Midterm 2 (Lectures 11-23) Flashcards
Catabolism
- breaking down of high energy molecules into simple molecules
- generate energy
Anabolism
- building of complex molecules from simple ones
- require energy
ATP- adenosine triphosphate
- intermediate energy carrying molecules where energy is stored
- fuels many endergonic enzymatic processes
- diffuse or transported to where energy is needed and deliver chemical energy from breaking of phosphate bond
When ATP is hydrolyzed, what part of the molecule is released to provide energy?
y-phosphate or terminal phosphate
Explain the combustion of glucose with oxygen that forms water and CO2.
- a large molecule is converted into many small molecules
- products has more entropy (more disorder) than reactants
How do enzymes catalyze a reaction by increasing the rate of the reaction?
- reducing free energy of activation (Ea)
- reactant molecules absorb energy to reach transition state
When enzymes catalyze a reaction, there is a reaction rate plateau at higher reactant concentrations. Why?
most enzymes are already occupied
What is needed for any reaction to occur?
energy
What is Ea or energy of activation?
- energy needed to start the reaction
- is like a barrier preventing reactions to occur without the input of energy
What is the role of an enzyme in metabolic reactions?
- allow cells to overcome Ea quickly and precisely
- biological catalyst
- increases rate of reaction by lowering Ea
- does not add energy to reaction
How does the shape of an enzyme affect metabolic reactions?
- 3D shape
- very selective
- each enzyme can only catalyze one type of reaction with specific substrates
- lock and key analogy
- shape is maintained after reaction
What kind of molecule is an enzyme?
- proteins
- organic catalysts
When enzymes catalyze a reaction, what is the name of the reactants involved?
substrates
What is end-product inhibition for feedback-regulated enzymatic pathway?
P0-E1-P1-E2-P2-E3-P3-E4-P4
P4 binds to E1 and deactivates it
Lab-Explain what would happen if you placed a dialysis sac containing a 5% salt solution into a beaker containing a 10% salt solution.
Water leaves the dialysis sac through osmosis, causing an increase in salt concentrations inside the dialysis sac. After a certain amount of time, dynamic equilibrium will be reached.
Lab-Explain what should happen when you add a salt water solution to living onion cells.
The onion cells lose water due to the hypertonic solution, which causes the inner content to shrivel up and distance itself from the cell wall.
Lab- Explain the roles of the four test tubes in Lab 4 where :
Tube 1 has 1 mL of H20
Tube 2 has 1 mL of 1% Glucose
Tube 3 has 1 mL of Culture Medium Before Fermentation
Tube 4 has 1 mL of Culture Medium After Fermentation
Tube 1 = Negative control group (no reaction expected)
Tube 2 = Positive control group (reaction is expected)
Tube 3 = Experimental group to prove presence of glucose before fermentation
Tube 4 = Experimental goup
Lab-Which are the four pigments involved in photosynthesis (order from left to right on the paper chromatography)?
carotene, xanthophyll, chlorophyll a, chlorophyll b
Lab- Explain the roles of the four test tubes in Lab 5 where :
Tube 1 has 5 mL of H20
Tube 2 has 5 mL of 50% Ethyl Alcohol
Tube 3 has 5 mL of Culture Medium Before Fermentation
Tube 4 has 5 mL of Culture Medium After Fermentation
Tube 1 = Negative control group (no reaction expected)
Tube 2 = Positive control group (reaction is expected)
Tube 3 = Experimental group
Tube 4 =Experimental group with yellow precipitate due to ethanol being a product of fermentation
Lab-What type of substances would enter and leave cells by simple diffusion?
H2O
CO2
O2
Lab-Three lengths of dialysis tubing containing 2.0M sucrose solution are put in three different solutions:
Solution A: distilled water
Solution B: 2.0M sucrose
Solution C: 4.0M sucrose
Which solution is isotonic, hypotonic and hypertonic?
Solution A = hypotonic
Solution B = isotonic
Solution C = hypertonic
What are the chemical constituents of the plasma membrane and how are they arranged?
1) phospholipid bilayer = hydrophilic heads outside the membrane and hydrophobic tails inside the membrane
2) proteins = embedded in bilayer
3) carbohydrate side chains = attached to proteins and lipids outside of membrane
Give three functions of the plasma membrane.
