Quiz 3

Question 1

What if substances are too big for a transport proteins?

Answer 1

Big molecules must use the bulk transport mechanism, which involves the formation of vesicles. The membrane is flexible and can bend into different shapes including the pinching off vesicles. This requires energy.

Question 2

What is endocytosis?

Answer 2

The importing of substances, there is three types; Phagocytosis, which is cell eating when the membrane bends around and pinches off this is for large food particles, Pinocytosis which is cell drinking with little water droplets and everything dissolved in them and Receptor mediated which involve receptors to import specific things.

Question 3

What is a receptor?

Answer 3

A specific membrane protein, receptors receive chemical signals form the outside of the cell which involves a physical interaction b/w the ligand and receptor. Each receptor only binds to one specific type of ligand structure.

Question 4

What is receptor-mediated endocytosis?

Answer 4

Receptors bind to a substance that the cell needs to uptake. Cathrin binds to these receptors on the inside of the cell;gathering them and the membrane into a pit shape that eventually becomes a vesicle. Cathrin is then released, the particle is used/consumed and the receptors are their way back to the membrane.

Question 5

What is clathrin?

Answer 5

Clathrin is a coat protein that helps facilitate vesicle formation. It is three proteins in a quaternary structure that associate with e/o and bind to active receptors and brings other clathrin.

Question 6

What is an example of receptor mediated endocytosis?

Answer 6

Fat delivery to cells. Lipoproteins transport fat to cells via the blood stream. there is a surface layer of phospholipid and cholesterol so fat doesn’t clog the bod with a core of triglycerides. Specific proteins associate with the fat droplet and the receptors of the cell recognize the apoprotein and promote endocytosis.

Question 7

What is a LDL?

Answer 7

A low density lipoprotein, low in density but high in cholesterol, this lipoprotein is referred to as “bad” cholesterol

Question 8

What is a HDL?

Answer 8

A high density lipoprotein, it is high in density due to a high protein/li[id ratio. These particles cab remove excess cholesterol form blood vessels (for transport to the liver)

Question 9

What do systems that preform active transport using ATP directly mediate?

Answer 9

Primary active transport

Question 10

What do systems that use carrier proteins by ion gradients mediate?

Answer 10

Secondary active transport

Question 11

What are a few of the proteins used in facilitated diffusion of active transport described as?

Answer 11

Uniporters only transport one type of molecule, symporters transport two molecules in the same direction, antiporters transport two different molecules in the opposite direction.

Question 12

What do Bacteria cell walls do?

Answer 12

Provide shape, protection form bursting in hypotonic environments (lysis).

Question 13

What are the two types of cell walls?

Answer 13

Gram positive which is a very simple cell wall with an outer peptidoglycan layer and plasma membrane beneath, and gram negative which has a complex cell wall with a thin peptidoglycan layer in between two plasma membranes, this membrane is known as a lipopolysaccharide which ca cause fevers because of its endotoxin’s

Question 14

What is peptidoglycan?

Answer 14

A thin sheet composed of; chains of a repeating disaccharide unit composed of two mono saccharides ( NAG & NAM), and small peptides attached to the NAM Subunits of the chains, bonds formed between peptides on adjacent chains cross-link the chains of gives strength to the structure.

Question 15

What are components of NAG & NAM?

Answer 15

A peptidoglycan polymer in each with a NAM peptide on NAM with DAP in made by dehydration. Multiple strands of NAG & NAM get cross linked to form thin sheets, this cross linking is called trans peptides ion and adds strength to the layer.

Question 16

What are antibiotics?

Answer 16

They usually affect peptidoglycan and are specific to certain types of bacteria based on their ability to target prokaryote-specific structures. Their two common targets are; prokaryotic ribosomes and prokaryotic cell walls.

Question 17

How does penicillin work?

Answer 17

As bacteria cell grows it synthesizes more peptidoglycan. Transpeptidation reaction is catalyze by a specific enzyme.The enzyme is inhibited by penicillin and inhibition leads to a weakened peptidoglycan which works best on gram positive cells. As the cell grows peptidoglycan is not formed and eventually the cell bursts (lysis)

Question 18

What is the capsule?

Answer 18

The capsule is secreted by the bacteria and is mostly polysaccharides that protect the cell from the environment and can be used to stick bacteria to the surface or other cells

Question 19

What are the two types of Pili?

