exam 2 bio104

integral proteins

extend part-way or all the way through the plasma membrane

transmembrane proteins

type of integral protein that goes across the membrane, involved in transport.

types of membrane proteins

channel, carrier, cell recognition, receptor, enzymatic

channel protein

provide passageways for molecules

carrier protein

bind specific substances and change shape to transport them

cell recognition protein

glycoprotein that helps the body defend itself against pathogens

receptor protein

a protein that binds specific signal molecules, which causes the cell to respond

enzymatic protein

protein that catalyzes a specific reaction

explain why the cell membrane is considered a fluid structure

the phospholipid bilayer allows lipids and proteins to move laterally, giving it its flexible nature

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane

explain what occurs with high temperature in the fluid mosaic model

increased fluidity

explain what occurs with low temperature in the fluid mosaic model

decreased fluidity

cholesterol in fluid mosaic model

keeps membrane fluid by preventing tight packing at low temps and reducing excessive movement at high temps

passive transport

requires NO energy, movement of molecules from high to low concentration, moves with the concentration gradient

simple diffusion

molecules pass directly through the membrane without assistance

facilitated diffusion

molecules move across the membrane with help of carrier proteins

osmosis

diffusion of water through aquaporins or directly across the membrane.

hypertonic solution

water moves out of the cell causing it to shrink

hypotonic solution

water moves into the cell causing it to swell

isotonic cell

cell is stable, water movement is balanced

active transport

requires energy, moves substances against their concentration gradient

Na+/K+ pump

uses ATP to move 3 Na+ out and 2 K+ ions in the cell, gradient maintains resting membrane potential

cotransporters

uses an existing ion gradient (from active transport) to move another substance.

ex. Na+/glucose cotransporters in kidneys and small intestine - bring glucose into the cells

exocytosis

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

endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane

phagocytosis

type of endocytosis in which a cell "eats" large particles or whole cells

pinocytosis

type of endocytosis in which the cell "drinks" extracellular fluid and its dissolved solutes

kinetic energy

energy of motion

ex. running person

potential energy

stored energy

ex. battery

entropy

a measure of disorder where heat is generated

ex. ice melting into water due to molecules becoming disordered

first law of thermodynamics

energy cannot be created or destroyed, instead changed from one form to another

ex. turning on a lightbulb changes electrical energy -> light energy

second law of thermodyanmics

energy cannot be changed from one form to another without the loss of useable energy

ex. heat lost from a engine during combustion

ATP (adenosine triphosphate)

consists of adenine + ribose (sugar) + 3 phosphate groups

- ATP loses a phosphate to become ADP and releases energy

- ADP gains a phosphate to become ATP and stores energy

ATP in cellular work

ATP binds myosin head and 1 phosphate is broken, providing energy for muscle contraction, allows myosin head to reach up and connect with actin to make the contraction happen

exergonic reaction

break bonds between molecules and releases heat

ex. cellular respiration

endergonic reaction

bonds are made and energy stored in bonds (requires energy)

ex. photosynthesis

coupling

exergonic reactions (like ATP hydrolysis) drive endergonic reactions (like protein synthesis)

explain how enzymes lower the activation energy to speed up a reaction

enzymes lower activation energy, making reactions happen faster by stabilizing the transition state

enzyme reaction

enzymes bind specific substrates at the active site, forming the enzyme-substrate complex, which is then converted into the product

explain why enzymes are usually only specific to 1 substrate

specific to one substrate due to the shape of the active site

enzyme degradation

enzyme breaks down a molecule into smaller parts

enzyme synthesis

enzyme builds a larger molecule from smaller parts

factors that affect enzyme activity

substrate concentration: higher concentration increases activity to a certain point

temperature: too high=denatures enzyme

too low=slows enzyme activity

pH: extreme levels (basic/acidic) can denature enzyme

explain where the active site and non-competitive inhibition site are on an enzyme and how they work when bound by a molecule

active site: where substrate binds and undergoes chemical reaction

noncompetitive inhibition: inhibitor molecule binds enzyme somewhere other than the active site

explain enzyme co-factor

non-proteins needed for enzyme to work/catalyze a chemical reaction

ex. vitamins (iron, copper,zinc) and coenzymes (FAD, NAD+, NADP+)

explain why cellular respiration occurs without oxygen (anaerobic respiration)

without oxygen, fermentation is used to regenerate NAD+ for glycolysis - produces 2-4ATP

aerobic respiration (O2 needed)

1. glycolysis (cytoplasm): breakdown of glucose into 2 pyruvate

2. preparatory phase (mitochondria): 2 pyruvate -> 2 acetylCoa

3. Krebs cycle (mitochondria): generate electron carriers (NADH, FADH2, and ATP) - occurs twice per glucose

4. ETC + chemiosmois (mitochondria): electrons from NADH and FADH2 are used to create proton gradient which drives ATP production

chemiosmosis

a process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme.

energy carrier molecules

molecules that transport energy in the form of high-energy electrons

ex. ATP, NADH, FADH2

anaerobic respiration (fermentation)

occurs without oxygen and allows glycolysis to continue with NAD+

types of fermentation

alcohol: yeast cells - 2 ATP, 2 alcohol, 2CO2, 2ADP

lactic acid: animal cells - 2 ATP, 2 lactate, 2 ADP

explain why fermentation produces less ATP than aerobic

fermentation does not use Krebs cycle or ETC, where most ATP would be generated

anaerobic - 2-4 ATP

aerobic - 36-38 ATP

structure of neuron

synaptic terminals: transmit signals from other neurons

dendrites: receive signals from other neurons

cell body: integrates signals; coordinates neurons metabolic activities

axon: conducts the action potential

myelin sheath: speeds up signal transmission

Central Nervous System vs Peripheral Nervous System

CNS: Brain and spinal cord

PNS: nerves radiating out from spinal cord to rest of body - Somatic (controls voluntary muscle movement) and Autonomic (controls involuntary functions)

classes of neurons

sensory (afferent): respond to a stimulus, motor (efferent): activate muscles and glands to respond to stimuli, interneurons: process information and connect sensory and motor neurons.

membrane voltage (mV)

resting potential (-70mV) = Na+(outside) high and K+ (inside) high

threshold (-55mV) = Na+(outside) high and K+ (inside) high

action potenital (+35mV) = Na+ rushes in large and K+ (inside)

repolarization to resting (-70mV) = Na+ inside is pumped out and K+ exiting is pumped back in

resting potenial

transports 3 Na+ out, 2 K+ in, maintaining a negative charge inside.

K+ leak channels allow some K+ to move out, making inside more negative.

depolarization

voltage-gated Na+ channels open, causing Na+ to rush in and the inside to become more positive.

repolarization

Voltage-gated K+ channels open, K+ exits, making the inside negative again.

Na+ channels close to prevent more Na+ from entering.