Biology Test #3 Notes: Cell Structures, Functions, and Membrane Transport

I. Cell Theory (data gathered over a 200 year period by several scientists)

 All living things are made up of at least one cell.

 The cell is the basic/smallest unit of structure and function in living things (the bricks of buildings).

 ______

 In 1665, Robert Hooke was the 1st to see and name the cell from cork found in plants using a ______.

 In 1676 Anton Von Leeuwenhoek was the 1st to view a ______.

 Robert Brown in 1831 was the 1st to see and name the ______of a cell.

Why did it take more than 160 years for Brown to view the nucleus after Leeuwenhoek’s discovery?

II. Parts of a Cell and Their Generalized Functions (3 general areas – cell membrane, cytoplasm w/organelles, and the nucleus)

1. Cell Membrane – A bilipid structure that is the outermost portion of the cell

Functions include:

(a) A boundary between the cell’s contents and the environment which regulates what enters and exits the cell.

(b) Communicates with other cells within an organism or between unicellular organisms.

(c) Contains proteins that identify the cell.

(d) It serves as an attachment site for some organelles and near-by cells

2. Cytoplasm and it’s Organelles- Cytoplasm may also be called the Intra-Cellular Fluid/ICF or Cytosol.

a) Cytoplasm is a viscous fluid made up of water, minerals, organic molecules, and organelles. It is located between the cell membrane and the nuclear membrane.

b) Organelles, or “little organs”, perform specific functions for the cell (division of labor).

 Ribosomes – Site of ______(where protein macromolecules are made using directions from DNA).

1  Endoplasmic Reticulum - Rough ER (endoplasmic reticulum) hold ribosomes (protein maker) on their membranes.

- Smooth ER makes new membranes for organelles and the cell using lipids, carb’s, & proteins.

- Both ER’s are pathways/tunnels for molecules to travel through cytoplasm or out of the cell.

 Golgi Apparatus/Body – Golgi combine small glucose molecules into larger starch or glycogen molecules. They attach these carbohydrates with lipids to proteins which now packaged to the correct size and shape and ready to be used or stored by the cell.

 Mitochondria – ______

Mitochondria have their own ______.

 Lysosomes – Hold digestive enzymes that breakdown old cell parts, nutrients, & foreign substances (toxins/bacteria).

 Cytoskeleton – An arrangement of proteins (microtubules & microfilaments) that support and give the cell its shape.

The cytoskeleton disassembles near the end of a cell’s life cycle allowing a cell to split into 2 new cells. The disassembled cytoskeleton will reform into the spindle apparatus, a temporary cell part that ensures that each of the 2 new cells will get the same # of chromosomes. After chromosomes evenly divide, the cell splits w/each new cell getting a portion of the spindle apparatus which will become their new cytoskeleton. This will give each new cell support and a specific shape.

. Microfilaments – Long, thin fibers that give a cell its shape and enables the movement of organelles within the cell.

. Microtubules – Hollow tubes that move chromosomes (spindle apparatus), they also make up centrioles.

 Centrioles – Pairs of bundled microtubules located in the cytoplasm that assemble the spindle apparatus (has its own DNA).

2  Cilia – ______, numerous microtubules on cell membranes functioning in movement of the cell or substances near cell.

 Flagella – ______, usually singular microtubule from the cell membrane that functions to move a cell (sperm tail).

Organelles primarily in plant cells  Cell Wall – A tough, supportive and protective covering of plants (of cellulose), fungi (of chitin), most bacteria, and some protists. The cell wall is located outside the cell membrane and allows most molecules to pass.

 Vacuoles – Large sac’s that store proteins, lipids, carbo’s, water, & waste. Can give a cell structural support (turgor).

 Plastids – Storage sac’s holding macromolecules & pigments. Pigments allow photosynthesizers to absorb light energy .

. Chloroplasts – Green pigmented plastid (filled w/chlorophyl) that absorbs light. Have their own DNA. . Chromoplasts – Yellow, orange, and red plastids that absorbs light.

. Leucoplasts – Nonpigmented plastids that store starch (carbohydrate), proteins, and lipids.

3. Nucleus – The nucleus is surrounded by the ______, which envelops nucleoplasm that protects ______.

DNA makes RNA (3 types), RNA then travels to the cytoplasm to make ______. Proteins determine an organisms ______.

