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Biological molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a monomer?

A

small repeating units from which larger molecules called polymers are made

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2
Q

What is a polymer?

A

Molecules made from a large number of monomers (3 or more) joined together

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3
Q

What is a condensation reaction?

A

A condensation reaction joins 2 molecules together with the formation of a chemical bond by removing water

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4
Q

What is a hydrolysis reaction?

A

A reaction which breaks a chemical bond between 2 molecules and involves the use of a water molecule

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5
Q

What is a monosaccharide? plus examples and extra info

A

they are the monomers from which all larger carbohydrates are made, for example Glucose, Galactose and Fructose (C6H12O6)
they are soluble
general formular of (CH²0)n
2 join to form disaccarides
many join to form polysaccharides

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6
Q

Important monosaccarides

A

Alpha glucose (penguin)
Beta glucose (Egyptian)
Galactose (raver)
Fructose (witches hat)

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7
Q

Disaccarides

A

2 monosaccarides joined in a condensation reaction with glycosidic bonds
equation- c6H12O6 + C6H12O6 —-> C12H22O11 + H20
reaction happens between OH groups on carbon 4 and 1
examples; Glucose+glucose= Maltose
Glucose+fructose=sucrose Glucose+Galactose=Lactose

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8
Q

Hydrolysis of disaccarides

A

During digestion glycosidic bonds in dissacarides are hydrolyzed into monosaccarides as only monomers are small enough to cross the cell surface membrane
equation; C12H22O11 + H2O —–> C6H12O6 + C6H12O6

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9
Q

What is a polysaccharide?

A

A type of polymer formed by many monosaccarides together via condensation reactions, large and insoluble so great for energy storage and structural molecules

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10
Q

Structure and function of starch

A

Starch is a storage polysaccharide in plants, it is how they store glucose made in photosynthesis ( it is later hydrolysed for respiration)
it is a polymer of alpha glucose with alpha 1-4 glycosidic bonds
It has a helical structure so is compact
also contains 1-6 glycosidic bonds so it can branch which provides more ends for faster enzyme action

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11
Q

structure and function of Glycogen

A

Glycogen is a polymer of alpha glucose
found mostly in liver and muscle cells
alpha 1-4 glycosidic bonds
is coiled which makes it compact
it is insoluble so doesn’t effect water potential
large so can’t move out of cell
highly branched 1-6 glycosidic bonds to give it a larger surface area for faster hydorolysis for respiration

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12
Q

Structure and function of cellulose

A

Cellulose is a polymer of beta glucose ( every other beta glucose has to flip 180⁰)
adds structure to cell walls
beta glucose form 1-4 glycosidic bonds and long straight chains
several chains are joined by many hydrogen bonds (Strong in large numbers)
This forms microfibrils which are further wound into cellulose fibers which provide strength and rigidity and support cell walls

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13
Q

Test for reducing sugars

A
  1. Add equal volumes of benedicts solution and sample to a test tube
    2.heat to 95⁰c for 5 mins
    3.formation of a brick red precipitate shows positive if it stays blue it is negative.
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14
Q

Test for non reducing sugars (sucrose)

A

1.boil a fresh sample with hydrochloric acid for 5 mins
(thus hydrolysises the glycosidic bonds to produce reducing sugars)
2. neutralise the solution by adding sodium hydrogen carbonate
3.Do reducing sugars test same result show positive/negative

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15
Q

Test for unknown concentrations of reducing sugars

A

Calibration curve to turn it into a quantities test
1. make up several known concentrations of reducing sugar
2.carry out Benedicts test
3.use a colourmeter to measure the absorbance
4.plot calibration curve
conc on x axis and Absorbance on Y axis
5.Carry out benedicts test on sample+measure its absorbance
6. use Y value on curve to find conc of unknown sample on X axis

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16
Q

Role of lipids

A

Source of energy- 2x as much energy per g the carbs when oxidised( so are good for respiration)

insulation- Don’t conduct heat well so help animals retain heat.Also electrical insulators and so make up myelin sheath around axons
protection-Important organs have a layer of fat to protect them
Waterproofing- plants and insects have waxy lipid cuticles to conserve water.Animals produce sebum

