Prin. of Bio Exam 2

diffusion

random, net movement of molecules from areas of high to low concentration

equilibrium

when there is no more net movement in any direction, molecules are randomly distributed

fluid mosaic model

the cell membrane is a phospholipid bilayer with embedded proteins

phospholipid bilayer

the membrane of cells, made up of polar hydrophilic heads and non polar hydrophobic tails

integral membrane proteins

proteins embedded in the membrane

transmembrane proteins

completely cross membrane with hydrophilic portions exposed on both sides

peripheral membrane proteins

not embedded in bilayer, but near membrane

selective permeability

means that the membrane is semi-permeable, allowing movement of some but not all molecules

passive transport

movement into and out of the cell that doesn’t require energy

osmoses

diffusion of water across membranes

facilitated diffusion

passive transport (doesn’t require energy), includes channel proteins, gated channels, and carrier proteins/transporters

what is phosphorylation

when protein kinase regulates other proteins by adding phosphate groups to them

channel proteins

allow transport of specific ions and polar molecules through a hydrophilic channel through the membrane

gated channels

may open and close to control diffusion, responds to ligands

carrier proteins

one way gate, changes shape during transport process, moves solutes down a concentration gradient

active transport

requires energy, two kinds: primary and secondary

protein pumps

membrane bound proteins that actively move molecules through the membrane

what are the two kinds of primary active transport

uniporter and antiporter

uniporter

moves single substance in 1 direction

antiporter

moves two substances in opposite directions

secondary active transport / symporter, and why is it called secondary?

moves two substances in the same direction, called secondary because only one of the substances is directly causing energy consumption to be moved across the membrane, while the second substance is just required to get through the symporter

botulinum toxin (botox)

toxin that causes paralysis of muscles

how do neurons communicate?

through exocytosis; vesicles filled with acetylcholine (ACh) fuse with the membrane of a cell and move outward

exocytosis

active transport out by vesicles

endocytosis

active transport into the cell via vesicles

phagocytosis

endocytosis through “eating”

pinocytosis

endocytosis through “drinking”

how does botox enter neurons?

through receptor mediated endocytosis

reception mediated endocytosis

repector proteins on outer membrane bind substance, reception initiates endocytosis

steps of cell signaling

signal, reception, response, deactivation

how does cell signaling and reception work

the cell receives a signal through membrane receptors

ligand gated channel

type of membrane receptor the opens when bound to signal protein (ligand)

protein kinase receptor

a kinase enzyme activated by a ligand

kinase

enzyme that takes a phosphate from ATP and places it on another enzyme, activating it

protein kinase cascades

chain reaction where one enzyme activates the next by adding a phosphate group

intracellular receptors

located inside the cell, responds to signals like light or lipid soluble signals that can pass through the membrane

how is cell signaling deactivated?

enzymes like protein phosphotase deactivate or degrade messengers

direct communication through cytoplasmic connections

allows direct transfer of primary and secondary signals through gap junctions (animals) and plasmodesmata (plants), supports multicellularity

quorum sensing

signals released into environment which allows multiple individuals to coordinate activity

forms of biological energy

chemical, light, electrical, thermal, mechanical

potential energy

stored energy (in any form)

kinetic energy

energy of movement that does work (work is the conversion of energy)

thermodynamics

“energy change”, the properties of energy and how it interacts with matter

what are the two laws of thermodynamics?

1. energy is neither created or destroyed; it can be transformed from one form to another

2. transfer of energy increases entropy, no transfer of energy is 100% efficient

entropy

the degree of random disorder in a system

metabolism

sum total of chemical reactions in an organism

anabolic reactions

making more complex things from less complex things, require input of energy to make chemical bonds

catabolic reactions

break down of complex reactants into less complex reactants, releases energy stored in chemical bonds

coupled reactions

catabolic reactions supply energy to anabolic reactions, ATP serves as a common carrier energy

catalysts

increase the reaction rate by reducing the activation energy required to proceed, are not used up or changed by a reaction

enzyme

biological catalysts, usually proteins but includes ribosymes

active site

where reactions occur on a protein, specific to the reactant (substrate)

orient substrate

control the spatial alignment of molecules to fit the active site

strain substrates

induced fit occurs when enzyme changes shape when bound to substrate

enzymes that temporarily add chemical group

one of the ways that enzymes work to induce reactions

irreversible inhibition

inhibitor covalently (permanently) bonds to enzyme, blocking the active site

reversible (competitive) inhibition

inhibitor similar in shape and size to reactant bonds to active site but is unable to participate in reaction, so nothing happens

