bio 1

nucleus structure

surruonded by double membrane called envelope containing pores which enable molecules to enter and leave nucleus
also contians chromatin and nucleolus which is site of ribosome production

rough endoplasmic reticulum

series of flattened sacs enclosed by memrane with ribosomes on the surface
folds and processes proteins made on the ribosomes

smooth endoplasmic reticulum

system of membrane bound sacs
SER produces and processes lipids

golgi apparatus

series of fluid filled, flattened and curved sacs with vesicles surrounding edges
processes and packages proteins and lipids
also produces lysosomes

mitochondria

oval shaped, bound by double membrane called the envelope
inner membrane folded to form projections called cristae
with matrix on the inside containing all the enzymes needed for respiration

centrioles

hollow cylinders containing ring of microtubules arranged at right angles to each other
involved in cell division

ribosomes

composed of two sub units and site of protein production

lysosome

vesicle containing digestive enzymes bound by single membrane

cytoskeleton

plays important role in providing mechanical strength as well as aiding transport within cells and enabling cell movement

protein transport

proteins produced on ribosomes
proteins produced on surface of RER folded and processed in RER
proteins transported from RER to golgi apparatus in vesicles
modified in golgi apparatus
golgi apparatus packages proteins into vesicles to be transported around cells where theyrer required
some of proteins such as extracellular enzymes leave cell by exocytosis

prokaryotic cells

cell wall - rigid outer covering made of peptidoglycan
Capsule - protective slimy layer which helps cell to retain moisture and adhere to surfaces
Plasmid - circular piece of dna
flagellum - tail like structure which rotatse to move cell
Pili- hair like structurs attach to other bacterial cells
Ribosomes - site of protein production

magnificaiton

ratio of image size to object size
Image/object

resolution

ability to distinguish between two objects close together
to provide detail in image

light microscopes

1000-2000x magnication
50-200nm resolution
viewing cells nad tissues
cheap, easy to use but limited resolution

scanning electron microscopes

50k-500k magnificaiton
0.4-20nm resolution
viewiing surface of cells and orgenelles, prvoiding depth in 3d images

tranmission electron microscopes

300k-1000000k magnification
0.05-1nm resoluition
detailing organelle ultrastructure

why is better resolution good

worth magnifying image more as image wills how more detial

electron microscope disdavnatges

large, every expensive
trained operatives
sample dead since must be dried out
may affect shape of features seen(artefact)
image balck and hiwhite but colours aded later, false colour electorn microscopes

laser scannign confocal micrsocpes

1k-2k magnification
50-200nm reosliution
3d images with good depth selection
living things
can focus on specific depth so image not confuesd by other components that are not in focus
relies on computer to piece together infromation from dots of lgohtht created b ylaesr
so tis interpretation rather than real life image

staining is

application of coloured stains to the tissue or cells
makes objects visible in light microscopes
increases contrast so object can be seen more clearly
often specific to certian tissues or organelles

in electron microsocpes, stains heavy metals or similar atoms

protein synthesis process

mrna leaves nucleus via nuclear pores
used by ribosomes on rough endoplasmic reticulum to construct protein
travels in vesicle to golgi apparatus
vesicle moved by cytoskeleton, using tiny proton motors htat walk along microtubules

golgi apparatus modifies protein(adding carbohydrate group) and repackages it into vesicle

vesical moved to scell surface(plasma) membrane
vesicle fuses with emmbrane to relase protein from cell

hydrogen bonds basic

weak forces of attraction
between water molecules or between parts of a larger molucle

each water omlecule polar, so attraction between oxygen of one molecule and hydrogen of another molecule

uneven distribution of charge
oxygen atoms attract electrons more strongly than hydrogen atoms
so electrons in water molecule pulled towards oxygen atom, gives oxygen end of molecule a more negative charge

this is shown as delta negative
hydrogen end is left with delta positive

hydrogen bonds and properties of water

cohesion - between 0 and 100c, hold water molecules together loosely
held together but can move past one another and water remains liquid

to evaporate, hydrogen bonds must be broken - allowing molecules to separate and form water vapour gas
takes lot of energy,s o remains liquid up to 100


at lower temperatuers molecules have less kinetic energy and move about less - less mvoement, more hydrogen bonds can form and at 0 - enough hydrogen bonds formed to hold water molecules in stationary position, forming ice

water molecules now held in formation known as open lattice, holds molecules further apart - so ice floats less dense than water

thermal stability

high specific heat capacity so a lot of energy needed to warm it up
because a lot of energy required to overcome force of its hydrogen bond between molecules
so body of water maintains fairly constant temperature
allows aquatic organisms to use less energy on temperature control

human body mostly water, so changes internal temperature slowly, so body temperature remains stable, reducing variations in metabolic rate that would occur with temperature change, so functions able to work corerctly

