Unit 3 Bio (Cells)

3 Pillars of Cell Theory

1) all living things are made of cells;
2) cells are the basic units of structure and function;
3) all cells come from existing cells

Cell

the smallest unit of life (has all the properties of life)

Surface Area to Volume Ratio

S:V ratio gets smaller the more size a cell has
1) volume of object = increases with cube of diameter; surface area = increases with square of diameter
2) Cell volume = size of cell; cell surface area = size of membrane
3) B/C Volume is getting larger quicker than the S, the S:V ratio gets smaller and smaller until the V eventually catches the S
4) Cells want much larger S compared to V because this allows them to exchange things like waste and nutrients with environment quicker (Think a concert hall with more exits compared to the people vs one with just one exit for a ton of people)
5) So: larger the volume, the worse the S:V ratio is, so the worse the exchange rates

Prokaryotic

Cells that do not have a nucleus.

Features:
1) have non-membrane-bound organelles
2) no nucleus; instead have nucleoid region
3) _ <10 µm (micrometers)

Include:
1) bacteria
2) archea

Eukaryotic

Cells that have an enclosed nucleus

Features:
1) have many membrane bound organelles
2) have a nucleus
3) 10-100 µm (micrometers)
4) plants, animals, fungi, protists

Prokaryotic and Eukaryotic Features

1) cell membrane that surrounds them
2) cytoplasm
3) DNA

Cytoplasm

Gel like substance in a cell

organelle

a structure within a cell with a specialized function

nucleus

organelle with two membranes that holds DNA. Includes (nuclear envelope, nucleolus, and nucleoplasm.)
1) tells proteins what to do
2) makes ribosomes (assembled in nucleolus)

Nucleoid Region

General area where DNA hangs out

Rough Endoplasmic Reticulum (RER)

The place where soon-to-be exported proteins are made by ribosomes (contains ribosomes)

Ribosomes

workers that assemble proteins
1) build primary structure of proteins

Smooth Endoplasmic Reticulum

Coral reef-like structure
1) synthesize lipids like steroids and membranes
2) detoxify substances
3) store calcium

Protein Transportation Steps (REALLY IMPORTANT)

Ribosomes make proteins in RER

Folding and structural modifications

Vesicle transports proteins to the Golgi

Golgi modifies packages further and sorts proteins

Proteins are packaged into vesicles again

Leave the cell destined for secretion

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Golgi

Distribution center
1) marks proteins
2) modifies proteins
3) sorts proteins
4) ships proteins

Endosymbiotic Theory

organelles with DNA and bacteria-like features are a product of an ancestor being absorbed by ancient eukaryote and domesticated to an organelle

Cytoskeleton (and 5 functions)

made of proteins (in both prokaryotes and eukaryotes) (Different sizes)
1) structure/support of cell
2) internal movement/transport
3) transport of entire cell
4) chromosome movement
5) cell splitting during cell divison

Cell Movement with Cytoskeleton

1) internal movement = organelles use cytoskeleton to move from 1 part of cell to another
2) external movement = cilia and flagella (microtubes wrapped in plasma membrane that use energy to create movement) and cytoplasmic streaming

Organelles Unique to Animal Cells vs Plant Cells

1) Animals = flagellum, lysosomes, centriole
2) Plants = central vacuole, chloroplast, + cell wall

Central Vcuole

Storage locker
1) stores water for plants

Contractile Vacuoles

pump to remove water (ex: paramecium using to pump out excess water and keep size)

Mitochandria

does cellular respiration
1) cellular respiration = breaks down food into carbon dioxide to release energy and create ATP

Chloroplast

Green bacteria-like organelle with DNA and ribosomes that does photosynthesis (found in plant cells)
1) photosynthesis = absorbs light and converts it to chemical bond energy by forming glucose

lysosomes

Digestive organelles
1) creates and uses digestive enzymes
2) produced by golgi

Diffusion

Movement of molecules from high to low concentration (down the concentration gradient.)

Concentration Gradient

Natural inclination of molecules to move from places of high concentration to areas with low concentration.

