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biology > topics 1-4 > Flashcards

topics 1-4 Flashcards

1
Q

monomers

A

smaller units from which larger molecules are made

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2
Q

examples of monomers

A

monosaccharides, amino acids, nucleotides

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3
Q

polymers

A

molecules made from a large number of monomers joined together

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4
Q

examples of polymers

A

polysaccharides, proteins, DNA

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5
Q

condensation reaction

A

joins two molecules; removal of a water molecule; forms a chemical bond

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6
Q

hydrolysis reaction

A

separates two molecules; requires the addition of a water molecule; breaks a chemical bond

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7
Q

monosaccharides

A

single sugar molecules (e.g., glucose, fructose, galactose).

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8
Q

disaccharides

A

formed by the condensation of two monosaccharides
(e.g., glucose + glucose = maltose, glucose + fructose = sucrose, glucose + galactose = lactose)

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9
Q

polysaccharides

A

formed by the condensation of many monosaccharides
(e.g., starch, glycogen, cellulose)

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10
Q

glycogen

A

store of glucose in animals; formed from α-glucose; more branches (1-6 gd bonds) than amylopectin (increases SA and allows enzymes to work simultaneously and hydrolyse it back into glucose); large and compact maximising the amount of energy it can store; insoluble means it will not affect the water potential and cannot diffuse out of cells

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11
Q

starch

A

amylose and amylopectin; store of glucose in plants

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12
Q

amylose

A

formed by a condensation reaction;
long, unbranched helix of alpha-glucose;
forms 1-4 glycosidic bonds;
coils up to form a helix (compact; stores a lot of energy-glucose)

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13
Q

amylopectin

A

formed by condensation reaction;
long, branched chain of alpha-glucose;
forms straight chains of 1-4 glycosidic bonds and branches out with 1-6 glycosidic bonds (increases surface area and allows enzymes to work simultaneously and hydrolyse it back into glucose)

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14
Q

cellulose

A

for structural strength of plant cell wall;
formed from β-glucose;
each alternate glucose is inverted;
formed by many condensation reactions and 1-4 gd bonds;
creates a long, straight chain;
the chains line up parallel to each other, held in place by H bonds which are individually weak, but collectively strong (fibril)

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15
Q

triglycerides

A

formed via condensation reactions between glycerol and three fatty acids, forming ester bonds;
used as an energy storage molecules;
properties: high ratio of C-H bonds to C atoms, insoluble in water (forms droplets).

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16
Q

phospholipids

A

formed via condensation reactions between glycerol, two fatty acids, and a phosphate group;
forms phospholipid bilayer in cell membranes;
properties: hydrophilic phosphate heads, hydrophobic fatty acid tails
the centre of the bilayer is hydrophobic so water-soluble molecules can’t easily pass through-the membrane acts as a barrier

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17
Q

saturated and unsaturated fatty acids

A

saturated: no C=C double bonds;
unsaturated: one or more C=C double bonds

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18
Q

emulsion test for lipids

A

add ethanol and shake (dissolves lipids) then add water;
positive result: milky/cloudy white emulsion

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19
Q

biuret test for proteins

A

add biuret solution (sodium hydroxide + copper (II) sulfate)
positive result: purple color (negative result: stays blue)

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20
Q

amino acids

A

monomer of proteins

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21
Q

dipeptide

A

two amino acids joined by a peptide bond

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22
Q

polypeptide

A

many amino acids joined by peptide bonds

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23
Q

primary structure

A

sequence of amino acids in polypeptide chain

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24
Q

secondary structure

A

hydrogen bonding causes folding into alpha-helix or beta-pleated sheet

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25
Q

tertiary structure

A

3D structure held by interactions between side chains (ionic bonds, disulfide bridges, hydrogen bonds)

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26
Q

ionic bonds in tertiary structure

A

form between the carboxyl and amino groups not involved in the peptide bonds;
weaker than disulfide bridge

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27
Q

disulfide bridges in tertiary structure

A

whenever two molecules of cysteine (amino acid) come close together; the S atom in one cysteine bonds to the S atom in the other cysteine