allows gases to remain soluble in water

water properties freezing

ice less dense than water as it forms open lattice structure so it floats
forming insulating layer on water and preventing water below ice from freezing

so organisms beneath ice dont freeze and nutrients can still circulate
ice itself acts as habitat for organisms eg polar bears

evaporation water properties

water - high latent heat of vaporisation
so a lot of energy needed to cause liquid to change into gas, efficient mechanisms used to cool surface of living things, eg sweating

water porpeteris

at most temperatures liquid - can flow and transport materials in living thigns
cohesion - attraction to ech other, produces surafce tension, creates habitat on surface for invertebrates + continuous columns of water pulled up to xylem

transparent - allows aquatic plants to cary out underwater photosynthesis
high density - allows to support organisms and flotation
solvent - as the molecules polar, water can dissolve wide range of subtances, thus can transport substances around body

allows ionic compounds eg magnesium chloride to separte into charged ions, so dissolve in water
allows fish to take up ions from water - dilutes toxic substanes

reactant - eg hydrolosis and photosynthesis
incompressibility - can be pressureds and pumped in transport systems

where are hydrogen bonds also found

alpha helices and beta pleated sheets of secondary structure of protein, pprotein tertiary structure, haemoglobin, cellulose, between bases in DNA

3 groups of polymers

nucleic acids, polysaccharides, proteins

nucleotides made of

phosphate group
pentose sugar
organic base - adenine, cytosine, guanine, thymine, uracil
IN RNA - thymine replaced by uracil

polysaccharide examples

starch, cellulose
monomer - monosaccharides

how many amino acids

20

condensation reaction

2 molecules join to become one larger molecule via formation fo covlanet bond and relaese of water
can be broken again by hydrolisis

hydrolisis

molecules that were covalently bonded together split apart using molecule of water

carbohydrates description

made of carbon, oxygen, hydrogen
(CH2O)x
monosaccharides, disaccharides, polysaccharides

monosaccharides descitpion

single sugar units used as monomers to build other carbohydrates, soluble ans weet reducing sugars

glucoe - 6 carbons, only carbonm, hydrogen oxygen
alpha and beta glucose same formula but different structures

|

glucose - repsiratiory substrate to provide energy for formation of ATP

pentose sugars dewscription

pentose monosaccharides 5 carbons eg ribose, deoyxribose

hexose sugars description

hexose monosccharides - 6 carbons eg glucose

alpha and beta glucose differnec - position of -H and -OH groups on first carbon atom

disaccharides descirption

two monosccchardies bonded together by glycosidic(covalent) bond
soluble and sweet
most reducing sugars but sucrose not

formed by condensation reaction between two monosaccharides
most common between carbon 1 of one monosaccharide and carbon 4 of another

forms 1, 4 glycosidic bond and releases water

glucose + fructose —> sucrose, glucose and glocuse combined ot form maltose
glucose and galactose cmombine to form lactose
disaccharides can be converted back to monosaccharides by hydrolysis

polysaccharides description

large insoluble molecules of many monosaccharides joined via condensation reactions
3 examples - starch, cellulose and glycogen
starch - combination of amylose and amylopectin

amylose description

long unbranched chain of alpha glucose subunites joined by 1,4 glycosiding bonds\

all have same orientation

chain of subunits coils up

hydroxyl group on carbon 2 of each subunit hidden inside coil, makes molecules less soluble
important as it prevents amylose affecting water potental of cell it is within, so no effect on osmosis

amylose for storage of glucose subunits and energy in plant cells, sotored as grains within cell - molecule compact

glucose subuinits removed easily from each end of molecule, used as building blocks to build other substances or substrate in repsiration tor elease stored energy
hydrogen bonds broken with heat

When iodine-amylose complex heated to 60, hydrogen bondsw break, helix unravels, iddine released

amylopectin and glycogen description

similar to amylose since both long chains of identical alpha glucose subunits bonded by 1,4 glycosidic bonds

Some subunits also 1,6 glycosidic bonds
meaning both moleucles branched and non helical

each molecule consists of one chain with no cross links between ,molecues - atoms C H O

amyloepctin few brancehs
glyocgen for storage of glucose subunits and energy in animal cells
amylopectin same but in plant cells

glycogen - more 1,6 glycosidig bonds, more brancehed so places where enzymes attach
increases furace area so molecule can be hydrolysed more quickyl and easily

same advantages of amylose andamylopectin - insoluble(so not afecting water potential), and compact(therefore energy dense)
both storeed as granules not fibres, and have all glucose units in same orentiation

celluloise description

long unbranched chain of beta glucose subunits joined by 1,4 glycosiding bonds

beta glucose monomers alternate at 180 degress to each other
chain straight

hydroxl groups on carbo n 2 of each subunit exposed, allowing hydrogen bonds to form between adjacent cellulos molecules
60-70 molecules bind together to form cellulose microfibril and many microfibrils join together to form macrofibrils
so cellulose is fibrous