Diffusion of 1 solute

Molecules move across the membrane at random moments, eventually creating equilibrium

equilibrium

balance

Diffusion of 2 solutes

same thing but until same ratio/# of both on both sides (equilibrium)

Selective Permeability

only certain molecules can pass through
1) cell membranes have selective permeability

Permeable molecules

Molecules allowed to pass through the cell membrane (allowed to pass through because phospholipids have nonpolar insides that polar cannot stick to to slide past.)
1) nonpolar molecules (easy, somewhat hard if they're big though)
2) small polar molecules (polar but small enough to sneak past w/ difficulty. ex: H20.)

Impermeable

Molecules that are not allowed to pass through the cell membrane (phospholipid insides are nonpolar, so some molecules won't rock w/ it)
1) large polar molecules (too big to even sneak through)
2) ions (charged and very polar.)

(Im)permeable Molecules Explanation

Phospholipids are amphipathic (polar head and nonpolar tails). B/C of the way they form, nonpolar insides form inside of the cell membrane, so polar can't adhere or sneak through unless really small.)

Osmosis

The difficusion of water molecules from high to low water concentration across a semi-permeable membrane
1) occurs when the solute cannot cross the membrane. Water moves to match the ratios

Toncity

Ability of a solution to make water move in and out of a cell through osmosis

Hypotonic Solutions

Outside water concentration is higher, causing water to move inside cell
1) animal cell = lysed (inflated)
2) plant cell = turgid (inflated; optimal state b/c liking having a lot of water to keep their cell membrane puffed out and strong)

isotonic Solutions

Balanced water concentration so no net flow of water
1) animal cell = normal
2) plant cell = flaccid ("normal" size but bad because they need the inflow of H20 to be stretched out)

Hypertonic

Outside water concentration is lower so water leaves the cell
1) animal cell = shriveled
2) plant cell = plasmolyzed (shriveled)

Passive Transport

Diffusion following the natural concentration gradient

Facilitated Diffusion

Diffusion that occurs with the help of a protein in the cell membrane
1) a type of passive transport
2) solute binds to protein and protein changes shape to move it across (then returns back)

Active Diffusion

Movement against the concentration gradient that requires energy in order to occur (ATP = way a cell used energy)
1) membrane protein using energy to change shape to move molecules across the membrane
2) from low to high
3) using ATP to create a gradient

phosphorylation

when a phosphate is added to a transport protein using ATP hydrolysis
1) changes shape of protein and moves ion across membrane
2) produces phosphate and ADP

Transport/Carrier Protein

Protein in the cell membrane that carries an impermeable protein through the membrane

Passive vs Acrtive

1) Active requires ATP to change the shape of the protein
2) Active moves against the concentration gradient (low to high)

1st Law of Thermodynamics (Law of Conservation of Energy)

energy cannot be created or destroyed; can only converted from one form to another

2nd Law of Thermodynamics

the entropy (disorder) in the universe always increases
1) creating order costs energy while creating disorder does not cost energy

Diffiusion & the 2nd Law of Thermodynamics

1) higher concentration = more ordered than when particles are spread out
2) mols move from high to low to occupy more possible locations, increasing the randomness/entropy

Net diffusion

overall directional movement of mols from an area of high concentration to an area of low concentration

energy

ability to cause something to change

entropy

randomness

kinetic energy

movement of molecules

potential energy

stored energy

reactants

what is needed for a reaction

products

what is produced by a reaction

Chemical Covalent Bonds

represent stored/potential energy

endergonic reaction

stores energy
1) makes chemical bonds

exergonic reaction

releases energy
2) breaks chemical bonds

activation
energy

energy required for a chemical reaction
1) needed by stable molecules to break bonds

Enzymes

proteins (usually) that lower activation energy
1) bio catalysts = speed up reactions by lowering activation rate
2) not consumed in reaction (reusable)
3) usually proteins
4) selective with reactions; shape determines specificity b/c only specific substrates fit into activation sites*
5) reactants could try to reach AE on their own with heat, but need to maintain homeostasis.

substrate

the specific reactant an enzyme reacts on

active site

region of enzyme where substrate fits into

Glycoprotein

attached to cell membrane
1) cell to cell signaling

Cell to Cell Signaling

when cells communicate by sending signals to one another

Competitive Inhibitors

blocks substrates from enzyme's activation site

Noncompetitive Inhibitors

misshapes the enzyme without blocking out the activation site

Endocytosis

Vesicle entering the cell w/ something in it

Exocytosis

Vesicle leaving the cell carrying something