1) protects the inside contents of the cell
2) selectively permeable barrier
3) supports and maintains the cell’s shape
What is a concentration gradient?
region where there is an increase or decrease of chemical substance’s density
Name one physical process that may limit the size to which a cell can grow.
surface area to volume ratio : only limited amount of substance can pass through membrane at a time
What is a semi-permeable membrane?
through diffusion, facilitated diffusion, passive or active transport, only certain molecules or ions can cross the membrane
What is osmosis?
diffusion of water across a selectively permeable membrane
What is osmotic pressure?
equalizing height of both sides of water levels by applying external pressure
Describe the fluid mosaic model concept of membrane structure.
proteins are embedded in a phospholipid bilayer, but not equally distributed in both halves
What is the difference between active and passive transport? Give an example of active transport.
active transport requires energy
example is going against a concentration gradient (high concentration to low concentration)
Give two factors that would affect the permeability of substances through living membranes.
size
presence of carrier or channel proteins
Define phagocytosis and pinocytosis.
phagocytosis: large substances are taken up by the cell
pinocytosis: cell ingests substances
Define isotonic, hypotonic, and hypertonic.
isotonic: no net movement of water
hypotonic: cell gains water from solution
hypertonic: cell loses water to solution
What happens to a cell placed in a hypertonic solution? In a hypotonic solution? In an isotonic solution?
hypertonic = cell loses water to solution hypotonic = cell gains water from solution isotonic = no net movement of water in or out of cell
Define a vacuole. What are the differences between plant and animal vacuoles?
vacuole: vesicle from plasma membrane, ER or Golgi
plants: vacuoles hold water
animals: vacuoles pump out excess water
Name the structures found in the nuclear membrane,
nuclear envelope, nuclear lamina, nuclear pores, chromatin, nucleolus, ribosomes
What are the main functions of the nucleus?
encloses the genetic information of the cell
What effect does the cell wall have when a plant is placed in a hypotonic solution?
cell wall is turgid and resists water pressure
Define turgid, turgor pressure and plasmolyzed cell.
turgid: cell wall inflates to resist water pressure
turgor pressure: water pressure inside a plant’s cell
plasmolyzed cell: cytoplasm shrivels and plasma membrane pulls away from the cell wall
Compare plasma membrane and the cell wall.
plasma membrane: thin stricture, made of phospholipid bilayer, selectively permeable
cell wall: thick structure, permeable, made of cellulose
What organelles are found in a plant cell and not in an animal cell?
cell wall chloroplast central vacuole nucleolus plasmodesmata
What organelles are found in an animal cell and not in a plant cell?
nucleus surrounded by membrane
plasma membrane
Lab-What is the general shape of the yeast cell?
round
Lab-To what kingdom do yeasts belong to?
Kingdom Fungi
Lab-The experiment in Lab 4 had you observe germinating seeds and their cellular respiration process by oxygen being used, and carbon dioxide being produced. If you conducted this in the dark, would you expect different results?
There wouldn’t be a difference, because none of the tissue of the germinating seeds is photosynthetic at this present stage.
Lab-The experiment in Lab 4 had you observe germinating seeds and their cellular respiration process by oxygen being used, and carbon dioxide being produced. How do you prove that CO2 is produced during cellular respiration?
pump the gas produced to a solution of barium hydroxide
Lab-The experiment in Lab 4 had you observe germinating seeds and their cellular respiration process by oxygen being used, and carbon dioxide being produced. Flour worms were observed as well. Which organism had a faster respiration rate?
flour worms due to being a more active organism and has a greater proportion of active cell per unit of mass
Lab-How would changes in temperature outside of a homeothermic animal like humans affect cellular respiration?
will have to use up more of their energy to keep themselves warm or cool
Lab-Where in the cell does catabolism take place?
cytoplasm = glycolysis
matrix of mitochondria = Krebs cycle
inner membrane of mitochondria = electron transport chain
Lab-What are the 3 outputs of fermentation by yeast?
- ATP
- CO2
- Ethyl Alcohol (ethanol)
Define an oxidized reaction and a reduction reaction.
oxidized: loses an electron (becomes more positive)
reduced: gains an electron (becomes more negative)
Which molecule in this redox reaction NaCl becomes oxidized and reduced?
Na is oxidized and becomes Na+ cation
Cl is reduced and becomes Cl- anion
What is oxidized and reduced in the combustion of methane? CH4 + O2 —–> CO2 + H2O. Mention a couple of chemical properties.
Carbon is oxidized
Hydrogen is reduced
electrons shared unequally
lower potential energy
polar
release of energy (exergonic reaction)
Define electronegativity.
tendency of an atom to attract electrons
What is the net charge of a water molecule?
zero, hydrogen has a partial positive charge and oxygen has a partial negative charge causing it to be more electronegative
