the polymer interacts with phospholipid head, then the phospholipid "flip flops" carrying the RNA inside the vessicle

RNA can 

1. store info

2. self replicate

3. have enzymatic function (ribozymes) 

neither DNA nor proteins have all 3 functions 

1. one of the RNA molecule mutates and has the enzymatic ability to attach nucleotides together to make new RNA from pre-existing RNA (advantage of faster replication) 

2. second mutation produces enzymatic ability to synthesize nucleotides (no reliance on prebiotic synthesis) 

B & S synthesized 10^15 RNA molecules (long) 

each RNA containing a constant (same in all) region and variable region

also made short RNAs complementary to part of long RNA; short RNAs had a tag which allowed them to bind to beads

if long RNAs mutated and obtained enzymatic activity, the long RNA would be held to the short RNA bound to the bead 

repeat. results: enzymatic ability of pool 10 3 million times higher than random pool

* basically short RNAs would H bond to long RNAs, but eventually long RNAs would fall off with "wash" unless phosphodiester bonds began to form. so this experiment selects for the most efficient maker of phosphodiester bonds (so most catalytic activity --> ribozymes) 

bottom line: chemical selection improves the functional characteristics of a group of RNA molecules over time by increasing the proportions of those molecules with enhanced function 

DNA good for info storage: DNA relieves RNA of informational role and allows RNA to do other functions, and DNA is more stable (less likely to suffer mutations) 

proteins have a greater catalytic potential and efficiency and proteins can before other tasks like stability (cytoskeleton) and transport

1. in situ hybridization

2. microarray

3. RT-PCR

4. northern blot

1. antibody staining

2. enzymatic activity (limited)

3. Western blot

4. protein microarray

a gap junction in animals

there are six connexin proteins in one cell, and they align with six connexin proteins in an adjacent cell

allows passage of ions and small molecules; also allows adjacent cell to share metabolites and directly signal each other

group of cells having a similar structure or function

humans have over 200 different cell types that are grouped into a few general categories

1. dermal tissue

2. ground tissue

3. vascular tissue

animals contain muslce and nervous tissue- plants do not

vascular tissues are very different

may be replaced by periderm with age (bark)

although it is tightly woven together in layers

injestion (food is consumed)

digestion (nutrients are broken down into smaller molecules)

absorbtion (ions, water, and small molecules diffuse or are transported out of the digestive canal into the body fluids)

elimination (undigested waste products are excreted)

carbs, proteins, lipids, nucleic acids, vitamins

water and minerals

energuy source, part of some proteins, source of carbon

muscle weakness, weight loss, ketone formation (decreasing blood pH)

provide amino acids to make proteins and muscle

weight loss, muscle loss, weakness, weakened immune system

major component of cell membrances, energy source, thermal insulator, building blocks of some hormones

hair loss, dry skin, weight loss, hormonal and reproductive disorders

provides sugars, bases, and phosphates that can be used to make DNA, RNA, and ATP

none (your cells can synthesize components of nucleic acids from amino acids and sugars)

8 essential acids (lsoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine)

are not stored; if you eat some meat, you should be fine, but most plants do not contain every essential amino acid in sufficient quality)

polyunsaturated fatty acids

cannot be synthesized by animal cells

example: linoleic acid (vital precursor to arachidonic)

they are found primarily in plants

strict carnivores obtain them from fish or adipose tissue of birds and mammals

serve as coenzymes

water soluble (not stored- like vitamin C)

fat soluble (stored in fat- like vitamin A)

no, not all animals require the same vitamins

inorganic ions

some can be stored

many are required in only trace amounts

includes carnivores, herbivores, and omnivores

they eat food in large pieces

carnivores can be divided into predators and scavengers (and generally do not chew their food)

herbivores are highly adapted for chewing

lick or suck fluid from plants or animals

do not need teeth except perhaps to puncture an animal's skin

evolved independently in many types of animals

only in some very simple invertibrates (sponges and some single celled organisms)

uses phagocytosis to bring food particules directly into a cell

cannot meet metabolic demands of active animal for long, because there is no mechanism for storing food

simple extracellular digestion

one opening is the entry and the other the exit

allows for digestion and distribution of nutrients

food particules are eventually phagocytosed

alimentary canal/GI tract

accesory structures, like tongue, teeth, salivary glands, liver, gallbladder and pancreas

some fish lack a stomach

birds lack a gallbladder

moistens and lubricates food to facilitate swallowing

dissolves food particales to facilitate taste

kills ingested bacteria

initiates digestion of polysaccharides with amylase (not very important)

how does the pharynx and esophagus aid in digestion and absorbtion?

