Biology Grade 12 - Exam Review

Functions of Water

Functions of Water

• Help control body temperature

• Lubricates joints

• Absorbs shocks

• Acts as Universal solvent

Properties of Water

• Colourless, tasteless, and odourless

• Can exist as solid, liquid, or gas

• Has polar covalent bonds and an asymmetrical structure making it polar

Cohesion

Water molecules attracting other water molecules with a high surface tension

• Used by plants to suck water out the ground

Adhesion

Water forms bonds with other polar molecules

• Water sticks to xylem and is able to go against gravity

Less Dense as Solid

As water freezes it expands to form a lattice of V-shaped molecules

• Helps aquatic life stay in habitat despite freezing temperatures

High Specific Heat

Large amounts of heat needed to heat water

• Regulation of body temperature

High Heat of Vaporization

Large amounts of heat needed before water turns to gas

• Sweating and panting

Monomers

are small subunits (such as one molecule of glucose)

Polymers

are larger units composed of monomers coming together (such as lactose)

Hydrolysis Reaction

Using water to break apart a big molecule into separate molecules

Condensation Reaction

A synthesis reaction in which two smaller molecules form a larger molecule and water is produced as byproduct of reaction.

Neutralization Reaction

Reaction between an acid and a base where water and a saalt determining pH is produced.

Redox Reactions

Involves compounds both losing and gaining electrons

• Used in cellular respiration and photosynthesis

OIL RIG

Organic Molecules

Carbon-containing molecule, often bonded to other carbon atoms or hydrogen, often made by living things

Carbon

• Can form up to 4 covalent bonds

• Allows it to form a variety of geometrical structures making up the backbone of organic molecules

Alkanes

All single bonded carbons -ane

Alkenes

At least one double bond -ene

Alkynes

At least one triple bond

• -yne

Functional groups

The components of organic molecules that are most commonly involved in chemical reactions

• The number and arrangement of _________ give each molecule its unique properties

Alkyl

R-CH3

Name ends in -yl

Alcohol

R-OH

name ends in -ol

Aldehydes

Carbonyl group attached to end carbons

-al

Ketones

Carbonyl group attached to middle carbons in backbone

-one

Carboxylic Acid

Carboxyl group attached to end carbon

-oic acid

Amine

-amine

Has an amine groups on R-NH2

Organic Phosphate

-OPO32-

ends in phosphate

Thiols

Sulfhydryl group R-SH

Name ends in -thiol (propanethiol)

Isomers

molecules with the same chemical formulae but different atom arrangements.

Structural Isomers

Structural isomers have the same molecular formula, but the atoms are arranged in a different order

Ex. Glucose and Fructose

Stereoisomers

same arrangement of atoms, but their orientation in 3D space differs.

Ex. Glucose and Galactose

Carbohydrates

Single chain of C with hydroxyl groups, and may contain carbonyl group

• Monosaccharides; glucose, fructose, galactose

Disaccharides

• Composed of two monosaccharides

• Covalent bond is called glycosidic linkage, forms between two specific hydroxyl groups (ex. glucose + galactose = lactose)

Polysaccharide

• All composed of glucose

• Contain glycosidic linkages

• Starches and glycogen (Storage): α1-4 Enzymes allow us to break down starch and glycogen.

• Cellulose (structural support): β1-4

Build: Condensation synthesis

Break: Hydrolysis

Lipids

• Hydrophobic due to high proportion of C-H bonds

• Efficient energy storage due to C-H bonds (twice as much as carbohydrates, not as easily accessible by cells)

• Insulate against heat loss, protect organs, component of cell membranes

Triglyceride

1 glycerol + 3 fatty acids linked by Ester Linkages

Glycerol = three-carbon alcohol (three –OH groups)

Fatty acids are long hydrocarbon chains containing a single carboxyl group (–COOH) at one end

Saturated Fatty Acids

have only single bonds between carbon atoms and have the maximum number of hydrogen atoms attached to the carbon skeleton

• Come from animal fats

• Chains are straight and can stack on top each other making them solid at room temperature

Unsaturated Fatty Acids

have at least one double bond between carbon atoms and have fewer than the maximum number of hydrogen atoms attached to the carbon skeleton

• Come from plant fats

• hydrocarbon chains have kinks or bends because of the double bond resulting in liquid at room temperature

Cis Bonds

the two pieces of the carbon chain on either side of the double bond are either both “up” or both “down,” such that both are on the same side of the molecule

• Hydrogen on same side

Trans bonds

The two pieces of the molecule are on opposite sides of the double bond, that is, one “up” and one “down” across from each other

• in cooking cis bonds transform into ____

Phospholipids

Main component of cell membranes (used to make them)

Composed of 2 fatty acids + 1 phosphatidylcholine

have both hydrophobic and hydrophilic portions

• Hydrophilic head faces aqueous environment and interior of cell.

