Biology Exam 3

• Passive diffusion through membrane pores
• Passive diffusion through the membrane's hydrophobic layers
• Carrier-mediated diffusion (facilitated diffusion)
• Active Transport
• Endocytosis (phagocytosis, pinocytosis, receptor-mediated endocytosis)
• Exocytosis (secretion)

The spontaneous movement of particles (molecules, atoms, ions) from a region of high concentration to a region of low concentration

• When the rate of movement of a substance across a semi-permeable membrane is the same in both directions
• ---> there is no net flow

The difference in concentration on either side of a semi-permeable membrane

• Diffusion of water (down a conentration gradient)
• ---> no energy required

10%

• Diffusion of a substance down its concentration gradiant through the hydrophobic barrier of a membrane
• Through water channels, aquaporins
• The rate of diffusion is proportional to the concentration gradient
• No energy is required
• Equilibrium occurrs when the concentration gradient is zero

proteins known to form pores in cell membranes

It lyses (bursts)

Crenation (It shrivels)

It is turgid (normal)

It is plasmolyzed

It is flaccid

CO2, O2, N2

only molecules soluable in both water and lipid can pass through because of the hydrophobic layer

• Transport specific for particular substances such as amino acids, sugars, vitamins, and minerals (ions) down the concentration gradient
• It requires a membrane transport protein
• No energy required for this
• Equilibrium occurs at zero concentration gradient

they are either a channel (that can open/close) that the substance flows through, or a protein that takes the substance then "flip flops" and changes fold to move it into the cell

• Form of transport that requires a membrane transport protein to move particular substances up a concentration gradient
• energy is required to pump these substances up the gradient
• can be up or down concentration gradient
• examples of substances moved by active transported this way are amino acids, sugars, vitamins, minerals (ions)

• Outside cell: Na+ is high concentration, K+ is low... pump will pump against concentration gradient
• Cytoplasmic Na+ binds to the sodium potassium pump
• Na+ binding stimulates phosphorylation (addion of a phosphate) to ATP
• Phosphorylation causes the protein to change its conformation opening towards the outside of the cell, the shape change releasing Na+ and making a shape to accept the K+
• K+ binds to the protein triggering the phosphate to be released
• Loss of the phosphate changes the conformation back to original Na+ accepting, releasing K+ inside the cell
• Cycle repeats

• Transport
• Enzyme activity
• Signal Transduction (recognition by receptor)
• Cell-cell recognition
• Intercellular joining/cell-cell adhesion
• Attachment/adhesion to the cytoskeleton and extracellular matrix

• ATP gives the proton pump energy to pump H+ ions (or protons) out of the cell so that they can bind to sucrose and bring it into the cell through the sucrose-H+ cotransporter
• sucrose can later be broken down to make more ATP

• An inherited disease that affects the exocrine glands
• it causes the production of abnormally thick mucus, which leads to the blockage of the pancreatic ducts, intestines, and bronchi
• often results in respiratory infection
• 1 in 2500 live births affected
• mild to severe symptoms depending on the specific mutation causing the effect

• Failure to thrive
• viscous, abnormal gland secretions
• pathological changes in respiratory tract
• shortened lifespan

• Cystic Fibrosis Transmembrane Conductance Regulator
• (CFTR)

Because CFTR helps transport chloride ions which helps control the movement of water in tissues, which is necessary for the production of thin free flowing mucous. If this protein is defective, the chloride ions are not transported and therefore water doesnt flow through, and mucus does not flow, but it builds up and blocks pathways such as in the lungs

• a substance enters a cell without passin through the cell membrane
• movement of membranes requires energy
• ex: an amoeba engulfs a bacteria via phagocytosis
• 3 types

• Phagocytosis
• Pinocytosis
• Receptor Mediated Endocytosis

• The cell ingests large objects such as bacteria, viruses, cell remains, etc
• stored in a food vacuole

• uptake of solutes and single molecules such as proteins
• stored in vesicles
• ex: vesicles form in a cell lining a small blood vessel

• only endocytosis to use a receptor (others can take in anything in the spot they engulf)
• cytoplasm membrane folds inward to form coated pits and proteins or trigger molecules lock into receptors in the plasma membrane and are engulfed after they bind. These inward budding vesicles bud to form cytoplasmic vesicles
• Ex: a coated pit and a coated vesicle form during receptor mediated endocytosis

