IB Biology Joni Rogan Escuela de Lancaster A.C.. Course outline - Theory  1: The chemistry of life  Statistical analysis  2: Cells  3: Genetics 

IB Biology Joni Rogan Escuela de Lancaster A.C.

Course outline - Theory  1: The chemistry of life  Statistical analysis  2: Cells  3: Genetics  4: 5: Ecology and evolution  6: Human health and physiology

Theory Assessment  Makes up 76% of final grade  3 exam papers:  Paper 1- 30 MCQ  Paper 2- data based Qs, Extended response  Paper 3- short answer questions

Course Outline- Practical  Practicals make up 24% of final grade.  The marks are in 2 parts:  Investigations  Group 4 projects

Investigations  Throughout course as fits with theory  You are assessed on 2 examples of each of the following:  Design  Data collection  Concluding  Evaluating

Group 4 Projects  Cross-curricular Science project in small groups (with Chemistry and Physics)  You design and carry out an investigation on a theme  You are marked on:  Manipulative skills  Personal skills

To do well in IB Biology.....  Work hard and learn at home throughout the year  Use the rubrics  Learn the command terms  Take the practical work seriously

Biological Molecules Topic 1

What are living things made of?  4 most commonly occuring elements?  Other elements?

ElementRole served in living things Sulfur Component of amino acids Phosphorus Component of nucleotides in DNA and RNA Iron Role in oxygen transport in animal blood. Component of cytochrome proteins involve in electron transport in plants, animals and prokaryotes Sodium Role in nerve impulse in animals. Essential for maintaining metabolic activities in some bacteria. Calcuim Component in strengthening bones and teeth.

What are elements are made of?  Chemistry revision!

What are we made of? Richmond upon Thames College

Introduction  For each of the following you should be able to: Describe the properties Know the general formulae & structure Understand the role in animals & plants Water Carbohydrates Lipids Proteins Nucleic acids

Water  What is it made of?  How is it chemically arranged and held together?  What does this mean for how it behaves?  How is this useful for life?

Water  Water is a polar molecule  It forms weak hydrogen bonds  It remains a liquid over a wide temperature range  Water molecules stick to one another = cohesion (surface tension)  Water molecules stick to other substances = adhesion (capillarity) O H H + + -

Water  It has a high specific heat capacity – so water can maintain a reasonably constant temperature (homeostasis)  It has a high latent heat of vaporisation – so animals use water to cool themselves  It is less dense as a solid (ice)…  … and ice is a poor conductor  Water is a good solvent

PropertyChemistryUse in living organism CohesionWater molecules stick to each other because of Hydrogen bonds Water is used as a transport medium in the xylem of plants, it can be pulled up tall plants. SolventWaters’ polartiy means it can dissolve particles with positive or negative charges or other polar molecules. Water is the medium for metabolic reactions. It also can be used as a transport medium. ThermalWater has a large heat capacity, high energy is needed to break the Hydrogen bonds. Blood (mainly water) can carry heat from warmer parts of body to cooler parts. Water is most useful as a liquid, and is a liquid in most parts of the earth. When water evaporates, energy to break Hydrogen bonds comes from the liquid water, which cools it down. So water can be used as a coolant.

Carbohydrates  Contain the elements Carbon Hydrogen & Oxygen  There are 3 types:  Monosaccharides Monosaccharides  Disaccharides Disaccharides  Polysaccharides Polysaccharides

Monosacharides  (CH 2 O) n  If n=3, triose (glyceraldehyde)  If n=5, pentose (fructose, ribose)  If n=6, hexose (glucose, galactose)  Monosaccharides are used for  Energy  Building blocks O CC C C C C

Isomerism  They can exist as isomers:  &  glucose OH  

Disaccharides  Formed from two monosaccharides  Joined by a glycosidic bond  A condensation reaction:  glucose + glucose  maltose  glucose + galactose  lactose  glucose + fructose  sucrose

Condensation reaction O CC C C C CO CC C C C C OH

Condensation reaction O CC C C C CO CC C C C C OHOHOH

Condensation reaction O CC C C C CO CC C C C C O H2OH2O

O CC C C C CO CC C C C C O A disaccharide 1,4 glycosidic bond 41

Polysaccharides  Polymers formed from many monosaccharides  Three important examples:  Starch Starch  Glycogen Glycogen  Cellulose Cellulose

Starch Insoluble store of glucose in plants formed from two glucose polymers:  Amylose  -glucose 1,4 glycosidic bonds Spiral structure  Amylopectin  -glucose 1,4 and some 1,6 glycosidic bonds Branched structure

Glycogen  Insoluble compact store of glucose in animals   -glucose units  1,4 and 1,6 glycosidic bonds  Branched structure

