bacteria

Question 1

model organism for bacteria

Answer 1

E. coli
gram negative
rod shaped

Question 2

properties of prokaryotes

Answer 2

do not contain nucleus
1-5 microns in length, but various shapes
complex cell wall = tough protective coat

Question 3

organotrophic

Answer 3

can utilise any type of molecule as food (sugars, amino acids, hydrocarbons etc)

Question 4

phototrophic species

Answer 4

harvest light energy in various ways

Question 5

lithotrophic species

Answer 5

inorganic nutrients
fixes C from CO2
relies of H2S to fuel energy needs

Question 6

two families of prokaryotes

Answer 6

archaea
bacteria

Question 7

where is DNA located in prokaryotes?

Answer 7

in the cytoplasm, typically as a single haploid circular chromosome, enclosed by the plasma membrane
also contains RNA/proteins and other small molecules

Question 8

what is a plasmid?

Answer 8

an additional piece of circular DNA that is separate from the chromosomes
can be lost if no longer needed

eg. for genes that confer advantages like antibiotic resistance

Question 9

flagella vs pili

Answer 9

flagella for movement by helical rotation
pili = short protein appendages, smaller than flagella, for adhesion, but some can generate force

both anchored to cell surface by multi protein complexes

Question 10

define pathogenic

Answer 10

causing disease

Question 11

how do pathogens differ from other bacteria species?

Answer 11

they have additional virulence genes that confer their pathogenicity, either on a separate plasmid or integrated into the chromosome

Question 12

features of a gram positive cell wall

Answer 12

single membrane
thick cell wall made of cross linked peptidoglycan

Question 13

features of a gram negative cell wall

Answer 13

two membranes (inner/outer) separated by a periplamic space
thin peptidoglycan wall

inner membrane = phospholipid bilayer
outer membrane = LPS (lipopolysaccharide), can be fever-causing

Question 14

a gram staining procedure will dye which type of bacteria?

Answer 14

gram POSITIVE bacteria - thick peptidoglycan cell wall retains violet dye

Question 15

examples of gram positive and negative bacteria

Answer 15

positive: staph, strep
negative: E coli, Salmonella

Question 16

describe the capsule / slime layer

Answer 16

glycocalyx
= polysaccharide external layer
prevents phagocytosis (complement can’t penetrate sugars)
helps bacteria adhere to surfaces

Question 17

what are endospores?

Answer 17

intracellular spores - highly resistant structure

some gram positive bacteria produce this as a survival mechanism

Question 18

define the microbiome

Answer 18

The collection of all microbes, such as bacteria, fungi, viruses, and their genes, that naturally live on our bodies and inside us

Question 19

3 key functions of the microbiome

Answer 19

1. digesting fibre
2. protect against pathogens
3. immune response

Question 20

plant cells: three major differences from animal cells

Answer 20

tough cell wall
chloroplasts
vacuoles

Question 21

define choloplasts + basic structure

Answer 21

organelles that capture energy of sunlight in plant cells

highly folded system of internal membranes containing chlorophyll molecules which absorb light

Question 22

origin of chloroplasts

Answer 22

endosymbiotic event (similar to mitochondria)

early eukaryotic cell engulfed photosynthetic bacteria and retained it in symbiosis

Question 23

products of photosynthesis

Answer 23

ATP and NADPH

Question 24

how are the products of photosynthesis used by chloroplasts?

Answer 24

ATP and NADPH used in electron transport chain for the carbon fixation cycle (this stage is known as the Calvin Cycle)

(note this is the light cycle - chloroplasts also have a dark cycle)

Question 25

what makes up most of plant cell walls?

Answer 25

cellulose, a polysaccharide
long fibres oriented along lines of stress
hence the cell wall is tough but not rigid

Question 26

structure of the plant cell wall

Answer 26

cellulose forms microfibrils, which are interwoven with other structural proteins (eg. in wood, lignin)

primary cell walls can expand to accomodate growth

Question 27

what is turgour pressure?

Answer 27

a swelling pressure that develops as the result of an osmotic imbalance between the interior of the plant cell and its surroundings
(keeps lettuce leaf crisp)