Unit 2 - Cells

A dialysis bag is filled with distilled water and then placed in a sucrose solution. The bag's initial mass is 20 g. and its final mass is 18 g. Calculate the percent change of mass, showing your calculations in the space below.

% change in mass = 18g -20g x 100 = -10% 20g

prokaryotic cell

- NO nucleus - DNA free in cytoplasm - smallest of all cells - most have a cell wall - no membrane-bond organelles

Pinocytosis (drinking)

-Cells receive bulk amounts of fluid -"cell drinking"

Membrane Cycling

Cycling of membrane by endocytosis and exocytosis

Predict what would happen to the mass of each bag in this experiment if all the bags were placed in a 0.4 M sucrose solution instead of distilled water. Explain your response.

I predict that if the molarity of the sucrose solution in the bag was less than 0.4 M (0-0.2M) the water would leave the bag, but if the molarity of the sucrose solution is more than 0.4 M (0.6-10M) then the water would enter the bag. Since, if the solute has a higher concentration than it will want to go to a lower concentration.

What results would you expect if the experiment started with glucose and IKI solution inside the bag and only starch and water outside? Why?

I would expect that if glucose and IKI solution were inside the bag that they would move outside the bag and if starch and water were outside the bag only water could enter inside the bag. Therefore, making the mass of the bag be less since more substances are exiting then entering the bag. The reasoning for this is because the bag would have a higher concentration and would want to move to the lower concentration or the beaker.

Which cell design won the race. Offer an idea as to why?

Our design won the race because it was thin enough yet weighed enough to diffuse the quickest, since there was less area to cover. Therefore, meaning the vinegar could reach the center of the agar the quickest, yet still having weight to it.

In the winter, grass often dies near the roads that have been salted to remove ice. What causes this?

Plasmolysis causes the grass to die because the salt acts as the hypertonic solution and forces all the water inside the grass's cell to leave. Thus, making the grass die.

What is plasmolysis?

Plasmolysis is the shrinking of cytoplasm of a plant cell, in response to diffusion of water out of the cell and into a hypertonic solution surrounding the cell.

Light microscope

allows you to view living organisms

Endoplasmic Reticulum

structure-Smooth Endoplasmic- lacks ribosomes; Rough Endoplasmic- has ribosomes that stud the outer surface of the membrane. function-Smooth ER- metabolic processes; providing ample machinery for steroid synthesis, store calcium ions. Rough ER- to make more membrane, produce proteins that will be inserted into the growing ER membrane, transported to other organelles.

golgi bodies

structure-Stack of flattened sacs in numbers of hundreds and are not connected to one another. One side of the Golgi stack serves as a receiving dock for transportation vesicles, a vesicle fuses with the Golgi sac adding to its membrane, and the other side of the Golgi is the shipping side that gives rise to the vesicles and bud off to and travel to other sites. function-After leaving the ER many transport vesicles travel to the Golgi. Molecular warehouse and finishing factory for products manufactured by the ER.

Cytoskeleton

structure-There are three kind of fibers that make up a cytoskeleton: microfilaments, the thinnest fiber; microtubules, the thickest; and intermediate filaments, in between in thickness. (Microfilaments, Intermediate filaments, and Microtubules). function-A network of protein fibers extending throughout the cytoplasm of the cell. These fibers function like a skeleton in providing for both structural support and cell motility (internal movement of cell parts and locomotion of a cell).

Endocytosis

substances enter when plasma membrane balloons inward -active -both high and low, low and high -no channel protein -vesicle used -largest or bulk

the surface area in a cell is equivalent to?

the cell wall

Concentration Gradient:

the greater the difference the faster the rate

volume in a cell is?

the plasma membrane

Transport proteins

transport specific substances across the membrane; channel proteins for example open only when they receive the correct signal, allowing substances they transport to flow.

