Biology chemistry of life slide show

1. The chemistry of life

2. Characteristics of life
• Consist of cells (unicellular/multicellular)
• Grow and develop (in size and number/change according to function)
• Regulate metabolic processes (chemical reactions/energy transfer e.g.
respiration/excretion)
• React to stimuli (colour/light/temp./pressure)
• Reproduce (develop from existing organisms, sexual/asexual)
• Adapt to environments (survival in changing env.: evolution)
• Homeostasis: maintain controlled environment

3. Biological organisation
Atoms of same kind = elements e.g. H
Atoms that combine form molecules e.g. O (atom); O2 (molecule)
Compounds = molecules that contain atoms of 2/more elements e.g. H2O

4. Atoms and Molecules
• The cell is the smallest LIVING UNIT. The cell is the building
block of life
• But the basic building blocks for EVERYTHING in the Universe is
the atom
Atoms are NOT LIVING

7. Compounds
Compounds can be divided into 2
categories
• Organic compounds: come from
living things. E.g…
Sugar (obtained from sugar
cane/sugar beet)
• Inorganic compounds: come from
earth. Eg…
Salt (mined from earth/extracted
from ocean)
• Not only different in origin.. But
also in their properties

8. What are organic compounds?
• Molecules containing carbon
(C) and hydrogen (H)
• Combined with several other
elements (N, O, S, P)
• = 90% of all compounds
• Origin in living organisms
• Life has evolved based on
carbon-containing
compounds
• Thus… organic chemistry = of
utmost importance in
understanding living
organism

10. What are inorganic compounds?
• No living origin
• Do not contain C (except
CO2, CO, -CN)
• Do not contain C and H
together
• Elements and simple
molecules
• Do not burn in O2
• Most important = H2O

11. What’s the diff???
Organic Inorganic
• Easily decomposed (e.g. sugar – into
carbon and water when heated)
• More difficult to decompose (e.g.
salt must be heated to very high
temperatures)
• From living organisms • From the Earth
• Contains C & H (carbon backbone) • Can contain C / H but never both

12. Water (H2O)
• In our bodies: roughly 70% (same as Earth)
• Source of O2 (photosynthesis)
• Solvent for most biological reactions
• Habitat for many organisms
• Has polar molecules

13. Forces
• Form H bonds with one another
• Strong intermolecular forces are responsible for cohesion forces between
water molecules
• Can form strong adhesion forces with many other substances
• Cohesion & adhesion forces = responsible for capillarity

14. Capilarity activity
You will need:
• 4 small cups
• Water
• Colouring agent
• Tissue paper

15. Hydrophilic: Hydrophobic:
• Substances that react readily with
water
• Water-soluble
• E.g. sucrose, table salt)
• Substances that do not dissolve in
water
• E.g. fats and oils

16. Minerals
= certain elements essential in normal
functioning of
cells, metabolic processes, well-being
Take part in key chemical reactions
Macronutrients:
• Minerals we need in large quantities
every day
• C, H, O, N, P, S, Ca, Mg
Micronutrients:
• Need only small quantities every day
• E.g. Fe, Na, I2

17. How are minerals obtained?
Plants
•From the soil
Animals
•From food they eat

18. Acids, bases, salts
• pH scale: indicates degree of acidity/alkalinity
• Acid: (pH of 0 - 6) excess H+ ions
• Neutral: pH of 7
• Alkaline: (pH of +7 – 14) excess OH- ions

20. pH in our bodies
•How acidic are you?
•Let’s do a test…
Video: pH in the body
https://youtu.be/A8bKPPOB0Rs

21. Salts

22. Electrolytes
• When salts dissolve in water, ions
dissociate to form electrolytes
• Electrolytes conduct electric
currents
• Carry the electrical energy for
muscle contractions and
transmission of nerve impulses
• An electrolyte imbalance can be
quite detrimental to your health.