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28
Q

quaternary structure

A

the quaternary structure is the way the polypeptide chains are assembled tg

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29
Q

how do enzymes speed up reactions

A

enzymes lower the activation energy by providing alternative pathway

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30
Q

lock and key model

A

active site is a fixed shape/doesn’t change shape;
it is complementary to one substrate;
after a successful collision, an enzyme-substrate complex forms leading to reaction

31
Q

induced fit model

A
  1. before reaction, enzyme active site not completely complementary to substrate/ doesn’t fit substrate
  2. active site shape changes as substrate binds and enzyme-substrate complex forms
  3. this stresses / distorts bonds in substrate leading to a reaction
32
Q

how does enzyme concentration affect the rate of enzyme-controlled reactions

A

there are more active sites for the substrates to bind to
however, its only applicable to a certain extent;
at some point, enzyme activity will plateau because there are too many active sites and not enough substrates

33
Q

how does temperature affect the rate of enzyme-controlled reactions

A

rate of reaction increases as particles gain more kinetic energy;
leading to more collisions;
if temperature is too high enzymes denature

34
Q

how does pH affect the rate of enzyme-controlled reactions

A

at very acidic and alkaline pH values the shape of the enzyme is altered so that it is no longer complementary to its specific substrate

35
Q

competitive inhibitors

A

have a similar shape to substrate;
compete with the substrate molecules to bind to the active site but no reaction takes place

36
Q

what happens when there’s a higher concentration of competitive inhibitors

A

if there’s a higher conc of inhibitors, it will take up nearly all active sites and hardly any of the substrate will get to the enzyme

37
Q

what happens when there’s a higher concentration of substrates

A

if there’s a higher conc of substrates, the substrates chance of getting to an active site before the inhibitor increases
increasing substrate conc increases rate of reaction

38
Q

non-competitive inhibitors

A

they bind to the enzyme away from its active site which causes the active to change shape so the substrate molecules can no longer bind to it

39
Q

what happens when you increase the substrate concentration when non-competitive inhibitors are present

A

non-competitve inhibitors don’t compete with the substrate molecules to bind to the active site because they are a different shape;
inhibits enzyme activity

40
Q

DNA

A

double-stranded helix, holds genetic information (ACGT)

41
Q

RNA

A

single-stranded, transfers genetic information from DNA to ribosomes (ACGU)

42
Q

nucleotide

A

DNA and RNA are polymers of nucleotides
nucleotides are made from: a pentose sugar (sugar with 5 C atoms) and phosphate group (sugar-phosphate backbone and a nitrogen-containing base (ACGT)

43
Q

polynucleotide structure

A

nucleotides join tg to form polynucleotides via a condensation reaction between phosphate group of one nucleotide and the sugar of another;
form a phosphodiester bond

44
Q

DNA structure

A

double-helix;
composed of two polynucleotides joined tg by H bonds between complementary bases;
(a+t, c+g)

45
Q

complementary base pairing

A

adenine pairs with thymine (2 H bonds)
guanine pairs with cytosine (3 H bonds)
equal amounts of A+T and C+G

46
Q

RNA structure

A

a pentose sugar (sugar with 5 C atoms) and phosphate group (sugar-phosphate backbone and a nitrogen-containing base (ACGU)

47
Q

difference between DNA and RNA

A
  1. deoxyribose/ribose
  2. thymine/uracil
  3. double strand/single strand
  4. long/short
48
Q

how does DNA replicate?

A

semi-conservative replication

49
Q

what does semi-conservative replication mean?

