Cells: The Living Units

Question 1

What is cell theory?

Answer 1

• Cells are the structural building blocks of all plants and animals
• cells are produced by division of pre-existing cells
• cells are the smallest structural units that perform all vital functions

Question 2

What is the cell membrane

Answer 2

also known as the plasmalemma, it is a selectively permeable barrier between inside and outside the cell

Question 3

What contributes tot the bulk of the cell mass?

Answer 3

Cytoplasm

Question 4

What is the difference between cytosol and cytoplasm?

Answer 4

Cytosol is just the jelly-like fluid-containing part of the cytoplasm
-Cytoplasm consists of Cytosol and Organelles

Question 5

What are organelles?

Answer 5

subunits of cells that compartmentalize a cell’s biochemical reactions and functions

Question 6

Why are membrane organelles important?

Answer 6

• they can segregate molecules and
• provide a membrane surface for synthesis and detox
• ER, Golgi, mitochondria, nuc, and lysosomes

Question 7

What are the nonmembranous organelles?

Answer 7

ribosomes, cilia, centrioles, microvilli, and cytoskeleton

Question 8

what does the nucleus do?

Answer 8

it controls cellular activities and houses the cell’s genetic material

Question 9

What is the cell membrane’s basic structure?

Answer 9

lipid bilayer

-can carry various types of lipids

Question 10

What does more cholesterol lipid in the membrane mean?

Answer 10

it means that the membrane at that part is more rigid and impermeable to water

Question 11

What makes up about 1/2 the bulk of membranes?

Answer 11

proteins

-integral (imbedded) or peripheral (loosely associated)

Question 12

What kind of molecule is often attached to membrane proteins?

Answer 12

carbs

-if there are enough of these, it makes a glycocalyx

Question 13

What are the functions of the outer cell plasma membrane?

Answer 13

• serves as a protective barrier against substances and forces outside the cell
• contains proteins that serve as receptors for monitoring the outside environment and for communication
• controls what leaves or enters a cell

Question 14

What are the different kinds of endocytosis?

Answer 14

pinocytosis- cell drinking (smaller), nutrient absorption
Phagocytosis- cell eating, kills stuff and presents it
Receptor mediated endocytosis- more selective. Receptor ligand binding induces clustering and internalization of the material by endocytosis

Question 15

What are ribosomes?

Answer 15

sites for protein synthesis

-made of proteins and rRNA

Question 16

what happens to proteins generated by free ribosomes in the cytoplasm?

Answer 16

they either stay there or are passed on to the mitochondria or nucleus

Question 17

What happens to proteins generated by ribosomes attached to the Rough ER

Answer 17

they are either secreted from the cell, become incorporated into membranes, or are lysosomal enzymes

Question 18

What is the ER?

Answer 18

and extensive membrane structure sontinuous with the nuclear enelope

Question 19

Where is calcium stored in the cell?

Answer 19

smooth ER

Question 20

What does the golgi apparatus do?

Answer 20

modifies proteins and manufacture various types of sugars as well as sorting and packaging of proteins

Question 21

What are the 3 major shipping routes out of the golgi?

Answer 21

• Secretion out of the cell (exocytosis
• Delivery of integral membrane proteins to organelles and cell membrane
• Delivery to lysosomes

Question 22

What are lysosomes?

Answer 22

contains hydrolytic enzymes that catalyze and degrade various biomolecules and cell organelles.

Question 23

Where are the enzymes in lysosomes made?

Answer 23

the rough ER, processed in the golgi, and then shipped off

Question 24

What is Tay Sachs disease?

Answer 24

a genetic disorder du to inability to remove gangliosides leading to early death of the neuron in the brain
-deficiency in hexosaminidase A

Question 25

What are peroxisomes?

Answer 25

membrane bound vesicles containing enzymes that function in the synthesis of bile acids, breakdown of peroxides and lipids, neutralization of free radicals, and degradation of toxic substances such as alcohol
-these are particularly prevalent in the the liver

Question 26

What are mitochondria?

Answer 26

They produce ATP, this occurs at the inner surface of the cristae membrane

Question 27

What are some unique features of mitochondria?

Answer 27

• 2x membrane
• has its own DNA
• Ribosomes are in there too
• Mitochondria are inherited from mother

Question 28

What are microfilaments?

Answer 28

polymers of actin forming filaments about 7 nm in diameter.

Question 29

What are some functions of microfilaments?

Answer 29

• anchoring the cytoskeleton to integral membrane proteins
• cell movement
• cleavage of cytoplasm during cell division

Question 30

What are intermediate filaments?

Answer 30

made of various different protein monomers that form filaments about 10-12nm in diameter

Question 31

What is the primary function of intermediate filaments?

Answer 31

to increase structural stability within the cytoplasm of a cell

• have high tensile strength
• also strengthens cell-cell and cell-extracellular junctions

Question 32

Microtubules, what are they?

Answer 32

polymers of alpha and beta tubulin proteins.

• stiff but bendable
• 25nm in diameter

Question 33

What are the functions of microtubules?

Answer 33

• provide structural support
• control and maintain cell shape
• move membranous organelles
• form the spindle apparatus during mitosis
• movement of cilia and flagella

Question 34

What is the centrosome

Answer 34

special organization of microtubules (centrioles) and motor proteins
-it sets up the mitotic spindle and forms and organizes cilia and flagella

Question 35

Does the Nucleus have a 2x membrane like the mitochondria?

Answer 35

yes, the outer part is continuous with the rER

Question 36

What is DNA organized into?

Answer 36

linear molecules called chromatin

Question 37

what happens to the chromatin when a cell divides?

Answer 37

it coils and condenses into chromosomes

Question 38

What is the nucleolus?

Answer 38

a region in the nucleus where component for ribosomes are synthesized

Question 39

What is heterochromatin?

Answer 39

Darker stained, more tightly packed DNA material in the nucleus usually representing the inactive genetic material

Question 40

What is Euchromatin?

Answer 40

more lightly stained, less packed DNA material in the nucleus usually representing the actively transcribing DNA.