Jacksparrow MCAT B/B

What are the four tenets of Cell Theory?

1. All Living things are composed of cells.

2. The cell is the basic functional unit of life.

3. Cells arise only from preexisting cells.

4. Cells carry genetic info in the form of DNA.

genetic material is passed on from parent to daughter cell.

What does it mean to be a eukaryotic cell?

have nuclei and membrane bound organelles.

What does it mean to be a prokaryotic cell?

cells that have no nuclei.

What is the nucleus?

control center of the cell.

region of space within the cell that's surrounded by a double membrane envelope.

houses all of our genetic information and machinery.

How does the environment in the nucleus compare to the environment of the rest of the cell?

nuclear membrane is selectively permeable,

the environment in the nucleus is separate and distinct from the environment in the rest of the cell.

What are nuclear pores?

allow selective two way exchange of material between the cytoplasm and the nucleus.

doors into and out of the nucleus.

The nuclear membrane is a [double or single?] membrane.

double membrane.

What is a histone?

protein in the nucleus

around which Eukaryotic DNA winds.

This helps organize the DNA.

What is a chromosome?

a DNA molecule with some/ all of the genetic information of a cell.

The presence of the nuclear envelope permits the separation of what two steps of the central dogma of biology?

Transcription and Translation

What is the nucleolus?

structure in the nucleus

that synthesizes ribosomal RNA (rRNA).

It appears as a large dark spot in the nucleus.

What is a mitochondrion?

double membraned organelle

with structures in its inner membrane that

allow it to generate ATP.

What does it mean that mitochondrion are semi-autonomous.

It means that mitochondrion can do a couple of functions on their own independently from the cell.

These functions are below.

1. Mitochondria contain some of their own genes (in the form of cicular DNA strands) and have their own ribosomes (That are similar in size to prokaryotic ribosomes!)

2. Mitochondria can divide independently of the cell as a whole (by performing binary fission).

What is the function of the mitochondria's outer membrane?

selective barrier between the cytosol and the inner environment of the mitochondrion.

What are cristae?

infoldings of the inner mitochondrial membrane.

These foldings increase the surface area available for electron transport chain enzymes.

What is the mitochondrial matrix?

space inside the mitochondrion's inner membrane.

What is the intermembrane space?

The space between the outer and inner membrane of the mitochondrion.

What are the two functions of the mitochondria?

1. The mitochondria produce useful chemical energy in the form of ATP through the Citric Acid Cycle and the Electron Transport Chain

2. Mitochondria can induce apoptosis by releasing Electron Transport Chain enzymes.

What is apoptosis?

intentional/programmed cell death.

What are lysosomes?

membrane bound structures containing hydrolytic enzymes. They are found floating in the cell's cytoplasm

What is the function of lysosomes?

To digest both foreign material that has been brought into the cell and damaged/uneeded organelles.

also degrades misfolded proteins

How does a lysosome digest something?

Whether it is digesting food or unneeded organelles, the lysosome must interact with a membrane bound carrier of some sort(usually something ending in -some). The lysosome will fuse its membrane with the carrier, inject its hydrolytic enzymes into the new macro structure, and digest whatever the original carrier was carrying. Lysosomes fuse with vesicles to exert their effects!

What is an endosome?

endocytic vesicle that pinches off from the membrane during endocytosis.

What are the three places an endosome can transport material to?

1. To and from the Plasma Membrane

2. To the lysosomes

3. To the trans-Golgi

What happens if a lysosome releases its enzymes?

the enzymes will begin to break the cell down

from the inside out in a process known as autolysis.

What is the Endoplasmic Reticulum? (ER)

series of interconnected membranes that are contiguous with the nuclear envelope.

What are the two types of Endoplasmic Reticulum?

Rough ER and Smooth ER

What is rough ER and what is its function?

Rough ER is ER studded with ribosomes. These ribosomes take in ingredients from the cytosol, but secrete their proteins directly into the lumen of the ER. This is the function of the ER, and believe it or not, being able to make proteins that are protected from the cytosol is actually pretty useful.

What is smooth ER and what are its 3 functions?

Smooth ER is ER that takes on a tubular form and has no ribosomes in its membrane.

Smooth ER is where lipids are synthesized (for example the phospholipids in bilayers and steroids).

Smooth ER also detoxifies certain drugs and poisons. Finally, proteins that were synthesized into the Rough Endoplasmic Reticulum travel to the Smooth ER so they can be packaged and transported to the Golgi Apparatus.