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17
Q

Triglycerides structure

A

Made of 1 molecule of glycerol joined to 3 fatty acids via 3 condensation reactions to form 3 Esther bonds between the carboxyl group of fatty acid and hydroxyl group of the glycerol

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18
Q

Saturated fatty acids vs unsaturated fatty acids

A

Saturated fatty acids have no double bonds(all bonds are saturated)
Unsaturated fatty acids have double bonds between the carbon atoms in the hydrocarbon chain thus makes them bend+ liquid at room temp as cannot pack Close together
Polyunsaturated- more than 1 double bond between carbons

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19
Q

structure of triglycerides related to their properties

A

Triglycerides are hydrophobic/non polar
They conatin lots of energy as high ration of C-H bonds compared to C-C
Low energy:Mass ratio excellent for energy storage as more energy smaller space
High ratio of H-O bonds, they release water when oxidised so xan be important water source for animals(dessert)

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20
Q

Emulsion teat for lipids

A

Add ethanol to sample and mix
then add water and mix
White emulsion will be visible if fat present
Seed must be crushed first

21
Q

Phosopholipids structure

A

1 glycerol bonded with 2 fatty acid tails with Ester bonds formed between the Carboxyl and hydroxyl groups the other fatty acid is replaced with phosphate group
they are made of 2 parts
Hydrophilic head- attracted to water this is caused by polar nature of the phosphate group (-)
Hydrophobic fatty acid tails-these are repelled by water and face away from water as they are non polar

22
Q

What do phosolipids form in water?

A

Form a bilayer with the fatty acid tails pointing inwards as they repel water and attract fats and the hydrophilic heads pointing outwards as they attract water and repel fats.
Can also form a micellar and ect

23
Q

Water properties

A

A metabolite- This meas water can be involved in metabolic reactions such as condensation and hydrolysis
Solvent- allows metabolic reactions to occur and aslo allows transport of substances
High specific heat capacity- This buffers change in temp helps mammals maintain core temp despite enviro changes as it takes lots of energy to break bonds
Large latent heat of vapourisation- provides cooling effect as lots of energy is required to evapourate it and so when this occurs it takes heat energy away from body to cool it
Cohesion- supports the formation of continuous coloums of water (xylem)
Also produces surface tension which supports small organisms on water surface
Density- water us more dense than ice, provides a habitat

24
Q

Structures of amino acids

A

They contain N C H O and some contain sulphur
there are 20 different amino acids
general structure is
H H O
H N C C OH
R
Amino group, R group and Carboxylic acid group
The oxygen has a double bond
Ejat differentiates them is there R group all of whichbl have diff sizes and are grouped by properties

25
Q

Formation of a peptide bond

A

2 amino acids join to form a dipeptide by a condensation reaction
The hydroxyl group(OH) from the Carboxyl group react with hydrogen of another amino acids forming peptide bonds through condensation reaction/removal of water

26
Q

Polypeptide chains

A

These are formed by many amino acids joining together through condenstation reactions to form a polypeptide chain
They always have an amine group at one end and a Carboxyl group at the other end
number of peptide bonds will be one less than the no of amino acids orginaly joined together

27
Q

Primary structure

A

This is the number and sequence of animosity acids in a polypeptide chain
The primary structure determines the position of the bonds- between R groups so affects final shape
Shape dictates function so a single amino acid in P structure can change whole shape and possibly make it inactive
Primary structure- sequence of amino acids joined together by peptide bonds formed from condensation reactions

28
Q

secondary structure

A

Hydrogen bonds form between the slightly positive charge of the hydrogen in the -N-H group and the slightly negative charge of the oxygen in the -C=O group. That the polypeptide chain has
form weak H bonds throughout the polypeptide, no of them makes them strong
due to these bonds the polypeptide coil into alpha helices or folds into beta pleated sheets

29
Q

Tertiary structure

A

This is the further folding of the secondary structure into specific, complex 3D shape which determines function
The tertiary structure shape is decided by where bonds form between R groups
H bonds- weak and easily broken as temp rises
Ionic- also weak form between oppositly charge R groups+ PH breaks them
Disulphide bridges- covalent bonds between sulphur atoms, extremely strong
primary structure decides where these bonds form and therefore tertiary structure