23. Importance of
Electrolytes:
• Calcium: Most abundant. 99% found in skeletal structure.
Critical for transmission of nerve impulses, blood clotting,
and muscle contraction.
• Magnesium: Plays an important role in the synthesis of
DNA and RNA. Helps maintain normal nerve and muscle
function, stabilizes blood sugar, boosts the immune
system, and promotes the formation of bones & teeth.
• Chloride: Works closely with Na to maintain balance of
fluid in cells, maintains pH balance in the body, balances
out positive ions of blood, tissue and organs.
• Sodium: Controls total amount of water in body, regulates
blood volume, maintains muscle & nerve function. Too
little = most common electrolyte disorder with symptoms
of headache, confusion, fatigue, muscle spasms.
• Potassium: keeps electrolytes in balance and regulates
heartbeat and muscle function. Deficiency has symptoms
of muscle weakness and cramping, however severe cases
can also be deadly.

25. Activity: What do I smell?
• What causes scent?
Molecules!
• Molecules, when inhaled, bind with
molecular receptors in our noses. This
sends an signal to the brain that we
experience as a smell
• Some molecules (N, O, H2O, CO2) have no
smell
• Most of the smells we experience ae
caused by organic molecules
Which smells do you love/grosses you out
the most?

26. Organic chemistry
= the study of carbon-containing compounds
and their reactions
• Organic compounds =
common in foods, drugs,
petroleum products, pesticides
• Large and complex
• Combustible in O2 to form CO2

27. There are 4 Organic Compounds That Make Up
All Living Things
•Carbohydrates
•Lipids
•Proteins
•Nucleic Acids
These molecules are huge, so
they are called
macromolecules.
Are polymers (i.e. made of
smaller monomers/building
blocks)
The food you eat contains all 4 organic compounds.
When your body digests the food, you break the
food down into its most basic parts ie monomers
(simple sugars, fats and amino acids) so that your
body can use them to do different cellular processes.

28. Carbohydrates
• Contains C, H and O (1:2:1)
• As name implies, often have general formula : CH2O
• Responsible for short-term energy storage in living organisms
• Main structural components of plants

31. Monosaccharides (Building blocks of Carbs)
•Simple/’’single’’ sugars
•Cannot be broken down into
simpler carbohydrates
•3-7 C atoms
•Have a prefix that depends
on nbr of C atoms
•Followed by suffix –ose
•Soluble in water
• 5C (pentose) sugars: ribose (RNA)/
deoxyribose (DNA)
• 6C (hexose) sugars: glucose, fructose
(fruit), galactose (brain sugar)

33. Glucose
• Source of energy for most living
organisms
• Used to form other organic
compounds (amino acids / fatty
acids)
• In blood: under homeostatic
control
• Glucose test: with Benedict’s
solution / Fehling’s A and B
solutions

34. Activity: Test for glucose

35. Disaccharides
• Two ‘’single’’ sugars join together, eliminating water
• Can be decomposed into 2 simpler carbohydrates
• Are soluble in water
Glucose + glucose = maltose (malt sugar)
Glucose + fructose = sucrose (table sugar)
Glucose + galactose = lactose (milk sugar)

36. Polysaccharides
• Long chainlike C molecules (Monosaccharides that link together)
• Macromolecule consisting of monomers
• Complex carbohydrates
• Most common: starch, cellulose & glycogen

37. Starch
• Usual form in which carbs are stored in plants
• Insoluble in water
• Common in potatoes and grains
• Soft, pliable substance, easily chewed and swallowed
• During digestion: links between individual glucose units = broken
• Allows glucose molecules to pass through intestinal wall, into bloodstream

38. Activity: test for starch

39. Cellulose
• Main structural component of plants
• Bonding in cellulose makes it
indigestible by humans
• When we eat cellulose, it passes
right through intestine
• Provides bulk to stools, prevents
constipation
• Ruminants have specific microbes

40. Glycogen
• Similar to starch but chain is highly branched
• ‘’animal starch’’ reserve carbs are stored in animal cells (muscle and liver)
• Excess glucose in blood = stored as glycogen until it is needed
• Soluble in water