What is an organelle?

any specific sub unit within the cell that has a specialized function.

These functions range from generating energy, protecting the cell, digesting things, transporting stuff, etc.

What is the Golgi Apparatus?

series of stacked membrane bound sacs inside of the cell.

What is the Golgi Apparatus' function?

to receive materials from the ER and modify these materials by adding various functional groups.

These functional groups serve to both modify the function of the materials and to direct them to certain locations in the cell. Once the material has been modified and has a location-determining functional group, the material will leave the Golgi Apparatus in an appropriate vesicle and travel to its intended location. This intended location can be inside the cell, outside the cell, or back to the Endoplasmic Reticulum.

What is a vesicle?

small membrane bound sacs.

What is exocytosis?

when material is packaged into a secretory vesicle, the secretory vesicle fuses with the plasma membrane, and the contents of the secretory vesicle are released outside of the cell.

What kinds of proteins are usually found in the Rough ER?

Proteins that are destined for secretion or proteins that are destined for integration into a membrane.

How do the concentration of organelles in different cell types vary?

The concentration of organelles is different from cell type to cell type.

These differences are functional. For example, cells that need a lot of energy have a lot of mitochondria. Cells that secrete a lot have high RER and Golgi Apparatus.

What is a peroxisome?

single membrane bound organelle containing Hydrogen Peroxide.

This Hydrogen Peroxide is generated with the help of a crystalline core.

What are the 3 functions of the peroxisome?

Because of their hydrogen peroxide, peroxisomes are important in the breakdown of long chain fatty acids (Beta Oxidation).

Peroxisomes also participate in the synthesis of phospholipids and contain some enzymes for the Pentose Phosphate Pathway.

What is the Cytoskeleton?

large network of 3 structural components that provides shape and structure to the cell.

These structural components also serve as paths by which things can be transported to various locations in the cell.

What are the three structural components of the Cytoskeleton?

1. Microfilaments

2. Microtubules

3. Intermediate Filaments

What are the characteristics and 3 roles of Microfilaments?

Microfilaments are solid polymerized rods of Actin. When organized into bundles and networks, Actin filaments provide resistance to compression and fracture for the cell. Actin filaments can also generate force for movement by interacting with Myosin. Finally, Actin Filaments are important for the formation of the cleavage furrow in mitosis/meiosis. This is accomplished by an actin ring which forms at the site of division between cells. The ring contracts, and the cell gets pinched into two.

What are the characteristics and 3 roles of Microtubules?

Microtubules are hollow polymers of Tubulin proteins. Microtubules radiate throughout the cell, providing pathways along which vesicles can travel. This is accomplished by motor proteins like Kinesin and Dynein, which travel along the microtubules and drag vesicles with them. Microtubules are also important in the structures of Cilia and Flagella. Finally, Centrioles are composed of microtubules and use them to exert their effects during mitosis.

What is a centrosome?

A centrosome is the region of the cell where the centrioles are found.

What is a centriole?

hollow structure composed of nine triplets of microtubules.

What are the functions of the Centriole?

organizing center for the Microtubules within a cell.

Also, the centrioles play an important role in the separation of chromosomes during mitosis.

What are the characteristics and 3 roles of Intermediate Filaments?

Intermediate filaments are a diverse group of filament proteins, e.g. Keratin, Desmin, vimentin, and Lamin. Intermediate filaments are able to withstand a lot of tension, which makes the cell structure more rigid and is important in the overal maintenance of the cytoskeleton. Intermediate filaments also anchor organelles to certain locations in the cell. Finally, Intermediate filaments are important in cell-cell adhesion.

What are the four tissue types?

1. Epithelial Tissue

2. Connective Tissue

3. Muscle Tissue

4. Nervous Tissue

What are the functions of the epithelial tissues?

Epithelial tissues cover the body and line its cavities.

These tissues, being exterior tissues, provide protection against infection and dessication (drying out). In some tissues, epithelial cells are also involved in absorption, secretion, and sensation.

What is parenchyma and of which tissue type is it usually comprised?

Parenchyma are the functional parts of an organ.

What does it mean when we say epithelial cells are polarized?

Because epithlelial cells cover the body and line its organs, one side of an epithelial cell will be attached to underlying structural cells and the other side will be exposed to the lumen of an organ or the outside world. Because of these dramatically different environments, the two sides of the epithelial cell are actually pretty different. We call this phenomenon polarization.

What is a lumen?

A lumen is the inside space of any hollow tubular structure.