• Hydrophobic interior of membrane prevents movement of water through membrane

Steroids

4 attached hydrocarbon rings and several functional groups (three hex shapes and one pent shape)

• Ex. Cholesterol, Testosterone, Estrogen, etc

Nucleic Acids

• Storage of genetic information

• Work together to translate stored data into functioning proteins

• Makeup DNA and RNA

• Made from nucleotides

Nucleotide

• A nitrogenous base (guanine, cytosine, adenine, uracil, thymine)

• A pentose sugar (Deoxyribose, or ribose)

• A phosphate group

The portion without the phosphate group is called a nucleoside

Forms nucleic acids from phosphodiester bond

Coenzyme Nucleotides

• NAD+ and FAD+ aid in the transport of protons

• ATP is the usable energy produced during cellular respiration

Proteins

Large polymers that consists of many amino acid subunits joined together by peptide bonds into folded three-dimensional molecules

• are extremely diverse due to the number of different monomers (20 (21) amino acids) and the combinations made with them.

  • The shape determines the function of the ______.

Amino Acid

• Central Carbon

• R Chain above

• Hydrogen below

• Amino group (left)

• Carboxyl group (right)

have both acid (carboxyl) and basic (amino) qualities

the R group changes the qualities of the ______.

Essential Amino Acids

There are 8 amino acids that cannot be synthesized by the body and must be obtained through diet

Primary Structure

the specific sequence of amino acids

• One error in the sequence could mena misfolding and affects protein function

Secondary Structure

As the chain of amino acids grows, the chain coils and folds at various locations along it’s length creating hydrogen bonding between C=O of one amino acid and N-H of another amino acid creating either alpha helix or beta pleated sheet

Tertiary Structure

the supercoiling of a polypeptide controlled by side-chain interactions with its environment

• mainly caused by the different polar, non-polar, and hydrophobic R groups and the interaction with water

• Sulphur containing R groups form disulphide bridges

Quaternary Structure

between different polypeptide chains coming together to form a 3-dimensional blob

• Some proteins need to form this structure to be functional

The specific shape of a protein allows for its specificity and selectivity as a messenger (hormone), surface receptor, building block, or enzyme

Enzymes

• Biological catalysts

• Make chemical reactions in the body proceed at a speed that sustains life

Denaturation

a change in the 3D shape of a protein caused by changes in temperature, pH, ionic concentration or other environmental factors

*protein enzymes function best within a narrow range of temperature, pH and salt concentration

Activation Energy

The initial energy needed to start a chemical reaction is called the _________

_______ is often supplied in the form of heat from the surroundings

How Enzymes lower the Activation Energy

• Enzymes (or catalysts) are biological catalysts that speed up a chemical reaction without being consumed or changing the products of the reaction

• They do this at the active site by;

  • Orienting substrates correctly

  • Straining substrate bonds

  • Providing a favorable microenvironment

  • Covalently bonding to the substrate

Substrate Specificity

• Enzymes have a very specific shape to bind to a specific substrates active site

The enzyme binds to its substrate, forming an enzyme-substrate complex

Induced Fit Hypothesis

1. Substrate binds to active site, forming the enzyme-substrate complex

2. Functional groups interact which changes the shape of enzyme active site to an induced fit, better accommodating the shape of substrate

3. Enzyme now stretches and bends bonds that would normally break, but bending lowers the Ea

4. Once bond breaks, the enzymes loses its affinity for the products

5. Products are released

Anabolism

refers to chemical reactions in which simpler substances are combined to form more complex molecules.

• Require energy

• Build new molecules and/or store energy

Catabolism

Refers to chemical reactions that result in the breakdown of more complex organic molecules into simpler substances

• Usually release energy that is used to drive chemical reactions

Factors Affecting Enzyme Activity

1. Enzyme concentration and substrate concentration

2. Temperature and pH

3. Enzyme activators and inhibitors

Competitive Inhibition

• Substance called inhibitor competes with substrate for the enzyme’s active site

• Enzyme cannot perform

• Inhibition is reversible if the substrate’s concentration is increased over the competitor’s

Non-competitive Inhibition

• Inhibitor attaches to a different spot on enzyme, allosteric site

• This changes the shape of the enzymes active site and therefore it loses affinity for substrate.

Feedback Inhibition

• Method of control where a product formed later in a chain of reaction returns to the beginning to allosterically inhibit an earlier enzyme

Allosteric Regulation

Allosteric regulators can either stimulate (make the reaction go faster) or inhibit (make the reaction go slower)

• Activators keep the conformation in a state that has a high affinity for the substrate

• Inhibitors keep the conformation in a state that has a low affinity for the substrate

Cofactors and Coenzymes

Certain enzymes require _____ and _______ to carry out reactions.

