bio paper 1

Light microscope

Uses light to magnify, due to wavelength of light it is limited to x1500 magnification and max 200nm resolution

Transmisson electron microscope

Electron microscope which creates a 2D image, specimens are dead, max magnification is over x500,000 and max 0.5nm resolution

Scanning electron microscope

Electron microscope which produces a 3D image, specimens are dead, max magnification is over x500,000 and max 3-10nm resolution

Eukaryote

A cell that contains a nucleus and membrane bound organelles

Prokaryote

A cell that does not have a nucleus or membrane bound organelles

Metabolism

All of the chemical reactions that occur within an organism

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement

Components of the cytoskeleton

Microfilaments, microtubules, intermediate filaments

Histones

Proteins which DNA coils around to form chromatin

Chromosomes

Chromatin condenses and coils to form _____; there are 46 in humans (23 pairs)

Nucleolus

Area in the nucleus which produces ribosomes

Double membrane organelles

Nucleus, mitochondria, chloroplast(, endoplasmic reticulum, golgi apparatus)

Vesicle

Membrane-bound sac that functions in moving products in, out, and within a cell

Lysosome

A vesicle with (hydrolytic) digestive enzymes in it

Centriole

Involved in assembly and organisation of spindle fibres in cell division

Smooth Endoplasmic Reticulum/SER

Synthesis of lipids

Rough Endoplasmic Reticulum/RER

Processes and transports proteins made at attached ribosomes

Golgi apparatus

Modifies, sorts, and packages (into vesicles) proteins from the rough endoplasmic reticulum

Cell wall

Strong, supporting layer around the cell membrane in some cells; cellulose in plants; chitin in fungus; peptidoglycan in prokaryotes

Tonoplast

The membrane surrounding the permanent vacuole in plants

Granum

Stack of thylakoids inside a chloroplast, containing chlorophyll for photosynthesis

Flagella, cilia

Provide locomotion or move substances over the outer surface of the cell, form from cytoskeleton (microtubules)

Pili

Appendages that allow prokaryotes to attach to each other and to transfer DNA (plasmids)

Amount of bonds for basic elements

Carbon can have 4 bonds; Nitrogen can have 3 bonds; Oxygen can have 2 bonds; Hydrogen can have 1 bond

Cohesion and adhesion

Hydrogen bonds in water causes them to stick to each other and also other things

Glycosidic bond

Covalent bond between carbohydrates formed by condensation

Starch

Made of alpha glucose, in plants, amylose and amylopectin

Glycogen

Made of alpha glucose, in animals, more branched than amylopectin

Cellulose

Made of alternating beta glucose straight chains, each chain is joined together with intermolecular hydrogen bonds

Benedict's test

Turns from blue to brick red in the presence of a reducing sugar, warmed; if non reducing sugar, boiling with acid will break the bonds and make it reducing and then you can do the original test

Iodine

Turns from yellow-brown to blue-black in the presence of starch

Triglycerides

Made up of a single molecule of glycerol and three molecules of fatty acid by ester bond; used for energy storage, protection and insulation

Saturated fatty acid

No carbon-carbon double bonds in the chain

Unsaturated fatty acid

One or more carbon-carbon double bonds in the chain, causing "kinks" in the chain

Phospholipid

A lipid consisting of a glycerol bound to two fatty acids and a phosphate group; phosphate head is hydrophilic while the fatty acid tails are hydrophobic

Sterols

Contain a four-ring carbon structure and an OH- tail

Cholesterol

A sterol which regulates the fluidity of cell surface membranes

Emulsion test

Test for lipids; Mix your sample with ethanol, then add water, if a white cloudy emulsion forms then a lipid is present

Amino acids

Organic compound containing a carboxyl (—COOH), a Hydrogen, an amino (—NH2) and a variable R group; monomer of proteins

Peptide bond

Bond that forms between the carboxyl group of one amino acid and the amino group of another amino acid; formed by condensation reaction

Polypeptide

A polymer of many amino acids linked together by peptide bonds

Primary structure of protein

Sequence of amino acids

Secondary structure of protein

Folding and twisting of amino acid chain; alpha helix and beta pleated sheet

Interactions between R groups

Hydrophobic/hydrophilic interaction, Hydrogen bonds, Ionic bonds, Disulfide bonds (covalent)

Globular proteins

Water soluble proteins; fold so the hydrophobic R groups are in the centre and the hydrophilic are on the outside so spherical

Conjugated protein

A protein containing a non protein component called a prosthetic group

Insulin

Globular protein hormone used in the regulation of blood glucose

Haemoglobin

Globular protein that carries oxygen in the red blood cells; contains 2 alpha helix and 2 beta pleated sheet chains; 4 haem groups containing iron

Catalase

Enzyme (globular) that catalyzes breaking down hydrogen peroxide; contains haem groups which allow the enzyme to interact with the hydrogen peroxide

Fibrous protein

Water insoluble proteins; long + thin; structural; only primary and secondary structure

Types of fibrous proteins

Keratin, present in skin, hair and nails; Elastin, stretch and recoil in blood vessels and alveoli; Collagen, connective tissue in skin, tendons, ligaments and the nervous system