Exocytosis (exit)

vesicle moves to the cell surface and fuses with the plasma membrane -removes material from the cell -active -both high and low, low and high -no channel protein -vesicle used -largest or bulk

Hydrophobic

water "fearing"/ repel water

eukaryotic cells

- nucleus - contains DNA -membrane bond organelles- nucleus, endoplasmic reticulum, golgi apparatus, vesicles -much larger

Phagocytosis (eating)

-Cell engulfs microbes, large particles, and cellular debris - "cell eating" - Done by amoebas and white blood cells

Membrane Cycling-Exocytosis

-Makes membrane larger -Vesicle leaves lysosome or golgi and becomes part of membrane

Membrane Cycling- Endocytosis

-Makes membrane smaller -Vesicles head to lysosomes or golgi body where they are incorporated

Fluidity of the Membrane

-Phospholipids and proteins are free to drift around (left right, forwards, backwards) -Phospholipids and proteins can spin around -Short unsaturated tails increase fluidity -Cholesterol reduces flexibility

why are cells so small?

-The larger the cell gets the longer it takes molecules to reach the center of the cell and the more nutrients it needs. -Cells need a large surface area and small volume to assure they can get all they need to survive.

active transport

-active -low to high -uses a channel protein -no vesicle is used -any expect largest

isotonic (equal)

-equal amounts of solute are present -The concentration of solute is the same on both sides of the cell -No net change to in cell size

hypotonic (hippo)

-less solute (what is being dissolved) is present -The concentration of the solute outside the cell is less than what is inside the cell -Water diffuses in -Cell becomes turgid (swells) -When a cell is swollen it is said to have turgor pressure

hypertonic (hyper-water goes outside)

-more solute (what is being dissolved) is present -When compared to the cell, the concentration of the cell, the concentration of the solute is greater outside than inside the cell -Water diffuses out -Cell shrinks

diffusion

-passive -high to low -does not use a channel protein -no vesicles used -small and nonpolar

facilitated diffusion

-passive -high to low -uses a channel protein -does not use a vesicle -medium, charged polar

osmosis

-passive -high to low -uses a channel protein -vesicle is not used -water

a cube as how many faces?

6

Give an example of a type of cell in a living organism (animal or plant) that is shaped very differently than the classical round or boxy shape that you see drawn in introductory textbook chapters on cells. How is that unique shape tied to the function that cell has?

A diatom cell found in algae and in water and is shaped somewhat circular but is more in rather an almond shape, or an elliptical or triangular shape. The reasoning the diatom shape can differ and change so much is because it is responsible for monitoring the past and current environmental conditions and can help researchers know the quality of water.

As a cube increases in size, what happens to the surface area to volume ratio?

As the cube increases size the surface area increases but the volume ratio stays the same when the ratios are simplified because there is the same amount of mass throughout the cube, but more space for diffusion to happen because of the increase in surface area.

Why can't cells get very very big?

Cells cannot get very big because the amount of time it takes to diffuse into other substances would take too long because as the cell gets bigger it makes the cell less helpful for functions such as in plants and in bodies, and they wouldn't be very efficient.

Describe different ways that cell shape can be modified so that diffusion rate will be decreased and life's processes can be supported.

Different ways that cell shape can be modified to make diffusion rate quicker is by making the cell be longer and thinner. Thus, having a smaller spherical cell is possible as long as the size of the cell is very small in comparison to help with diffusion time.

Why did you calculate the percent change in mass rather than using the change in mass?

I calculated the percent change in mass rather than change in mass because the percent change in mass would indicate how great the change was with the mass initially and the mass prior.

Explain the relationship between the change in mass and the molarity of sucrose within the dialysis bag.

Most of the time as the molarity of the sucrose within the dialysis bag increased with the change in mass because when there is a high solute and a low water within the bag, and the beaker with high water allows the water to move from high to low concentration. Thus, making the mass increase when there is more solute or a higher molarity.

Why are the two words fluid and mosaic used to describe the membrane?

The 'fluid' word describes how some parts of the membrane can move around freely because they are not attached to other parts of the cell, and 'mosaic' because of the arrangement the membrane can form and due to its flexibility, it can be compared to a mosaic piece of work (i.e. separated and floating freely).

