closing of channel changees because of concentration of specific ion on each side

what are carrier proteins

• bind a substance, changes its own shape, and moves molecule from out to in

  • channels transport faster, carrier diffuse faster

what is osmosis

• movement of free water molecules throughout semipermeable membrane according to concentration gradient

• water move to side w less concentration

• red blood cells can absorb too much water and burst (hemolysis)

what is tonicity

• describes how extracellular solution can change the volume of a cell by affecting osmosis

  • often directly correlates to omolarity (total solute concentration)

  • water move along concentration gradient

hypotonic

extracellular is lower so water enters cell

hypertonic

extracellular is higher so it leaves cell

isotonic

equal conentrations in cell

electrochemical gradient def

• a diff of charge across membrane because of ions and proteins

  • interior of cell negative

  • cells have higher concentration of K than Na

  • Na has concentration and charge driving it in cell

  • K has concentraiton driving out, charge driving in

moving against gradient def

• requires energy harvested from ATP

  • pumps move to work against a gradient and requre much of cells metabolic energy

  • primary active transport moves ions across memebrane and creates difference in charge and is directly dependant on ATP

  • secondary active is movemen of material due to electrochemical gradient established by primary active transport

carrier proteins for active transport

• uniporter: carries one ion or molecule

• symporter: 2 in same direction

• antiporter: 2 in diff direction

• dont require atp

• can also carry uncharged molecules like glucose

secondary active transport def

• uses KE of Na ions to bring other compounds against concentration gradient into cell

  • Na concentration builds outside cell from Primary active T

    • channel protein opens and Na and other substances move

      • amino acids and glucose enter this way

      • used to store high energy H ions for ATP production

        • PE → KE

endocytosis def

moves particles like large molecules, parts of cells, or cells into a cell

phagocytosis definition

cell “eats” particle

• membrane prepares by coating itsef with clathrin (protein)

  • merges vacuole with lysosome

Pinocytosis

cell "drinks” by taking in molecule and water which cell needs

• smlaler os it doesnt need to merge with lysososme

• uses caveolin protein

  • performs similar process to phagocytosis

receptor-mediated endocytosis

receptor proteins in membrane have specific binding affinity for certain substances

• clathrin used

• foregin things like flu virus cross react with receptors and enter cells

exocytosis def

expells material from cell