• Proteins to be exported are made "into" the ER where they are glycosylated (carbohydrates are added)
• The ER pinches off vesicles containing these proteins
• The vesicles move to the golgi
• they pass from inner to outer golgi, undergoing further modifications
• Vesicles carrying these proteins pinch off. Some move to the cell surface where the proteins may be secreted/released
• Membrane bound proteins in golgi vesicles move to the cell membrane when the vesicles fuse with it

• a genetic disorder characterized by high cholesterol levels, specifically high levels of low density lipoprotein (LDL-bad cholesterol)
• caused by a defect in chromosome 19
• body is unable to remove LDL

• two types: mild and severe
• fatty skin deposits on hands elbows, knees, ankles, cornea of eye
• cholesterol deposists in eye lids
• chest pain
• heart atttacks early

• lifestyle changes, changing what you eat and lowering amount of fat eaten
• medications: statins, bile acid sequesterint resisns
• severe form may need treatment called apheresis (where blood or plasma is removed from the body and special filters remove extra LDL and blood plasma is returned)

• A process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane (such as transport of proteins in ER golgi transport)
• secretion of proteines like enzymes, peptide hormones

• A change in energy
• That change is always downhill (exergonic) or uphill (endergonic)

no but energy forms can be interconverted

• endergonic: (uphill) requires input of energy, such as photosynthesis
• ---> molecules are synthesized (built up)
• exergonic: (downhill) releases energy
• ---> molecules are broken down

• 1. exergonic
• 2. exergonic
• 3. endergonic
• 4. endergonic
• 5. exergonic
• 6. exergonic?
• 7. endergonic
• 8. exergonic
• 9. exergonic

• Active Transport
• Biosynthesis
• movement

require or yeild some energy

• H2O + Energy (electrical) ---> H2 + O2
• ---> endergonic
• Reverse reaction: H2 + O2 ---> H2O + Energy(heat, light, sound)

energy available to do work

deltaG= Gfinal-Ginitial

deltaG= Gproducts- Greactiants

G initial is high G final is low. if delta G (final-initial) is less than 0 reaction is exergonic. if greater than 0 its endergonic

• beginning requirements: more free energy (higher deltaG), less stable, greater work capacity
• In a spontaneous change: the free energy of the system decreases (deltaG<0), the system becomes more stable, te released free energy can be harnessed to do work
• end result: less free energy (lower deltaG), more stable, less work capacity

• Gravitational motion
• Diffusion
• Chemical reactions

• exergonic
• they release energy

•              -O       ^-O      ^-O                 Adenine
•               |           |          |                  |
•       ^- O--P--^-O--P--O--P-----O----Ribose
•               ||         ||          ||
•              ^-O       -O      -O

same as ATP but one phosphate is detached and plus energy is included

• ADP: adenosine diphosphate
• ATP: Adenosine triphosphat

• first the phosphate and ADP are in a stable condition, unlikely to change
• then, with the addition of energy, it becomes possible to combine the phosphate and ADP to generate ATP which is highly unstable
• after, separation of a phosphate gives rise to ADP and P again with the release of energy, the same amount of energy that was required to bring P and ADP together. The released energy can do work.

• Coupling reactions happens so that one reaction releases the energy to drive another
• Unfavorable reactions are coupled to favorable reactions in our cells
• endergonic and exergonic reactions will couple

• ATP yeilds 100 U energy + ADP + phosphate
• relaxed muscle + 20 U of energy yeilds a contracted muscle
• coupled reaction: relaxed muscle + ATP yeilds contracted muscle +ADP+ Phosphate + 80 U energy released as heat

• Cells burn (oxidize) nutrients: C6H12O6 [carbohydrate] + O2 --->   CO2 + H2O + E (Energy) 
• Energy from oxidation is used to make ATP:  E + ADP + P   ---->    ATP
• Sum of two equations: C6H12O6 + O2 + ADP + P ----> CO2 + H2O + ATP
• Hydrolysis of ATP yeilds energy for cellular work

