Grade 11 Biology

What are 4 important physical properties of water?

Buoyancy, viscosity, thermal conductivity, and specific heat capacity

Explain buoyancy of water using its density.

Water is very dense, allowing dense materials to float

What is viscosity and how does water compare to other liquids, air?

Resistance to flow and how much energy is needed to change shape. Water is less viscous than other liquid but still far more viscous than air

How does water’s thermal conductivity and specific heat capacity compare to air?

Water has a much higher thermal conductivity than air. High specific capacity of water is much higher than air

How is the ringed seal adapted to water’s physical properties (3 ways)?

Hydrodynamic torpedo shape allows it to avoid viscosity of water. Low density blubber increases the buoyant force. Water’s high thermal conductivity can steal heat so the seal also has a low thermal conductive blubber.

What are 3 ways in which the black throated loon is adapted to water’s physical properties?

Shape is hydro and aerodynamic. To maintain heat, they have low conductive feathers, and a hydrophobic dry layer that prevents water from entering

What is the hypothesis for the origin of water?

Water came from collisions with water rich comets (extraplanetary origin). When earth cooled, the water condensed and the force of Earth’s gravity kept it on the surface

What is Goldilocks Zone?

Refers to the habitable zone for a planet around its neighbouring star. Distance is perfect for liquid water to exist.

What are the 4 main types of organic molecules/macromolecules?

Carbohydrates, Lipids, Proteins, and Nucleic Acids

What are monosaccharides and how are they classified?

Simple sugars which form more complex molecules like carbohydrates. Classified by the number of carbon atoms they have: pentose or hexose

What is glucose an example of? What are three important characteristics of glucose?

An example of a simple hexose monosaccharide. Solubility: Is polar because it contains -OH. Stability: Is stable due to -OH groups. Oxidation: High energy yield when oxidized

How are glucose molecules linked to each other to form a carbohydrate?

-OH group on carbon 1 joins -OH group on carbon 4, creating a 1,4-glycosidic bond, losing a water molecule in the process

What is starch? Is it soluble?

A hexose polysaccharide which serves as a storage for alpha glucose in plants. Insoluble because of how large it is

What is the difference between amylose and amylopectin starch?

Amylose has a linear structure. Amylopectin is highly branched, making it an efficient store for glucose

What is glycogen? Describe its structure. Is it soluble?

Storage for alpha glucose in animals. Highly compact structure due to extensive branching. Insoluble

What is cellulose? Does it branch? What two components of a plant is cellulose important for?

Polysaccharide formed from beta glucose. No, it forms a straight chain. Important for cell walls and microfibrils.

What is the difference between alpha-glucose and beta-glucose?

In alpha-glucose, the -OH group of C1 is oriented downwards. In beta-glucose, the -OH group of C1 is orientated upwards

What are four types of lipids?

Oils, fats, wax, and steroids

What are waxes and steroids?

Waxes are lipid molecules found naturally on the surface of leaves. Steroids are lipid molecules composed of 4 carbon rings.

What are triglycerides composed of? What type of bond exists between components?

One glycerol molecule and three fatty acid chains. Ester bond.

What is the structure of a fatty acid?

Hydrocarbon chain with carboxyl group.

What is the structure of a glycerol?

Three carbons with three hydroxyl groups.

What are saturated hydrocarbons (including melting point and where they are found)?

No double-bonds and straight linear shape. High melting point. Found in meat and dairy products (ex. butter)

What are unsaturated hydrocarbons (including melting point and where they are found)?

Kinks and bends in shape due to double bonds. Low melting point. Found in oils.

What is the difference between trans unsaturated and cis unsaturated hydrocarbons?

Trans unsaturated fats create less of a kink and have a slightly higher melting point than cis (thus are solid). They are made industrially. Cis unsaturated fats are found naturally.

Do plants and animals use unsaturated or saturated fats for energy storage?

Plants use unsaturated fats. Animals use saturated fats.

What is the structure of a phospholipid?

Glycerol molecule bonded to 2 fatty acid chains (one saturated and one unsaturated) and a phosphate through a condensation reaction

How is a phospholipid bilayer formed? Do they have cis or trans unsaturated fatty acids?

