EL: To begin investigating what cells are and the molecules they are made of

CHEMICAL NATURE OF THE CHEMICAL NATURE OF THE CELL 1CELL 1

CELL THEORYCELL THEORY• All living things are made cells – they are the building blocks from

which living things are made.

• New cells are produced from existing cells.

Where do cells fit in to the Where do cells fit in to the bigger picture?bigger picture?

Where do cells fit in to the Where do cells fit in to the whole organism?whole organism?

ATOM

CELL

TISSUE

ORGAN

MOLECULE

ORGANELLE

ORGANISM

Did you know?Did you know?Some organisms are one cell (uni

cellular)

Other organisms have more than one cell (multi cellular)

Organisms have adapted to serve the needs of their cell or cells

CELLS ARE CELLS ARE REALLY REALLY SMALL!SMALL!

Types of cellsTypes of cellsProkaryotic

◦ Very small: less than 2m in diameter

◦ Lack internal compartments

◦ Bacteria and archaeans

Eukaryotic

◦ Much larger: 10-100m in diameter

◦ More complex structure – compartments called organelles

◦ Animals, plants, fungi and protists

What is a cell?What is a cell?

CELL BOUNDARY (PLASMA MEMBRANE)

INTRACELLULAR AQUEOUS

ENVIRONMENT – CYTOSOL or CYTOPLASM

EXTRACELLULAR AQUEOUS

ENVIRONMENT

A fluid filled compartment containing atoms and molecules

WHAT IS A CELL?WHAT IS A CELL?

Outputs: useful products for export

(biomacromolecules)

Chemical reactions between inputs driven by

energy in response to external/internal signals

Inputs(small molecules)

Signals

Output: waste products

A chemical factory

Outputs: useful products for export

(biomacromolecules)

WHAT IS A CELL?WHAT IS A CELL?

Outputs: useful products for export

(biomacromolecules)

Chemical reactions between inputs driven by

energy in response to external/internal signals

Inputs(small molecules)

SignalsOutput: waste products

A chemical factory

Outputs: useful products for export

(biomacromolecules)

What are cells made of?What are cells made of? Six atoms make up most of the

matter in living organismsCarbon, hydrogen, nitrogen, oxygen,

sulfur and phosphorus

These atoms can combine to form large molecules

Many important concepts in Unit 3 Biology can be explained by the interaction between these molecules

Molecular representationsMolecular representationshttp://www.concord.org/~btinker/

workbench_web/unitIV_revised/molecular_representations.html

MoleculesMoleculesNon-polar moleculesMolecules that have no overall charge are called non-polar. They are not attracted to water molecules and are described as hydrophobic (water fearing)

Polar moleculesMolecules that have regions of positive and/or negative charge are called polar. They are attracted to other polar molecules, like water, and are described as hydrophillic (water loving)

Water moleculesWater moleculesCells contain the molecule water – H2OWater is called a polar molecule The oxygen atom attracts the electrons it

shares with the hydrogen atoms more strongly This makes the oxygen atom slightly

negative and the hydrogen atoms slightly positive ()

water moleculeswater molecules The oxygen atom of one water

molecule attracts the hydrogen atom of another water molecule - this is called hydrogen bonding

Carbon moleculesCarbon molecules

Many molecules contain carbon due to its ability to form strong stable covalent bonds with carbon and other atoms

Each carbon atom can form four covalent bonds – these bonds can be single (saturated), double or triple (unsaturated)

Hydrocarbon moleculesHydrocarbon moleculesHydrocarbons are made of

carbon and hydrogen atoms (eg methane – CH4)

Hydrocarbons are non-polar

Hydrocarbon moleculesHydrocarbon moleculesOther groups can be substituted

for a H, giving it a new chemical character (eg methanol – CH3OH)

These functional groups can make a hydrocarbon polar and explain many of the molecular interactions in a cell

Common functional groups are OH, COOH, NH2 and HS

BIOMACROMOLECULESBIOMACROMOLECULESLarge molecules that are integral to the structure and function of cells are called biomacromolecules. There are four types:

Carbohydrates Proteins

Lipids Nucleic acids

BIOMACROMOLECULESBIOMACROMOLECULES Cells make biomacromolecules from smaller subunits

Each kind of biomacromolecule has characteristics or properties that make it effective for carrying out its particular function

Use pages 9-26 from your text book and/or the Biomacromolecule MP3 G-Casts at http://www.gtac.edu.au/site/gcasts/g_casts.html to fill in the table below.

