Essential Cell Biology - Chapter 2

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What is a nucleus made of?
Protons (+) & Neutrons
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What determines an atoms atomic weight?
Number of protons (same as number of electrons)
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What happens if there are too many or too few neutrons?
The nucleus may disintegrate by radioactive decay
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What is radioactive decay?
Spontaneous breakdown of atomic nucleus - results in anger and matter release from nucleus
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What is an isotope?
An element form which has different number of neutrons in it's
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What is an unstable atom? (And causes radioactive decay?
When an atoms binding energy is not enough to hold the nucleus together
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What is atomic or molecular weight
How much a cell weighs relative to hydrogen - Protons + neutrons
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What unit would you use to specify atomic mass?
Daltons - 1 dalton = mass of 1 hydrogen
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How much does a proton/neutron weigh?
1/(6x10 to the power of 23)gram
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What is avogadro's constant?
Number of atoms or molecules in a mole (6x10 to the power of 23)
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How do you work out moles of a substance?
Multiply how many grams of substance by 6x10 to the power of 23
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How many electrons in each shell? 1st, 2nd, 3rd, 4th, 5th
1st - 2, 2nd - 8, 3rd - 8, 4th - 18, 5th - 18
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What is a covalent bond?
When electrons are shared equally
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What is an ionic bond?
When electrons are donated or received
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What is a molecule?
Cluster of atoms joined by covalent bonds
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What is bond length?
The right amount of distance in which atoms can bond
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What is bond energy?
The amount of energy required to break apart 1 mole of covalently bonded substance
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What are single bonds?
When 1 electron per atom or molecule is shared in bond
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What are double bonds?
When 2 electrons per atom or molecule is shared in bond
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What is a polar covalent bond?
When electrons are shared unequally
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What is a polar structure?
Negative on one side, positive on the other
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How is bond strength measured? (Unit)
Kilocalories (Kcal/mole) or kilojoules (KJ/mole)
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What are enzymes?
Biological catalysts
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What are salts?
Ions that are held together only by ionic bonds
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What is an ion?
A charged particle
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What are positive ions called?
Cations
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What are negative ions called?
Anions
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What is electrostatic attraction?
When negatively charged atom or molecule is attracted to a negative one
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What is a hydrogen bond?
Weak bond between two molecules resulting from an electrostatic attraction between proton and an electronegative atom
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What bond holds together hydrogen and oxygen in water?
Covalent
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If an atom gains electrons it is said to be ____ charged
Negatively
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If an atom looses electrons it is said to be ____ charged
Positively
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What are acids?
Substances with pH less than 7
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What is a base?
Substance that accepts a proton when dissolved in water - usually forms salt and water
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What does H3O+ determine?
How acidic a solution is
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Strong aides loose their protons _____
Easily
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What is the defining property of a base?
It raises concentration of OH- ions
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What is the defining property of an acid?
It raises concentration of H3O+ ions
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What is meant by dissociates?
When molecules split up in a solution into different elements
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What is the concentration of pure water?
10 to the power of 7 M
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What is a buffer?
A solution which resists pH change on the addition of acidic or basic components
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What is an organic molecule?
A molecule that is built around carbon chain - large carbon compound
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What are the four major families of small organic molecules?
1 - sugars, 2 - fatty acids, 3 - amino acids, 4 - nucleotides
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What are the four major families of larger organic molecules?
1 - polysaccharides, glycogen and starch (in plants), 2 - fats and membrane lipids, 3 - proteins, 4 - nucleic acids
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What is the formula for monosaccharides?
(CH2O)n
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Which two sugars can glucose be converted into by switching orientations of -OH groups?
Mannose and glactose
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What are isomers?
Sets of molecules with the same chemical formula but different structures
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What are optical isomers?
Sets of molecules that are the mirror image of themselves
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What bond holds together monosaccharides?
Glycosidic
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What is an oligosaccharide?
A sugar with 2 - 10 monosaccharide units
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What is a condensation reaction?
A reaction when water is released?
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What is hydrolysis?
A reaction when water is used to break up a bond
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What are the two distinct features of a fatty acid molecule?
1 - hydrocarbon tail, 2 - carboxyl group
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What is meant by the term amphipathic?
A molecule that possess hydrophobic and hydrophilic regions
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What makes a fat saturated?
When it has no double bonds between carbon atoms in hydrocarbon tail - allowing more room for hydrogen
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What makes a fat unsaturated?
When it has double bonds between carbon atoms in hydrocarbon - which cause the chain to kink
