Chapter 7 - Cell - Objectives

Unit 2 checked by your instructor and edited thoroughly – very important unit:

Chapter 7 - Cell - Objectives:

1)What are the goals of microscopy?

The goals are to produce a magnified image of the specimen (magnification), separate the details on the image (resolving power), and to render the details visible to the human eye or camera.

2)How do you calculate the magnification of a microscope?

To calculate the total magnification you must multiply the objective by the eyepiece lens.

3)What is the resolving power of a microscope?

The resolving power of a microscope is the measure of image clarity. What cell structures can you see with the a) naked eye: Human height, length of some nerve/muscle cells, chicken egg, frog egg; b) light microscope: most plant and animal cells, nucleus, most bacteria, mitochondrion.

4)What is the difference between light and electron microscopes – which is better for live specimens? What can you see with a microscope?

The light microscope is better to use for living specimen because to prepare a slide for the electron microscope you must put the specimen in large amounts of alcohol, ultimately killing it. You can observe mitochondria and chloroplasts and eukaryotic and prokaryotic cells with the microscope. Viruses and other organelles are toooo small for the regular microscope!

5)What is better for studying cell surfaces – Scanning EM or Transmission EM?

A scanning electron microscope is used to see the surfaces of things such as cells two dimensionally whereas the transmission electron microscope is used to see on the inside of small cellular things and it is more 3D.

6)What is cell fractionation/ centrifugation used for?

Cell centrifugation is a procedure to break up parts of a substance such as blood. It is used to separate the major organelles of cells so that their individual functions can be studied. You spin the cells in a centrifugation apparatus and exert massive g forces on it to separate the heavy stuff from the light stuff! Nucleus and mitochondria are heavy, ribosomes and proteins are light….

7)What do ALL cells contain to qualify to be a cell?

Cells must contain a plasma membrane, cytoplasm, chromosomes, genes/DNA, and ribosomes.

8)What is a PROKARYOTE? What does it contain? Give examples of a prokaryote

ALL bacteria are prokaryotes. It contains the simplest essentials of a cell – cell membrane, cell wall, DNA, ribosomes, cytoplasm.

9)What is a EUKARYOTE? What does it contain? Give examples of a eukaryote

Eukaryotic cells are those of animal and plant cells for the most part. They contain the major organelles of cells are more complex than prokaryotic cells.

10) Compare a plant cell and an animal cell

The main differences between plant and animal cells are that animal cells do not have chloroplasts, central vacuoles, a cell wall, or plasmodesmata. Plant cells do not have lysosomes, centrioles, or flagella.

11)Complete the table – Cell Parts/Organelles and their Functions (end of this h/o). Use the following websites for interactive animations to do this:

a) (Eukaryotic cell animation)

b) (Prokaryotic cell animation)

c) (Take the quiz by clicking the next button)

Chapter 8 – Plasma/Cell Membrane

1)Why is the plasma membrane considered to be selectively permeable?

Plasma membrane is selectively permeable because it lets in and out only certain material.

2)What are phospholipids? What chemical features of this macromolecule make it an ideal candidate to make up the cell membrane?

Phospholipids are amphipathic molecules that have both hydrophobic regions and hydrophilic regions. This makes it an ideal candidate to make up a cell membrane – because the cells exterior and interior has water (so the plasma membrane has hydrophilic molecules on the exterior and the interior) and the interior of the membrane remains hydrophobic..

3)How are proteins included in the structure of the plasma membrane?

Proteins are either on the outside/inside of the membrane (peripheral) or they pass through the membrane (integral proteins) like the channels and receptors - doorways through the plasma membrane.

4)What is the fluid mosaic plasma membrane model? Draw the model and label the parts (outline sketch okay).

Fluid mosaic model means that the membrane is liquid and it is made of different macromolecules serving different functions – like a mosaic tile/collage.

5)Why is this membrane model referred to as a) ‘Fluid’ and b)‘Mosaic’? Explain clearly including the roles of unsaturated fatty acids, cholesterol, carbohydrates and the function of different integral and peripheral proteins in the membrane.

a)The membrane is referred to as fluid because the integral proteins and lipids move laterally and can rarely flip. Phospholipids with unsaturated fatty acids move faster than the saturated ones because unstauration makes it kinky – more wiggling! . Cholesterol restricts it except at low temperatures.

b)The membrane is said to be mosaic because the structure is not the same on the inside and outside. There are peripheral proteins on the inside, integral proteins than pass thru, cholesterol on the inside, and carbohydrates on the outside. Carbs (make up antigens) are involved in different function than the proteins (can be enzymes/G proteins/receptors…).

6)Why do substances need to move in and out of cells? When do they do this?

The substances need to move in when the cell needs nutrients/during cell signalling and they move out when the cells have too much waste.

7)What substances can be TRANSPORTED easily across the plasma membrane without any assistance? Why?

Substances such as small polar molecules and hydrophobic molecules can be transported easily because the polar molecules are small in size and nonpolar molecules can go through because the plasma membrane is lipid – that is nonpolar.

8)What substances need assistance to be TRANSPORTED into and out of cells? Why?