41. Lipids
• = fats and oils
• Long chains of C and H (few functional groups that contain O)
• Phospholipids also contain phosphorous (P)
• Stores energy in bodies of living things
• Makes up certain structures in cells e.g. cell membrane
• Insoluble in water (hydrophobic)

42. Structure of lipids
• When lipid molecule = broken down it releases energy
• Glycerol = type of alcohol with 3 hydroxyl groups
• Fatty acids = have long hydrocarbon chains

44. Functions of fats
• Stored under skin as insulation against cold
• Energy reserve
• Structural component of cell membrane
• Waterproofing
• Necessary for metabolic reactions
• Vit A,D,E,K are only soluble in fats
• Therefore:
important to include
Omega fatty acids
in our diet

45. • Waxy type of fat formed naturally in the body
• Only 25% comes from food you eat
• Essential for forming of cell membranes
• When your skin = exposed to sun, UV rays change cholesterol into Vit D
• Too much in blood can lead to plaques in blood vessels (artherosclerosis) which
can lead to heart attack
Cholesterol

46. Fat emulsification
• Fats are emulsified by adding soap (alkaline)/lemon juice (acidic)
• Fats in stomach = emulsified by acid in gastric juice

47. Activity: Test for lipids
• Fats (lipids) soluble in non-polar solvents (ether);

48. Proteins
= the working molecules of life
• Consist of atoms of C, H, O and N (sometimes S, P and Fe)
• Most of chemical reactions that occur in living organisms are
catalysed/enabled by proteins
• Involved in all cellular reactions
• Very complex structure

49. Structure of proteins
• Polymers of amino acids
• Amino acids interact with one another, causing protein chain to twist in
specific way
• These shapes = very important
• E.g. insulin promotes absorption of glucose out of blood into muscle cells
(needed for energy)

50. Functions of proteins
• Play a role in transport (haemoglobin in blood, carrier molecules in cell membrane)
• Nutrients (albumin in eggs, meat protein)
• Hormones (insulin)
• Movement (actions in muscles)
• Protection against disease (antibodies)
• Reserve source of energy
• Structural role in cell membranes
• Structural components in muscle, skin, cartilage, nails, wool, hair
• Important in structure, growth, maintenance and repair of cells

52. Amino-acids
• The monomers of proteins (building blocks)
• Only 20 different amino acids: used to make the MANY proteins in plants
and animals!
• Bond together by means of peptide bonds.
• A chain of less than 50 amino acids is called a polypeptide.
• 50+ amino acids make a protein.
• Bacteria and plants produce own amino acids
• Animal cells can produce some amino acids. Those that cannot be produced
are called essential amino acids, and these must be ingested (eaten).

53. Where are proteins produced?
• In ground plasm of cell at ribosomes
• DNA controls processes via RNA
Video
https://youtu.be/gG7uCskUOrA

54. Levels of organisation of proteins
Determined by
nbr and
sequence of
amino acids
Refer to shape of polypeptides
(many amino acids but not a protein yet)
Determine the
actual structure
and functioning
of proteins

56. Properties of proteins
• Heat/pH causes a protein to denature
• Low temp makes proteins inactive
• Polymers are formed by condensation synthesis
• For every monomer added, water is released
• Polymers are broken up by hydrolysis: adding H2O
• Controlled by enzymes

57. Enzymes
• = Proteins that act as catalysts
• Catalyst: start/accelerate reactions without taking part in the reactions/
undergoing changes themselves
• Same properties as proteins
• pH & temp specific
• Optimum temp in body = 37 degrees
• Sometimes inactive until needed again (toxins may inhibit permanently)

58. Reactions
• Enzymes make chemical reactions occur at a suitable rate for an organism’s
survival
• Without enzymes, the metabolic rate in cells would be too slow for an
organism to survive
Anabolic/Catabolic reactions

59. Lock-and-key mechanism
• Active site: a region on the enzyme molecule that has a specific shape
• Substrate molecule: matches the specific shape of the active site
• Enzyme and substrate fit together like a key fits a lock
• When joined together: chemical reactions takes place
• When reaction is finished: the product is set free from the enzyme
• Can be used over and over again

