biology alevel core concepts

Atom

Smallest unit of an element that retains all chemical properties ,has a nucleus containing protons and neutrons with electrons orbiting

Water formation

It has a negative oxygen and a positive hydrogens therefore it is polar and can form hydrogen bonds

High specific heat capacity in water

Large amount of energy is needed to raise the water temperature which prevents large fluctuations in water to keep aquatic habitats stable

High latent heat of vaporisation in water

Lots of energy needed for it it turn to gas needed for temperature control for body cooling

molecule

2 or more atoms held together by covalent bonds

element

pure substance made of one type of atom

compound

substance formed from two or more different elements chemically bonded together.

organic

molecules containing carbon and other elements, typically associated with living organisms.

inorganic

a charged atom or group of atoms that does not contain carbon

magnesium

component of chloropyll needed for photosynthesis

iron

component of haemoglobin and myoglobin enabling oxygen transport and storage

phosphate

components of DNA ,RNA, ATP, phospholipids needed for genetic information, energy transfer and cellular membranes.

calcium

important for bone structure and teet

Cohesion in water

The attraction of water molecules for each other because of the dipole structure of water producing hydrogen bonds between them

High surface tension in water

Cohesion between water molecules produces surface tension

High density in water

Ice is less dense than water as the hydrogen bonds holds then further apart than in liquid therefore ice can float and acts as an insulator

Water is transparent

Allows light to pass through for plants to synthesise

Monosaccharide

An individual sugar molecule

Disaccharide

2 monosaccharides combined via a glycosidic bond

Isomers

Molecules that have the same chemical formula but a different arrangement

Alpha glucose

OH group is on the bottom of carbon 1

Beta glucose

OH group is on the top of carbon 1

Monosaccharides functions

-source of energy in respiration

-building blocks for larger molecules

-intermediate in reactions

-constituents of nucleotides

Disaccharide components

Glucose+glucose= maltose (germinating seeds)

Glucose + fructose =sucrose(transport in phloem of flowering plants)

Glucose + galactose = lactose(mammalian milk)

Reducing sugars (glucose)

Add Benedict’s solution and heat if positive = blue to green to yellow to orange to brick red precipitate negative = blue

Starch

Add iodine positive= blue/black negative = yellow

Non reducing sugar(sucrose)

Add HCl to hydrolyse glycosidic bond and then neutralise with sodium hydrogen carbonate then add Benedict’s solution and then heat positive= brick red precipitate negative = blue

Protein

Add biuret solution and shake gently positive = purple negative = blue

Lipid

Add ethanol then 1:1 with water and shake vigorously positive = cloudy white emulsion negative = colourless

Starch(amylose)

1-4 alpha glucose, helical, stored in plants for respiration, Insoluble and no osmotic effect on cells

Starch(amylopectin)

1-6 and 1-4 alpha glucose,branched, stored in plants for respiration, in soluble and no osmotic effect on cells

Glycogen

1-4 alpha glucose ,branched ,long chains of C6H12O6 ,insoluble can be broken at the end for respiration

Cellulose

Beta glucose, fibrous chains, parallel chains, hydrogen bonds , C6H12O6 rotates 180° ,strong support for cell wall prevents from bursting when it is turgid

Chitin

Beta glucose , acetyleamin , unbranch polymer waterproof lightweight

Elements of lipids

Carbon,hydrogen,oxygen

Lipid solubility

Leopards are non polar therefore they have no charge to bond with water but they combine with proteins as a Lipoprotein in the blood plasma

Functions of lipids

-Energy source and storage

-protection

-oxidation

-membranes

-waterproofing

-insulation

-hormones

Bonded via 3 ester bonds

Factors contributing to heart disease

Diet high in saturated fats, smoking ,lack of exercise, aging

Low density lipoprotein

Diet high in saturated fats which builds up causing an atheroma that can form in the coronary arteries which restricts blood flow to the heart muscle therefore less oxygen and glucose is delivered to cardiac muscles which can result in the vessels getting blocked therefore causes a heart attack

High density lipoprotein

Diet high in unsaturated fats that carry unsaturated fats so liver for breakdown therefore a lower risk of cardiovascular and coronary heart disease a.k.a. high cholesterol

structures of a protein

Primary ,Secondary ,tertiary,quaternary

Primary structure of a protein

The sequence of amino acids in a polypeptide chain (peptide bond)

Secondary structure of a protein

The folding of the potty peptide chain into a alpha helix or a beta pleated sheet(hydrogen bonds)

Tertiary structure of a protein

The folding of a polypeptide chain into a 3-D globular shape

Quaternary structure of a protein

Two or more polypeptide chains bonded together(disulphide,ionic, Hydrophilic and hydrophobic interactions)

Dispirited is bonded via a peptide bond

Globular proteins

Water soluble, transports proteins, haemoglobin

Fibrous proteins

Water insoluble ,structural proteins, collagen

Hydrolysis

Water is added to break the glycosidic bond

Condensation

Water is removed to create a glycosidic bond

Induced fit

Substrate collide with the active site, active site changes shape to fit the substrate and enzyme substrate complex is formed change in the enzyme shaped places a strain on the substrate lowering the activation ,energy active site returns to original shape after reaction ,product is released

Lock and key

Enzyme have a specific shape active site which is complimentary to the shape of the substrate and enzyme substrate complex is formed. Product is released active site does not change shape.