Ions, polar molecules and other large charged particles need assistance to get in and out of cell because these molecules don’t dissolve in hydrophobic substances.

9)What macromolecule helps these substances to get into the cells? Where are they located?

Integral proteins help these substances to get in and out of cells. These proteins are in the cell membrane. They make doorways – channels or they are carrier proteins that bind to substances like glucose and amino acid and ‘carry’ them into the cell – providing safe passage for a hydrophilic polar molecule in a hostile hydrophobic lipid membrane world is what its all about!

10)When substances ‘Diffuse’ into a cell, what can you tell about its relative concentrations inside and outside the cell?

The substances move from a higher concentration to a lower concentration. This means that the concentration is higher on the outside of the cell.

11) Based on energy requirements, draw a flow chart to indicate the different types of TRANSPORT in and out of cells.

12) What is the difference between Passive and Active Transport? Are these both examples of diffusion?

Passive transport is driven by the intrinsic kinetic energy of the molecules while active transport requires ATP. Active transport is not diffusion.

13) What is the difference between Simple Diffusion and Facilitated Diffusion?

Simple diffusion is when molecules go through a lipid bilayer and facilitated diffusion requires carrier/channel helper proteins.

14) How do carrier proteins work? What substances use carrier proteins? What type of diffusion is this?

Molecules bind with the carrier; then the protein changes shape and the molecule is released. Amino acids, sugars, nucleotides, and other small molecules use carrier proteins. This is facilitated diffusion.

15) What is Osmosis? Is it diffusion or Active Transport?

Osmosis is the diffusion of water.

16) Explain the terms – isotonic, hypertonic, and hypotonic with a quick sketch.

Isotonic is when the concentration of the cell is equal to the concentration of the environment. Hypertonic cell is when the solute concentration in the cell is greater than outside. Hypotonic cell is when the solute concentration is lower in the cell than it is outside. ITS ALL RELATIVE!

17) What happens to an animal cell and a plant cell when placed in diwater?

The animal cell will lyse; the plant cell will become turgid. They will both absorb water! Plant cells are in the flaccid state normally in nature. So they are hypotonic in their normal state!

18) What happens to an animal cell and a plant cell when placed in isotonic saline?

Isotonic means there should be no difference in solute concentration between inside of cell and outside. So no water should move in or out. Animal cells are in this state normally inside the body. Plant cells will wilt or become flaccid.

19) What happens to an animal cell and a plant cell when placed in sucrose/sugar water?

The animal cell will shrivel and the plant cell will plasmolyze as water moves out.

20) What is the Sodium Potassium pump – why is it important?

The sodium-potassium pump actively maintains the gradient of sodium and potassium ions across the membrane. It is important as it generates the membrane potential – keeps the inside of the membrane negative and outside positive as 3 sodium ions go out and 2 potassium ions come in. This is like charging a battery! – ready to discharge and work when cell needs it. This pump needs ATP to pumpions and is used in active transport.

21) What is cotransport? What gets transported?

In cotransport, a membrane protein couples the transport of two solutes. Here a proton pump pumps a H+ out to charge up the battery (instead of sodium and potassium ions) and when it discharges, and comes back in, a “friend” comes along –that is “cotransport” of a molecule of sugar.

22) What is exocytosis? Does it need ATP?

Exocytosis is the release of wastes OR secretion of proteins/enzymes by having vesicles attach to the plasma membrane, fuse with the membrane and then release their contents to the outside of the cell. This requires ATP.

23) What is endocytosis? What are the 2 types of endocytosis? Do they need ATP?

Endocytosis is when a cell brings in macromolecules and particulate matter by forming new vesicles from the plasma membrane. Endocytosis includes phagocytosis (for solids) and pinocytosis (for liquids) and both of them need ATP.

Chapter 9 Cell Respiration Objectives

1)What is cell respiration? What is the overall reaction? Where does it occur?

Cell respiration is the process of breathing oxygen to take into the body convert it chemically into food and breath out the unneeded parts (CO2) of the result. It mainly takes place in the mitochondrion of animals.

2)Where do the reactants of cell respiration come from and where do the products go?

The reactant glucose comes from all the food we eat and the oxygen from the breathing and the products go out through exhaling/peeing (CO2 + H2O ) and most importantly the ATP is used for cellular work.

3)What is the reason for a cell to go through cell respiration?

Cells go through cell respiration so that they can get ATP for activities like movement as muscle contraction needs ATP, synthesize proteins and make enzymes which get used in every reaction in the body, move organelles, transport material against their concentration gradient through active transport, replicate DNA, and more….

4)How does cell respiration relate to photosynthesis?

Cell respiration is the opposite of photosynthesis in all ways and it occurs in ALL LIVING ORGANISMS.

5)Do plant cells photosynthesize or respire? ()

Plants photosynthesize and respire – know this! So they fix carbon as glucose in photosynthesis and use some of it up in cell resp! Whatever glucose is left makes new plant parts – growth and accounts for net primary productivity.

6)Write the formula for glucose. Why is it a central molecule in cell respiration?

Glucose- C6H12O6 This is a central molecule for cell respiration because this can be converted into carbon dioxide, water, and ATP.

