HEAL 1500 session 5-7 (hya made)

Summarize the cell theory and state its importance to the study of biology

- A cell is the basic unit of life

- All living organisms are made of cells

- New cells come from preexisting cells

This is important in evolutionary history and diversity

Explain how a cell's size relates to its function

small cells have a greater surface-area-to-volume ratio, thus a greater ability to move material into and out of the cell

Compare and contrast the information that may be obtained from a light microscope and an electron microscope

- Light microscopes use light rays to magnify objects + can be used for LIVING specimens

- Electron microscopes use a stream of electrons to magnify objects + have a higher resolving power than light microscopes

Summarize the role of the plasma membrane

The plasma membrane (made of a phospholipid bilayer) forms the outer membrane of the cell & regulates what enters and exists the cell

What is the plasma membrane?

Phospholipid bilayer with proteins that are attached and embedded

- Hydrophilic heads face the cytoplasm and extracellular fluid

- Hydrophobic tails face inward

- Contains cholesterol for support

- Contains glycoproteins and glycolipids: carbohydrate chains attached to proteins and lipid which identify the cell as "self" or "foreign" and act as receptors

What is the fluid mosaic of the plasma membrane

** DYNAMIC, proteins freely move laterally

The fluid mosaic model describes the cell membrane as a flexible, two-dimensional liquid where diverse molecules float and shift past one another

Summarize the role of organelles in a eukaryotic cell

Organelles are compartments within eukaryotic cells where specialized reactions occur

What types of molecules can and cannot pass freely through the membrane and example?

Small, hydrophobic substances pass freely though the phospholipid bilayer

eg) gases like oxygen, carbon dioxide, estradiol

Ions and large molecules need help passing through

eg) water can cross the membrane by passing though channels called aquaporins

What are aquaporins?

Integral membrane proteins channels which facilitate water diffusion through the membrane

Describe the main differences between a eukaryotic and a prokaryotic cell.

Eukaryotic cells have a nucleus and membrane-bound organelles, whereas prokaryotic cells lack these

Describe the possible evolution of the nucleus, mitochondria, and chloroplast

Nucleus: through invagination of the plasma membrane (the process where a surface, cell layer, or membrane folds inward on itself to form a pocket, cavity, pouch, or tube)

Mitochondria & chloroplast: by engulfing prokaryotic cells

Summarize how the fluid-mosaic model describes the structure of the plasma membrane

Describes the plasma membrane as a phospholipid bilayer in which proteins are embedded

The protein can move within the bilayer, creating varied patterns

Compare and contrast diffusion, osmosis, facilitated transport, and active transport

Diffusion: the random movement of particles from an area of HIGH concentration to an area of LOW concentration until they're equally distributed

Osmosis: the net movement of water across aw semipermeable membrane from high --> low conc.

Facilitated transport: requires a protein carrier to help molecules move through a membrane according to their concentration gradient

Active transport: requires a carrier plus energy

What is osmosis and what drives it?

The net movement of WATER across a semipermeable membrane from high --> low conc.

Osmotic pressure drives osmosis

What are isotonic solutions

The same concentration of impermeable solutes, normal body fluids are isotonic to cells

(Intravenous solutions that have an equal salt and particle concentration to human blood)

Cells do not change in size as a result

What are hypotonic solutions

Solutions that have fewer solutes WATER GOES INTO CELLS (which causes water to shift out of the blood vessels and into the cells)

Cells swell and can burst (lysis)

What are hypertonic solutions?

Solutions that have more solutes WATER EXISTS THE CELL (They draw water out of the cells and into the blood vessels)

Cells shrink (crenation)

What is diffusion?

The random movement of particles from an area of HIGH concentration to an area of LOW concentration until they're equally distributed

* Molecules move in both directions, but the NET MOVEMENT is from high to low conc.

At equilibrium. the same number of molecules move in and out of the cell

Is diffusion passive?

Yes, it doesn't require energy

What is facilitated transport?

- The transport of molecules across the plasma membrane from higher conc. to lower conc. VIA A PROTEIN CARRIER

- Protein transporters are very SPECIFIC and only move certain molecules:

- Channels (tunnels, gated or not)

- Uniporter carriers (open on one side, close, then open on other side)

Is facilitated transport active or passive?

Passive, requires no energy

What is active transport?

The movement of molecules from a LOWER TO HIGHER conc. (goes against conc. gradient)

What is the difference between primary active transport and secondary active transport?

Primary active transport: a PUMP always uses ATP, uniport (one molecule) or cotransport (molecules A and B)

Secondary active transport: energy is provided by one if the molecules (A) going according to its gradient:

- Symport: (A and B molecules go in the same direction)

- Antiport: (A and B molecules fo in opposite directions)

Does active transport require energy?

Yes because it goes against the conc. gradient

What is bulk transport used for?

Bulk transport used to move large molecules across the membrane

Discuss the various ways cells can move materials in bulk into and out of the cell

Other than diffusion, osmosis, facilitated transport, and active transport, materials can enter the cells via endocytosis: invagination of the plasma membrane (phagocytosis or pinocytosis) and leave cells via exocytosis

What is exocytosis?