Cellulose  Structural polysaccharide in plants   -glucose  1,4 glycosidic bonds  H-bonds link adjacent chains O O O O O

Lipids  Made up of C, H and O  Can exist as fats, oils and waxes  They are insoluble in water  They are a good source of energy (38kJ/g)  They are poor conductors of heat  Most fats & oils are triglycerides

Triglycerides  Formed by esterification…  …a condensation reaction between 3 fatty acids and glycerol: Glycerol H C H C C H H H H O O O

Fatty acids  Carboxyl group (-COOH)  attached to a long non-polar hydrocarbon chain (hydrophobic): H H C H H C H H C H C O O H C H H C H H C H H C H H A saturated fatty acid (no double bonds)

HH C O O H C H H CC CC H C H H C H H A polyunsaturated fatty acid C O O H C H H C H H C H H C H C H H C H H C H H A monounsaturated fatty acid HH

Esterification H C H C C H H H H O O O C O O H C H H C H H C H H C H H Glycerol Fatty acid

Esterification H C H C C H H H H O O O C O O H C H H C H H C H H C H H Ester bond water

Esterification  This happens three times to form a triglyceride: glycerol fatty acids

Phospholipids  One fatty acid can be replaced by a polar phosphate group: glycerol Hydrophobic fatty acids hydrophilic phosphate

Functions of lipids  Protection of vital organs  To prevent evaporation in plants & animals  To insulate the body  They form the myelin sheath around some neurones  As a water source (respiration of lipids)  As a component of cell membranes

Research Topics 1) Hydrogenated fats What are they? What foods are they in? How do your bodies deal with them? Why do some people want them banned? 2) Atkins Diet Why does the diet get people to lose weight? What is the difference between how carbohydrates and fats are stored and metabolised? Why are Doctors worried about people on the diet?

Proteins  Made from C H O N & sometimes S  Long chains of amino acids  Properties determined by the aa sequence Amino acids H C H NC H H O O R  ~20 aa  Glycine R=H  Alanine R=CH 3 amine carboxyl

Peptide bonding H C H NC H H O O R H C H NC H H O O R

H C H NC H H O O R H C H NC H H O O R

C H NC H H O R H C H NC H H O H O O R water Peptide bond A condensation reaction

Peptide bonding C H NC H H O R H C H NC H O O R A dipeptide

Primary structure  The sequence of aas is known as the primary structure  The aa chain is a polypeptide Secondary structure  H-bonding forms between adjacent aa R groups  This results in the chains folding:

Secondary structure  -helix  -pleated sheet

Tertiary structure  Bonding between R-groups gives rise to a 3D shape  H-bonds =O HN-  Ionic bonds –NH 3 -COO-  Disulphide bridge --CH 2 S-SCH 2 - affected by temp & pH affected by pH affected by reducing agents

Quaternary structure  Some proteins have more than one polypeptide chain  Each chain is held together in a precise structure  eg Haemoglobin

Types of proteins  Fibrous proteins  e.g. collagen  Insoluble  structural  Globular proteins  e.g.enzymes  Soluble  3D shape

Functions of proteins  Enzymes –  Transport –  Movement –  Cell recognition –  Channels –  Structure –  Hormones –  Protection – Amylase Haemoglobin Actin & myosin Antigens Membrane proteins Collagen & keratin Insulin Antibodies

Nucleic acids  DNA & RNA  Made up of nucleotides: phosphate pentose sugar base

Nucleotides  2 types of base:  Pyrimidines -  Cytosine C  Thymine T  Purines  Adenine A  Guanine G

Complimentary base pairing  Adenine will only bind with Thymine  Cytosine will only bind with Guanine TCGA

DNA structure nucleotide Condensation polymerisation of the deoxyribose nucleotides

Questions  What things must DNA be able to do to allow an organism to survive?  How is it possible that DNA can control all of the chemical reactions occurring inside a cell?  What type of protein molecules control DNA replication (can you name any specific ones)?  Why is DNA replication called “semi-conservative”?

Replication  During cell division the DNA must replicate  The DNA double helix unwinds (helicase enzyme does this) at the replication fork  The exposed bases bind to free floating nucleotides in the nucleoplasm  The enzyme DNA polymerase binds the complimentary nucleotides  Replication is semiconservative

Replication  DNA polymerase can only work in one direction  Therefore on one DNA strand replication occurs in small sections called okazaki fragments  The okazaki fragments are then joined together by an enzyme called DNA ligase

Questions  Briefly explain the purpose of DNA replication  Summarise the steps involved in DNA replication (3)  Explain the jobs of the following enzymes:  Helicase  DNA polymerase  How long do you think it would take for one bacterial cell to replicate all of its DNA?

