med term

Question 1

Cell theory:

Answer 1

a. All living things are composed of cells b. The cell is the basic functional unit of life c. Cells arise only from preexisting cells d. Cells carry genetic information in the form of deoxyribonucleic acid (DNA). This genetic material is passed on from parent to daughter cell.

Question 2

Cell theory has created a dilemma for viruses:

Answer 2

1. They contain genetic material 2. But are NOT able to reproduce on their own 3. Viruses are ONLY able to replicate by invading other organisms and use ribonucleic acid (RNA) instead of DNA for their genetic information a. Due viruses violating the cell theory tenets of not arising from preexisting cells and also due to them having their genetic material in the form of RNA. Viruses are not considered to be living organisms.

Question 3

Prokaryotic organisms

Answer 3

Prokaryotic organisms are always single cell Do NOT contain a nucleus

Question 4

Eukaryotic organisms

Answer 4

Eukaryotic organisms

i. are either unicellular or multicellular
ii. Contains a true nucleus enclose in a membrane
iii. Most organelles are membrane bound, which allows for compartmentalization of functions
iv. Membranes of eukaryotic cells consist of phospholipid bilayer
1. This membrane is unique due to the surface is hydrophilic, electrostatically interacting with aqueous environments, while the inside of the membrane is hydrophobic, which allows for a selective barrier between the interior of the cell and the external environment.
v. Eukaryotic cells reproduce by mitosis which gives rise to the formation of two identical daughter cells

Question 5

Cytosol

Answer 5

cytosol is the semifluid where the organelles are suspended It allows for the diffusion of molecules through the cell

Question 6

Nucleus:

Answer 6

Nucleus is where the genetic material deoxyribonucleic acid (DNA) is encoded.

i. It is the control center of the cell
ii. It contains all the genetic material necessary for replication of the cell
iii. The nuclear membrane or envelope surround the nucleus
1. The nuclear membrane is a double membrane which maintains nuclear environment separate and distinct from the cytoplasm
a. Nuclear pores in the nuclear membrane allow selective two way exchange of material between cytoplasm and nucleus

Question 7

Within the Nucleus:

Answer 7

i. Chromosomes are organized DNA
ii. Genes are coding regions which contain (DNA) genetic material
iii. Histones are organizing proteins (which linear DNA is wound around them)
1. Further winding of the linear DNA strand makes chromosomes
iv. DNA location in the nucleus allows for the compartmentalization of DNA transcription separate from RNA translation

Question 8

Nucleolus

Answer 8

v. A subsection of the nucleus is known as the nucleolus (it is where the ribosomal RNA (rRNA) is synthesized)
1. Nucleolus are Identifiable as a darker spot in the nucleus
2. Nucleolus takes up 25% of the volume of the nucleus

Question 9

Mitochondria

Answer 9

i. Often called the power plant of the cell. This is due to its important metabolic functions.
ii. Two layers in the mitochondrion: Inner membrane and Outer membrane

Question 10

Outer mitochondrial membrane

Answer 10

Outer Mitochondrial membrane serves as a barrier between cytosol and inner environments of mitochondrion

Question 11

Inner mitochondrial membrane

Answer 11

iv. Inner membrane arranged in numerous in folding also called cristae
1. Cristae are highly convoluted structures that increase the surface area available for electron transport chain enzymes
2. Contains the molecules and enzymes of the electron transport chain

Question 12

mitochondrial unique cellular aspect

Answer 12

vi. The mitochondria are different from other parts of the cell due to their semi autonomous 1. They have some genes and replicate independently of the nucleus via binary fission.

Question 13

Mitochondria and cytoplasmic or extranuclear inheritance

Answer 13

vii. The mitochondria is an example of cytoplasmic or extranuclear inheritance(the transmission of genetic material independent of the nucleus.) 1. Mitochondria are thought to have originated when a anaerobic prokaryote engulfed a aerobic prokaryote resulting in a symbiotic relationship 2. The mitochondria has more functions than just keeping the cell alive by proving it with energy, it is also capable of killing the cell through the release of enzymes from the electron transport chain. This release of these enzymes begins the process of apoptosis (or programmed cell death).

Question 14

e. Lysosomes

Answer 14

i. Lysosomes are membrane bound structure which have hydrolytic enzymes (these are capable of breaking down many substrates including those ingested by endocytosis and cellular waste products) iii. The lysosomal membrane isolates the enzymes to prevent damage to the cell 1. Yet when the release of these enzymes occurs the process is called autolysis

Question 15

Endosomes

Answer 15

Lysosomes work with endosomes (which are responsible for transport, package and sorting cell material traveling to and from the membrane. They also transport material to the trans-Golgi, cell membrane, lysosomal pathway for degradation. (check last portion accuracy)

Question 16

f. Endoplasmic Reticulum

Answer 16

i. The (ER) endoplasmic reticulum is a series of interconnected membranes which share a common border with the nuclear envelope ii. It is a double membrane which is folded into many invaginations, thus creating complex structures with a central lumen iii. Two varieties of endoplasmic reticulum 1. Rough 2. Smooth

Question 17

RER (rough Endoplasmic Reticulum

Answer 17

iv. Rough ER (RER) is studded with ribosomes (these allow the translation of proteins destined for secretion directly into its lumen.)