• _____ are generally metals

Fluid Mosaic Model

A biological membrane consists of a fluid phospholipid bilayer in which proteins are embedded and float freely

4 Main Function:

1. Transport

2. Enzymatic Activity

3. Triggering Signals

4. Attachment and Recognition

Phospholipid Bilayer

• polar head (phosphate) - attracted to water, water soluble

• non polar tail (2 fatty acids) - repels water

• this makes a water barrier in the middle to control the movement of water in and out

• held together by weak intermolecular forces, allows for movement of molecules in membrane (hydrogen bonding, hydrophobic interactions)

Integral Proteins

imbedded through the membrane- involved in movement of materials into and out of the cell

Peripheral Proteins

stick out of the inside layer- connect the cytoskeleton

Glycoprotein

protein with a carbohydrate stuck to it, enables cells to recognize each other

Glycolipid

lipid with a carbohydrate stuck to it

• provide stability and mobility by reacting to temperature

Cholesterol

Embedded with the phospholipid bilayer

• At higher temperature, increases intermolecular forces, holds membrane together

• At lower temperature, prevents phospholipids from solidifying into a gel, keeps membrane fluid

Diffusion

The process of random movement of molecules from an area of high concentration to an area of low concentration (a concentration gradient)

Simple Diffusion

Occurs through integral membrane proteins in the phospholipid bilayer that allow ions and water to diffuse into and out of the cell

Facilitated Diffusion

Solute molecules cannot diffuse through the membrane on their own

• Combine with carrier molecules in the membrane that change shape (i.e. alter their tertiary or quaternary structure) to allow the solute to pass into or out of the cell

• Carrier molecules might be integral membrane proteins

Primary Active Transport

• Requires energy from ATP in order to force the solutes to move against the concentration gradient

• Ex. The Na+/K+ Pump

Secondary Active Transport

Requires the movement of other solutes with the concentration gradient to provide the energy needed to “drive” the transport of other molecules against the concentration gradient

Osmosis

• Passive transport

• Movement of water from area of low solute concentration to an area of high solute concentration.

Isotonic

If there is an equal concentration solutes on both sides of the membrane, the solution is _______.

Hypertonic

there is an unequal concentration solutes on both sides of the membrane, the solution with the higher concentration of solutes is the _______ solution

Hypotonic

If there is an unequal concentration solutes on both sides of the membrane, the solution with the lower concentration of solutes is the ______ solution

Endocytosis

Large molecules and food particles are ingested through ________.

• Cell surface invaginates (folds to make a small pocket) that is lined by the cell membrane

• Invagination continues until the two ends of the cell membrane fuse and a vesicle is formed

• If the contents are food, the vesicle is fused with a lysosome and its contents are digested

Pinocytosis

Cell drinking

• Tiny, liquid-containing vesicles are formed

Phagocytosis

Cell eating

• Particles or entire cells are engulfed and trapped in large vesicles

Receptor Mediated

Receptors on the cell surface interact with particles outside the cell, causing endocytosis

Exocytosis

Cellular vesicle fuses to the membrane and expels its contents outside the cell

• Method for getting rid of waste or delivering needed macromolecules to the extracellular fluid

Central Dogma of Genetics

• Take information from DNA, transcribe it into RNA (info that can be read by ribosomes) and translated to make proteins

• There are proteins that are common in all organisms and proteins that are specific to organisms.

DNA

The primary carrier of genetic information in all organisms

• Built from deoxyribose, nitrogenous base, and phosphate group

• The genome (____ in the nucleus) is passed on in the form of chromosomes

• There are 46 chromosomes in humans

Histones

Strands of DNA wrap tightly around a core group of eight stabilization proteins, known as _______.

Negatively charged DNA and positively charged ______ attract each other

Together DNA and _______ are called a nucleosome.

Antiparallel

The two strands of DNA run in opposite direction

3’ to 5’ and 5’ to 3’ (the prime is it denote the carbon number from the pentose sugar)

Human Chromosomes

Have 46 ________.

There are 22 pairs of somatic and one pair of sex which contains hereditary information about an individual’s sex.

They are numbered 1 to 22 based on size.

Variable Number Tandem Repeats

Sequences of base pairs that repeat themselves over and over again in noncoding regions of DNA

• Used as a defense mechanism to protect coding regions

Mendel and Meischer

• First documented scientists to work with DNA

• ________ crossbreed peas to show how traits are passed on

• ________ collected pus and removed acidic substance from large amount of phosphorus from the nucleus of white blood cells.

Griffith

Discovered the transforming principle;

• Aa change in genotype or phenotype caused by a direct uptake of genetic material by a cell.

Avery, McLeod, and McCarty

Further confirmed DNA transformation

• Their results confirmed DNA as the transforming substance, however they were hesitant to confirm as many scientists believed protein as the genetic material.

Hershey and Chase

• Concluded DNA is the hereditary material

• Used bacteriophage virus to infect bacteria

• Depending on what radioactive atom was detected in the bacteria would confirm which substance was the genetic material

Chargaff’s Rules

• Discovered the ratio of pyrimidines and purines were equal in ratio

• This was later called complementary base pairing

Wilkins and Franklin

used X-ray crystallography to study the shape of the DNA molecule

• determined the shape of DNA was an “X” with a sugar-phosphate backbone facing the outside of the molecule, a double-helix, and rotated

Watson and Crick

the ones who are credited with discovering the structure of DNA while they have never completed experiments on DNA

• Stole Rosalind’s Franklin’s information without crediting her

DNA Replication

3 Steps:

• Strand Separation

• Building Complementary Strands

• Dealing with Errors