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biology year 1 > topic 1 : biological molecules > Flashcards

topic 1 : biological molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is glucose

A
  • hexose sugar (six carbons)
  • main substrate for respiration
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2
Q

what are the two isomers of glucose?

A
  • alpha glucose (OH below)
  • beta glucose (OH above)
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3
Q

what is a ribose sugar and where is it found?

A
  • 5 carbon atom (pentose sugar)
  • DNA contains an isomer of ribose : deoxyribose, (lacks OH group on second carbon of sugar ring)
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4
Q

three examples of disaccharides

A

maltose, sucrose and lactose

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5
Q

examples of 3 polysaccharides

A

glycogen, starch and cellulose

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6
Q

what is a condensation reaction and what bond is formed from condensation reaction with glucose

A

molecules are bonded together with the removal of water.
with the case of glucose, 1,4 glycosidic bonds are formed

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7
Q

what is glycogen? (long answer, 4 main points)

A
  • main storage in animals
  • contains 1,4 and 1,6 glycosidic bonds, made from alpha glucose
  • branched, so it can be broken down easily to release energy.
  • large, but compact, so maximises the amount of energy released.
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8
Q

explain why glycogen releases energy more slowly than glucose

A
  • glycogen is a polymer
  • glycosidic bonds need to be broken
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9
Q

explain why triglycerides are a good energy store (compared to carbs and proteins)

A
  • they contain no water, do not affect the movement of water/osmosis
  • they have more gram-for-gram energy release (they have more C-O bonds that are being hydrolysed than proteins and carbs do)
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10
Q

what is starch and what are the names of the two polysaccharides that mix to make starch

A
  • starch stores energy in plants,
  • made of alpha glucose
  • made of amylose and amylopectin
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11
Q

explain why the water content of triglycerides is different from the water content of carbohydrates and proteins

A
  • triglycerides are non polar
  • carbs and proteins are polar
  • triglycerides repel water, carbs and prot interact with water molecules
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12
Q

what is amylose (how does it fit to its function?)

A
  • unbranched chain of 1,4 glycosidic bonds
  • amylose is coiled and this makes it compact so lots of energy is stored.
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13
Q

what is amylopectin (how does it fit to its function)

A
  • amylopectin is a branched molecule with 1,4 and 1,6 glycosidic bonds.
  • has lots of side branches, so it can be digested quickly by enzymes and can release energy quickly
  • also compact, but not as compact as amylose (but that means that it can store lots of energy)
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14
Q

what is cellulose

A
  • made from beta glucose
  • component of cell wall
  • long and unbranched chain containing 1,4 glycosidic bonds (but they flip every 2 glucose mol.)
  • microfibrils and microfibres are strong threads (made from cellulose long chains joined together by hydrogen bonds)
  • they provide structural support in plant cells
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15
Q

what are lipids

A

biological molecules which are only soluble in organic solvents such as alcohols

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16
Q

what are the two types of lipids and give their definitons

A

saturated lipids : found in animal fats, contains c-c double bonds. this means that they are more dense and solid at Room temp.

unsaturated lipids : found in plants, contain c=c double bonds, melt at a lower temp than saturated fat. This means that they are most likely to be liquid at room temperature.

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17
Q

how is a triglyceride synthesised

A
  • made up of one molecule of glycerol and three fatty acids.
  • they are joined by ester bonds in condensation reactions
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18
Q

how does the structure of lipids relate to their functions

A
  • lipids are waterproof (fatty tail is hydrophobic)
  • very compact –> release more energy than carbohydrates or proteins (more C-O bonds hydrolysed)
  • lipids are non-polar and insoluble in water, they are good for storage of energy
  • they conduct heat slowly - provide insulation
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19
Q

how does the structure and properties of phospholipids relate to their function in cell membranes?

A

phosphate heads are hydrophilic
tails are hydrophobic

  • form a bilayer in cell membrane
  • phosphate heads pointing towards the aqueous environment and the tails away from the aqueous environment.
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20
Q

what are amino acids and what do they look like (draw)

A

strucutre : (refer to notes) –> NH2, R group and carboxyl
amino acids are monomers of proteins

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21
Q

how is the structure of proteins determined?

A

by the order and number of amino acids, bonding and the shape of the protein.