Nucleotide

Monomer of nucleic acids made up of a pentose sugar, a phosphate group, and a nitrogenous base

Phosphodiester bond

Bond between adjacent nucleotides; formed by condensation

Pyrmidines

Cytosine, thymine, uracil (1 ring)

Purines

Adenine, guanine (2 rings)

Antiparallel

Description of the opposite arrangement of the sugar-phosphate backbones in a DNA double helix

Semi-conservative replication

Method of DNA replication in which parental strands separate, act as templates, and produce molecules of DNA with one parental DNA strand and one new DNA strand

DNA helicase

An enzyme that unwinds the DNA double helix during DNA replication

DNA polymerase

Enzyme that joins nucleotides together

Triplet code

3 bases of DNA that code for a single amino acid

Degenerate code

More codons than there are amino acids to be coded, so most amino acids are coded by more than one code

Transcription

The process where the DNA sequence in a gene is copied into mRNA

RNA polymerase

Enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription

Translation

The process where genetic information coded in mRNA directs the formation of a specific protein at a ribosome

tRNA

transfer RNA; type of RNA that carries corresponding amino acids to the ribosome; complementary to the mRNA codon

ATP

Adenosine triphosphate; universal energy currency; hydrolysis reaction to form ADP + Pi releases energy

Properties of ATP

Small, water soluble molecule that can easily be transported around the cell, easily broken down, easily made, releases energy in small quantities so none wasted

Enzymes

Biological catalysts; often globular proteins

Enzyme-substrate complex

A temporary complex formed when an enzyme's active site binds to its substrate

Active site

Region on an enzyme that binds to a substrate

Activation energy

Minimum amount of energy required to start a chemical reaction; enzymes lower this

Lock and key model

The model of the enzyme that shows the substrate fitting perfectly into the active site

Induced fit model

The model where the substrate induces the enzyme to alter its shape slightly, putting the bonds of the substrate under pressure

Intracellular vs Extracellular enzymes

Intracellular enzymes are used within cells while extracellular enzymes are secreted from the cell

Digestion of starch

Starts in mouth, amylase catalyses reaction starch to maltose; maltase in the small intestine catalyses reaction maltose to glucose

Digestion of protein

Trypsin is a protease, catalyses the digestion of proteins into smaller peptides that can then be broken down further into amino acids by other proteases

Temperature and enzymes

When temperature increases, molecules have more kinetic energy, giving a greater chance for an enzyme to meet a substrate, so the rate of reaction increases; once the temperature reaches 40°C, the enzymes begin to denature; Optimum is 37°C

pH and Enzymes

Require optimum pH level to function at the right rate otherwise they denature; ions interfere with hydrogen and ionic bonds and so changes the shape of the active site

Competitive inhibition

The inhibitor has a shape that fits the active site of an enzyme and competes with the substrate

Allosteric site

A site on an enzyme other than the active site, to which a specific substance binds, changing the shape and activity of the enzyme

Non-competitive inhibitor

An inhibitor that binds to an enzyme at an allosteric site; changing the shape of the enzyme so the substrate can no longer fit

End product inhibition

A negative feedback loop which regulates the reaction rate; if there is too much product it inhibits the enzyme which leads to its own synthesis and vice versa

(Enzyme) cofactors

Non-protein components that are required for enzyme catalysis; called a coenzyme if it is organic molecule

Precursor activation

When a precursor enzyme undergoes a change in shape (particularly in tertiary structure) to be activated

Fluid mosaic model

Structural model of the plasma membrane where molecules are free to move sideways within a lipid bilayer

Glycoproteins and glycolipids

Proteins and lipids attached to a carbohydrate; involved in cell to cell recognition

Extrinsic protein

Protein that spans only one part of the bilayer

Instrinsic protein

Protein that spans the whole bilayer; carrier/channel proteins

Temperature and membrane structure

When temperature is higher, permeability increases because particles move faster and vice versa; when temperature increases too much channel and carrier proteins will denature

Solvents and membrane structure

Solvents less polar than water disrupt or dissolve cell membranes; for example alcohols

Diffusion

Passive; net movement of particles from high concentration to low concentration

Facilitated diffusion

Passive movement of molecules across cell membranes through protein channels

Active transport

Requires energy; moves material across a cell membrane against a concentration gradient; ATP binds to carrier protein, releasing energy, which changes the shape of it to force the material to the other side of the membrane

Bulk transport

Process in which large particles and macromolecules are transported through plasma membranes; takes energy

Endocytosis

Bulk transport into the cell; pinocytosis of liquids, phagocytosis of solids; ATP is required for movement of vesicles

Exocytosis

Bulk transport out of the cell; ATP is required for movement of vesicles

Osmosis

Diffusion of water across a partially permeable membrane

Water potential

The amount of water in relation to solute; maximum value is 0, pure water; water goes from high to low water potential

Hydrostatic pressure

The pressure of water against the walls of its container

Hypotonic

Lower solute concentration/higher water potential than cell; causes plant cell to be turgid and animal cells to swell and burst as water moves into the cell