Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology UNIT 2 > Biological Molecules > Flashcards

Biological Molecules Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is key for organism survival (in terms of molecules)?

A
  • organisms must make or take in all molecules required
  • carbohydrates (including fibre)
  • proteins
  • lipids
  • vitamins and minerals
  • nucleic acids
  • water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Role of carbohydrates

A
  • Energy storage and supply
  • Structure
  • (Fibre to give gut a bulk to push against- to ease flow of materials through the gut)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Role of proteins

A
  • structure
  • transport
  • enzymes
  • antibodies
  • hormones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Role of lipids

A
  • membranes
  • energy supply
  • thermal insulation
  • electrical insulation in neurones
  • protective layer
  • some hormones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Role of vitamins and minerals

A

Form parts of larger molecules
Take part in some metabolic reactions
Coenzymes/enzyme activators

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Role of nucleic acids

A

Information molecules, carry instructions for life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Role of water

A

Takes part in many reactions
Support in plants
Solvent for metabolic reactions
Transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What chemical elements are found in most biological molecules?

A

Carbon, hydrogen, oxygen, nitrogen

Sulfur, phosphorus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why is water sometimes described as a biological molecule?

A

Because of its importance to life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Define metabolism

A

The sum total of all the biochemical reactions taking place in an organism’s cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define catabolic and anabolic reactions

A

Catabolic - breaking larger molecules into smaller ones

Anabolic- building smaller molecules into larger ones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why is carbon so important in biological molecules?

A

Form long chains
Bond with other atoms, different structures and properties
Multiple-bonding feature, valency of 4, carbon is a framework atom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why aren’t lipids called polymers?

A

The smaller molecules bonded together are very different from each other. A polymer is a group of similar monomers joined together.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the basic steps of a condensation reaction?

What are the basic steps of a hydrolysis reaction?

A

Condensation

  • a water molecule is released
  • new covalent bond formed
  • larger molecule formed by the bonding together of smaller molecules

Hydrolysis

  • a water molecule is used
  • a covalent bond is broken
  • smaller molecules formed by the splitting of a larger molecule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does hydrogen bonding occur between water molecules?

A

Water is a polar molecule, the electrons in the O-H covalent bond aren’t shared evenly.
Hydrogen bonds form between the slightly electropositive hydrogen and the slightly electronegative oxygen atom of another molecule.
Hydrogen bonds are weak interactions that can occur between OH and NH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Relate intermolecular interactions in water to the roles of water in living organisms

A

Hydrogen bonding!

  • cohesion=surface tension, transpiration stream
  • adhesion=xylem capillary action
  • ice less dense, floats, insulates water below=allows aquatic life to survive winter
  • high specific heat capacity= large bodies of water long time to warm, still warm in winter
  • solvent for hydrophilic substances=cell cytoplasm metabolic reactions
  • reactant in hydrolysis (eg photosynthesis)

-good transport medium, and cooling effect of evaporation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the structure of an amino acid

A
  • amine group at one end (excess amine groups toxic, remove by deamination)
  • carboxyl group at the other end
  • carbon in between
  • R group on second carbon (some hydrophobic/philic, glycine has H, 20 different R groups)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Describe the formation and breakage of peptide bonds in the synthesis and hydrolysis of dipeptides and polypeptides

A

Condensation- amino acids joined together.
H from amine group combines with OH from carboxyl group
Water lost.
Covalent peptide bond between amine group of one and carboxyl group of another amino acid.
2 amino acids=dipeptide
Many amino acids=polypeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Explain the term, primary structure

A

The specific sequence of amino acids held by peptide bonds (in a polypeptide)

20
Q

Explain the term, secondary structure

A

Coiling (alpha helix) or pleating (beta pleated sheets) due to hydrogen bonds between H and O

21
Q

Explain the term, tertiary structure

A

The final 3D shape of a polypeptide due to disulfide bonds, hydrophobic/hydrophilic interactions (R-group), and ionic interactions (oppositely charged R groups)