Formed as a result of containing both hydrophilic and hydrophobic layers (amphipathic molecules). Unsaturated fatty acids as the bilayer needs fluidity.

What is the structure of steroids? What are the characteristics of oestradiol and testosterone?

Composed of three hexose rings and one pentose ring. Oestradiol has an OH group on both sides. Testosterone has a double-bonded O on one side and an OH on the other.

What are the three parts of a structure of amino acids?

Amino group. Central alpha carbon bonded to one H and a side chain (which determines its physical and chemical properties). One carboxyl group.

How many amino acids are there? Explain the diversity of R-groups?

20 amino acids. R-groups can be hydrophobic or hydrophilic. If hydrophilic, they can be polar or charged. If charged, acidic or basic.

How do amino acids join?

Condensation reactions where a peptide bond forms when a carboxyl group engages with an amino group. Water is released.

What are non-essential and essential amino acids? How many of each?

Non-essential: amino acids that the body can synthesize on its own. (11) Essential: amino acids which the body can’t synthesize and have to be obtained from food. (9)

How many possible codon combinations are there? What does this mean for the genetic code?

64 codon combinations. Means that the genetic code is degenerate and some amino acids are coded for by multiple codons.

What is a protein?

Proteins are structures made up of one or more polypeptide chains

What are 4 examples of single polypeptide proteins and their functions?

Lysozyme: present in tears and saliva and breaks down bacteria. Alpha neurotoxins: present in snake venom. Glucagon: Regulates blood sugar levels. Myoglobin: Oxygen bonding protein.

What is denaturation of a protein?

The secondary, tertiary, or quaternary structures of a protein are destroyed, causing the protein to lose its function.

What is the primary structure of a protein? What does it determine?

The number and sequence of amino acids held together by peptide bonds. Sequence of amino acids determines which intramolecular bonds will form and the three-dimensional shape that the protein will take.

What is the secondary structure of a protein? What are the 2 possible structures?

The folding patterns in the chain as a result of hydrogen-bonding. Alpha helices (coils and twists) and beta-pleated sheets

How do hydrogen bonds form for the secondary structure?

Occurs between amine and carboxyl groups

What is the tertiary structure?

Folding of the chain through interactions of the R-groups. Give rise to three dimensional shapes.

What are 4 possible interactions between R-groups for tertiary structure?

Hydrogen bonds, ionic bonds (R-groups undergo bonding or dissociation of hydrogen ions which gives them a charge), disulfide covalent bonds (between cysteine amino acids), and hydrophobic interactions

What is the effect of polar and nonpolar amino acids on tertiary structure? –? Hydrophilic amino acids orientate towards a watery environment while hydrophobic embed in the core. Stabilizes structure and allows protein to dissolve.

What is the quaternary structure of a protein?

Interaction of 2 or more polypeptide chains to form a protein.

What are non-conjugated vs conjugated proteins? Give an example of each.

Non-conjugated proteins consist only of amino acids (ex. insulin has 2 chains). Conjugated proteins consist of amino acids and non-protein components (ex. haemoglobin also contains haem).

What are the differences in shape, amino acid sequence, function, and solubility of globular vs fibrous proteins?

Globular: Spherical shape, diverse amino acid sequences, physiological functions, soluble in water. Fibrous: Long strands and strong shape, short amino acid sequences with repeating units, structural support, insoluble in water.

What is an example of a globular protein? Why is it globular?

Insulin, 2-chain hormone. Needs to be soluble and spherical to efficiently move through blood.

What is an example of a fibrous protein?

Collagen, made of 3-chains twisted into a triple helix structure. Strong and elastic.

What is the purpose of enzymes? Are they specific?

Act as catalysts that speed up chemical reactions. Specific and can only bind to one substrate or a range of similar substrates.

What are anabolic vs catabolic reactions?

Anabolic reactions build larger molecules from smaller ones and require energy. Catabolic reactions break down big molecules into smaller ones and release energy.

What is the active site of an enzyme?

Binds with substrate of a complementary shape chemically and geometrically.

What is the induced-fit model for enzymes?

When the substrate binds to the active site, it triggers a change in the 3-dimensional shape of the enzyme, inducing a tighter fit. Induces weakening of bonds in the substrate, reducing the activation energy. The substrate is converted to the product and is released, the enzyme returns to its original shape.