Start Chapter 1 questions

ACTIVITY/HOMEWORKACTIVITY/HOMEWORK

Type of biomacr

o-molecul

e

Atoms in molecul

e

Sub-units/

monomers

Structure

(picture)

Polar/Non Polar

Cellular function

s

ReflectionReflectionHow well did you remember the

content of the lesson today from Unit 1

OR

How well did you understand the new content today?

CHEMICAL NATURE OF CHEMICAL NATURE OF THE CELL 2THE CELL 2

EL: To review our biomacromolecule table from last class and learn how

biomacromolecules are synthesised

HOMEWORKHOMEWORK

Type of biomacr

o-molecul

e

Atoms in molecul

e

Sub-units/

monomers

Structure

(picture)

Polar/Non Polar

Cellular function

s

lipidslipidsMade of C, H and O atoms

Subunits are fatty acids or glycerol

Insoluble in water due to non-polar HC regions

Three important cellular functions◦ Chemical energy storage (store two

times as much energy as carbohydrates)◦ Structural◦ Chemical signal

lipidslipidsType Function

Fatty acids (eg stearic acid, oleic acid)

Energy sourceSubunit of other lipids

Triglycerides Energy storage

Phospholipids Structural component of plasma membranes

Glycolipids Recognition sites on plasma membranes

Steroids (eg cholesterol, sex hormones)

Component of plasma membranes (regulates fluidity)Signaling molecule

Terpenes (eg Vitamin A) Antioxidant

lipidslipids

Saturated◦ single covalent

bonds between atoms

◦ Straight molecule

◦ Solid at room temperature

Unsaturated◦ Double or triple

covalent bonds between molecules

◦ Bent molecule◦ Liquid at room

temperature

Glycerol – a fatty alcoholGlycerol – a fatty alcohol

Glycerol has three OH groups that bond with three fatty acids◦When the fatty acid group reacts with

the alcohol group, water is formed and is therefore a condensation reaction

◦However, there are no repetative linkages: so lipid not a polymer

phospholipidsphospholipids

Phospholipids have:◦a hydrophopic tail of two fatty

acids attached to a glycerol ◦A hydrophillic phosphate head

with another small groups attached to the phosphate

carbohydratescarbohydrates

Also made of C, H & O atoms in a 1:2:1 ratio

Subunits are simple sugars called monosaccharides and disaccharides

Solubility in water – depends on size and polarity

Three important cellular functions◦ Chemical energy storage◦ Component of other important molecules (eg

DNA)◦ Structural (esp. in plants)

carbohydratescarbohydratesType Example Function

Simple carbohydrates

Monosaccharides (single sugar unit)General formula: (CH2O)n

Glucose Energy source

Fructose Energy source

Ribose Component of DNA

Disaccharides(two sugar units)

Sucrose Transport sugar in vascular plants

Lactose Component of milk

Maltose Obtained in breakdown of starch

Complex carbohydrates

Polysaccharides(many sugar units)

Starch Storage molecule in plants

Glycogen Storage molecule in animals

Cellulose Component of plant cell wall

Chitin Component of insect and crustacean exoskeleton

Nucleic acids – DNA & Nucleic acids – DNA & RNARNA

Subunits are called nucleotides and are composed of:

◦ A five carbon (pentose) sugar Ribose in RNA Deoxyribose in DNA

◦ A negatively charged phosphate group

◦ An organic nitrogen containing compound called a base Purines: Adenine (A) and Guanine (G) Pyrimidines: Thymine (T) and Cytosine in DNA

or Uracil in RNA

Nucleic acidsNucleic acids

Double ring

Singlering

PURINESAdenineGuanine

PYRAMIDINESThymineCytosineUracil (in RNA)

Nucleic acidsNucleic acids 5’-Sugar molecule of one

nucleotide binds to the phosphate group of the next in a condensation polymerisation reaction

(http://www.gtac.edu.au/site/gcasts/UNIT3/bio-macromolecules/index.html)

A phosphodiester bond is formed between the nucleotides creating a polynucleotide strand

Polynucleotide strand extends in a 5’-> 3’ direction – said to have directionality

Nucleic acidsNucleic acids

DNA is made of two polynucleotide strands that are held together by hydrogen bonding between the complementary base pairs

