1.2 cell structure

Question 1

what kingdom are prokaryotes?

Answer 1

Monera

Question 2

what are the 2 domains of prokaryotes?

Answer 2

Archaebacteria – found in extreme environments like high temperatures, salt concentrations or pH (i.e. extremophiles)
Eubacteria – traditional bacteria including most known pathogenic forms (e.g. E. coli, S. aureus, etc.)

Question 3

how do prokaryotes reproduce?

Answer 3

via binary fission

Question 4

describe the process of binary fission

Answer 4

1. The circular DNA is copied in response to a replication signal
2. The two DNA loops attach to the membrane
3. The membrane elongates and pinches off (cytokinesis), forming two cells

Question 5

prokaryotic features (9)

Answer 5

Cytoplasm, nucleoid, plasmids, ribosomes, cell membrane, cell wall, slime capsule, flagella, pili

Question 6

compartmentalization

Answer 6

having membrane-bound organelles

Question 7

benefits of compartmentalization

Answer 7

efficiency of metabolism
localised conditions (pH, osmolarity, etc.)
number and location of organelles can be changed.

Question 8

how did eukaryotes evolve from prokaryotes

Answer 8

via endosymbiosis

Question 9

4 kingdoms of eukaryotes

Answer 9

protista, fungi, plantae, animalia

Question 10

universal organelles (prokaryote & eukaryote)

Answer 10

ribosomes, cytoskeleton, plasma membrane

Question 11

eukaryotic organelles (plant & animal)

Answer 11

nucleus, ER, golgi apparatus, mitochondrion, peroxisome, centrosome

Question 12

plant-cell-only organelles

Answer 12

chloroplast, vacuole, cell wall

Question 13

animal-cell-only organelle

Answer 13

lysosome

Question 14

ribosomes

Answer 14

Structure: Two subunits made of RNA and protein; larger in eukaryotes (80S) than prokaryotes (70S)

Function: Site of polypeptide synthesis (this process is called translation)

Question 15

cytoskeleton

Answer 15

Structure: A filamentous scaffolding within the cytoplasm (fluid portion of the cytoplasm is the cytosol)

Function: Provides internal structure and mediates intracellular transport (less developed in prokaryotes)

Question 16

plasma membrane

Answer 16

Structure: Phospholipid bilayer embedded with proteins (not an organelle per se, but a vital structure)

Function: Semi-permeable and selective barrier surrounding the cell

Question 17

nucleus

Answer 17

Structure: Double membrane structure with pores; contains an inner region called a nucleolus

Function: Stores genetic material (DNA) as chromatin; nucleolus is site of ribosome assembly

Question 18

endoplasmic reticulum

Answer 18

Structure: A membrane network that may be bare (smooth ER) or studded with ribosomes (rough ER)

Function: Transports materials between organelles (smooth ER = lipids ; rough ER = proteins)

Question 19

golgi apparatus

Answer 19

Structure: An assembly of vesicles and folded membranes located near the cell membrane

Function: Involved in the sorting, storing, modification and export of secretory products

Question 20

mitochondrion

Answer 20

Structure: Double membrane structure, inner membrane highly folded into internal cristae

Function: Site of aerobic respiration (ATP production)

Question 21

peroxisome

Answer 21

Structure: Membranous sac containing a variety of catabolic enzymes

Function: Catalyses breakdown of toxic substances (e.g. H2O2) and other metabolites

Question 22

centrosome

Answer 22

Structure: Microtubule organising centre (contains paired centrioles in animal cells but not plant cells)

Function: Radiating microtubules form spindle fibres and contribute to cell division (mitosis / meiosis)

Question 23

chloroplast

Answer 23

Structure: Double membrane structure with internal stacks of membranous discs (thylakoids)

Function: Site of photosynthesis – manufactured organic molecules are stored in various plastids

Question 24

vacuole

Answer 24

Structure: Fluid-filled internal cavity surrounded by a membrane (tonoplast)

Function: Maintains hydrostatic pressure (animal cells may have small, temporary vacuoles)

Question 25

cell wall

Answer 25

Structure: External outer covering made of cellulose (not an organelle per se, but a vital structure)

Function: Provides support and mechanical strength; prevents excess water uptake

Question 26

lysosome

Answer 26

Structure: Membranous sacs filled with hydrolytic enzymes

Function: Breakdown / hydrolysis of macromolecules (presence in plant cells is subject to debate)

Question 27

draw a prokaryotic cell

Answer 27

see ipad

Question 28

what does the S in 70S and 80S ribosome stand for?

Answer 28

Svedberg units

Question 29

What type of DNA replication takes place during binary fission?

Answer 29

semi-conservative

Question 30

resolution

Answer 30

Resolution is the ability to distinguish between two points in a microscope’s field of view.

Question 31

What is the difference between prokaryotic and eukaryotic DNA?

Answer 31

Eukaryotic DNA is associated with histones, whereas prokaryotic DNA is not.

Question 32

disadvantage of using an electron microscope to observe organisms and cells

Answer 32

Specimens cannot be viewed in full, natural colour.

Question 33

which has a higher resolution: light or electron microscope?

Answer 33

electron microscope

Question 34

What is the destination of a protein synthesised by free ribosomes?

Answer 34

cytoplasm, lysosomes, mitochondria, chloroplasts and the nucleus

Question 35

The smooth endoplasmic reticulum is responsible for the synthesis and storage of:

Answer 35

lipids and steroids