What are 2 requirements for substrate-active site collisions?

Substrates and active sites must collide in the correct orientation and with enough energy for the reaction to start.

What is the consequence of denaturation for enzymes?

Alters the enzyme's structure, particularly the active site, leading to loss of substrate-binding ability and enzyme activity. Can be permanent or reversible.

What is the effect of temperature on enzyme activity?

Increases enzyme activity exponentially up to an optimal point. Higher temperature causes denaturation (drop).

What is the effect of pH on enzyme activity?

Each enzyme has an optimal pH range, deviations lead to increased activity and potential denaturation (bell curve).

What is the effect of substrate concentration on enzyme activity?

Increases reaction rate (linearly) until the enzyme becomes saturated. Beyond saturation, the rate of reaction levels off.

What are intracellular enzyme-catalyzed reactions? What are 2 examples?

Metabolic reactions that take place in the cell and are catalysed by enzymes produced by free ribosomes. Glycolysis (cytoplasm) and Krebs cycle (matrix).

What are extracellular enzyme-catalyzed reactions? What is an example?

Metabolic reactions that take place outside the cell and are catalysed by enzymes produced by bound ribosomes and secreted outside the cell by exocytosis. Chemical digestion within the gut/digestive system.

How do endotherms like mammals and birds maintain a constant body temperature?

Use lost heat released from metabolic reactions to maintain constant body temperature.

What are cyclical vs linear pathways in metabolism? Give examples.

Linear: A metabolic pathway where substrate is not recycled (ex. glycolysis). Cyclical: A metabolic pathway where the substrate is recycled (ex. Krebs cycle and Calvin cycle).

What is a competitive inhibitor?

Chemically similar to the substrate. Binds to the active site of the enzyme, blocking substrate. As the concentration of substrate is increased, the effect of the inhibitor is reduced.

What is an example of a competitive inhibitor?

Statin drugs competitively inhibit enzymes involved in cholesterol synthesis, thus lowering cholesterol levels.

What is a non-competitive inhibitor?

Binds to the allosteric site, modifying the active site and prevents binding of substrate. Rate of reaction is lower than normal at all substrate concentrations.

What is end-product inhibition? What is an example?

End-product acts as a non-competitive inhibitor. Isoleucine is an essential amino acid that can be synthesized from threonine by bacteria. Acts as a non-competitive inhibitor for its pathway.

What is mechanism-based inhibition? What is an example?

irreversible binding of the inhibitor to the active site through a covalent bond. Produces a stable inhibitor-enzyme complex that is permanent. An example is penicillin, which binds to transpeptidase irreversibly. Transpeptidase is no longer able to maintain bacterial cell walls, causing bacteria to burst.

What are the three parts of a nucleotide?

Pentose sugar (five carbon atoms), nitrogenous base, and phosphate group.

What are the five nitrogenous bases and which are purines (2 rings) / pyrimidines (1 ring)?

Purines: Guanine (G), Adenine (A). Pyrimidines: Thymine (T), Cytosine (C), Uracil (U).

What type of bond links nucleotides together?

Phosphodiester covalent bonds. Phosphate group attached to 5’ C sugar and -OH group of 3’ C of other sugar. Releases one water molecule.

What is the difference between DNA and RNA ribose?

Deoxyribose (there is no oxygen on 2’ C.

What is the difference between DNA and RNA bases, as well as the # of strands?

DNA has thymine, RNA has uracil. DNA contains two antiparallel strands while RNA is single-stranded.

What is complementary base pairing?

Pairing happens through hydrogen bonds between a purine and a pyrimidine, ensuring equal length. AT contains 2 hydrogen bonds compared to 3 bonds of GC.

What is the central dogma and in what direction do all processes occur?

Replication, Transcription, and Translation. All processes occur in the 5’ to 3’ direction.

What is the structure of a nucleosome?

DNA wrapped around a core of 8 proteins called histones. An additional ninth histone protein (H1) is attached to linker DNA which attaches different nucleosomes together.

Summarize the Hershey Chase Experiment.

T2 bacteriophage injected genetic material into a bacteria. DNA labelled with radioactive phosphorus, protein labelled with radioactive sulfur. Only the bacteriophages with radioactive phosphorus caused the bacteria to become radioactive. Therefore, it's DNA that makes up genetic material.

What does Chargraff’s Data tell us?

Previously thought that there was an equal number of nitrogenous bases in DNA. Chargraff found that amount of adenine = thymine, guanine = cytosine.

Why is DNA replication necessary?

Necessary for cell growth, cell reproduction, and tissue repair.

What does it mean for DNA replication to be semi-conservative?

Each new double strand of DNA that is produced contains one strand of original DNA (acts as template strand) and one strand of newly synthesized DNA through complementary base pairing.

What is the purpose of helicase and single strand binding proteins?

Unwinds DNA by breaking hydrogen bonds between bases, forming a replication fork. Single strand binding proteins ensure bonds don’t form again.

What is the purpose of gyrase?

Moves ahead of helicase, relieves tension and prevents supercoiling

What does DNA primase do?

Attaches RNA primers to the template strand to initiate replication. DNA polymerase III binds to these and assembles free nucleotides.

How many RNA primers are required for leading strand vs lagging strand?

Replication in the leading strand (5’ to 3’) only requires one primer. Replication in lagging strand (3’ to 5’) requires constant primers as DNA polymerase III can’t synthesize continuously.

What does DNA polymerase I do?

Replaces RNA bases from primers with DNA bases once replication is complete.

What is the purpose of DNA ligase?

Catalyze formation of phosphodiester bonds between Okazaki fragments.

How many mistakes does DNA polymerase III make? How is this reduced?

DNA polymerase III makes a mistake every 1000 nucleotides added. DNA proofreading makes errors 1 in 1 billion.

What is polymerase chain reaction used for?

Technique used to amplify small fragments of DNA (make copies)

Explain the 3 phases of polymerase chain reaction.

Denaturation: DNA is heated enough to around 95 C to break H-bonds. Annealing phase: Sample cools to 60 C and primer sequence bond to target sequence on each strand. Extension phase: Primers allow Taq Polymerase to start replication on new strands, which is taken from a bacteria because it doesn’t denature at high temperatures.

What is the purpose of gel electrophoresis?

Separates DNA fragments based on size and charge, allowing scientists to identify people in forensics.

How does gel electrophoresis work?

DNA molecules move through a gel matrix thanks to an electric current. DNA is negative so it moves towards the positive end. DNA molecules group together based on size. Shorter fragments move faster and they are found further up the matrix.

What is the purpose of transcription?

Produce mRNA, which carries genetic information from DNA in the nucleus to ribosomes in the cytoplasm.

Why is DNA used only as a template to synthesize mRNA?

Sequence of DNA doesn’t change to ensure it is conserved, ensuring that functional proteins are always made.

What is the initiation stage of transcription?

Transcription factors bind to a non-coding region on DNA called the promoter. RNA polymerase then binds to the DNA and separates the strands by breaking H-bonds between them.

What is the elongation stage of transcription?

RNA polymerase adds RNA nucleotides along template strand (antisense) through complementary pairing to produce coding strand (sense)

In what direction does RNA polymerase read the strand build in?

Reads the strand in 3’ to 5’ but builds in 5’ to 3’.

What is the termination stage of transcription?

Termination sequence is reached. RNA polymerase and mRNA is released (mRNA is cleaved).

What are non-coding regions of DNA? What are 4 examples?

Regions of DNA that don’t contain information to make proteins, making mutations expendable when replicating. Introns: regulate gene transcription. Telomeres: protect ends of chromosomes. Regulators: gene expression is regulated, example is promoter regions. Genes for tRNA and rRNA.

What is the purpose of post-transcriptional modifications to mRNA?

Prepares mRNA for harsh journeys and removes expendable non-coding regions.

Describe what post-transcriptional modifications are made.

Introns are spliced out, and the exons join together to form mature mRNA Addition of guanine cap at 5’ and poly-A tail (AAAAA), which protect mRNA molecules from degradation.

What is the leader and trailer?

Non-coding regions of mRNA that flank the protein-coding sequence. Leader at 5’ and trailer at 3’ end.

Describe the process of alternative splicing.

Small nuclear ribonucleoproteins (snRNPs) form base pairs with introns. Looped intron and spliceosome form. Intron is cut off. Exons are ligated and spliceosome disassembles.