Cellular Structure

Question 1

what is cell theory?

Answer 1

1. All organisms are composed of cells
2. The cell is the smallest unit showing all of the characteristics that define life
3. All cells come from pre-exisiting

Question 2

what are 4 things all cells have?

Answer 2

1. plasma membrane
2. cytosol
3. chromosomes
4. ribosomes

Question 3

what is the major difference between Prokaryotic and Eukaryotic Cells? what do they both have?

Answer 3

Eukaryotic cells have a nucleus and other membrane bounded organelles
-both have DNA, ribosomes, plasma membrane, cytosol

Question 4

what is the nuclear envelope? what does it do?

Answer 4

• double membrane that surrounds nucleus

- controls movement of material between cytoplasm and nucleus

Question 5

what is the nucleus?

Answer 5

• control center of the cell

- contains chromosomes (DNA)

Question 6

what is the nuclear pore?

Answer 6

pore in membrane that allows passage of larger molecules out of the nucleus

Question 7

what is the nucleoli?

Answer 7

in center of nucleus; contains portion of chromosome
responsible for production of rRNA and ribosome
assembly

Question 8

what are ribosomes?

Answer 8

• site of protein synthesis - Location of translation during protein synthesis
• Non-membrane bounded organelles
• Composed of protein + rRNA

Question 9

what is the endoplasmic reticulum? what are the 2 parts?

Answer 9

• Network of membranous sacs and tubes that extend throughout the cytoplasm
• smooth ER
• rough ER

Question 10

why us rough er “rough”? what are its functions? why is smooth er “smooth”? what are its functions?

Answer 10

‘rough’ because it’s studded with ribosomes
-membrane synthesis
-protein synthesis
'smooth" - because it lacks ribosomes
-synthesize lipids
-help to detoxify drugs and poisons

Question 11

what is the process of synthesizing and packing of proteins?

Answer 11

1. Polypeptide formed during translation by
   ribosome attached to outer surface of rough ER
2. Polypeptide passes into internal space of rough
   ER where it folds into correct conformation
3. Molecule packaged into transport vesicle
4. Vesicle buds off ER and travels to Golgi

Question 12

what is the golgi apparatus?

Answer 12

• flattened pancakes –> membranous sacs
• Receives and modifies substances from ER
• Sends modified products to final destination

Question 13

what are lysosomes responsible for? what do they contain?

Answer 13

Carry out intracellular digestion

• Sacs of hydrolytic enzymes capable of breaking down organic molecules
• used to digest food particles
• breakdown damaged organelles
• destroy foreign materials

Question 14

how does a lysosome function?

Answer 14

it fuses with food vacoule (or old organelle) and than hydrolytic enzymes digest components

Question 15

what is the mitochondria?

Answer 15

• the powerhouse of the cell

- site of cellular respiration (Use chemical energy in organic molecules to make ATP)

Question 16

what are the 4 components of a mitochondria?

Answer 16

1. smooth outer membrane
2. highly folded inner membrane
3. intermembrane space between these membranes
4. matrix (in center)

Question 17

what are chloroplasts?

Answer 17

sites of photosynthesis ( Convert light energy into chemical energy (sugar))
-Present in all photosynthetic eukaryotes

Question 18

what are the green pigments in chloloplasts?

Answer 18

chlorophyll

Question 19

what are the components of a chloroplast? its a what ind of system?

Answer 19

3 membrane system

• 2 smooth out membranes
• stroma
• thylakoids (Flattened membrane sacs located in stroma)

Question 20

what is the cytoskeleton? what is its function?

Answer 20

Structural network of protein fibers extending throughout the cytoplasm of a cell

• Provides support
• Maintains shape of cell and organelles
• Allows for movement

Question 21

what are centrosomes?

Answer 21

• Microtubule organizing center
• Organizes microtubules into a ‘spindle’ structure during meiosis and mitosis
• Contain a pair of centrioles

an organelle near the nucleus of a cell which contains the centrioles (in animal cells) and from which the spindle fibers develop in cell division.

Question 22

where are plant cell walls located? what is their function?

Answer 22

• outside of the cell membrane
• Protects cell from mechanical damage
• Gives strength and support to the cell

Question 23

all plant cells have what kind of wall? what other kind of cell wall do they sometimes have? what are plant walls composed of? what holds adjacent cells together?

Answer 23

• primary cell wall
• secondary cell wall
• cellulose fibers
• the middle lamella

Question 24

what are plasmodesmata? what are they lined with?

Answer 24

• Tiny channels running through cell walls
• Connect adjacent plant cells
• Lined by cell membrane

Question 25

what is the function of plasmodesmata?

Answer 25

Allows cytosol to move freely from one cell to the next without having to pass through either a cell wall or a cell membrane

Question 26

what is the plasma membrane? what does it control?

Answer 26

-Boundary that separates the living cell from its surroundings -Controls movement of molecules into and out of the cell --> selectively permeable

Question 27

what is selective permeability?

Answer 27

allows some substances to cross more easily than others