A

half of the strands in the new DNA are from the original DNA molecule;
leads to genetic continuity

50
Q

semi-conservative replication (process)

A
  1. DNA helicase breaks the H bonds between bases on the two polynucleotide strands (helix unwinds)
  2. each original single strand acts as a template for a new strand; complementary base pairing makes free-floating DNA nucleotides are attracted to their complementary exposed bases from original template strand
  3. condensation reactions join the nucleotides of the new strands together catalysed by DNA polymerase; H bonds form between the bases
  4. each new DNA molecule contains one strand from the original DNA molecule and one new strand
51
Q

meselson+stahl experiment

A

used 2 isotopes of N to show that DNA replicates using semi-conservative replication
(heavy-15);(light-14)
1. grow 2 samples of bacteria (one in lightN broth and one in heavyN broth)
2. sample of DNA taken from each batch and spun in centrifuge
3. bacteria grown in heavyN broth taken out and put in lightN broth and left for one round of DNA replication
4. DNA settled in the middle, mixture of both heavyN and lightN

52
Q

ATP

A

adenosine triphosphate;
immediate source of energy for metabolic reactions

53
Q

what is ATP made up of?

A

one adenine base, ribose sugar and 3 phosphate groups (ATP synthase)

54
Q

where is the energy in ATP stored?

A

stored in high energy bonds between the phosphate groups and is released via hydrolysis reactions
ATP → ADP + Pi (ATP hydrolase)

55
Q

properties of water

A

high specific heat capacity: stable temperature for organisms
high latent heat of evaporation: efficient cooling mechanism
cohesion: surface tension, water transport in plants
solvent: dissolves ionic compounds and other substances, medium for metabolic reactions
metabolite: involved in hydrolysis and condensation reactions

56
Q

phosphate (inorganic ion)

A

DNA/RNA backbone;
energy storage/release in ATP

57
Q

hydrogen (inorganic ion)

A

pH regulation

58
Q

iron (inorganic ion)

A

transports oxygen with haemoglobin

59
Q

sodium (inorganic ion)

A

involved in cotransport of glucose and amino acids

60
Q

cell surface membrane

A

phospholipid bilayer with embedded proteins; selectively permeable; barrier between internal and external environments

61
Q

nucleus

A

nuclear envelope, nuclear pores, nucleolus, DNA/chromatin;
controls the cells activities through transcription;
nuclear pores allow substances to move between nucleus and cytoplasm(mRNA);
nucleolus makes ribosomes which are made up of proteins and ribosomal DNA

62
Q

mitochondria

A

double membrane; inner membrane folded to form cristae;
matrix contains small 70s ribosomes, small circular DNA and enzymes involved in glycolysis;
site of aerobic respiration to produce ATP

63
Q

golgi apparatus

A

fluid filled membrane bound sacs with vesicles; receives protein from RER and modifies then; packages protein into vesicle for transport;
makes lysosomes

64
Q

lysosomes

A

type of golgi vesicles; containing lysozymes; hydrolyses pathogens or worn out cell components

65
Q

ribosomes

A

float free in cytoplasm or bound to RER; not membrane bound; site of translation

66
Q

RER

A

ribosomes bound to a system of membranes; folds polypeptides to secondary/tertiary structure; packages to vesicles, transport to the golgi apparatus

67
Q

SER

A

system of membranes; synthesises and processes lipids

68
Q

chloroplasts

A

thylakoid membranes stacked to form grana; linked by lamellae; liquid is stroma; double membrane; contains starch granules and circular DNA; chlorophyll absorbs light for photosynthesis to produce organic substances

69
Q

cell wall

A

made of cellulose in plants and algae; chitin in fungi;
rigid structure, prevents the cell changing shape and bursting

70
Q

vacuole

A

contains cell sap; surrounding membrane is tonoplast;
maintains pressure in the cell

71
Q

differences in prokaryotic cells

A

no membrane bound organelles;
no nucleus, circular DNA, not associated with proteins;
cell wall is made of murein;
70s ribosomes;
one or more plasmids

72
Q

scanning electron microscope

A

uses electrons to form a 2D image;
beam of electrons scan surface;
shorter wavelength so higher resolution; x1500000 magnification

73
Q

transmission electron microscope

A

uses electrons to form a 3D image; electromagnets focus beam of electrons onto specimen, more dense=more absorbed=darker;
shorter wave,entry of electrons; x1500000 magnification

74
Q

magnification vs resolution

A

how much bigger the image of a sample is compared to the real size; magnification
how well distinguished an image is between 2 points; resolution

biology (4 decks)

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