Transports molecules OUTSIDE the cell via the fusion of a vesicle with the plasma membrane

(sort of life reverse endocytosis)

What is endocytosis and describe each type

Transports molecules or cells INTO the cell via invagination (folding into itself) of the plasma membrane to form a vesicle

Phagocytosis: endocytosis of pathogens (eg) bacteria) by white blood cells

Pinocytosis: endocytosis of fluid with small particles

Receptor-mediated endocytosis: particles first bind to receptors in the plasma membrane; this initiates endocytosis

Describe the functions of the following organelles: endoplasmic reticulum (ER), Golgi apparatus, and lysosomes

- Smooth ER synthesizes lipids and rough ER synthesizes protein; both are packaged in vesicles

- Golgi apparatus modifies lipids and proteins from the ER and sorts and packages them in vesicles

- Lysosomes contain digestive enzymes that break down cell parts or substances entering by vesicles

What is the endoplasmic retulum?

What is the golgi apparatus?

Modifies, sorts, and packages proteins and lipids for use inside or outside the cell

What are lysosomes?

a membrane-bound cell organelle that contains digestive enzymes to break down waste, old cell parts, and foreign invaders

Explain how the nucleus, ribosomes, and rough endoplasmic reticulum (ER) contribute to protein synthesis

Nucleus: contains DNA, which directs the synthesis of proteins

Ribosomes: aid the mRNA in the production of proteins

Rough ER: where proteins are synthesized and folded

Describe the organelles of the endomembrane system involved in the export of a protein from the cell

The endomembrane system is composed of:

- Nuclear envelope: has pores through which ribosomal subunits can pass out

- Rough ER: where membrane proteins are made

- Smooth ER: where phospholipids are synthesized

- Golgi apparatus: where proteins and lipids are modified

- Vesicles: which transport their contents to the plasma membrane for export or to lysosomes for digestion

What is the endoplasmic reticulum?

What is the nuclear envolope

a double-membrane barrier that surrounds and protects the nucleus in eukaryotic cells.

What is the vesicles

List the three types of fibers in the cytoskeleton

microtubules, actin filaments, intermediate filaments

Describe the structure of cilia and flagella

Cilia and flagella: both contain an inner core of microtubules within a covering of plasma membrane

Describe the function of cilia and flagella

Cilia: function by moving cells slowly in their environment and by sweeping debris

Flagella: function in moving a cell quickly

List the types of junctions found between animal cells, and state a function for each.

Adhesion junctions: mechanically attach adjacent cells and prevent overstretching

Tight junctions: provide a zipperlike barrier between adjacent cells and do not allow movement of molecules between the two cells

Gap junctions: are channels used for communication between adjacent cells

What are the types of functions found between animal cells?

Adhesion junctions, tight junctions, and gap junctions

What are adhesion junctions?

Adhesion junctions: mechanically attach adjacent cells and prevent overstretching

What are tight junctions?

Tight junctions: provide a zipperlike barrier between adjacent cells and do not allow movement of molecules between the two cells

What are gap junctions?

Gap junctions: are channels used for communication between adjacent cells

Summarize the roles of enzymes in chemical reactions

Enzymes speed up the chemical reactions in biological systems by lowering the activation energy of reactions

Describe the basic steps required to break down glucose by cellular respiration

EDIT LATER:

- Glycolysis begins with glucose and ends with two molecules of pyruvate

- Two molecules of ATP and NADH are produced

- Acetyl CoA enters the citric acid cycle --> continues breakdown of glucose & ends with the production of two molecules of ATP, NADH, and FADH2

- The electron transport chain accepts high-energy electrons, which are passed carrier to carrier along the chain

- The energy is used to produce ATP

- Oxygen is the final electron acceptor and water is produced

Explain why the ATP resembles that of a rechargeable battery

- When ADP binds with phosphate, energy is being stored in the molecule just like a battery

- When ATP is broken down to ADP and phosphate, energy is being released to be used in other reactions

Explain the differences between cellular resperiation and fermentation

- Cellular respiration used oxygen as the final electron acceptor in a reaction at the end of the electron transport chain that produces water

- Fermentation occurs in the absence of oxygen, and the citric acid cyle and electron transport chain do not function

- Instead, pyruvate is converted to lactate in animal cells or to ethanol and CO2 in yeast cells

Light microscopy resolution, pros, and cons

Resolution: ~200 nm

Pros: Simple, widely available, live-cell imaging

Cons: Limited

Structured illumination resolution, pros, and cons

Resolution: ~30-50 nm

Pros: Improved resolution, compatible with live cells

Cons: Lower acquisition, limited depth

STED Microscopy resolution, pros, and cons

Resolution: ~30-50

Pros: Super-resolution, precise localization

Cons: High phototoxicity, expensive

SEM (scanning electron microscopy) resolution, pros, and cons

Resolution: ~1-10 nm

Pros: 3D-like surface imaging

Cons: Sample coating required, only non-living samples

Electron microscopy (TEM)

Resolution: ~0.1-1 nm

Pros: Atomic-scale resolution

Cons: Requires fixed/dead samples

nc-AFM (non-contact AFM)

Resolution: Sub-angstrom (~0.1 nm)

Pros: Can resolve single atoms, non-destructive imaging

Cons: Slow scanning, requires ultra-stable conditions

What are glycoproteins and glycolipids

Ccarbohydrate chains attached to proteins and lipid which identify the cell as "self" or "foreign" and act as receptors

Symport vs antiport

- Symport: (A and B molecules go in the same direction)

- Antiport: (A and B molecules fo in opposite directions)