The genetic code  The sequence of nucleotide bases forms a code  Each ‘code word’ has three letter – a triplet code  Each codon codes for a specific amino acid e.g:  GGG = proline  CGG = glycine  ATG = tyrosine  ACT = stop (no amino acid)

Protein synthesis  The DNA codes for proteins  A copy of DNA (mRNA) is made in the nucleus (transcription)  The mRNA is used to make a protein (translation) in the cytoplasm

Transcription  The DNA unwinds  Only one DNA strand will be transcribed (the sense strand)  Free nucleotides join onto complimentary bases  RNA polymerase links adjacent nucleotides  The completed mRNA moves out of the nucleus In RNA there is no thymine (T). Instead, another base, uracil (U) takes its place. U forms hydrogen bonds with A

Transcription

Amino acid activation  transferRNA:  tRNA binds onto a specific amino acid

Translation  mRNA binds to a ribosome  tRNA carries an amino acid to the ribosome

Translation  A second tRNA brings another aa  The two aa’s bind  The process repeats

Translation  A polypeptide chain forms  Eventually a stop codon is reached

The Human Genome Project  A multinational project aimed at sequencing the entire human genome  Visit the Human Genome Web site:  www.ornl.gov/hgmis/project/about.html www.ornl.gov/hgmis/project/about.html  www.sanger.ac.uk www.sanger.ac.uk

Acknowledgements  Animated cell models used by kind permission of The Virtual Cell website:  Feel free to use this presentation for educational non-profit making purposes.

Quiz  1. Which of the following is not an important property of water a) Its polar nature Its polar nature b) Its low specific heat capacity Its low specific heat capacity c) Its high latent heat of vaporisationIts high latent heat of vaporisation d) Its low density in solid formIts low density in solid form

Quiz  2. The general formula for a monosaccharide is: a) (CH 2 O) n (CH 2 O) n b) (CHO) n(CHO) n c) C(H 2 O) nC(H 2 O) n d) C n H 2 O nC n H 2 O n

Quiz  3. Sucrose is made up of a) glucose + fructose glucose + fructose b) glucose + galactoseglucose + galactose c) glucose + glucoseglucose + glucose d) galactose + fructosegalactose + fructose

Quiz  4. Amylopectin is made up of: a)  -1,4 glycosidic bonds  -1,4 glycosidic bonds b)  -1,4 &  -1,4 glycosidic bonds  -1,4 &  -1,4 glycosidic bonds c)  -1,4 & 1,6 glycosidic bonds  -1,4 & 1,6 glycosidic bonds d)  -1,4 & 1,6 glycosidic bonds  -1,4 & 1,6 glycosidic bonds

Quiz  5. Formation of a triglyceride does NOT involve: a) A condensation reaction A condensation reaction b) Esterification Esterification c) Polymerisation Polymerisation d) A reaction between 3 fatty acids & glycerol A reaction between 3 fatty acids & glycerol

Quiz  6. The general formula of a saturated fatty acid is: a) C n H 2n O 2C n H 2n O 2 b) C n (H 2 O) n C n (H 2 O) n c) (CH 2 O) n(CH 2 O) n d) (CH 2 ) n O(CH 2 ) n O

Quiz  7. Which of the following is not responsible for a proteins tertiary structure a) ionic bondingionic bonding b) covalent bondingcovalent bonding c) hydrogen bondinghydrogen bonding d) disulphide bondingdisulphide bonding

Quiz  8. Which of these is not an amino acid: a) alaninealanine b) cysteinecysteine c) glycineglycine d) cytosinecytosine

Quiz  9. Which process involves tRNA: a) transciptiontransciption b) translationtranslation c) DNA replicationDNA replication d) gene mutationgene mutation

Quiz  10. The formation of RNA does not involve: a) ribose sugarribose sugar b) thyminethymine c) removal of waterremoval of water d) phosphatephosphate

Answers  Sorry, that is not the correct answer Click here to go back

Answers  That’s right – water has a high specific heat capacity Click here to go to the next question

Answers  That’s right Click here to go to the next question

Answers  That’s right, cytosine is an organic base Click here to go to the next question

Answers  That’s right Click here to go to the next question

Answers  That’s right, in RNA thymine is replaced with uracil Click here to go back to the start Press escape to exit

IB Biology Joni Rogan Escuela de Lancaster A.C.. Course outline - Theory  1: The chemistry of life  Statistical analysis  2: Cells  3: Genetics 

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IB Biology Joni Rogan Escuela de Lancaster A.C.. Course outline - Theory  1: The chemistry of life  Statistical analysis  2: Cells  3: Genetics 

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