22
Q

Explain the term, quaternary structure

A

Multiple polypeptide chains, held by many bonds/interactions

23
Q

Structure of haemoglobin

A 
Globular protein
Peptide bonds between amino acids
4 chains, 2 different subunits
Chains held by hydrogen bonds
Fe2+ prosthetic group
Water soluble
Function is to carry oxygen from alveoli to body tissues and CO2 from body tissues to alveoli
Haemoglobin+4O2-> oxyhemoglobin (HbO8)
24
Q

Describe the structure of a collagen molecules

A

Fibrous protein
Insoluble in water
3 polypeptide chains
Left handed alpha helix
Every 3rd amino acid is glycine
Adjacent molecules joined by covalent cross-links
Function is to provide mechanical strength (artery wall withstand blood pressure, tendons bones to skeletal muscle, cartilage)

25
Q

Features of globular proteins

A

Type of tertiary structure
Rolled up, ball shaped
Hydrophobic R groups turned inwards towards centre
Hydrophilic R groups on outside, so water-soluble since water molecules can easily cluster around them.
Metabolic roles
Enzymes, plasma proteins, mammal antibodies

26
Q

Features of fibrous proteins

A 
Form fibres
Regular, repetitive primary structure
Insoluble in water
Structural roles
Bone, cartilage, keratin in fingernails and hair
27
Q

Describe the molecular structure of alpha-glucose

And some properties

A

Monosaccharide carbohydrate
Chain or ring structure
OH at C1 below the plane of the ring
Hexose, one water molecule for every carbon atom present C2H12O6

Soluble in water
Sweet-tasting
Form crystals

28
Q

Monosaccharides are grouped according to the number of carbon atoms in the molecule, give the names of three different types

A

3 carbon, triose sugars
5 carbon pentose sugars
6 carbon hexose sugars

29
Q

State the structural difference between alpha- and beta- glucose

A

Alpha- OH on carbon 1 is below the plane of the ring

Beta- OH on carbon 1 is above the plane of the ring

30
Q

Describe the formation and breakage of a named disaccharide a named polysaccharide

A

Disaccharide- maltose
Condensation
OH on carbon 1 reacts with H on carbon 4 of another alpha glucose
Water is lost
Glycosidic (covalent)bond formed (1,4-glycosidic bond)
Hydrolysis, water molecule breaks covalent 1,4-glycosidic bond

Polysaccharide- amylose (thousands of alpha glucose)
Condensation, many alpha glucose molecules bonding, one water molecule released for every glycosidic bond
Hydrolysis, glycosidic bonds broken, water used up

31
Q

What happens to nutrients in the body

A
  • become a part of your body, digested and rebuilt
  • provide energy for metabolism
  • removed from body if it can’t be digested
32
Q

Starch: structure, functions and relate to living organisms

A

A mixture of long, straight chained amylose and branched amylopectin (1,6- and 1,4-glycosidic bonds, all alpha glucose)
Insoluble in water
Can be broken down to glucose and respire to release energy
Energy storage polysaccharide in plants, in chloroplasts, membrane-bound starch grains and plant-storage organs

33
Q

Cellulose: structure, functions and relate to living organisms

A
  • Beta-glucose subunits
  • Straight chained
  • Hydrogen bond cross links between many molecules (forms micro/macro fibrils, cross over for extra strength)
  • Arrangement of macrofibrils determines how cells can grow or change shape
  • Embedded in pectins (glue) to form cell wall
  • Can be embedded with other substances for waterproofing or extra support
  • structural polysaccharide in plant cell walls
  • Natural arrangement allows apoplast pathway
  • Water moving into plant cell doesn’t cause it to burst, the cell wall prevents it
  • In turgid cells, it helps to support the whoe plant
34
Q

Glycogen: structure, functions and relate to living organisms

A

Made of alpha-glucose subunits
1-4 linked chains are shorter and more branched than starch, so more compact
Insoluble in water
Can be broken down to glucose and respired to release energy
Energy storage in animals
Forms glycogen granules in liver, muscle and other cells