30
Q

Quaternary structure

A

Contains 2 or more polypeptide chain that are also linked by H, ionic and disulphide binds
They can also contain prosthetic groups
e.g. Haemoglobin is 4 polypeptide chains and a prosthetic group

31
Q

denatured proteins

A

the shape of a protein is essential to function
proteins denatured at high Temps
increase temp increases k energy of molecules making them vibrate
this can break weak H bonds holding structure together
as bond break tertiary shape is lost
this is denaturation
also be caused by PH which can disrupt ionic bonds in T structure

32
Q

How Enzymes work

A

Enzymes are biological catalysts.They increase the rate of reaction of a chemical reaction without being effected or used up.
They speed up the r of r by lowering the activation energy needed foe a reaction to occur by placing pressure on the bonds and bending the bonds in the substrate during the formation of the enzyme substrate complex, meaning bonds can break easier and less energy is nessecary
substrates——–> products

33
Q

What conditions must be met for reactions to occur (enzymes)

A

They must successfully collide to form enzyme substrate complexes
free energy of products must be higher than free energy or substrates
Must reach activation energy (minimum amout of energy required to start a specific reaction)

34
Q

Enzyme structure

A

enzymes are proteins with specific tertiary structure giving them a unique 3D shape
The part of the enzyme involved in reactions is the active site the rest hold thus in the correct shape using H, I and Disulphide bonds
a sites have a shape which is complimentary to one substrate allowing them to fit/bind together
This fitting or binding is called a enzyme substrate complex where the substrate is held to the A site with temporary bonds formed with the amino acids this is what stresses bonds + lowers A energy

35
Q

Induced fit model of Enzyme action

A

In this model the active site isn’t sully fixed in its shape and the substrate induces a change in shape of the active site making it more complimentary to the substrate.
1. A site is not complimentary to substrate
2.substrate enters A site and induces change in shape of A site as enzyme substrate complex forms
3.this stresses the bonds in substrate and lowers A energy
4.When the product leaves A site it then returns to previous shape

36
Q

Factors effecting enzymes

A

temp
ph
substrate conc
enzyme conc
inhibitors

37
Q

Effect of tempreature

A

Every enzyme has a optimum temp
as temp increase so doesn’t kinetic enrgy so they move around more and collide more to form enzyme substrate complexes so r of r increases
if it gets too high this causes the H bonds and ionic bonds between R groups to break, changing tertiary structure and shape of A site so no longer complimentary to substrate so fewer ES complexes form
enzyme is now denatured- permenant

38
Q

Effect of PH

A

Ph is a measure of hydrogen ions concentration
each enzyme has an optimum Ph
a decrease in Ph of 1 means 10x more H+ ions
If the Ph rises too low or too high it can break the hygmdrogeb bonds and the ionic bonds between the -NH and -C=O groups of the amino acids in T structure
this causes the active site to change shape and the substrate is no longer complementary.No ES complexes will form and r of r decreases either side of optimum as it is denatured

39
Q

effect of substrate conc

A

as the substrate conc increase the r of r increase and them levels off
the initial r of r is slow when little cubstrate conc as not all A sites of the enzymes are saturated
substrate is the limiting factor
as substrate conc increases A site’s are filled and r of r increase due to more ES complexes forming, Substrate no longer limiting factor
when R of R levels off this is due too enzymes not being able to form and more ES complexes as all A sites are filled/saturated and all the substrates are used up
enzyme conc is now limiting factor

40
Q

effect of enzyme conc

A

As enzyme conc increases the r of r does too and then levels off
This is beacause the r of r is low when there is a low enzyme conc as all the A sites of the enzymes are saturated and so the enzyme conc is limiting factor.
As the enzyme conc increases, there are more A sites available for substrates to bind to.So r of r increases due to more ES complexes forming.
When r of r levels off as the enzymes cannot form any more ES complexes as there are more A sites than substrates
Substrate conc is now the limiting factor

41
Q

Effect of inhibitors

A

Competitive- similar shape to substrate so can bind to A site and block it
prevent ES complexes forming
not permenantly bound to A site so when it leaves substrate can bind
reduces r of r as fewer ES complexes can form so fewer products form
some products will still be formed because not all A sites are occupied by the inhibitors
Non competitive-
bind to site on enzyme away from A site
Bind to allosteric site
change shape of A site so no longer complimentary to substrate
fewer ES complexes form and r of r is decreased
fewer products form

