Ap bio chapter 6. 1

What is the difference between Magnification and Resolution?

Magnification- ratio of an objects image size to its real size.

Resolution- measure of the clarity of the image; it is the minimum distance two points can be seperated and still be distinguished as two points.

What is a major disadvantage of an electron microscope?

In the process of preparing the specimen, the cells are killed.

Scanning Electron Microscopy vs.

Transmission Electron Microscopy

Scanning- Useful to study the surface of a specimen. Show a 3D image of the surface of a specimen.

Transmission- Used to study the internal ultrastructure of cells. Profiles a thin section of a specimen.

In the cell fractionation, which organelles are the smallest ones isolated in this procedure?

Ribosomes

Which two domains consists of prokaryotic cells?

Bacteria and Archaea

Describe the difference between the location of DNA in prokaryotic and eukaryotic cells?

Eukaryotic- DNA is in an organelle called the nucleus, which is bounded by double membrane.

Prokaryotic- DNA is in concentrated in a non membrane enclosed nucleoid.

Cell Wall

Plasma Membrane

Bacterial Chromosome

Nucleoid

Cytoplasm

Flagella

Cell Wall- rigid structure outside the plasma membrane.

Plasma Membrane- membrane enclosing the protiens.

Bacterial Chromosome- Chromosome is bacteria

Nucleoid- Region where the cell's DNA is located (not enclosed by membrane.

Cytoplasm- Region between the nucleus and the plama membrane of a eukaryotic cell.

Flagella- Locomotion organelles of some bacteria

Why are cells so small? Explain the relationship of surface area to volume.

Cells are so small because if a cell grows beyond a certain limit, not enough material will be able to cross the cell membrane. As a cell increases in size the volume grows proportianately more than its surface area. (Area is proportional to a linear dimension squared, whereas volume is proportional to the linear dimension cubed)

Describe why many neurons and intestinal cells each have greatly increased surface area.

A sufficiently high ratio of surface area to volume is especially important in cells that exchange a lot of material with their surroundings.

Describe the nuclear envelope. How many layers is it? What connects the layers?

Nuclear Envelope- Double membrane enclosing the nucleus; perforated by pores; continuous with ER

What is the nuclear lamina? Nuclear matrix?

Nuclear Lamina- a netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope.

Nuclear matrix- a framework of fiber extending throughout the nuclear interior.

Found within the nucleus are the chromosomes which are made of chromatin. What are the two components of chromatin? When do the thin chromatin fibers condense to become distinct chromosomes?

The two components of chromatin are DNA and Protiens. When thin chromatin fibers coil up (condense), be coming thick enough to be distinguished as seperate structures.

When are the nucleioli visible? What are assembled here?

Ribosomes are assembled.

What is the function of ribosomes? What are their two components?

Ribosomes- complexes made of ribosmal RNA abd protein, are the cellular components and carry out protein synthesis. The two components are Ribosmal RNA and proteins.

Type of Ribosome Location Product

Free Ribosomes

Bound Ribosomes

Free Ribosomes

• Location- Suspended in Cytosol.

• Product- Enzymes

Bound Ribosomes

• Location- Attached to the outside of the endoplasmic reticulum or nuclear envelope.

• Product- Lysosomes

List all the structures of the endomembrane system.

Endoplasmic Reticulum (smooth and rough), Lysosomes, Golgi Apparatus, Vacuoles.

Explain lumen, transport vesicles, and the difference between smooth and rough ER.

Lumen- the ER membrane separates the internal compartment of the ER.

Transport Vesicles- vesicles in transit from one part of the cell to another

Smooth vs. Rough:

Smooth- lacks ribosomes

Rough- has ribosomes on surface.

List and describe three major functions of the smooth ER.

1. Synthesis of lipids, oils, phospholipids, and steroids.

2. Other enzymes of smooth ER help detoxify drugs and poisons.

3. Metabolism of carbohydrates.

Why does alcohol abuse increase tolerance to other drugs such as barbiturates?

Barbiturates, alcohol, and many other drugs induce proliferation of smooth ER which are associated with detoxification enzymes, thus increasing rate of detoxification.

The rough ER is studded with ribosomes. As proteins are synthesized, they are threaded into the lumen of the rough ER. Some of these proteins have carbohydrates attached to them in the ER to form glycoproteins. What does the ER then do with these secretory proteins?