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Where are fatty acids stored?
In cytoplasm of cell in droplets made of triacylglycerol molecules
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What is a tricylgycerol made of?
3 fatty acids attached to a glycerol molecule (covalently bonded)
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What are lipids?
Molecules insoluble in water but soluble in organic solvents
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What is a lipid bilayer?
Basis for cell membrane
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What is a phospholipid bilayer?
A membrane made of phospholipids - 2 rows, hydrophobic tails in centre, hydrophilic head on outside
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What is meant by amphipathic?
When a molecule has hydrophilic and hydrophobic parts
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What is the difference between phospholipid's and glycolipids?
Glycolipids contain one or more sugars instead of a phosphate group
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What do glycolipids help build?
Cell membrane
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What are aminoo acids?
Small organic molecules that contain a carboxyl group, amino group and R side chain attached to alpha-carbon atom
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What do amino acids help build in a cell?
Proteins
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What is a polymer?
Large molecule composed of repeated subunits
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What is a peptide bond?
Covalent bond that joins 2 amino acids in a protein (carboxyl end meets with amino group end)
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What is a polypeptide?
A chain of amino acids
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How are peptide bonds formed?
In a condensation reaction
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What is N-terminus?
A polypeptides amino group end (NH2)
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What is C-terminus?
A polypeptides carboxyl group end (COOH)
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What forms can sugars and amino acids come in?
Optical isomers in L-forms and D-forms
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What is DNA and RNA build of?
Nucleotides
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What are Nucleosides?
Nitrogen-containing ring compound that's linked to a 5-carbon sugar (either deoxyribose or ribose)
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What is a nucleotide?
Nucleosides that contain one or more phosphate group attached to the sugar
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What two forms do nucleotides come in?
Ribonucleotides and deoxyribonucleotides
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What are the nitrogn-containing rings in nucleotides referred to as?
Bases - because they can bind H+ therefore increase OH- concentration
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Nucleotides can act as ____ term carriers of ____ ____.
Short, chemical, energy
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What is adenosine triphosphate (ATP)?
Considered to be energy "currency" of life
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How is ATP formed?
Through reactions where energy is sourced from breaking down of foodstuffs
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How does ATP release energy?
When it's phosphate bonds rupture
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What is ATP composed of?
A base, ribose and phosphate chain
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What bond holds ATP's phosphate chain together?
Phosphoanhydride bond
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How is a Phosphoanhydride bond broken?
Through hydrolysis
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What do nucleotides help build?
Nucleic acids
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What are nucleic acids? (In therms of structure)
Long polymers where nucletides linked by covalent phosphodiester bonds between phosphate and hydroxyl groups
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What are RNA's bases?
A, G, C, U
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What are DNA's bases?
A, G, C, T
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What is the main difference between DNA and RNA?
DNA stores hereditary info for longer - RNA carries molecular instructions for shorter
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Name the two pairs of DNA's bases
G & C - A & T
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Name the two pairs of RNA's bases
G &C - A & U
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How big and complex is a macromolecule?
Between a small organic molecule and organelles
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How are macromolecules formed?
By covalently linking small organic monomers into long chains or polymers
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What is a monomer?
(Almost) Identical molecules that join together to make polymers
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What does ribulose bisphosphate carboxylase do?
Converts CO2 to sugars in plants
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What is a microtubule?
A tube structure that gives structure to a cell - made of tubulin
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What do histone proteins do? (DNA)
Make spool-like structures to wrap up DNA in chromosomes
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What does myosin (protein) do?
Act as molecular motors to produce force and movement
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What is a polymer?
A chain of monomers (almost identical molecules)
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How do monomers bond in a polymer?
Through condensation reaction
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What is polymerisation?
The process of monomers going to create a polymer in a chemical reaction
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Sunbits in a polymer are assembled in a chain in a ____
Sequence
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Polymer chains have great flexibility because of their ____ ____
Covalent bonds
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Why are some biological macromolecules are constrained (structurely)?
Because of weak non covalent bonds in molecule
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What are van der Waals attractions?
Form of electrical attraction caused by fluctuating electric charges that occur when two atoms come close
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Give an example of a hydrophobic interaction
Phospholipids in cell membranes
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Why are non-covalent bonds good in bonding macromolecules?
Allow to bond to many thousands of different molecules in cell - because of multipoint contacts - molecules have to be close to bond
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Other cards in this set

Card 2

Front

What determines an atoms atomic weight?

Back

Number of protons (same as number of electrons)

Card 3

Front

What happens if there are too many or too few neutrons?

Back

Preview of the front of card 3

Card 4

Front

What is radioactive decay?

Back

Preview of the front of card 4

Card 5

Front

What is an isotope?

Back

Preview of the front of card 5
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