35
Q

Glucose: functions and relate to living organisms

A

Soluble in water
Energy SOURCE (not store)
Takes part in metabolic reactions
Can enter the respiratory pathway that releases energy which can be used to generate ATP

36
Q

Structure and function of a triglyceride

A

One glycerol molecule, covalent ester bond, three fatty acid molecules.
Hydrophobic (water insoluble) charges evenly distributed, can’t form hydrogen bonds with water, won’t affect cell water potential
Compact energy store (fats in adipose tissue)
Thermal insulation
Protective properties
Respiration of lipid gives out more water than carbohydrates
Respiration of lipid gives out twice as much energy as carbohydrates
Water used as metabolic water in organisms

37
Q

Structure and functions of phospholipids

A

One glycerol molecule, two fatty acid chains, one phosphate group. All covalent bonds formed by condensation reactions.
Phosphate head hydrophilic, fatty acid tails hydrophobic
Insoluble in water, most of molecule is hydrophobic
Water soluble head allows formation of membranes
Organisms in cold climates more unsaturated fatty acids, so membranes remain fluid
Phosphate groups may have carbohydrates attached for cell signalling

38
Q

Cholesterol functions in living organisms

A
  • 4 carbon based ring structures
  • Made mostly by liver cells
  • Small, narrow, can sit between phospholipid tails to regulate membrane fluidity
  • Strength to membrane
  • Steroid hormones, directly pass through phospholipid bilayer to reach target receptor
  • Can pass through nuclear envelope if target receptor is inside the nucleus (steroid hormones)
  • Can be deposited in blood vessel linings and cause atherosclerosis, leads to circulatory problems
  • Familial hypercholesterolaemia, genetic disorder, cells keep secreting cholesterol above requirements (lack a particular cell surface receptor)
39
Q

Test for presence of protein

A

Biuret test
Add biuret reagent (NaOH and CuSO4)
Reacts with peptide bonds
Pale blue-> lilac

40
Q

Test for reducing sugars

A

Add Benedict’s solution (alkaline CuSO4)
Heat to 80’C
Blue-> red(orangey) precipitate

41
Q

Test for non-reducing sugar

A 
Boil in HCl
Cool and neutralise with Na2CO3
Add Benedict's solution
Heat to 80'C
Blue-> orange(red) precipitate
42
Q

Test for starch

A

Add solution of iodine

Brown->blue(black)

43
Q

Test for lipids

A

Mix with ethanol (dissolves lipid)
Pour mixture into water, mix it
Cloudy white emulsion forms
Lipid comes out of solution near top of water

44
Q

How to use colorimetry to determine the concentration of glucose in a solution

A

Benedict’s test reveals the presence of reducing sugars
It results in an orange-brown precipitate
The more reducing sugar there is present, the more precipitate will be formed and the more Benedict’s solution will be ‘used up’. If the precipitate is filtered out, the concentration of the remaining solution can be measured
This will tell you how much Benedict’s solution has been used up, and this can be used to estimate the concentration of reducing sugar in the original sample
Zero the device using a cuvette containing a ‘blank’- usually water Prepare a calibration curve by
Taking a range of known concentrations of reducing sugars
Carry out Benedict’s test on each one then filter the precipitate out of each solution. Use a colorimeter to give readings of the amount of light passing through the solutions Plot the readings on a graph to show % transmission against concentration
Measure the % transmission of the unknown in the colorimeter
Use this to read the equivalent reducing sugar concentration from the % transmission

45
Q

Which sugars are reducing or non reducing sugars?

A

Reducing sugars-
Loses electrons to other substances (reduces other things, it itself gets oxidised)
All monosaccharides
Some disaccharides (Maltose, lactose, fructose)

Non-reducing sugars-
Some disaccharides
All larger sugars

Biology UNIT 2 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions