Exam Review (Sem. 1) Notes | Knowt (2024)

1. What does it mean for a cell to differentiate? How are genes involved in this process?

Cell Differentiation - process by which a cell becomes specialized to perform a specific function via activation of some genes by chemical signals and not others

Gene Packing

Differentiated cells have different regions of DNA packaged as euchromatin and heterochromatin

Euchromatin - expanded form that is accessible for transcription (active gene)

Heterochromatin - condensed form that is not accessible for transcription (inactive gene)

2. What structures are common to all cells?

Plasma Membrane - barrier that maintains homeostasis

Genetic Material - DNA that controls cells metabolism

Ribosomes - translate proteins

Cytosol - fluid for metabolic reactions

3. Label a diagram to show the structure of membranes.

4. Know the main properties of different forms of transport.

https://knowt.com/note/feaae143-6cf6-4799-8b3a-e08d0adde76e/17-Transport

Passive Transport

Simple Diffusion

Movement of small substances directly across membrane from HIGH concentration to LOW concentration until equilibrium reached

No energy needed

Small and non-polar molecules (e.g. O₂, CO₂, glycerol)

Facilitated Diffusion

Facilitated = with help

Movement of large, charged, or hydrophilic particles through protein channels or by carrier proteins from HIGH to LOW concentration

No energy needed

Osmosis

Diffusion of water across a semi-permeable membrane from HIGH concentration to LOW concentration

Equal concentration of water and dissolved substances on both sides of membrane - equilibrium

Managing Water Balance

Cell survival depends on balancing water uptake & loss

Active Transport

Movement of molecules against concentration gradient

Protein pump transports solutes “uphill”

“Costs” energy = ATP

Vesicular Transport

Materials destined for secretion are transported around cell in vesicles

E.R - membrane bulges/buds to create vesicle sent to Golgi

Golgi - vesicles fuse, materials modi ed, then secreted via fusing with plasma membrane, or directly into extracellular fluid, or sent in vesicle to lysosome

Bulk Transport

Bulk Transport - movement of very large molecules or large quantities in/out of cell through vesicles and vacuoles

Endocytosis - enter cell without crossing membrane

Phagocytosis = solid substances are ingested

Pinocytosis = liquids/dissolved substances are ingested

Exocytosis - exit cell without crossing membrane

5. What is osmolarity? Relate this to hypertonic, hypotonic, isotonic, as well as solute concentration.

measure of solute concentration

Direction of osmosis is determined by comparing total solute concentrations

Hypertonic - high solute (high osmolarity)

Hypotonic - low solute (low osmolarity)

Isotonic - equal solute concentration (no net water flow)

Managing Water Balance

Cell survival depends on balancing water uptake & loss

6. Be able to predict the movement of water for cells placed in different solutions.

https://create.kahoot.it/details/b2d27bac-ecb0-4f5e-9a75-7750fcf983e9?authuser=0

https://www.google.com/url?sa=i&url=https%3A%2F%2Fquizizz.com%2Fadmin%2Fquiz%2F5fbbddaf5b68b6001b9762d6%2Fosmosis-practice-problems&psig=AOvVaw0FdB8vLY8juE0-b6U4NLYO&ust=1705860466158000&source=images&cd=vfe&opi=89978449&ved=0CBEQjRxqFwoTCPjgoczH7IMDFQAAAAAdAAAAABAH

7. What is the endosymbiotic theory, and what is evidence for this theory?

theory that explains how eukaryotic cells came to be and especially with Mitochondria and Chloroplasts

8. How does mitosis differ from meiosis? What are their respective roles in multicellular organisms?

Mitosis - involved in growing organisms

Meiosis - involved in producing next generation and passing of genes

9. Describe the development and suppression of cancer.

Mutagen & Metastasis

agent that changes genetic material of an organism (either acts on DNA or replicative machinery)

Ex: viruses, radiation, reactive oxygen species (ROS), and metals (arsenic)

spread of cancer from one location (primary tumour) to another and forming a secondary tumour

Oncogene

gene that has potential to cause cancer

When a proto-oncogene is mutated or subjected to increased expression, it becomes a cancer-causing oncogene

Tumour suppressor genes prevents cancer

10. Calculate length, magnification, and mitotic index.

https://drive.google.com/file/d/1F9U4KkASSIfEA9xEC0l7No_og5FI0_a-/view

Mitotic Index

Mitotic index = number of cells in mitosis ÷ total number of cells.

1. Explain the special properties of water and provide examples of each.

2. Explain the characteristics of a good solvent.

• polar

• angular shape

• spheres of hydration

• breaks ionic bonds

• examples

3. Identify the types of intermolecular and intramolecular bonds and their properties.

London Forces

• bonds formed due to temporary unequal distribution of electrons

• very weak

• non polar and polar molecules

• cumulative affect within larger molecules

Dipole-Dipole Forces

occur between polar molecules, like HCl

• onlypolar molecules

  • positive on one end and negative on the other

• strongerthan London Forces

Hydrogen Bonds

• dipole-dipole forces that form between electropositive H of one polar molecule and an electronegative N, O, or F of another

Strongest intermolecular force

4. Define isomer and describe the relationship between structure and function. Give specific examples.

Structural Isomer - molecule with same molecular formula but with different arrangement of atoms

Differences in shape of isomers leads to differences in their physical and chemical properties

e.g.

Starch found in plants (amylose or amylopectin) is a polymer of α-glucose in 1-4 arrangement or 1-6 arrangement respectively

digestible

Cellulose found in cell wall of plants is a polymer of β-glucose in 1-4 arrangement - can’t be digested by most animals

not digestible

5. Know the characteristics of carbohydrates. Be able to identify based on a diagram.

Carbohydrate

• carbon, hydrogen, and oxygen in a 1:2:1 ratio

• at least 2 hydroxyl groups

• an aldehyde or ketone group

• Polar

• Hydrophilic

• linked by glycosidic bond

6. Know the characteristics of lipids. Be able to identify based on a diagram.

Fats

• class of greasy, oily, or waxy compounds that are non-polar and water insoluble and not polymers

• Composed of C, H, O “CHO”

• Two major classes: those with fatty acids and those without

Saturated Fat

• linear fatty acid that contains only single-bonded carbons (e.g. stearic acid) and originate from animal sources

• Solid at room temperature

Unsaturated Fat

• bent fatty acid that has one (mono) or more (poly) double-bonded carbons (e.g. oleic acid)

• Liquid at room temperature

• can be cis or trans (isomers)

Trans Fatty Acids

• do not commonly occur in nature

  • produced by hydrogenation (adding H)

• Linear and usually solid at room temp

Triglyceride

• glycerol joined to three fatty acid “tails”

• Condensation Reaction - occurs between hydroxyl groups on the glycerol and the carboxyl group on each fatty acid

  • ester linkages

• Triglycerides are largest class of lipids

• Contain twice the stored energy as same mass of carbohydrates

• Animals store as solid fats, while plants store as liquid oils

Phospholipid

• consist of a phosphate “head” (polar) attached to glycerol and two fatty acid “tails” (non polar)

• Main component of cell membranes - lipid bilayer

Wax

• large lipid made from long fatty acid chains linked to alcohols or carbon ring

• Function - water resistance and protection

• Hydrophobic

• extremely non-polar

• firm pliable consistency

• Ex: wax coating on fruits, leaves, and stems (cutin), beeswax

Steroid

• small lipids that have four fused hydrocarbon rings

Cholesterol

• important structural component of cell membranes and functional groups

• People with elevated levels of wrong type of cholesterol are more

  likely to experience heart disease or stroke

• Other steroids include sex hormones (testosterone, estrogen and progesterone)

7. Know the characteristics of proteins. Be able to identify based on a diagram

Proteins

• central carbon atom

• amino groups (NH or NH₂)

• carboxyl group

• hydrogen atoms

• R-group

• joined through peptide bonds

• know that proteins are made of multiple structure (primary, secondary, tertiary and quaternary)

• polar and non-polar

8. Know the details of enzymes.*

• globular protein catalysts

• Speed up rate of specific reaction by lowering activation energy (E_A)

• Enzymes not consumed in reaction - continue to work indefinitely

• each are specific to a chemical reaction

• specific 3D structure

• They denature due to changes in heat and pH

• There are many due to each enzyme only performing with one substrate

• They have active sites that act as a sponge, being molded by the substrates (induced fit model)

• As number of substrate or enzyme molecules increases, so

  does chance of a successful collision

  • Rate of activity ceases to rise as enzyme molecules are saturated with substrate (occupied)

9. Draw and fully label a potential energy diagram for an endothermic or exothermic reaction with the use of an enzyme and without.

10. Compare and contrast catabolic and anabolic reactions.

1. Explain what happens to the carbons in a glucose molecule during respiration.

1. Carbons are in glucose

2. Glucose becomes Pyruvate

3. During Pyruvate Oxidation, 2 CO₂ is produced

4. Throughout the Kreb’s Cycle, 4 CO₂ is produced

5. As there are 6 Carbons in Glucose, 6 CO₂ are produced

2. Describe anaerobic pathway of lactate fermentation and alcohol fermentation.

Fermentation pathways lack electron transport systems

Alcohol Fermentation

glucose from food is converted into carbon dioxide, ethanol (alcohol), and ATP (energy)

• C₆H₁₂O₆ -> 2CO₂ + 2C₆H₆O + energy

• used Plants and Yeast

• Need to restore stocks of NAD+ to keep making ATP via Glycolysis

• For glycolysis to continue, NAD+ must be replenished

• Total production of 2 ATP per glucose molecule

• Example: bread making, brewing beer, wine

Lactate Fermentation

glucose from food is converted into lactate and ATP (energy)

• C₆H₁₂O₆ -> 2C₃H₅O₃ + energy

• Need to restore stocks of NAD+ to keep making ATP via Glycolysis

• For glycolysis to continue, NAD+ must be replenished

• Total production of 2 ATP per glucose molecule

• Lactic acid (lactate) is toxic biproduct

• Example: yogurt, some cheeses, strenuous exercise

3. Compare and contrast aerobic respiration and anaerobic respiration in terms of organisms it occurs in, energy yield, organelles involved, when the processes happen, and the conditions required for the process to occur.*

4. Explain what happens to light that is absorbed or reflected by a leaf.*

• Carotenoids absorb some blue and green wavelengths

• Phycobilins absorb most of green, yellow and orange wavelengths

• Photosynthetic pigments are sensitive to specific ranges of spectrum

• Electrons within pigment are excited by a specific wavelength of light

• Chlorophyll a and chlorophyll b absorb blue and red wavelengths, while reflecting and transmitting middle of spectrum (green and yellow)

• Leaves appear green because “chlorophylls” are most abundant pigments, but other pigments are hidden beneath this overpowering green colour

Focus on pigments

• Light energy of a certain wavelength (680nm) excites chlorophyll a in photosystem II causing release of electrons

• Excited electrons are transferred to carrier molecules within the thylakoid membrane

• Electrons released by photosystem II are transferred through series of proteins in thylakoid membrane (ETC) to PSI

• Light energy (700nm) excites chlorophyll a in photosystem I causing electrons to move into second series of membrane proteins

• Photolysis (splitting of water by light) provides electrons to replace ones lost by P680, oxygen gas, and H+ ions

5. Know all the products, reactants, stages, organelles of photosynthesis. Including where they enter/exit.

Products: O₂ and C₆H₁₂O₆

Reactants: CO₂ and H₂O

Stages: Light Reactions, Calvin Cycle

Organelles: Chloroplasts (Stroma, Thylakoid)

6. Compare and contrast photosynthesis and cellular respiration in terms of organisms they occur in, membrane bound organelles, final electron acceptors, enzymes involved, source of electrons, cause of electromotive force, when and why the process happens, and the conditions required for the process to occur.

1. Explain Chargaff’s rule and be able to determine the amount of each nucleotide in a sample.

Chargaff’s Rule: If you know nucleotide sequence of one strand, you can deduce sequence of other strand.

JUST REMEMBER THAT THE BASES GO TOGETHER. e.g. if A is 22%, T will be 22% NOT 28%

2. Be able to sequence the complimentary and template strand of DNA.

1. Template Strand is always 3’-5’

2. Build the Template 5’-3’

   1. e.g. 3’-ATG-5’

   2. e.g. 5’-TAC-3’

3. Describe how DNA replication results in a lagging strand.

When DNA polymerase III builds the 3’-5’ strands (which is building away from the replication fork), as DNA polymerase III can only build from 5’-3’, the strand (lagging) is built discontinuously away from replication fork. This makes the strands fragmented.

Watch DNA replication - 3D by yourgenome it’s a really good explanation

4. Describe the results of the Meselson and Stahl experiment.

5. Explain the central dogma of genetics

DNA stores genetic code necessary for synthesizing all the different proteins in our body

6. Be able to transcribe and translate DNA into a protein.

Practice Ms. Giroux’s questions

7. Be able to sequence and compare the DNA sequence of individuals.

Practice Ms. Giroux’s questions

8. Be able to solve problems (monohybrid, sex-linked, incomplete dominance, codominance, and multiple alleles)

Monohybrid

the mating of two individuals that are heterozygous for a given trait.

Sex-linked

Some alleles are found on the X chromosome. The allele is recessive, so for it to be seen in the phenotype the dominant allele must be absent.

Incomplete Dominance

Neither allele is dominant over the other.

Codominance

occurs when pairs of alleles are both expressed equally in the phenotype of a heterozygous individual. Heterozygotes therefore have an altered phenotype as the alleles are having a joint effect.

Practice Ms. Giroux’s questions

9. What are blood types? What determines what blood type you are?*

Blood types are the type of blood that you can receive through your parents. The genetics of blood typing shows codominance. There are three alleles for human blood type.

I_A= A allele

I_B= B Allele

i=O Allele

Your blood type is determined by your genes. As blood types are codominant, Both IA and IB are dominant over i, but neither IA or IB dominate each other.