The nucleus also contains the nucleolous which makes the ribosomes. Ribosomes (made up mostly of RNA) then travel to the cytoplasm where most will attach themselves to ______ER.

III. Cell Shape & Function, Size Limitations, and Cell Types

 The cell is the smallest living portion of any organism, unicellular (one-celled) or multicellular (many-celled). In a multicelled organism, like a human, there can be over 200 different types of cells, trillions in all.

 3 characteristics determine a cell’s function:

a) b) c)

 In multi-celled organisms, individual cells may specialize. Specialized cells perform a limited amount of jobs.

Advantage of Cell Specialization – Increased ______.

Disadvantage of Cell Specialization – Increased ______.

3 Cell Size Limitations:

 If a cell gets too large, the distance between the nucleus (containing DNA which controls protein synthesis) and other organelles becomes too great for effective control and communication.

 As a cell grows, its surface area (cell membrane) grows at a slower rate than its volume (organelles, cytoplasm, & nucleus).

Why does this limit cell size?

a) Prokaryote Cells -

- Kingdoms: b) Eukaryote Cells –

- Kingdoms:

IV. Microscopy (The Microscope)

Properties of Light Microscopes

Magnification – An increase in the size of an image.

Resolving/Resolution Power – How clear the magnified specimen appears.

Field of View – How much of the image is seen through ocular. 40x = 100x = 400x =

Depth of View – How resolute/clear images appear at different distances from the ocular/eyepiece.

 Increasing the magnification will decrease resolving power, field of view, and depth of view.

Data Table Contrasting Light vs. Electron Microscopes

Microscope Characteristics Light Microscope Electron Microscope

Highest practical magnification

Radiation source & medium of travel Light – Air Electron beam – Vacuum

Radiation focussing mechanism

Specimen image Colored specimen’s, stain’s, & dye’s can be seen No light = no color

Specimen type (dead or alive)

Size & Cost

4 Structures and Functions of a Common Light Microscope

 Color each microscope part by its color as indicated in the data table, below left. Be sure to color in the word in the data table and on the picture of the light microscope, below right.

Microscope Part Function Microscope Part

Arm & Base The 2 parts held while carrying a scope (light blue, dark blue)

Ocular/Eyepiece Holds a 10x lens for magnification and where (red) the specimen is viewed

Ocular Tube Creates a distance between ocular lens and (light green) objective lens for correct magnification

Revolving Nosepiece Moves objectives w/different magnifying /Objective Turret powers to be rotated above specimen (pink)

Objective Lens Carries the 2nd lens for magnification 4, 10, 40, & 100x (dark green)

Stage w/clip Holds slide/specimen in place for viewing (black)

Stage Aperture Hole in the stage allowing light through (not seen in this view)

Iris Diaphragm Controls light passing through specimen (orange)

Light Source Provides light needed to produce an image (yellow)

Course and Fine Moves the stage up and down to focus or Objective Knobs improve resolution of the image (dark & light brown)

Condenser Condenses/focuses light before it passes and Knob through the specimen

Light Intensity Knob Regulates light intensity from the source (gray)

Slide Adjustment Moves slide/specimen (forward, left, right, (not seen in this view) backword) w/o you touching the slide

5 III. Membrane Transport (Active and Passive)

HEY!?!?! How do cells get… amino acids to build proteins? Nucleotides to build DNA & RNA? Carbon dioxide and water for photosynthesis? Water, minerals, vitamins, etc.?

Plants acquire carbon dioxide from the air via their leaves and water from the soil via their roots. Animals acquire water and nutrients from plants and other animals via their mouths.

 What gets across a cell’s membrane? How do molecules get in? How does the cell rid itself of waste? Is energy needed for membrane transport (the movement of molecules across a cell’s membrane)?

Homeostasis – Homeostasis is an organisms way of maintaining normal function.

Examples include: ______

- Homeostasis is maintained by negative and positive feedback mechanisms (see test #1 notes).

- Because cells are the basic unit of structure and function, if they die, the tissues they comprise may die. If tissues die, organs may fail. If organs fail, the organism can die.

Maintaining the cells internal environment (the fluid that surround cells – ECF/Extra Cellular Fluid) so the cell has all the raw materials needed to live and function properly is vital to the organism’s survival.