7)What is ATP? Why is it the most important product made in cell respiration?

ATP is the substance made of 3 PO4 groups and since it is a nucleotide, it has the phosphates connected to a ribose sugar and adenosine nitrogen base (oh but the ribose sugar is not used for giving the energy in this molecule). It is necessary in many situations and for many reactions as listed in ques 3.

8)How does ATP do its job as an energy molecule?

It does its job by releasing one of its three PO4 molecules so that it can attach to another substrate molecule, energizing it, lowering the free energy, and making it get together and form bonds with another substrate.

9)What does food or glucose contribute in order to make ATP?

Glucose provides electrons usin the H atom, in order to make ATP. NAD carries this to the electron transport chain.

10)What happens to the electrons for it to make ATP?

Electrons flow down a hill moving from less electronegative atoms in protein complexes to more electronegative atoms in the Electron Transport Chain of the mitochondria. As they do this downward movement (in their potential energy), they release their energy creating the H+ or proton pump. When the protons charge up creatin a “battery” situation again – lots of protons on the intermembrane area. The protons then flow back (discharge) through the ATPase making ATP.

11) What happens to the Carbon and Oxygen in glucose?

The carbon and oxygen in the glucose ends up as parts of water and carbon dioxide molecules. SO only the H atoms/electrons get to make ATP directly!

12) What molecule ‘CARRIES’ the electrons from glucose to finally make ATP?

NAD = it becomes NADH

13)Fill in Information: Aerobic Cell Respiration Overview from PowerPoint

1. Respiration involves Glycolysis, (Shuttle), the Krebs cycle, Electron Transport and Oxidative Phosphorylation.
2. Glycolysis - breaks glucose (6Carbon) into two pyruvates (3Carbon in each). Packages Hydrogen Electrons into NADH.

Glycolysis (in anaerobic/aerobic respiration) Gain – 2 pyruvates, 2 ATP, 2NADH

1. Shuttle - takes pyruvate from cytoplasm to mitochondria matrix. Gain- (2 NADH), 2 CO2 (2 carbonslost), 2 Acetyl CoA (2Carbon in each).
2. Krebs cycle - takes the two 3 Carbon compounds from Glycolysis and extracts all Carbons and Oxygens as CO2 and Hydrogen electrons in NADH/FADH2.

Krebs Cycle (aerobic respiration) Gain – 4 CO2 (all Carbons lost now), 2 ATP, 6 NADH, 2 FADH2.

1. Electron Transport Chain: occurs in mitochondrial inner membrane. Input- 10 NADH, 2 FADH2, 6 O2. Gain- H2O
2. Oxidative Phosphorylation: occurs in mitochondrial inner membrane. Input- H+’s and ADP  ATP in “mill wheel”. Gain- 10 NADH  30 ATP, 2 FADH2 4ATP = 34 ATP.

Aerobic Cellular respiration generates around 36-38 ATP molecules for each sugar molecule it oxidizes.

14)What is Substrate Level Phosphorylation?

This is where 4 ATP are made from substrates durin glycolysis and Krebs.

15) What is Oxidative Phosphorylation?

This is where 34 ATP (90%) is made by the electron transport chain in mitochondria.

16) Compare Substrate Level Phosphorylation and Oxidative Phosphorylation

Most of the ATP is made in Oxidative Phosphorylation.

17) Complete the following: Location of Cell Respiration Pathways

Cytoplasm - Glycolysis (End product is pyruvates, ATP, and NADH)

Shuttle - Cytoplasm into the mitochondria matrix.

Kreb’s Cycle - Matrix of Mitochondria (fluid inside mitochondria)

Electron Transport Chain - Enzymes located all along the mitochondria inner membrane. H+ ions moved from NADH and make water molecules.

Oxidative phosphorylation:

H+ ions move back into process where ADP becomes ATP.

ATP Synthase is in the cristae. ATP is made in the mitochondria matrix.

18)What does the Electron Transport Chain involve? Does it make ATP?

The Electron Transport Chain has electrons from glucose flow down a hill moving from less electronegative atoms in protein membrane complexes (and one lipid carrier) to more electronegative atoms like a relay downhill race. These protein complexes include cytochromes and proteins with Fe-S centers. As the electrons do this downward ‘flowing’ movement (dropping their potential energy), they release their energy creating the H+ or proton pump. The final electron acceptor is the most electronegative atom – namely oxygen and water is the end product. Technically the electron transport chain does not directly make ATP, as it is made after the electron transport chain through the use of ATP synthase.

19) What is chemiosmosis? Does this make ATP?

Chemiosmosis is the movement of the H+ ions from the higher concentration in the intermembrane region of the mitochondria (between the 2 membrane coverings) to the matrix (juice inside) where it generates ATP by flowing through the ATP Synthase enzyme.

20) What is the proton gradient or proton motive force? How is it generated? Why is it important for ATP synthesis?

Proton motive force is the ‘charging up of the battery’ –that means pumping all the H+ ions first into the intermembrane space to create a high concentration gradient and because they cannot flow back except through the ATP synthase enzyme- it is a force that is produced capable of being released to produce ATP.