60. Enzymes in everyday life
1. Food and drinks
in yeast-respiration- bread to rise & alcohol produced as a waste
product-wine, beer etc
in lactic acid bacteria-cheeses & yoghurt
to break down starch into sugars in corn/wheat→syrups
2. Detergents-protease, lipase, carbohydrase,
3. Biodegradable plastic (plant polymers-shorter-easier to break down by
decomposers)
4. Leather-remove keratin & pigment stains
5. Prepare cotton for weaving & remove impurities
6. Esterase –to remove glue from paper to be recycled.

61. Co-enzymes & Co-factors
• Coenzyme: A substance that enhances the action of an enzyme
• = small molecules that cannot, by themselves, catalyse a reaction but they
can help enzymes to do so.
• = organic nonprotein molecules (co-factor) that bind with the protein
molecule (apoenzyme) to form the active enzyme (holoenzyme).
• A number of the water-soluble vitamins such as vitamins B1, B2 and B6
serve as coenzymes.

62. DNA=Deoxyribonucleic Acid / Deoxyribose Nucleic Acid
DNA= the code of Life
History
• Rosalind Franklin & Maurice
Wilkins took X-ray photos that
show DNA has a regular shape
• Double helix (1953): Watson &
Crick
• Wilkins, Watson & Crick: Nobel
Prize in 1962
• James Watson headed up the
Human Genome Project

63. DNA in our cells

64. DNA: packing 300 000 000 nucleotides in 1 cell!
• DNA is tightly wound around
histones
• Gene= a sequence of
nucleotides which code for a
specific protein / characteristic
• DNA wrapping-alleles should be
adjacent

65. DNA is made up of Nucleotides
(Nucleotides are monomers of DNA)

66. DNA: Structure
• A double helix
• Sugar-Phosphate backbone
connected by base pairs
• Bases are connected by weak
Hydgrogen bonds
• Deoxyribose sugar
• Nitrogen bases:
• Adenine
• Thymine
• Guanine
• Cytosine
A=T (Adenine bonds with Thymine via 2 weak Hydrogen
bonds)
G≡C (Guanine bonds with Cytosine via 3 weak hydrogen bonds)
Triplet code: 3 bases code for an amino acid

67. Nucleic Acids
• Transfer genetic information
• Determine which protein is produced by the cell
• Contain C, H, O, N, P
• Made up of building blocks: nucleotides
Two types of nucleic acids:
https://www.youtube.com/watch?v=NNASRkIU5Fw
Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA)
Found in the nucleus Found in the nucleolus, cytoplasm, ribosomes
Stores hereditary info that passes from one
generation to the next
Build required proteins from amino acids

68. • Contain a chemical

70. Vitamins
• Organic compounds essential for metabolic reaction
• Needed in small amounts
• Two groups
1. Fat soluble (Vit A, D, E and K) – if these build up in the body they can become toxic.
2. Water soluble (Vit B and C) – if too many are taken in, they are excreted in the urine.
See tables on pg 95 (Minerals) and pg 96 (Vitamins)

75. Presenting a Fruit /Vegetable
• Choose a fruit/ vegetable you
would like to investigate
• Find out the nutrients, amount
of water, pH, amounts and types
of organic & inorganic
molecules-including vitamins
and minerals found in the fruit /
vegetable
• Explain how important this
fruit/vegetable is in our diet
• Are there deficiencies /illnesses
we could suffer from if we didn’t
eat this fruit or vegetable?

76. Assessment: Report 20 + Presentation 5=25
Assessment Criteria 5 3 1
Effective presentation Clear, good pace, volume etc. Not well prepared
Unclear / irrelevant slides / pictures
Reading
Content All included
10
60%
6
Less than 20%
2
Structure Logical, clear
5
(A4 poster)
Mostly clear
3
Disordered and difficult to
understand / Follow
1
References 3 Report not included
2
No references
0
Planning Handed in on time
2