high tensile strenghts because of hydrogen bonds between adjacetn fibrils + completely insoluble
us

lipids basic description

not polymers
larrge grou pfof ocmpounds - triglycerides, phoshpolipids, steroids
insoluble in water, dont affect cell water potential therefore osmosis
droplest inside celll

lipids uses

thermal insulation
energy store
protect organs from mechanical damage
in membranes around cells to control exit and entry of molecules into cells
component of steroid hormones eg testosterone
buoyancy
waterproof prats of body ie skin
source of water vie respiration
electrical insulation around neurones

Aid apsorbiton, storage, production of fat-soluble vitamins A,D,E,K

triglyceride descrioption

macromolecule containing one glycerol molecule and 3 fatty acid chains
fatty acids attached to glycerol by condensation reaction
bonds called ester bonds, can be broken down by hydrolysis{

triglyceride properties

rich in energy, used to store excesse enrgy
can be broken down in aerobic repsiration to release this energy
water also released eg camels fat in humps
stores can be held under skina nad round major organs, protects major organs from pbhsycal shock

good insulators, used to insulate animals in cold envrironents eg whales, need buoyancy

saturated fatty acids description

fatty acids - logn chains of carbon atoms with hydrogen atoms bonded to them

if each carbon has 2 h atoms, no double or triple bonds, meaning saturated
found in animal fats - higher melting point and more solid at room tempreature
when eaten, case increase in low density lipoproteins, bad cholestroel
mycoprotein less lipid than meat from animals and more unsatured, so less increase in LDLS

unsatured fatty acdi descrpitpin

fewer hydrogen atoms, double or even triple bonds between adjacent acrbon atoms

unsaturated fatty acid -lower reatio of hydrogen atoms attached due to double or tirpple bonds
unsaturated fatty acids found in plant fats and oils, lower melting points and more likely to be liquid at room tempertaure eg vegtable oil

phospholids descrioptoin

similar to triglycerides, buyt one fatty acid chain replaced by phosphate groupo

two remaining fatty acid “tails” insoluble in water and hydrophobic
phsophate group includse choline, which is water soluble - alter characteristics of molecule
this group makes head end of phospholipid able to mix with water - hydrophilic

pohhospholipids property

form bilayers with hydrophobic tails in centre and hydrophilic heads pointing outwards to intreract with surrounding aqueous solution
this is basis of all cell membranes
middle of bilyar hydrophobic, difficult for polar molecules to pass through

amino acids

proteins made up of amino acids, 20 different
all same basic structure
Residual R group only one that differs

proteins description

polymers of long, unbranched chains of amino acidsm held together by peptide bonds
formed by condensation and occur between amine group of one amino acid and carboxylic acid group of another

4 types - enzymes, antibodies, transport, structural
2 amino acids - dipeptide
many - polypeptide

4 levels of protein structure

primary - sequence of amino acids, held together by peptide bonds
occuir between amine group of one amino acid and carboxyl of another
H from amine combines with OH from carboxyl in condensation reaction, molecule of water being produced

secondary structure of protein

formed when chain of amino acids foilded and coiled into regions with repeating patterns
alpha - helix
beta - sheets
hydrogen bonds hold folds and coils in place

tertiary structure of protein

formed when coiled and pleated chains folded further to produce final 3d shape of molecule
final folds and coils caused by interactions between R groups on amino acids
some R groups tatrcat or repel each other so interact to form range of bonds that hold 3 dimensional shape

bonds include hydrogen between polar R groups, ionic between R witih oppostite charges, covalent disulfite bonds between 2 sulfur containing r groups

additionally some R groups hydrophibic and twist away from water into centre of molecule
others hydrophilic and twist outwards so outside of molecule and can interact with water

quaternary structure

many proteins one polypeptide chain coiled and folde
but some consits of more than one polypeptdie chain - haemoglobin 4, collagen 3
multi subunit proteins make up quaternary structure

hameoglobin description

used to transport oxygen in oxyhaemoglobin
haeomoglobin cotnains 4 polypeptide chains called subuinits - 2 alpha, two beta

hamoglobin conjugated protein since each subunit has non protein prosthetic grup attached caled haem group - single iron ion(fe2+)
one oxygen molecule ca attach to each haem group, so haemolgobinmolecule can carry 4 oxygen molecules

talk about all 4 leves of structure

enzymes description

amylase
hydrolysses the bonds between glucose subunits in amylose
molecule has regions coiled in alpha helix and other foleded into beta sheets

compact globular shape contains active site that has specific and complemetnary to shape of substrate
active site holds at least one calcium ion acts as cofactor - essential for correct action of enzyme