ATP --> ADP + Pi + 7500 cal/mole

• Photosynthesis (in chloroplast) --> carbohydrates
• Metabolism (in mitochondria) --> energy

• all at once: explosive, uncontrolled reaction
• ---> fire
• small steps: controlled release of energy for synthesis of ATP
• ---> work is done

• stepwise oxidation of sugar allows the energy released to be stored by carrier molecules rather than released as heat
• if released all at once all energy is released as heat and none is stored

the oxydation of organic molecules

• Oxidation reactions: release energy and form products with less potential energy
• Reduction reactions: require energy and form products with more potential energy

• capture the energy from food to power biosynthesis, movement, active transport
• in glycolysis when glucose is oxydized, electron carriers capture the energy

• Glycolysis: NADH
• CAC: NADH and FADH₂

to the electon transport chain

H2O+ 34 ATP + free electron shuttles (NAD+ and FADH)

the inner mitochondrial membrane/ cristae (folds of the inner membrane that increase the inner membranes surface area)

cytoplasm

mitochondrial matrix

inner membrane

• electron transport chain
• chemiosmosis

muscle cells

electrons are transported from carrier molecules like NADH and FADH₂  (NADH will become NAD+) to carrier proteins stepwise, and finally to oxygen gas to form water and the energy released from various steps can move protons across the inner mitochondrial membrane to form aproton gradient

H+ ions or protons enter the stator from the intermembrane spance then enter the rotor. The rotor and internal rod spin around and the catalytic knob combines ADP and Pi to form ATP in the mitochondrial matrix

the etc receives the electrons from the carries and electrons flow through the etc and cause hydrongen to be pumped into the intermembrane space throught the rotor which generates a proton gradient. the atp synthase (along the inner membrane) then allows the protons to flow down their concentration electrochemical gradients back into the matrix. the protons flowing throught the atp synthase generate a mechanical energy which causes the part of the enzyme sticking into the membrane to rotate inside of a stationary head. This mechanical energy is then converted to chemical bond energy needed to combine ADP and Pi in the matrix

• phase 1: light reactions
• phase2: dark reactions

• light reactions: light energy is harnessed to provide energy carriers to drive the dark reactions
• Dark reactions: energy carriers from light reactions are used to fix carbon dioxide into sugar (glucose)

• Gamma Rays
• x rays
• uv
• visible light
• infrared
• microwaves
• radiowaves

• red 700
• green 550
• blue 500

chlorophyl absorbs red and blue light triggering photosynthesis and defracts green light so we see it

• light is absorbed by pigment (chlorophyll) in photosystem 1 which exites an electron to a high energy level. it falls back, releasing energy. released energy splits water into electrons protons and o2 as a waste product
• the electrons are passed down an electron transport chain including photosystem 1. in photsyste1 absorbed light aadds more energy to the electron
• during electron transport, released energy is used to pump protons into the lumen (inside) thylakoids, as wellas to synthesize NADPH from HADP. as proteins pass down their electrochemical gradient through atp synthase, atp is generated

high energy molecules (atp, and NAD (P) H) are used to reduce co2 to make sugars with oxygen as a biproduct

• G1 checkpoint: ensures that DNA is undamaged before its replicated in DNA synthesis
• G2 checkpoint: ensures chromosomes are lined up on equatorial plane before anaphase begins
• M checkpoint(at anaphase): sister chromatids must be pulled in opposite directions

• p21: repair of damaged dna
• p53: signals apoptosis when dna cant be repaired

bc although one works normal there is more chance that if that one breaks, the other does not function and cells will not go through apoptosis and divide wrong

• 2 N chromosomes
• 1 chromatid per chromosome in G1, 2 in G2
• Dna synthesis

• 2n chromosomes
• 2 chromatids per chromosome
• chromosomes condense
• centrioles move to opposite poles
• spindle forms
• nuclear membrane breaks down

• 2n chromosomes
• 2 chromatids per chromosome
• Chromosomes line up on equatorial plane

• 4n chromosomes
• 1 chromatid per chromosome
• Centromere splits to begin anaphase
• chromosome (1 chromatid each) separate to opposide poles along spindle

• 4n chromosomes
• 1 chromatid per chromosome
• spindle dissapears
• centrioles divide
• cytokinesis occurs
• nuclear membrane reforms