is it voluntary or involuntary?

it doesn't! (its only a pathway to the stomach)

swallowing begins in the esophagus voluntarily; action continues by involuntary peristalsis

hydrochloric acid- kills microbes, dissolves particulate matter

pepsinogen (is a zymogen): is converted to pepsin to begin protein digestion

herbivores must digest cellulose but lack cellulase

rely on microbes to digest cellulose into monosaccharides

because its specialized for increased surface area; the mucosa is folded, and the fingerlike projections of villi are covered by microvilli

increases surface area 600 fold, that increases the likelihood of encountering digestive enzyme and being absorbed

capillary (where nutrients other than fat are absorbed into the blood) and lacteal (lymphatic) vessel (allows for larger fat particles to enter, eventually dumped into blood)

the epithelial cells transport food molecules from the lumen to the capillaries and lacteals

paneth cell- secrets antibacterial peptides

enteroendocrine cell- produces hormones to control gastrointestinal secretions or motility

mucous cell- secrets mucous

columnar cell- immature absorptive cell

enterocyte cell- absorptive cell

they only live 2-3 days

crypt contains stem cells

herbivores! need much longer time to digest plant material

even within an individual animal, the length of the small intestine can change (can grow to increase surface area)

secretes digestive enzymes (in form of zymogens) and bicarbonate ion rich fluid

zygomen is an inactive enzyme precursor which usually involves a hydrolysis reaction for activity

bicarbonate neutralizes acidic stomach chyme as it enters the small intestine

bile:

what makes it?

what does it do?

where is it stored?

made by the liver

stored in the gallbladder

contains bicarbonate ions (which neutralize acids), bile aslts (solubilize fat)

in the mouth, there is starch digestion by salivary amilase

there is additional starch digestion by pancreatic amylase that takes place in the small intestine then

the monosaccharides are transported across intestinal epithelium into the blood

nutrients cannot just go in between the epithelial cells of the small intestine into the blood stream because there are tight junctions there, so they have to undergo facilitated diffusion or secondary active transport

facilitated diffusion: fructose

secondary active transport: both glucose and galactose (co-ported with sodium Na+)

lactose is a sugar that is present in all milk that is broken down lactase

90% of the world's population can't fully digest lactose after early childhood

the ability to digest lactose though is linked to genetic background

this is because is Neolithic times, adults that could digest lactose had a selective advantge

in lactose tolerant individuals, there is a single nucleotide change in the regulatory region of the lactase gene

pepsin in the stomach

also, your pancreas secretes trypsin and chymotripsin in their inactive forms, but then they are activated in the small intestine, which completes the digestion to amino acids

these amino acids are then transported into the intestinal cells and into the blood stream

* entirely digested in the small intestine, by pancreatic lipase, breaks down into triglycerides

phospholipids and bile salts help by emulsifying fat into small droplets with increased surface area for digestion

-bile salts additionally form micellese allowing lipids to diffuse into intestinal cells

once inside the epithelial cell, the fatty acids and monoglycerides reform triglycerides on the smooth ER, they get surrounded by proteins and then is aggregated into something called a chylomicrons capable of entering the lacteal via exocytosis (remember, its the lymph vessel that every epithelial cell has and that fat can go in to get into blood circulation)

nope! they are absorbed in their complete form;

the fat soluble vitamins actually follow the pathway for fat absorbtion

small amounts of water are absorbed in the stomach, but mostly in the small intestine (and a tiny bit in the large intestine)

cells in your stomach produce gastrin because of gastric distention, which both stimulates secretion of gastric acid (HCl) by the parietal cells of your stomach and enters the blood stream

also, CCK is synthesized and secreted by the small intestine and it causes the release of digestive enzymes and bile from the pancreas and gallbladder, respectively

secretin is produced by the small intestine, and controls secretions into the duodenum and water homeostasis

erosion of the alimentary canal (most commonly in the stomach, esophagis, and small intestine)

helicobacter pylori is a caustive agent

cholera caused by Vibrio cholerae from injesting contaminated food or water

chief concern is loss of nutrients and water and ensuing dehydration

the neuron is the fundamental building block and signaling unit of the brain

information travels within a neuron using action potentials (the ionic hypothesis)

information travels between neurons using neurotransmitters

1. the neuron is the fundamental structural and functional unit of the brain

2. the dendrites connect with the axon at a synapse

3. neurons connect with some neurons, but not others- this connection specificity allows neural circuits to be formed