pathway regulation

feedback inhibition occurs when the end product inhibits an upstream enzyme

redox reactions

electrons transferred from one compound to another

reduction reaction

gaining electrons (reducing)

oxidation

losing electrons

NAD+ (nicotinamide adenine dinucleotide)

acts as an “empty bucket”, picking up electrons through reduction, becoming NADH

(FAD+) flavin adenine dinucleotide

picks up electrons through reduction, becoming FADH2

glycolysis

“cut sugar”, the process that has a net gain of 2 ATP (2 required, 4 produced), also produces pyruvate and NADH

citric acid cycle

starts with oxidizing CO2 (electrons lost), produces 2 ATP, 6 NADH, and 2 FADH2

oxidative phosphorylation

occurs in inner membrane of mitochondria, includes the electron transport chain and chemiosmosis

electron transport chain

aerobic, the final electron acceptor, oxidizes NADH and FADH2 and reduces O2, the transport of protons powers ATP synthesis

chemiosmosis

occurs right after electron transoprt chain, protons move down electromechanical gradient through ATP synthase, making ATP

cellular respiration

includes glycolysis, the citric acid cycle, the electron transport chain, and chemiosmosis, produces roughly 32 ATP

respiration chart/process

fermentation

recycles NAD+ and then uses it for the continuation of glycolysis and a small amount of ATP production, creates lactic acid in animals and ethanol in plants

what causes fermentation?

lack of O2 (anaerobic) causes the electron transport chain to back up, NADH and FADH2 can’t be recycled

what does photosystem 2 do and what happens in it

electron energized by light capture, chlorophyll donates electron to electron transport chain but regains electron from water, producing O2, produces 1 ATP

photosystem 1

second part of the light reaction, electron finally accepted by photosystem 1 chlorophyll, reduces NADP+ to NADPH,

what is the problem of light reactions

ATP and NADPH are used to synthesize carbs, and there needs to be more ATP than NADPH but they are produced in roughly equal quantities

what is the solution for the problem of light reactions

cyclic electron transport

cyclic electron transport

excited electrons from photosystem 1 are put back into electron transport train, only produces more ATP, not NADPH

what are the three parts of the Calvin cycle

1. fixation of CO2

2. reduction of 3PGA to G3P

3. regeneration of RuBP from G3P

what fixes (attaches) the CO2 to RuBP

BUBISCO

discribe the reduction state of the calvin cycle

ATP and NADPH are used to produce G3P, which can be used to generate things like glucose, sucrose, starch, cellulosede

describe the regeneration stage of the calvin cycle

6 G3P produced in reduction, 5 of them used to reform RuBP, for every one cycle, one CO2 is fixed and one acceptor regenerated

C3 photosynthesis

normal, fixed CO2 into three carbon compounds

C4 photosynthesis

fixes CO2 into a four carbon compound, increases efficiency of carbon delivery for fixation in hot environments

CAM photosynthesis

stores CO2 at night as a four carbon compound for use during the day, decreases water loss from open stomata during the day, common in dry environments

four stages of cell division

1. reproductive signal

2. DNA replication

3. DNA segregation

4. cytokinesis

how do prokaryotes divide? describe the signal, replication, and segregation

binary fission, produces identical cells

signal: beneficial environmental conditions

replication: begins at ori (origin) and ends at ter (terminus)

segregation: ori regions move apart through replication

describe the eukaryotic signal stage

cell divides only when growth will benefit the whole organism, cell cycle regulated by checkpoints

growth factors

external signals for cell division

what are cancer cells

cells that divide without a growth factor present, benign tumors divide but aren’t invasive and don’t spread, malignant tumors divide and spread to near and distant tissues, which is called metastasis

Henrietta Lacks

diagnosed with and died of cervical cancer, some of her cancer cells taken for research and are still dividing today, HeLa cells used for all kinds of research

describe segregation in eukaryotic cells

DNA is separate from the rest of the cell, so segregation and cytokinesis are separate events, two types of segregation: mitosis and meiosis

interphase

the majority of the cell cycle, period of ordinary cell metabolism and functions, DNA highly extended and possibly replicated if the cell is going to divide

mitosis

occurs after interphase, PMAT

prophase

chromosomes condense, 2 sister chromatids per chromosome, nuclear envelope disintegrates

metaphase

chromosomes align in middle at metaphase plate, spindle fibers form

anaphase

centromeres holding sister chromatids split and chromosomes are pulled apart

telophase

opposite of prophase, nuclear envelope forms, DNA decondenses

cytokinesis

follows mitosis, cleavage in animal cells, cell wall constructed through the middle of the cell

karyokinesis

mitosis and meiosis

diploid organisms

have 2 sets of every chromosome