The 2x2x2 and the 1x1x8 have the same volume. Was their diffusion time the same?

The 2x2x2 and the 1x1x8 don't have the same diffusion time while having the same volume because while the 2x2x2 ratio is has a smaller ratio than 1x1x8, but with the 2x2x2 ratio it has less ways/sides to get to the center to fully diffuse. However, 1x1x8 has a smaller diffusion time because there was more faces(spread out) making the agar be thinner, allowing diffusion to be faster.

Which cell in Part 1 had the fastest diffusion time?

The cell that is 1 cm had the fastest diffusion time because it had less of an amount it needed to cover to become diffused in the vinegar.

Describe your cell design. What principles were you basing your design on to decrease diffusion time?

The design of my cell is long but rather thin in thickness. We were basing our design based on how long it takes for the diffusion process to fully reach the center because the thinner the agar is, the quicker it will take to diffuse.

Which substance(s) are entering the bag and which are leaving the bag? What experimental evidence supports your answer?

The iodine entered the bag, glucose went outside the bag, and starch did not move. The evidence to support this is the glucose and starch together were clear but after the diffusion the bag was black meaning the iodine entered the bag. Furthermore, the beaker was originally brown but changed to yellow because the glucose went outside the beaker. Lastly, the evidence that glucose left the bag is only the glucose could have left because starch is too big to leave the bag but having the bag change to clear to black and the beaker changing from brown and yellow shows the glucose left the bag and made the beaker substance color less concentrated.

Why did the onion cells plasmolyze?

The onion cells plasmolyzed because it is a plant cell that became hypertonic because of the solution surrounding it, causing the water to leave the cell.

Describe the set up of a phospholipid bilayer. Why do the phospholipids arrange themselves in a bilayer?

The phospholipids in the plasma membrane are arranged in two layers and each phospholipid molecule has a head and two tails. The head "loves" water and the tails of the phospholipid "fear" water. Furthermore, phospholipids arrange themselves in a bilayer because having a phospholipid head on either side prevents water from entering the cell membrane and reaching the hydrophobic tails from all sides of the membrane.

Methylene blue is a basic stain that reacts with acidic molecules in the cell to give varying shades of blue. Which part of the cell has absorbed the greatest amount of stain? Nucleus Why?

The reason the nucleus appears darker than the rest of the cell is because DNA and RNA are stored in the nucleus, and since they both are the chemical makeup of the cell they absorb more of the blue coloring.

In general, what is the relationship between the Surface Area to Volume Ratio and diffusion time?

The relationship between the surface area to the volume ratio and the diffusion time is when there is less surface area and more volume making the substance take longer to diffuse. Hence, when there is a smaller ratio between the two like 3:1 (surface area vs. volume) it will take longer than a 6:1 ratio.

Explain the results you obtained. Include the concentration differences and membrane pore size in your discussion.

The results I obtained showed the concentration of the beaker was high and moved to a low concentration in the bag, until equilibrium was reached between the two. The membrane pore size is big enough to fit the glucose outside of the bag but the starch is too big to fit because it's a chain of molecules, which is shown from the color changing to clear to black in the bag. However, the iodine(IKI) solution and water were small enough to fit inside the bag from a brown color to a yellow color in the beaker, and this process repeated until there was equilibrium.

Quantitative data uses numbers to measure observed changes. How could this experiment be modified so that quantitative data could be collected to show that water diffused into the dialysis bag?

This experiment could be modified so quantitative data could be collected by possibly weighting the initial and final mass of the bag and the beaker.

contransport

a transport protein couples the transport of one molecule to another

Transmission Electron Microscope

allows you to see more detail, but in dead organisms.

Scanning Electron Microscope

allows you to view 3D surfaces of dead organisms

Enzymatic proteins

biochemical reaction, that typically lower the activation of energy of the reaction, making reactions go much faster even when a catalyst is not being used.

Recognition proteins

embedded in the cellular membrane and allow cells to communicate with each other by cells attaching to other cells to allow cell communication.

