Biology IB SL B1

SL&HL B1.1.1—What do we call a bond formed when two atoms share electrons with each other.

Covalent

SL&HL B1.1.1—What kind of atoms can carbon bond with?

Other carbon atoms or atoms of other non-metallic elements.

SL&HL B1.1.1—Name the type, and number of covalent bonds that carbon can form.

Up to four single bonds or a combination of single and double bonds.

SL&HL B1.1.1—Give examples of the diversity of carbon compounds.

Carbon chains which can be branched or unbranched, single or multiple rings.

"SL&HL B1.1.1—What do the following scientific conventions which are based on international agreement mean - SI metric unit prefixes "kilo", "centi", "milli", "micro" and "nano".

kilo - 10^3

centi - 10^-2

milli - 10^-3

micro - 10^-6

nano - 10^-9

"

SL&HL B1.1.2—Name the type of general reaction where monomers join to form macromolecule polymers

Condensation (water is released)

SL&HL B1.1.2—Name three types of macromolecules produced in condensation reactions.

Polysaccharides, polypeptides and nucleic acids

SL&HL B1.1.2—Describe the production of the disaccaride lactose using a word equation.

glucose + galactose --> lactose + water

SL&HL B1.1.2—Describe the production of the polysaccharide starch using a word equation.

glucose (many) ---> starch + water (many)

SL&HL B1.1.2—What is the word equation for the production of nucleic acids.

nucleotides (many) ---> nucleic acids + water (many)

SL&HL B1.1.2—Describe the production of polypeptides using a word equation.

amino acids (many) ---> polypeptide + water (many)

SL&HL B1.1.3—What do we call the type of reaction where a water molecule is split to provide the -H and -OH groups that are incorporated to produce monomers.

Hydrolysis.

SL&HL B1.1.4—What do we call a five carbon monosaccharide?

Pentose sugar (be able to recognise this)

SL&HL B1.1.4—What do we call a six carbon monosaccharide?

Hexose sugar (be able to recognise this)

"SL&HL B1.1.4—Using glucose as an example, link the form and function of monosaccharides

Glucose has 5 hydroyxl groups. Hydroxyl groups, as water, have polar covalant bonds and so glucose is a polar molecule

a) Molecular stability - Stable covalent bonds

b( High solubility - Polar nature

c) Easily transportable - Soluble and can circulate in blood and fluids between cells.

d) High yield of energy from oxidation - Covalent bonds contain a lot of energy and so when they are broken (such as in respiration) they release a lot of energy.

"

SL&HL B1.1.4—Name the two forms of glucose and how they differ.

α-D-glucose, β-D-glucose, In alpha, the OH groups face the same direction. In beta, they face different directions.

SL&HL B1.1.5—Name three polysaccharides involved in energy storage

Amylose and amylopectin (plants), glycogen (animals),

SL&HL B1.1.5—Name the polysaccharide made of helical chains of alpha-glucose monomers, arranged with the same orientation, with 1-4-glycosidic bonds.

Amylose

SL&HL B1.1.5—Name the polysaccharide made of helical chains of alpha-glucose monomers, arranged with the same orientation, with 1-4-glycosidic bonds, and 1-6 branches ~every 10 subunits

Amylopectin

SL&HL B1.1.5—Name the polysaccharide made of helical chains of alpha-glucose monomers, arranged with the same orientation, with 1-4-glycosidic bonds, and 1-6 branches ~every 20 subunits

Glycogen

"SL&HL B1.1.5—Give three reasons why the structure of polysaccharides helps them function as energy storage compounds

1. Compact nature - due to coiling and branching during polymerization

2. Relative insolubility (so don't affect osmotic balance) - due to large molecular size, whereas glucose is soluble and would.

3. Relative ease of adding or removing alpha-glucose monomers - by condensation and hydrolysis to build or mobilize energy stores.

"

SL&HL B1.1.6—Name the polysaccharide made of straight chains of beta-glucose monomers, arranged with the alternating orientation, with 1-4-glycosidic bonds.

Cellulose

"SL&HL B1.1.6—Relate the structure of cellulose to its function as a structural polysaccharide in plants.

Straight chains that can be grouped in bundles and cross-linked with hydrogen bonds between hydroxyl groups (-OH).

This makes it very strong and stable molecule, it is insoluble, the fibres allow water to pass through them easily.

"

SL&HL B1.1.6—Why can cellulose not be used as an energy storage molecule?

Very few organisms produce the enzyme cellulase which is needed to digest cellulose.

SL&HL B1.1.7—What do we call the molecule formed when carbohydrates and polypeptides combine, via covalent bonds

Glycoproteins

SL&HL B1.1.7—Describe the role of glycoproteins in cell-cell recognition

Glycoproteins can act as antigens. This means they identify cells as "self" or "non-self" and can trigger an immune response.

SL&HL B1.1.7—Name the blood types and the associated glycoprotein antigens found on red blood cells

A, B, AB and there can be none.

SL&HL B1.1.7—A lipoprotein is an example of a conjugated molecule. Give two more examples.

Glycolipid, glycoprotein.

SL&HL B1.1.7—What do we call a molecule, found on the surface of a cell, that can trigger an immune response?

Antigen

SL&HL B1.1.8—Describe the solubility properties of lipids.

Lipids are substances in living organisms that dissolve in non-polar solvents but are only sparingly soluble in aqueous solvents. They are hydrophobic.

SL&HL B1.1.8—Name four types of lipids.

Lipids include fats, oils, waxes, and steroids.

SL&HL B1.1.9—Name the type of lipid made from one glycerol and three fatty acids.

Triglyceride

SL&HL B1.1.9—Name the type of lipid made from one glycerol, two fatty acids and a phosphate group.