- Homeostasis must be maintained even under times of stress.

- Stress includes: ______, malnutrition, physical exertion, pathogen ______(bacteria, viruses, etc.), and temperature ______.

- The ______of molecules (hormones to be transported to other cells, excess water, and waste products) from the ICF/IntraCellular Fluid (or Cytoplasm) to the ECF (outside the cell) is as essential to maintaining homeostasis as the entrance into the cell of molecules that provide the raw materials and energy needed for biochemical processes.

- The cell’s membrane structure allows it to be semi- or selectively ______, allowing some, but not all molecules through. Permeability fluctuates according to the ever changing needs of the cell. For example, if the cell needs more glucose (sugar), the cell membrane will be more permeable to sugar, allowing more sugar to enter the cell.

1. Passive Transport – The movement of molecules (H20 or solutes) across a cell’s membrane (in or out) w/o the use of ______to achieve equilibrium. Equilibrium is an equal concentration of a particular molecule in the ECF and ICF.

6 a) Simple Diffusion – The movement of molecules or ______(small molecules dissolved by water to form a solution) from an area of greater concentration to an area of lesser concentration. The cell’s membrane acts as a ______or boundary between areas of differing concentrations.

b) Facilitated Diffusion – The movement of molecules that move through specific channels/holes via proteins embedded in the cell membrane. Molecules may enter or exit, but only traveling down a gradient, or area of high to low concentrations. As with simple diffusion, facilitated diffusion occurs with no energy being used. Each molecule that enters or leaves must do so through a specific protein channel (100’s in all).

c) Osmosis – The movement of ______molecules across a cell’s membrane from an area of higher to lower concentration w/o the use of energy.

As the amount of water increases in the ICF/cytoplasm, so does the pressure is exerts on the cell membrane. The force of water on the cell membrane is termed ______(or osmotic) pressure.

When turgor/osmotic pressure is too low the cell wilts (plasmolysis) and when turgor/osmotic pressure is too high the cell bursts (cytolysis).

Type of Transport Diffusion Osmosis Facillated Diffusion Active Transport

Materials Moved (example:water, minerals)

Direction of movement(example, High conc. to Low conc.)

Energy Requirements

* Terminology associated with the movement of molecules across a cell’s membrane *

Hypertonic– The area (ICF or ECF) that possesses a higher concentration of a solute and a lower concentration of water.

Hypotonic – The area (ICF or ECF) that possesses a lower concentration of a solute and higher concentration of water.

7 Isotonic– A condition in which the ICF and the ECF are in equilibrium, or an equal molecule concentration.

______tonic ______tonic ______tonic

ECF = ECF = 42% solute 42% solute

ECF = 42% solute ECF = 42% solute ECF = 42% solute

Indicate, using red arrows, the direction solute molecules are moving (diffusion) in each of the cells above.

Indicate, using blue arrows, the direction water molecules are moving (osmosis) in each of the cells above.

2. Active Transport – The movement of molecules from an area of lower concentration to an area of higher concentration. To move molecules against the concentration gradient, cellular energy is needed (ATP).

a) Endocytosis – The movement of substances into a cell by being surrounded/engulfed by the cell’s membrane.

 Phagocytosis – Endocytosis of a large molecule or small unicellular organism.

 Pinocytosis – Endocytosis of large quantities of fluids or dissolved substances.

b) Exocytosis – Movement of large molecules or quantities of fluids/dissolved substances out of the cell.

8 Biology Test #3 Format: Cell Structures & Functions, and Cell Membrane Transport

1-15 = Multiple Choice (will cover anything not asked in matching or completion questions)

16-25 = Matching cell part/organelle to its description (answers may be used once, more than once, or not at all)

26-32 = Complete with the best possible answer

 Discuss in sentence format, a positive and negative aspect of “Cell Specialization”.

 Be able to discuss which organelles are found exclusively in plant cells and which can be found in both plant and animal cells.

 Draw and label a segment of a cell/plasma membrane that contains the following:

protein channel

hydrophobic tail

hydrophilic head

ECF

ICF

 Do all cells have the same number of individual organelles? Explain.

 Describe what is occurring during an experiment regarding diffusion or osmosis.

 What organelle produces glucose?

What organelle converts glucose into a different form of energy?

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