Answer 19

Fimbriae attach to surfaces or host cells with spikily needles that make them hard to remove. Sex Pilus which is for the transfer of DNA b/w bacteria cells to transfer plasmid

Question 20

What is a taxis?

Answer 20

The ability to move towards towards or away from a stimulus by a bacteria in a heterogeneous environment. Chemotaxis is the movement towards or away from the chemical stimulus which is a series of runs and tumbles, the run is longer is the concentration of the attraction is higher

Question 21

What is a flagella?

Answer 21

An external structure for movement of a cell, it is composed differently for each domain. Th bacterial flagellum rotates CCW for a run and CW for a tumble. Bacterial flagella motors are composed of many individual components

Question 22

What are archaea cells walls composed of?

Answer 22

They have no outer membrane but various coverings surrounding the plasma membrane, there is no true peptidoglycan but related molecules exist in some species. A similar membrane is the Archaea-specific lipopolysaccharides. They generally have stronger men range, due to a number of unquiet differences other than ester in their triglycerides

Question 23

What are Eukaryotic cell walls and what are they composed of?

Answer 23

The cell wall provides shape and function, to help plants hold themselves upright. The cell wall is made up of cellulose chains embedded in a matrix of other polysaccharides and proteins. Young plants have thin cells walls. The primary cell wall allows flexibility for growth that hardens over time. Some plants have a secondary cell wall. They also have a cell wall between adjacent cells

Question 24

What is the middle lamella, and what is it composed of?

Answer 24

The middle lamella supersets adjacent plant cells b/w their primary cell walls. The lamella is composed of sticky polysaccharides called pectins( it glues the cell together)

Question 25

What is pectin?

Answer 25

Pectin is a mixture of polysaccharides that are more complex in structure.

Question 26

How do plant cells communicate with each other?

Answer 26

Plant cell walls contain pores b/w cells called plasmodesmata, which allow the passage of H20 and other small solutes b/w cells. These pores can also open and close depending on the environmental conditions or age of the plant?

Question 27

What do animal cells have instead of a cell wall?

Answer 27

They secrete proteins and polysaccharides=extra cellular matrix. Some cells attach to the ECM using additional specialized proteins. The most common is fibronectin (interacts with collagen), and binds to a specific class of integral membrane proteins called integrins

Question 28

What does the ECM consist of?

Answer 28

Mostly glycoproteins and protein fibres, with collagen embedded in a network of other glycoproteins called proteoglycans

Question 29

What is a proteoglycan complex?

Answer 29

It is a polysaccharide molecule with core proteins bonded to it that have carbohydrates attached covalently to them , this structure is the proteoglycan molecule which then are non covalently bonded to the long polysaccharide to make the complex

Question 30

What are the three types of junctions and what do they look like?

Answer 30

There is the tight junctions which are the membranes of neighbouring cells that are fused by bands of proteins connecting them creating tight seals that prevents the absorption of materials from one side of a row into the intercellular region between them, and desmosomes that form a very strong connection b/w cells which tightly fasten cells together at certain points with strong protein filaments crossing the intercellular space, they are abundant in tighter issues , and gap Junius which are multi-subunit structure that form a channel b/w cells that allow the free exchange of molecules and to coordinate response to stimulus

Question 31

What is a conexon?

Answer 31

6 protein subunits that attach and form a gap junctions b/w cells with pores that open and close

Question 32

What is cytoplasm?

Answer 32

The interior of a prokaryotic or eukaryotic cell, comparable to chicken soup holding everythinb

Question 33

What is cytosol?

Answer 33

THe fluid portion of the cytoplasm, without structure or membranes, compared to chicken broth

Question 34

What is the origin of eukaryotes and the endosymbiosis hypothesis?

Answer 34

The most common eukaryotic ancestor from 2.1 billion years ago. Metabolic requirements set limits on cell size leading to cellular folding increasing surface are over time. As they increased the anaerobic cells were at a disadvantage and aerobic bacteria evolved , the anaerobic prokaryote ingest the aerobic to develop a beneficial relationship where the bacteria becomes a part of the cell to remove oxygen, which develops the mitochondria and all non photosynthetic eukaryotes. One of the anaerobic cells is thought to have consumed. Photosynthetic bacteria leading to the chloroplast and all photosynthetic eukaryotes