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22
Q

what are possible functions of proteins?

A
  • cell signalling (eg. hormones)
  • catalysing chemical reactions (eg. enzymes)
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23
Q

what is the primary structure of a protein

A

linear sequence of amino acids in the polypeptide chain, held together by peptide bonds.

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24
Q

what is the secondary structure of a protein?

A

folding of polypeptide chain into ALPHA HELIX/BETA-PLEATED SHEET.
- ONLY contains hydrogen bonds (electrostatic forces of attraction between O,N,F and hydrogen atom)

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25
Q

what is the tertiary structure of proteins?

A

(interactions with the R groups)

3D folding of secondary structure into a complex shape.
- shape determined by the type of bonding
- examples of bonds : Hydrogen bond, ionic bond and disulphide bond, vdv

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26
Q

what are hydrogen bonds

A

A hydrogen bond is a type of dipole-dipole interaction. it forms an attraction with the very electronegative O,N,F

27
Q

what are ionic bonds

A

transfer of electrons between metal and non-metal.
- electrostatic force of attraction between positive and neg ions

28
Q

what are disulphide bonds

A

covalent bonds between sulphur atoms in cysteine

29
Q

what is a quaternary structure

A

3D arrangement of more than one polypeptide

30
Q

what are some properties of fibrous proteins

A
  • long parallel polypeptides
  • little tertiary/quaternary structure (MAINLY SECONDARY STRUCTURE)
  • cross-linkage form between microfibres for TENSILE STRENGTH (max load material can support without damage)
  • INSOLUBLE
  • used for structural purposes (eg collagen)
31
Q

what are properties of globular proteins?

A
  • complex tertiary/quaternary structure
  • form colloids (substance which is in another medium)
  • many uses : hormones, antibodies, haemoglobin
32
Q

how does the structure of collagen relate to its function?

A

FIBOUROUS
- large number of H bonds = high tensile strength
- made up of distinct alpha chains : form triple gamma helix
- forms structure of bones, cartilage, connective tissues (tendons of muscles)

33
Q

how does the structure of haemoglobin relate to its function/

A

GLOBULAR
- water soluble protein - four PP chains
- each subunit contains a haem group (contains Fe2+ ion)
- carries O2 (can bind to Fe2+)
- released for tissue when required for respiration

34
Q

what is a purine

A

two nitrogen-containing rings
adenine and guanine

35
Q

what is a pyrimidine

A

one nitrogen-containing rings
uracil, cytosine and thymine

36
Q

how do nucleotides join together?

A

5’3’ phosphodiester bonds (condensation reaction for the backbone of the DNA)

37
Q

what bond keeps the two strands together

A

hydrogen bonds between the complementary nucleotides.

38
Q

what is semi conservative replication

A

DNA replication that produces two helixes that contain one old and one new strand

39
Q

what is conservative replication

A

DNA replicaiton that produces one helix made entirely of old DNA and one helix made entirely of new DNA

40
Q

how does semi conservative dna replication work?

A
  1. DNA double helix unwinds, done by DNA helicase (breaks bonds between nitrog. bases)
  2. the strands are used as templates
  3. free nucleotides join up to the old strands via complementary base pairing (A with T, C with G)
  4. DNA polymerase catalyses the formation of H bonds between the nucleotides and dna strand
  5. DNA ligase forms the phosphodiester bonds of the sugar phosphate backbone of the DNA

semi conservative because new DNA molecule contains one original strand and one newly-synth strand in each pair of DNA.

41
Q

what are the triplets of bases called in genetic code?

A

codons

42
Q

what is a gene

A

sequence of bases on a DNA molecule coding for a sequence of amino acids (proteins)

43
Q

what are the coding and non-coding regions of DNA called

A

coding - exons
non-coding - introns

44
Q

explain mutation of deletion

A

part of the genetic code gets deleted, produces harmful mutations as it is a frameshit, so all the codons will be differet

45
Q

explain mutation of insertion

A

A type of genetic change that involves the addition of a segment of DNA

46
Q

explain mutation of substitution

A

a type of mutation in which one nucleotide is replaced by a different nucleotide

47
Q

what are some features of genetic code?