Proteins that have carbohydrates covalently bonded to them. The carbohydrates are attached to proteins in the ER by specialized molecules built into the ER membrane.

Besides packaging secretory proteins into transport vesicles, what is another major function of the rough ER?

The membrane keeps them separate from proteins that are produced by free ribosomes and will remain in the cytosol.

Rough ER is a membrane factory for the cell; it grows in place by adding membrane proteins and phospholipids to its own membrane.

Describe what happens to a transport vesicle and its contents when it arrives at the Golgi.

…

What is a lysosome? What do they contain? What is their pH?

A lysosome is a membranous sac of hydrolytic enzymes that animal cell uses to digest macromolecules. Contains lysosomal enzymes.

One function of lysosomes is intracellular digestion of particles engulfed by phagocytosis. Describe this process of digestion. What human cells carry out phagocytosis?

Amoebas and many other protists eat by engulfing smaller organisms or other food particles. The food vacuole formed in this way then fuses with a lysosome, whose enzymes digest the food. Digestion products including simple sugars, amino acids, and other monomers, pass into the cytosol and become nutrients for the cell. Human cells such as macrophages (white blood cells) help defend against bacteria.

A second function of lysosomes is to recycle cellular components in a process called autophagy. Describe this process.

During autophagy, a damaged organelle or small amount of cytosol becomes surrounded by a double membrane, which is of origin unknown and a lysosome fused with the membrane of the vesicle.

What happens in Tay-Sachs Disease? Explain the role of lysosome.

A lipid digesting enzyme is missing or inactive, and the brain becomes impaired by an accumulation of lipids in the cells.

Vacuoles

Food vacuoles

Contractile Vacuoles

Central vacuoles

Food- formed by phagocytosis

Contractile- many freshwater protists pump excess water out of the cell, thereby maintaining a suitable concentration of ions and molecules inside the cell.

Central- In plants hydrolysis is carried out in vacuoles. Develops by the coalescence of smaller vacuoles, themselves derived from Golgi Apparatus and Endoplasmic Reticulum.

Three functions/ materials of Central vacuoles.

1. Proteins stockpiles in vacuoles of storage cells in seeds.

2. Main repository of inorganic ions, such as potassium and chloride.

1. Disposal sites for metabolic by-products.

Endomembrane system function to digest a cellular component.

1. Nuclear envelope is connected to rough ER, which is also continuous with smooth ER.

2. Membrane and proteins produced by the ER flow in the in the form of transport vesicles to the Goligi.

3. Golgi pinches off transport vesicles and other vesicles that give rise to lysosomes, other types of specialized vesicles, and vacuoles.

4. Lysosome is available for fusion with another vesicle for digestion.

5. Transport vesicle carries proteins to plasma membrane for secretion.

6. Plasma membrane expands by fusion of vesicles; proteins are secreted from cell.

Function of Mitochondria

Sites of cellular respiration, the metabolic process that generates ATP by extracting energy from sugars, fats, and other fuels.

Function of chloroplasts

Sites of photosynthesis

Why is the inner membrane of mitochondria highly folded?

Give the mitochondrial membrane a larger surface area, thus enhancing productivity of cellular respiration.

Peroxisomes

Contain enzymes that transfer hydrogen from various substrates to oxygen, producing peroxide.

Cytoskeleton

a network of fibers extending throughout the cytoplasm, organize the structures and activities of the cells.

Three functions: Support, Motility, and regulation.

Three fibers that make up cytoskeleton:

microtubules, microfilaments, intermediate filaments.

Four functions of microtubules

Shape and support Cell

Serve as tracks along which organelles equipped with motor proteins can move

Seperate chromosomes during cell division.

Another name for centrosomes? Role of centrioles?

Microtubule- organizing center.

Centrioles help organize microtubule assembly in animal cells.

Organization of microtubules

Composed of nine sets of triplet microtubules

Cilia vs. Flagella

Cilia- occur in large number, differ in beating pattern (oars)

Flagella- one or few

How do motor proteins called dyneins cause movement of cilia? How is ATP involved?

Adynein molecule persoms complex cycle of movement caused by changes in shape of the protein. ATP provieds energy.

Four functions of microfilaments.

Actin- globular protein

Form structural networks

Bear tension

Help support cell shape

Gives outer cytoplasmic layer of a cell