The two strands are anti-parallel

3’-carbon

3’-carbon5’-carbon

5’-carbon

Nucleic acids – DNA & Nucleic acids – DNA & RNARNA

Found within nucleus

Store information in a chemical code called a gene that directs cells to make proteins

Differences between DNA & RNADNA RNA

Double stranded Single stranded

Deoxyribose sugar (one less O atom)

Ribose sugar

Thymine base Uracil base

ProteinsProteins

Subunits are amino acids composed of:◦Central carbon atom attached to:

Hydrogen atom Carboxyl (COOH) group Amine group (NH2) R group

Type of R group:◦Distinguishes an amino acid and gives

it particular properties◦Gives protein molecule polar and non-

polar regions

Protein structureProtein structure

Each protein molecule has a characteristic 3D shape

The function of the protein depends on the shape of the molecule

Protein structure can be explained by four levels

Protein structureProtein structure

Primary:◦Sequence of amino acids

peptide bonded through condensation polymerisation reaction into polypeptide chain

Secondary:◦Parts of the chain undergo

coiling (-helices) and folding (-sheets) due to hydrogen bonding between amino acids.

◦Other parts form random loops

Protein structureProtein structure

Tertiary:◦Hydrophilic and hydrophobic R groups

of one amino acid attract like groups of another amino acid, making the chain more folded, coiled or twisted into the protein’s functional shape

◦Determines biological functionality

Quarternary:◦Many large protein molecules have two

or more polypeptide chains

Protein functionProtein function

Function of protein Example

Structural Collegen, keratin, fibrin

transport Haemoglobin, protein carrier, serum albumin

regulatory Hormone, enzyme

Making a Making a BIOMACROMOLECULEBIOMACROMOLECULE

Biomacromolecules are synthesised inside cells. This involves linking smaller sub-units to form large chains.

Carbohydrates, proteins and nucleic acids are formed when sub-units called monomers link to form a polymer in a condensation polymerisation reaction

Lipids are not polymers as they are composed of distinct chemical groups of atoms that don’t undergo a condensation reaction

 

Condensation Condensation polymerisation reactionpolymerisation reaction

The OH groups on adjacent monomers can react, eliminating a water molecule.

Nucleic acidsNucleic acids

2’ 3’

1’ 4’C 5’

H OH

Nitrogen base

Phosphate group (-ve)

O

2’ 3’

1’ 4’C 5’

H OH

Nitrogen base

Phosphate group (-ve)

O

5’-carbon

3’-carbon

SYNTHESIS OF SYNTHESIS OF BIOMACROMOLECULESBIOMACROMOLECULES

Autotrophs: organisms that are able to synthesise their own biomacromolecules from inorganic compounds

Plants and algae photosynthesisCertain species of chemosynthetic bacteria use

the energy released from areas of geothermal activity

Heterotrophs: synthesise their own biomacromolecules from organic molecules they have ingested

animalsfungimajority of bacteriamany protists

ActivitiesActivitiesUse the molecular model kits to make some

carbohydrate and lipid molecules

Use pipe cleaners to demonstrate different levels of protein organisation

Build a model of DNA using pipe cleaners and papererclips

For both, write a short script explaining DNA and proteins to a year 7 or 8 science class

ReflectionReflectionDid the hands on activities help

you to better understand biomacromolecules or do you think the table helped you more?

CHEMICAL NATURE OF CHEMICAL NATURE OF THE CELL 3THE CELL 3

EL: To investigate where biomacromolecules fit in to

the “tree of life”

ActivityActivity In groups of 3 – 4 (4 groups in total), go to

http://www.concord.org/~btinker/workbench_web/unitIV_revised/tree_life_wrkst.html

Investigate the biomacromolecule that has been assigned to you – you will zoom into organs and tissues of plants and animals in order to discover life's essential building blocks. The exercise includes just a few of the many possible "zooms" into the structures of living organisms.

Answer the following questions:◦ What can you find out about macromolecules building blocks of

our organs and tissues ? ◦ How different are these building blocks from one another? Are

there similarities between them?

Also answer the relevant questions to your molecule on the bottom of the main zoom page

Report back to the rest of the class what your group learnt

Activity/HomeworkActivity/HomeworkFinish Chapter 1 Questions,

including concept map (due next lesson)

Study for test (next lesson)

ReflectionReflectionDid the tree of life activity help

you to better understand biomacromolecules?

Why or why not?