Module 2 Section 1 - Cell Ultrastructure

Question 1

What are the 3 structural components of a cytoskeleton

Answer 1

1) Microfilaments
2) Microtubules
3) Intermediate Fibres

Question 2

What are the functions of a Cytoskeleton

Answer 2

• To provide mechanical strength
• Aiding transport with cells
• Enabling Cell movement

Question 3

what are microfilaments made of

Answer 3

the protein Actin

Question 4

what is the microfilament of the cytoskeleton responsible for

Answer 4

movement of the cell and cytoplasm during cytokinesis

Question 5

what are microtubules made of

Answer 5

the protein tubulin

Question 6

microtubules can also act as…

Answer 6

tracks for organelles moving around the cell

Question 7

intermediate fibres give…..

Answer 7

strength to cells and help maintain integrity

Question 8

what is the structure of the nucleus

Answer 8

• Double nuclear envelope
• nuclear pores
• nucleolus
• chromatin

Question 9

what is the double nuclear envelope

Answer 9

a double membrane which separates the nucleus and prevents damage. protects the DNA

Question 10

what are nuclear pores

Answer 10

allows molecules to enter(e.g. nucleotides for DNA replication) and leave the cell e.g. mRNA leaves the cell.

Question 11

what is the nucleolus

Answer 11

site of ribosome production, composed of RNA and proteins

Question 12

what is chromatin

Answer 12

the DNA (with associated histone proteins). contains the genetic code which controls the activity of the cell

Question 13

what is the function of the nucleus

Answer 13

-controls all the activity of the cell
-where genetic code (DNA) of the cell is stored, replicated, and copied into RNA
- the nucleus is attached to the rough ER (endoplasmic reticulum) so the mRNA can esily get to ribosomes

Question 14

what is the structure of rough endoplasmic reticulum (rough ER)

Answer 14

-stacks of membrane bound sacs which form sheets called cisternae
-it is also attached to nucleus and covered with ribosomes

Question 15

what is the function of the rough ER

Answer 15

site of protein synthesis

Question 16

what is the structure of the smooth ER

Answer 16

similar to rough ER but it lacks ribosomes - is a system of interconnected tubules

Question 17

what is the function of the smooth ER

Answer 17

responsible for carbohydrate & lipid synthesis as well as storage

Question 18

what is the structure of ribosomes

Answer 18

• a 2 subunit organelle
• made from RNA and protein
• not membrane bound
• about 22nm in diameter
• found free floating in the cytoplasm or attached to the rough ER

Question 19

what is the function of ribosomes

Answer 19

• this is where protein is made
• they assemble amino acids into proteins in chains using mRNA

Question 20

what is the structure of the mitochrondria

Answer 20

-oval shaped
-surrounded by 2 membranes
- inner membrane called cristae which increases the surface area
- the solution inside is called matrix which contains enzymes for respiration

Question 21

why is mitochrondrial dna important

Answer 21

it enables mitochrondrion to reproduce and create enzymes

Question 22

what is the function of mitochrondria

Answer 22

• site of aerobic respiration which releases atp (energy carrier in cells)

Question 23

what is the strucutre of the golgi apparatus

Answer 23

• stacks of flattened, membrane bound sacs (cisternae)
• these are contiously formed from the ER at one end and budding off as golgi vesicles at the other

Question 24

what is the function of the golgi appartus

Answer 24

• allows internal transport
• recieves proteins from the rough ER
• modifies and processes molecules (e.g. lipids and proteins) and packages them into vesicles
• these may be secretory vesicles (leaving the cell) or lysosomes (stay in the cell)
• make lysosomes
• lipid synthesis

Question 25

what is the structure of lysosomes

Answer 25

they are spherical sacs surrounded by a membrane

Question 26

what is the function of the lysosomes

Answer 26

- they contain powerful digestive enzymes called lysozymes their role is to break down worn out components of the cell or digest invading cells

Question 27

what is the structure of the centrioles

Answer 27

- a component of the cytoskeleton, composed of many microtubules - small hollow cylinders that occur in pairs next to the nucleus in animal cells - each centriole contains a ring of 9 microtubules

Question 28

what is the function of centrioles

Answer 28

makes a copy of itself during cell division and then helps to form the spindle in cell division

Question 29

what is the strucutre of the cilia

Answer 29

- hair-like extensions that protrude from some animal cell types - in cross section they have an outer membrane and a ring of nine pairs of protein microtubules inside with 2 microtubules in the middle - known as a 9+2 arrangement which allows movement

Question 30

what is the function of the cilia

Answer 30

- sensory function (e.g. nose), beat creating a current to move fluid/muscous/objects - for locomotion

Question 31

what is the structure of the flagella

Answer 31

- similar to cilia but longer -they protrude from the cell surface and are surrounded by the plasma membrane - like cilia they have a 9+2 arrangement

Question 32

what is the function of the flagella

Answer 32

-enables cell mobility -the microtubules contract to make the flagellum -propel the cell forward

Question 33

what is the structure of the chloroplast (plant cells only)

Answer 33

double membrane which encloses the stroma stroma contains: strach grains, lipid stores, DNA, RNA, Ribosomes series of membrane-bound flattened sacs called thylakoids in the stroma. stacked thylakoids are called grana which is connected by lamellae the grana contain chlorophyll

Question 34

what is the function of the chloroplast - plant cell only

Answer 34

photosynthesis reactions

Question 35

what is the structure of the cell surface membrane

Answer 35

a phospholipid bilayer (phosphorus and lipid) composed of proteins and lipids

Question 36

where is the cell surface membrane found

Answer 36

on the surface of animal cells inside the cell wall of plant and prokaryotic cells

Question 37

what is the function of the cell surface membrane

Answer 37

it regulates the movement of substances in and out of the cell contains receptor molecules that allow it to respond to chemical like hormones

Question 38

what is the structure of the cellulose cell wall

Answer 38

composed of b-cellulose microfibrils - complex carbohydrate cell wall fully permeable to substance thin layer called middle lamella marks the boundary between adjacent cell walls and 'cements' adjacent cells together

Question 39

what is the function of the cellulose cell wall

Answer 39

gives plant mechanical strength gives plant cell support and it's shape contents of plant cell can 'push' against the cell wall (turgid cell). this gives the cell good support

Question 40

what is the structure of large permanent vacuole

Answer 40

single membrane bound - called tonoplast contain cell sap selectively permeable barrier

Question 41

what is the function of the large permanent vacuole

Answer 41

stroes cell sap support herbaceous plants by make cells turgis hepls maintain shape and mains turgor pressure sugar and amino acids act as temporary food stroe