Question 18

SER (smooth Endoplasmic reticulum

Answer 18

v. Smooth ER (SER) lacks ribosomes and is utilized primarily for lipid synthesis (such as the phospholipids in the cell membrane) and the detoxification of certain drugs and poisons. 1. The Smooth ER transports proteins from the Rough ER to the Golgi apparatus

Question 19

g. Golgi Apparatus

Answer 19

i. The golgi apparatus is made up of stacked membrane bound sacs. ii. Materials from the ER transferred to Golgi Apparatus via vesicles iii. Inside Golgi these cellular products can be modified by the addition of groups like carbs, phosphates, sulfates iv. Golgi may also modify cellular products through the adding signal sequences (which direct the delivery of the product to a specific cellular location. 1. After modification and sorting in golgi, cellular products are repackaged in vesicles (and then directed to correct cellular location) 2. Example: If products are targeted for secretion, the secretory vesicle merges with the cell membrane and its contents are released via exocytosis

Question 20

h. Peroxisomes

Answer 20

i. They contain hydrogen peroxide ii. One of their main functions is to breakdown very long chain fatty acids via beta oxidation. iii. Peroxisomes participate in the synthesis of phospholipids and contain some of the enzymes involved in the pentose phosphate pathway i. Not all cells have the same relative distribution of organelles. Form will follow function. Cells that require a lot of energy for locomotion (such as sperm cells) have high concentrations of mitochondria. Cells involved in secretion (such as pancreatic islet cells and other endocrine tissues) have high concentrations of RER and Golgi apparatuses. Other cells, such as red blood cells, which primarily serve a transport function, have no organelles at all.

Question 21

cytoskeleton

Answer 21

a. Provides structure to the cell and helps it to maintain its shape b. It also provides a tube for the transport of materials around the cell c. It is composed of three components: i. Microfilaments ii. Microtubules

Question 22

i. Microfilaments

Answer 22

are made up of solid polymerized rods of actin. ii. Microfilaments play a role in cytokinesis (or division of materials between daughter cell. iii. During mitosis the cleavage furrow is formed from microfilaments. The microfilaments organize as a ring at the site of division between two new daughter cells. By the actin filaments within the ring contracting, it causes the ring to become smaller thus eventually separating and pinching off the two daughter cells.

Question 23

Actin filaments

Answer 23

1. Actin filaments organized into bundles and networks and are resistant to both compression and fracture thus providing protection for the cell. 2. Actin filaments can use ATP to generate movement by interacting with myosin such as in muscle contraction

Question 24

Microfilaments and mitosis

Answer 24

ii. Microfilaments play a role in cytokinesis (or division of materials between daughter cell. iii. During mitosis the cleavage furrow is formed from microfilaments. The microfilaments organize as a ring at the site of division between two new daughter cells. By the actin filaments within the ring contracting, it causes the ring to become smaller thus eventually separating and pinching off the two daughter cells.

Question 25

e. Microtubules

Answer 25

i. Microtubules are hollow polymers of tubulin proteins ii. Microtubules provide primary pathway to motor proteins (like kinesin and dynein carry vesicles)

Question 26

Kinesin and dynein

Answer 26

1. Kinesin walks along microtubules toward the plus ends, facilitating material transport from the cell interior toward the cortex. Dynein transports material toward the microtubule minus ends, moving from the cell periphery to the cell interior. 2. Motor proteins like kinesin and dynein are classic examples of nonenzymatic protein function, along with binding proteins, cell adhesion molecules, immunoglobulins, and ion channels. Motor proteins often travel along cytoskeletal structures to accomplish their functions.

Question 27

iii. Cilia and flagella

Answer 27

cilia and flagella are motile structures composed of microtubules.

Question 28

cilia

Answer 28

cilia are projections from cell which are involved in movement of materials along the surface of the cell. a. Example: cilia line the respiratory tract and are involved in the movement of mucus.

Question 29

Flagella

Answer 29

2. Flagella are structures involved in the movement of the cell itself. For example, movement of sperm cells through the reproductive tract.

Question 30

9+2 structure

Answer 30

iv. Cilia and flagella share the same structure, they are composed of nine pairs of microtubules forming an outer ring and two microtubules in the center (known as the 9+2 structure) (this is seen only in eukaryotic organelles of motility). It is quite distinct from the bacteria flagella which had a different structure and composition.

Question 31

Centrioles

Answer 31

1. Centrioles are found in a region of the cell called the centrosome.
   
   1. The centrosomes are the organizing centers for microtubules and are structured as nine triplets of microtubules with a hollow center.
   2. During mitosis the centrioles go towards opposite poles of the dividing cell and organize the miotic spindle.

Question 32

Centrosome and centriole

Answer 32

1. The centrosome of Eukaryotic animal cells is the microtubule-organizing center (MTOC) of the cell. They contain a pair of centrioles that are oriented at right angles with respect to one another and which are embedded in a mass of proteins. Each centriole is a specialized arrangement of microtubules.
2. The microtubules coming from the centrioles attach to the chromosomes via complexes called kinetochores. And then the centrioles exert force on the sister chromatids, pulling them apart.