Glycoproteins

helps the immune system

The sucrose solution in the beaker would have been ________ to the distilled water in the bag.

hypertonic

Mosaic

mixed composition of phospholipids, proteins and sterols

Temperature:

molecules move faster at higher temperatures

Passive Transport

movement of molecules without the use of energy

bulk transport

moves larger molecules (proteins) that cannot fit through protein channels

function of the cell wall?

provides an outer layer to the cell and protects it

Signal Transduction (Receptor) proteins

receptors that bind to signaling molecules and start a physiological response, by first signaling molecules from outside the cell, then a signaling molecule binds to the receptor protein, and lastly the signal triggers a specific cellular response.

Molecular Size:

small molecules move faster than large ones

vesicles

structure-A small structure within a cell consisting of a fluid enclosed by a lipid bilayer. function-Transport materials within the cell from mainly the Golgi to the other parts of the organelle.

cell membrane

structure-A thin layer of phospholipids that spontaneously arrange so that the hydrophobic tail is isolated from surrounding water and the hydrophilic head are on the outside of the membrane. function-Provides protection of a cell. In addition to a fixed environment inside the cell by controlling what goes in and what comes out.

Cilia and flegella

structure-Different in length and beating pattern, cilia and flagella have a common structure and mechanism of movement. Both are composed of microtubules wrapped in an extension of the plasma membrane. Cilia- short; Flagella- usually only one per cilia and is longer function-Cilia-transport cells or a group of cells from liquid or materials past them(dust, smog) Flagella- helps with movement (a rowing team)

Chloroplast

structure-Enclosed by an inner and outer membrane separated by a thin intermembrane space. The compartment inside the inner membrane holds a thick fluid called stroma, which contains chloroplast DNA and ribosomes as well as many enzymes. Contains a network of interconnected sacs called thylakoids inside the chloroplast, and thylakoids in stacks are called granum. function-They are the photosynthesizing organelles of all photosynthetic eukaryotes. The chloroplast's solar power system is much more efficient than anything yet produced. Befitting an organelle that carries out complex, multistep processes, internal membranes partition the chloroplast into compartments.

Mitochondria

structure-Enclosed by two membranes, each a phospholipid bilayer with a unique collection of embedded proteins. Intermembrane space, the narrow region between the inner and outer membranes. The inner membrane encloses the second compartment, mitochondrial matrix, which contains mitochondrial DNA and ribosomes, as well as many enzymes that catalyze some of the reactions of cellular respiration. function-Are organelles that carry out cellular respiration in nearly all eukaryotic cells. Converting chemical energy of foods such as sugars to the chemical energy of a molecule ATP.

ribosomes

structure-Has protein and RNA and appear to be very tiny. They are attacked to rough ER and some are floating throughout the cell. function-Used for cellular functions; protein builders or the protein synthesizers.

central vacuole

structure-Is the largest part; Has two parts with the cell sap and the tonoplast. The cell sap is the fluid within the vacuole. function-Helps the cell grow in size by absorbing water and enlarging. It also stockpiles vital chemicals and acts as a trash can safely storing toxic waste products.

Nucleus

structure-Made up of the nuclear membrane, nucleoplasm, chromosomes, and nucleolus. And is the largest organelle inside the cell. function-Contains the majority of the cell's genetic material and coordinates cell activities like protein synthesis and cell division.

cell wall

structure-Plant cell walls consist of fibers of cellulose embedded in a matrix of other polysaccharides and proteins. Cells initially lay down a relatively thin and flexible primary wall, which allows the growing cell to continue to enlarge. function-Distinguishes plants from animals. Protects the cells and provides the skeletal support that keeps plants upright on land.

Hydrophilic

water "loving"/ affinity for water

aquaporin

water channel protein in a cell

Based on your observations, rank the following by relative size, beginning with the smallest : glucose molecules, water molecules, IKI molecules, membrane pores, starch molecules.

water molecules, IKI molecules, glucose molecules, membrane pores, and starch molecules.

Intracellular Joining (Adhesion) proteins

when proteins on adjacent cells hook together briefly for cell interaction or sharing; provide adhesion and communication.