Activation energy

Energy required to enable a reaction to occur

Denature

When the enzymes active site has changed, therefore it would be unable to catalyse the reaction

Catalyst

They speed up chemical reactions without being used up during the reactions

Factors that effect the rate of enzymes

Temperature,pH,concentration

Competitive inhibitors

Binds to the active site similar shape complementary to the active site therefore prevents binding ,reversible

Non competitive inhibitors

Binds to the allosteric site site away from active site changes the active site active site is no longer complementary to substrate ,irreversible

Immobilised enzyme

When an enzyme is fixed, bound or trapped in an inert matrix

3 ways Enzymes can be immobilised

Alignant , gel membrane,polythene

Why immobilise the enzyme?

Stabilise the enzyme molecules and they have a wider range of optimum pH and temperature. It is less affected by temperature and pH changes.

Advantages of using immobilised enzymes

They can be recovered and reused ,can control the rate ,cheaper

Nucleus

Contains DNA which codes for protein synthesis

Nucleolus

Synthesis of RNA and ribosomes

Nuclear pore

Allows the transport of mRNA out of nucleus

Nuclear envelope

Separates DNA from cytoplasm

Cell membrane

Allows what enters and exits the cells through a selectively permeable membrane

Cytoplasm

Site of cellular reactions

Mitochondria

Site of aerobic respiration which synthesises for ATP

Rough endoplasmic reticulum

Transport proteins

Soft endoplasmic reticulum

Synthesises and transports lipids

Golgi body

Chemically modifies proteins produces lysosomes and glycoproteins packages proteins for secretion out of the cell

centrioles

Spindle formation in cell division

ribosomes

Protein synthesis

Lysosome

Contains an isolates hydrolyte enzymes release these enzymes and destroy organelles

Vesicles

Maintained osmotic pressure

Permanent vacuole

Storage of ions In plants

Chloroplast

Site of photosynthesis

Cell wall

Provides strength and support

Plasmodesmata

Exchange of large organic materials via cytoplasmic streaming allows communication between adjacent cells

Calculating magnification

Image size=actual image size*magnification

mm→um

x1000

Prokaryotic

They are small no organelles their DNA is free in the cytoplasm ,no nuclear envelope ,plasmid may be present. They have a cell wall ,chloroplast ,no mitochondria but may use mesa home for aerobic respiration are only present in some ,70s ribosome free in cytoplasm

Eukaryotic

Large organelles are membrane bound ,DNA combined with protein in chromosomes. The nuclear envelope is double membrane ,no plasmids ,cell wall in cellulose plants and chitin ,chloroplasts in plants ,has mitochondria ,no mesosome, 80s ribosomes free in cytoplasm or attached to the endoplasmic Reticulum.

Squares

Lining tissue covers surface of organs, thin layer of cells for exchange walls of alveoli, blood vessels lining of renal capsule of the nephron

Cuboidal

Secretion and reabsorption ,kidney tubules Glandular ducts

Columnar

Microvilli to increase surface area for absorption found in small intestine

Ciliated columnar

Syria waft to remove dust and dirt out of air passage found in trachea bronchi fallopian tubes

Glandular

Secrete enzymes, hormones, saliva, mucus found in saliva gland pancreas gastric glands in stomach mucosa

Skeletal muscle

Skeletal movements maintains posture and body position support soft tissue found in attached to bone by tendons generates locomotion in mammals

Smooth muscle

Rhythmical involuntary contraction but less powerful than skeletal muscle ,walls of hollow organs ,walls of digestive track ,wall of respiratory tract ,walls of blood vessels ,bladder ,skin

Cardiac muscle

Rhythmic contraction to pump blood to the heart found in the heart

Phospholipid bilayer

Hydrophilic head (Nonpolar )and hydrophobic tail (polar)

Function of the phospholipid bilayer

Diffusion lipid soluble substances can dissolve in the lipids, nonpolar molecules can pass through the phospholipid bilayer ,however polar molecules cannot easily pass through unless they are very smaller water through the aquaporens

Plasma membrane-Rolls within the cells

they separate cell components from cytoplasm (compartmentalisation) ,holding the components of metabolic pathway in place

plasma membrane -roles at surface of cells

Separate cell contents from the outside environment ,cell recognition and signalling ,regulating transport of materials into or out of cells

Fluid mosaic model

Phospholipid and proteins move around each other proteins are scattered within the phospholipid and do not form a continuous layer.

Osmosis

The net movement of water from an area of high water potential to an area of low water potential through a partially permeable membrane

Water potential of cells

Water potential = solid potential of the cytoplasm+ Pressure potential( water moves to the more negative side)