A
  • non-overlapping - each triplet read only once.
  • genetic code is degenerate - more than one triplet codes for the same amino acids, reduced effect of mutations
  • contains start and stop codons :start and stop protein synthesis
  • code is universal (same in all organisms and species)
48
Q

describe the process of transcription

A

DNA STRAND TRANSCRIBED INTO MRNA
- DNA HELICASE catalyses the H bonds broken between complementary base pairs. DNA uncoils.
- one strand is used as template (antisense), other strand is coding
- free nucleotides join up to the antisense strand by complementary base pairing.
- adjacent nucleotides joined together by phosphodiester bonds (catalysed by RNA polymerase) and this forms sugar phosphate backbone
- molecule of mRNA formed
- leaves nucleus by nuclear pore and goes to ribosome in cytoplasm

49
Q

describe the process of translation

A

AMINO ACIDS ASSEMBLED TOGETHER TO FORM PP CHAIN
- mrna attaches to ribosome on RER
- tRNA molecule (has specific amino acid binding site) binds to mRNA via anticodon
- H bonds form between anticodon and codon
- second tRNA molecule binds to next codon and the two tRNA molecules form a peptide bond
- third tRNA molecule joins and first one leaves

process repeated until formation of polypeptide chain
(this happens until STOP CODON REACHED ON mRNA)

50
Q

what are enzymes

A

biological catalysts which increase the rate of a chemical reaction by lowering activation energy.

51
Q

what is the induced fit model

A

the idea that the structure of the enzyme is distorted so that the active site of the enzyme moulds around the substrate.

52
Q

how does enzyme concentration affect the rate of reaction?

A
  • rate of reaction increase as enzyme conc increase, more active sites for substrates to bind.
  • but, increasing the conc above a certain point has no effect on the rate of reaction as there are more active sites than substrates
  • substrate conc will be a limiting factor
53
Q

how does the substrate concentration affect rate of reaction?

A
  • as conc of substrate increase, r.o.r increase : more enzyme-substrate complexes
  • but, beyond a certain point, r.o.r will no longer increase
  • enzyme conc will become limiting
54
Q

how does temperature affect rate of reaction in enzymes

A

rate of reaction increases as temp increase (more KE)
- rate of reaction decreases beyond optimum temp : enzymes denatured (H BONDS are broken within the protein)

55
Q

how does pH affect the rate of reaction in enzymes?

A

As the pH value is increased above/decreased below the optimum pH, the enzyme activity decreases.
- this is because enzymes denature at extreme pHs.

56
Q

what is a competitive enzyme inhibitor

A

inhibitor molecule competes with the substrate for binding to the active site of the enzyme
- prevents substrate from binding
- can be reversed by increasing substrate conc!!

57
Q

what is a non-competitive inhibitor

A

an inhibitor that binds to a different part of the enzyme (NOT THE ACTIVE SITE) and changes the shape of the enzyme.
- decrease R.O.R as active site does not fit substrate
- sub cannot bind to enzyme
- CANNOT BE REVERSED BY INCREASING SUB CONC!!

58
Q

what are ions required for

A

they are required for plant growth and development

59
Q

what are nitrate ions required for

A

they are required to make DNA and amino acids

60
Q

what are calcium ions needed for

A

needed to form calcium pectate for the middle lamellae in plants

61
Q

what are phosphate ions needed for

A

making atp (by phosphorylating adp)
making dna and rna

62
Q

what are magnesium ions needed for

A

needed to produce chlorophyll

63
Q

what are the main properties of water (5 points)

A
  • it is a polar molecule : ionic substances can dissolve in water (can transport nutrients in plants)
  • polar solvent : many metabolic reactions take place
  • has a high specific heat capacity : the temp does not fluctuate - allow organisms in rivers and lakes to survive in different seasons
  • relatively large latent heat of vaporisation : evaporation of water provide cooling effect (eg. sweat)
  • cohesion and adhesion : water molecules stick together (cohesion) - hydrogen bonds between h2o mol (transportation in plants in the xylem tube)
    cohesion means that there is surface tension at the water-air.
    adhesion : h2o molecules can adhere to the side of the tube-like cells
64
Q

is ice more or less dense than water

A

less dense
- water in ice spread out and fixed in place
- ice floats on top of water : INSULATING LAYER
- increase chance of survival of organisms in large bodies of water (prevent them from freezing when temp decrease)

biology year 1 (4 decks)

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