Phospholipids

SL&HL B1.1.9—Name the type of reaction that forms of triglycerides and phospholipids from components including fatty acids and glycerol.

Condensation reactions.

"SL&HL B1.1.10—Difference between the chemical bonds present of saturated, monounsaturated and polyunsaturated fatty acids

Saturated - have no double carbon (C=C) bonds, they are saturated with hydrogens.

Monounsaturated - have one carbon (C=C) bonds

Polyunsaturated fatty acids - have many carbon (C=C) bonds

"

"SL&HL B1.1.10—Difference in between the physical properties of saturated, monounsaturated and polyunsaturated fatty acids

Fats e.g. butter, animal fat - are saturated - they have high melting points, are solid at room temperature, are used by animals, particularly endotherms whihc can maintain high body temperatures, to store excess energy.

Oils e.g. in plants - are unsaturated or polyunsaturated - have lower melting points, are liquid at room temperature, plants store energy in this form

"

"SL&HL B1.1.11—Give three reasons why tiglycerides in adipose tissues are suited for energy storage and thermal insulation

Triglycerides make them suited to long-term energy storage functions.

1. Insoluble - so don't move from the storage location, and act as thermal insulators to body temperature and habitat.

2. Undergo hydrolysis to release glycerol and fatty acids which can be used to release energy in respiration.

3. They contain twice as much energy per gram as carbohydrates.

"

SL&HL B1.1.11—In what type of animals do we find a thick later of adipose tissue under the skin and why?

Endotherms such as birds and mammals. The adipose tissue traps heat energy made by the animals.

SL&HL B1.1.11—What do we call the type of tissue made of cells that store fat in the form of triglycerides in their vacuoles

Adipose tissue

SL&HL B1.1.12—What do we call molecules which have both hydrophobic and hydrophillic regions?

Amphipathic

SL&HL B1.1.12—Why do phospholipids spontaneously form bilayers in water?

Phosphlipids have hydrophobic tails (fatty acids) and hydrophilic regions (phosphate group). They are amphipathic. The tails extend towards each other to exclude the water, the heads face the water.

"SL&HL B1.1.13—Name two steroids, and describe their structure.

Oestradiol - Has hydroxyl group

Testosterone - Has carbonyl group

Both are made from cholesterol, both have the same 17-carbon, 4-ring structure

"

SL&HL B1.1.13—What ability do non-polar steroids have regarding the the phospholipid bilayer

They can diffuse directly across the cell membrane, and the nuclear membrane to where they influence transcription.

SL&HL B1.2.1—Draw the structure of an amino acid, naming the five different parts.

Central alpha carbon atom, amine group, carboxyl group, R-group and hydrogen attached.

SL&HL B1.2.2—Name the type of reaction that forms dipeptides and longer chains of amino acids

Condensation

SL&HL B1.2.2—Write the word equation for the type of reaction that forms dipeptides and longer chains of amino acids

Amino acid 1 + amino acid 2 --> dipeptide + water

SL&HL B1.2.3—How are all the 20 amino acids made?

By plants using products of photosynthesis. These pass to animals in their food. Animals can change some amino acids into others.

SL&HL B1.2.3—What do you call amino acids which cannot be synthesized by animals and must be obtained from food?

Essential amino acids.

SL&HL B1.2.3—What do you call amino acids which can be made from other amino acids?

Non-essential amino acids.

SL&HL B1.2.3—What kind of diet requires care to get sufficient essential amino acids?

Vegan

SL&HL B1.2.3—Is an animal or plant diet more likely to supply amino acids in the proportions needed im the human diet?

Animal

"SL&HL B1.2.4—Explain why there is an infinite variety of possible peptide chains

20 different amino acids are coded for in the genetic code

Peptide chains can have any number of amino acids, from a few to thousands

Amino acids can be in any order.

"

"SL&HL B1.2.4—How many sequences are possible in a polypeptide chain of 20 amino acids?

20n

- so 2010 = 10,240,000,000,000 different polypeptide chains are possible

"

SL&HL B1.2.4—Give examples of polypeptides

Haemoglobin, keratin, lipase, collagen, histones, insulin.

SL&HL B1.2.5—Name a physical condition and a chemical condition which can denature proteins

Physical - heat, chemical - pH

SL&HL B1.2.5—What is the consequence of intramolecular bonds forming between the R-groups of an amino acids chain e.g. hydrogen bonds

Folds the chain into the precise 3D shape of the protein.

SL&HL B1.2.5—What do we call the pH or temperature at which protein conformation is at its ideal or normal shape.

Optimum

"SL&HL B1.2.5—Describe and explain the effect of pH on protein structure

Describe - protein confirmation is at its ideal or normal shape at the optimum pH. Above or below this the confirmation will change and become less ideal.

Explain - Extremes of pH will flood the plasma or cytoplasm with H+ or OH- ions. These interfere with the hydrogen bonds or ionic bonds which hold together the complex 3D shapre of the protein

We say the protein has been denatured, has undergone denaturation.

"

"SL&HL B1.2.5—Describe and explain the effect of temperature on protein structure

Describe - protein confirmation is at its ideal or normal shape at the optimum temperature. Above this temperatuer the confirmation will change and become less ideal.

Explain - High temperatures increases molecular motion to such an extent that the intramolecular bonds holding together the 3D shape can break, changing the shape and function.

We say the enzyme has been denatured, has undergone denaturation.

"

SL&HL B1.2.5—What word describes when intramolecular bonds holding together the 3D shape of proteins are disrupted by extremes of pH which flood the plasma or cytoplasm with H+ or OH- ions or high temperatures which increase molecular motion.

Denatured or denaturation.