42
Q

what are the larger molecules broken down into in digestion

A

carbohydrates hydrolysed into simple sugars
fats are hydrolysed into glycerol,fatty acids and monoglycerides
polypeptides and proteins are hydrolysed into amino acids

43
Q

Enzymes what they break down and where they are produced

A

salivary glands- salivary amalyse- carbohydrates
stomach- endopeptidase and exopeptidase- protein
pancreas- pancreatic amalyse - carbohydrates, Lipase- fats, exopeptidase- proteins
Ileum-membrane bound dipeptidase- Protein
dissacharidases- Carbohydrates

44
Q

Key organs in digestive system

A

Salivary glands- salivary amalyse, hydrolysed starch to maltose

oesophagus- peristalsis

stomach- mix with gastric juices, kills microorganisms and contains exopeptidase and endopeptidase hydrolysed polypeptide to dipeptides

pancreas- secrete pancreatic juices containing amalyse, exopeptidase , endopeptidases and lipase

small intestine (ileum)- adapted to provide a large surface area for the absorbtion of the products of digestion
Maltase embedded in epithelium cell membrane, hydrolysed Maltose to glucose for rapid absorption.Also sucrose,lactase and dipeptase

large intestine
rectum

45
Q

Starch digestion

A

1.food enters the mouth and is broken up by teeth, then mixed with saliva
2.salivary amalyse starts to hydrolyse glycosidic bonds in starch producing maltose
3. in the stomach this salivary amalyse is denatured due to Ph
4.in small intestine pancreatic amalyse continue to hydrolyse
5.maltose then hydrolysed to glucose by membrane bound maltose, embedded in cell membrane of epithelial cells In ileum.
6.Glucosr is then absorbed in the Ileum

46
Q

protein digestion

A

endopeptidase- proteins and polypeptide are hydrolysed by protease.Beginning in the stomach.Endopeptidase hydrolyse internal bonds within the polypeptide chain producing shorter chains+ increasing surface area for next enzyme

Exopeptidase- hydrolyse peptide bonds at the terminal ends of polypeptide chain producing dipeptides and animo acids. They are specific , one complimentary to N terminal and one to C terminal end

dipeptidase- enzymes embedded in the cell surface membrane of the epithelial cells Hydrolyse the single peptide bond in the dipeptide to single amino acids.These can now be absorbed by cotransport

47
Q

Glucose absorption

A

They are absorbed into the epithelial cells by co transport and enter blood via facilitated diffusion
1. sodium ions are actively transported out of cells into blood by sodium pottasium pump, requiring ATP
2.This creates concentration gradient of Na+
3.Na+ and glucose enter via facilitated diffusion using co-transporter proteins. 2 binding sites one specific to Na+ and one to glucose
Na diffuses down its concentration gradient
Glucose diffuses against conc gradient
4. glucose moves into blood by facilitated diffusion

48
Q

Amino acid absorption

A
  1. Sodium ions actively transported out of E cell into the blood by sodium pottasium pump
    2.Creates a conc gradient of Na+
    3.Na+ and amino acids enter by facilitated diffusion using co transporter proteins. 2 bindings one specific for Na+ and one specific for amino acids
    Na moves into cell down its conc gradient
    amino acids against its conc gradient
  2. amino acids move into the blood by facilitated diffusion
49
Q

Lipid digestion and absorption

A

1.Lipid droplets are mixed with bile salts to form smaller droplets
2. Increase SA for faster hydrolysis by lipase
3.triglycerides are hydrolysed into glycerol, fatty acids and monoglycerides
4.bule salts, glycerol and fatty form Micelles
5.Micelles make fatty acids soluble in water and bring them to surface of E cell membrane + maintains higher conc relative to E cell
6.fatty acids enter E cell by simple diffusion
7.Smooth endoplasmic reticulum- fatty acids+glycerol recombine to make triglycerides
8.Golgi- triglycerides are modified+ proteins added to form chylomicrons and packaged into vesicals
9.chylomicrons transported into a lymph vessel by exocytosis, then enter blood

Biology (5 decks)

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