Eukaryotic cells

Question 1

Advantages of compartmentalization

Answer 1

-efficiency of metabolism
-localized conditions
-toxic/damaging substances can be isolated
-numbers and locations of organelles can be changed, dependent on the cells requirments

Question 2

Determinants

Answer 2

• Contain a nucleus
• Compartmentalized by membrane-bound structures (organelles) that preform specific roles

Question 3

4 kingdoms

Answer 3

1) Protista
2) Fungi
3) Plantae
4) Animalia

Question 4

Protista

Answer 4

unicellular but multicellular without a specialized tissue

Question 5

Fungi

Answer 5

have cell wall made of chitin and obtain nutrition via heterotrophic absorbtion

Question 6

Plantae

Answer 6

have cell wall made of cellulose and obtain nutrition autrotrophically (photosynthesis)

Question 7

Animalia

Answer 7

no cell wall, obtain nutrition via heterotrophic ingestion

Question 8

Nucleus

Answer 8

-spherical with double membrane
-pores in the membrane
-genetic info in the form of chromosomes (DNA, histone proteins)
-mRNA is transcribed
mRNA leaves the nucleus via the pores (DNA is too large)
-uncoiled
-chromosomes are referred as chromatin

Question 9

Mitochondrion

Answer 9

-double membrane
-smooth outer membrane and folded inner membrane
-the folds are reserved to as cristae
-variable in shape
site of ATP production by aerobic respiration (if fat is used as a source of energy it is digested here)

Question 10

Free ribosomes

Answer 10

-80S ribosomes 20nm (larger)
-dark granules in the cytoplasm
-no membrane
-synthesizes the proteins to function in the cytoplasm, for use within the cell. eg; enzymes

Question 11

Rough endoplasmic reticulum (rER)

Answer 11

-flattened membrane sacs, called cisternae
-often located near the nucleus
-80S ribosomes are attatchted to the outside of the cisternae
-rER synthesizes proteins which are transported, by vesicles, to the golgi apparatus for modification before secretion outside the cell

Question 12

Smooth rER

Answer 12

-no ribosomes present

Question 13

Golgi apparatus

Answer 13

-This organelle also consists of flattened membrane sacs called cisternae, like rER.
–Different to rER:
–No attached ribosomes
–Often sited close to the plasma membrane
-The cisternae are shorter and more curved that those of the rER
-The Golgi apparatus processes (modifies) proteins from from the rER. The proteins are then repackaged in vesicles for secretion outside the cell.

Question 14

Vesicles

Answer 14

-a single membrane with fluid inside
-very small in size
-used to transport materials inside the cell

Question 15

Lysosomes

Answer 15

-spherical with a single membrane
-formed from golgi vesicles
-contain digestive enzymes for breakdown of: ingested food in vesicles, unwanted/damaged organelles, the cell itself
-high concentration of enzymes cause this organelle to stain heavily and hence appear dark on micrographs

Question 15

Vacuoles

Answer 15

-single membrane with fluid inside
-in plant cells vacuoles are large and permanent, often occupying the majority of the cell volume
-in animal cells vacuoles are smaller and temporary and used for various reasons, e.g. to absorb food and digest it

Question 16

Flagellum

Answer 16

-thin protection (often singular) from the cell surface
-contain microtubules
-used to move the cell

Question 17

Cilia

Answer 17

-Thin projections from the cell surface
-Contain microtubules
-Used to either move the cell or to move the fluids next to the cell

Question 18

Microtubules

Answer 18

-Small cylindrical fibres called microtubules
-Have a variety of functions, e.g. part of the structure of flagella and they play a role in cell division

Question 19

Centrioles

Answer 19

-Consist of two groups of nine triple microtubules
-Are mainly found in animal cells, not present in vascular plants or fungi.

Question 20

Function of the palisade cells in the leaf mesophyll

Answer 20

-Where most of the photosynthesis occurs in the leaf
-contain a lot of chloroplasts to help them perform this photosynthesis
-are closely packed to optimize light absorbtion

Question 21

Chloroplast

Answer 21

-A double membrane
-Inside are stacks of thylakoids
-Each thylakoid is a disc composed of a flattened membrane
-The shape of chloroplasts is variable but is usually ovoid
-The site of photosynthesis and hence where glucose is produced.
-Starch grains maybe present if photosynthesis is happening quickly

Question 22

Cell wall

Answer 22

-an extracellular component not an organelle.
-secreted by all plant cells (fungi and some protists also secrete cell walls).
-Plant cell walls consist mainly of cellulose which is:
–Permeable
–Strong
–Hard to digest