4. information travels only in one direction in a neuron

sensory neurons, motor neurons, interneurons

each class is functionally and biochemically distinct- as such each class is subject to specific disease states

sensory- syphilis

motor- Parkinson's

interneuron- ALS

multiple sclerosis- axons

Gaucher's- cell bodies

fragile X- dendrites

botulism toxin- synapses

hydrolyses proteins

produced in the pancreas as the inactive trypsinogen

1. Na+/K+ ATPase (sodium-potassium pump)

2. ion specific channels allow passive movement of ions

3. negatively charged molecules such as proteins are more abundant inside the cell

there are more ungated K+ channels than ungated Na_ channels

the membrane is more permeable to K+ at rest

depolarization: cell membrane is less polarized, less negative relative to surrounding solution (ex: going from -70 mV to -55 mV)

hyperpolarization: cell membrane is more polarized, more negative (ex: going from -70 mV to -75 mV)

1. synaptic or graded potentials

2. action potentials

depolarization or hyperpolarization

varies depending on the strength of the stimulus

occurs locally on dendrites or cell body

spread a short distance and dies out

acts as triggers for action potential

carry electrical signal along an axon

always the large same amplitude depolarization

all or none- cannot be graded

actively propagated- regenerated itself as it travels

the spike overshoots 0 mV to +30 mV suggesting selective ion transport

--> so they hypothesized the existange of voltage gated ion channels

upstroke: manipulated by changing Na+

downstroke: manipulated by changing K+

the Na+ gate is open, the K+ gate is closed

sodium enters the cytosol

sodium channel is inactivated; potassium channel is open

potassium flows out of the cytosol

the sodium channel is closed, the potassium channel is open

potassium is flowing out of the cytosol

Na+ and K+ voltage gated channels move their respective ions in opposite directions across the membrane

the K+ voltage gated channel is 1 millisecond slower to open than the Na+ voltage gated channel

an action potential reaches the pre-synaptic region; this triggers Ca++ channels to open; 

Ca++ causes neurotransmitter filled vsicles to fuse with the plasma membrane, releasing their contents

neurotransmitters bind to the post-synaptic receptios, triggering graded potentials which may or may not trigger a new action potential

either ionotropic, where the pore opens when the neurotransmitter binds

or, metabotropic, where the neurotransmitted binding causes signaling beginning with the G protein binding site

during short term memory, there is a single pulse of serotonin that enhances glutamate release between sensory and motor neurons

during long term memory, there are multiple pulses of serotonin that lead to growth of new synapses in addition to more glutamate release

lead to growth of new synapses, in addition to more glutamate release

increases cAMP levels, causing kinases to move into the nucleus where they phosphorolate the transcription factor CREB

this phosphorylated CREB turns on the genes required for building new synapses

short term: temporary change in the amount of neurotransmitter release

long term: more permanent change in amount of neurotransmitter release due to structural changes in the size or number of synapses; requires protein expression for these changes

it recognize stimulus and initiates signal transduction by creating graded potentials in itself or adjacent cell

when the response is strong enough, an action potential is sent to the CNS

the amount of depolarization is directly related to the intensity of the stimulus

membrane potential = receptor potential

when a stimulus is strong enough, it will depolarize the membrane to the threshold potential at the axon hillock and produce an action potential in a sensory neuron

strength of the stimulus is indicated by the frequency of action potential generated

a stonger stimulus generates more action potentials in a shorter amount of time

brain interprets higher frequency of action potentials as a more intense stimulus

it opens ion channels in sensory receptors, which depolarize the membrane and produce a graded response

this graded response may produce few or many action potentials in the sensory receptor

mechanoreceptors (transduce mechnanical energy)

thermoreceptors (respond to cold and heat)

nocireceptors (pain receptors, responding to extreme heat, cold, pressure, and certain molecules such as acids)

electromagnetic receptors (detect radiation within a wide range of the EM spectrum; includes photoreceptors, which respond to visible light energy)

chemoreceptors (respond to specific chemicals)

what happens if you physically touch or deform a mechanoreceptor cell?

what kinds of cells can be mechanoreceptors?

it opens ion channels in the plasma membrane

neurons or specialized epithelial cells

they are commonly found in the walls of organs that can be distended

stretching deforms them and they depolarize

sends action potential to the brain

eg. stretching in stomach is interepreted as fullness

specialized epithelial cells

(also deformable stereocilia can resemble hairs)

ion channels open or close when cilia bend; this changes membrane potential

found in the ear and equilibrium organs, body surface of fish, and some amphibians

audtition: ability to detet and interpret sound waves

short wavelengths are high frequency = percieved as high pitch/tone

long wavelengths are lower frequency = percieved as low pitch/tone

1. outer ear: pinna and auditory canal

2. middle ear: ossicles connect eardrum to oval window

3. inner ear: chochlea and vestibular system

sound waves enter the outer ear

tympanic membrane virbates back and forth

ossicles transfer vibration to oval window

sends pressure waves through the cochlea

waves travel from vestibular canal to tympanic canal and dissipate against round window

sounds we hear pass through basilar membrane, making it vibrate

hairs bending in one direction sends an action potential

bending in the other direction shuts off the neurotransmitter release

located in the inner ear next to the cochlea

utricle and saccule detect linear movements of the head

semicircular canals detect motion in 3 dimensions

-when the head moves, fluid in the canal shifts in the opposite direction, pushing on cupula and bending hair cells

each canal is oriented in one of 3 planes

respond to either hot or cold temperatures directly or by being acted upon by activating or inhibiting enzymes within their plasma membrances

can be hot or cold thermoreceptors (both are free neuronal endings)

thermoreceptors in the brain detect core body temperature

activation of receptors can cause physiological and/or behavioral adjustments to maintain body temperature

free neuronal endings in skin and internal organs that respond to tissue damage or to stimuli about to cause tissue damage

nocireceptors can also respond to external stimuli like extreme temperatures and internal stimuli like molecules released from injured cells

fish can detect electrical signals from other fish

platypus bill detects electrical currents from prey

homing pigeons use magnetite to navigate home

pit vipers sense heat from prey as infrared radiation

photoreceptors!

(a photon is a fundamental unit of EM raditation with the properties of both a particle and a wave)

a flatworm that has a simple visual organ, which is an eyecup containing endings of photoreceptor cells; it detects presence or absence of light

although there is a layer of pigment that shields one side so can detect direction of light, it does not form vidual images

found in some vertebrates, mollusks, snails

light is transmitted through the pupil to the retina at the back of the eye; photoreceptors trigger electrcal changes in neurons

anterior holds the aqueous humor

posterior holds thick vitreous humor (maintains eye shape)

the adjusting of the lens by the ciliary muscles

(cornea and the lens bend incoming light)

the small area of retina directly behind the lens with numerous photoreceptors for color

responsible for sharpness of daylight vision

rods are sensitive to low intensity light, do not discriminate colors, used mostly at night

cones require more light for stimulation, detect color, fewer cones than rods

the outer segment contains pigment

the inner segment (middle) contains nucleus and other organelles

synaptic terminal with neurotransmitter filled vessicles (NO AXONS)

2 compounds bonded together

retinal and opsin

retinal plus 1 of 3 possible opsin proteins

each type of opsin determines wavelength absorbed, responds to either red, green, or blue light

you can have mutations in genes producing cone pigments, resulting in problems

red green color blindness is the most common and predominantly in men

they lack or have abnormal red or green cone pigments

red and green opsin genes located on X chromosome (blue on an autosome)

support, protection, and locomotion

hydrostatic, exoskeleton, and endoskeleton

what is a hydrostatic skeleton?

give an example of some animals that have hydrostatic skeletons?

a combination of muscles and water-based fluid (works because water is nearly incompressible); hydrostatic pressure is used to move the body

cnidarians (their bodies and tentacles can elongate or shorten)

an external skeleton surrounding and protecting the body

varies in complexity, thickness, and durability

anthropods: made of chitin, segmented for movement, must be shed to grow

internal structures

they don't protect the body surface, only internal organs and other structures, but minerals give firmness

spnges, echinoderms, and vertebrates

where two or more bones come together?

fused joints (not used for movement)

pivot joints (allow for rotational movement, like a vertebra)

hinge joints (allow movement in one plane, like your arm)

ball-and-socket joints (allow movement in several planes, like your femur into your pelvis)

nope, its living dynamic tissue

organic components: osteoblasts that form bone, and osteoclasts that break down bone and collagen (for strength and flexibility)

mineral components: Ca 2+, PO4-, and other ions

cardiac, smooth, and skeletal

structure, function, and control

muscle is a grouping of cells (muscle fibers) bound together by connective tissue

tendons link bones to skeletal muscle

skeletal muscle fibers increase in size during growth but few new fibers are formed

thick: myosin

thin: actin and other proteins

the sarcomeres shorten as thin filaments slide past stationary thick filaments

myosin cross bridges attach to think filament and force thin filament towards the center of sarcomere

cross bridge repeats motion as long as stimulation to contract continues

junction of motor neuron's axon and muscle fiber

axon divides into terminals containing vesciles of acetylcholine

region of muscle fiber under axon terminal is folded into junctional folds to increase surface area

ACh receptor is ligand gated ion channel

Na+ flows into muscle cell leading to depolarization and an action potential