2.1 eukaryotic and prokaryotic cell structure and function

Question 1

what is the cell theory?

Answer 1

cells are a fundamental unit of structure , function and organisation in organisms

Question 2

what are tissues?

Answer 2

groups of similar cells that develop from the same kind of cell

Question 3

what are the four main types of tissue in the human body?

Answer 3

• epithelial tissue
• connective tissue
• muscle tissue
• nervous tissue

Question 4

what is an organ?

Answer 4

a structure made up of several different types of tissues grouped together to carry out a particular function in the body

Question 5

what is an organ system?

Answer 5

a group of organs working together to carry out a particular functions in the body

Question 6

what are the main features of a prokaryotic cell?

Answer 6

• cell wall
• pili
• flagellae
• cell surface membrane
• plasmid
• nucleoid
• 70S ribosomes

Question 7

what is the use of a cell wall to prokaryotes?

Answer 7

• prevents swelling and bursting + maintains shape, support and protection
• made of peptidoglycan (polysaccharide chains)
• some have capsule to be less easily identified by immune system

Question 8

what is the use of pili to prokaryotes?

Answer 8

• thread-like protein projections
• used for attachment to a host cell and for sexual reproduction

Question 9

what is the use of a flagella to a prokaryote?

Answer 9

tail-like structure which rotates to move the cell around

Question 10

what is the use of a cell membrane?

Answer 10

respiratory enzymes in mesosomes (foldings)

Question 11

what is the use of a plasmid in prokaryotes?

Answer 11

circles of DNA

Question 12

what is the use of a nucleoid in a prokaryote?

Answer 12

genetic material folded up

Question 13

what are 70s ribosomes used for in prokaryotes?

Answer 13

protein synthesis is carried out
has two subunits: 30S+50S

Question 14

what are the two types of bacterial cell wall?

Answer 14

Gram-positive + Gram-negative

Question 15

how do we differenciate them?

Answer 15

Gram-staining

Question 16

why is this important?

Answer 16

different types of bacteria are vunreable to different types of antibiotics and one of the factors that affects their vunreability is what type of cell wall they have

Question 17

Gram-positive bacteria

Answer 17

• think layer of peptidoglycan containing chemicals such as techoic acid
• the crystal violet in the stain gets trapped in the layer and resists decolouring when the bacteria are dehydrated
• it does not pick up the red safranin counterstain leaving the positive purple/blue colour

Question 18

Gram negative bacteria

Answer 18

• thin layer of peptidoglycan with no techoic acid between two layers of membrane
• the outer membrane is made of lipopolysaccharides
• aftercrystal violet is applied the bacteria are dehydrated in ethanol
• the lipopolysaccharide layer dissolves leaving the thin layer of pepidoglycan exposed and so takes up the red counterstain and cella appear red

Question 19

why are antibiotics effective against bacteria?

Answer 19

they target 70S ribosomes and cell walls because eukaryotic cells don’t have those so are not effected

Question 20

nucleus

Answer 20

• has double membrane
• contains genetic information
• contains nucleolus (pure DNA and protein)

Question 21

mitochondria

Answer 21

• bound by double membrane
• membrane folds to form cristae
• matrix inside cell is used for cellular respiration (forms ATP)

Question 22

centrioles

Answer 22

• pair near the nucleus
• involved in cell division
• pull apart to produce a spindle of microtubules

Question 23

80S ribosomes

Answer 23

• 40S+60S subunits
• protein synthesis

Question 24

Rough endoplasmic recticulum

Answer 24

isolates and transports these proteins once they have been made

Question 25

smooth endoplasmic recticulum

Answer 25

transports steroids and lipids

Question 26

golgi apparatus

Answer 26

stacks of membrane that modify proteins made elsewhere in the cell and package them into vesicles for transport

Question 27

lysosomes

Answer 27

organelle full of digestive enzymes used to break down worn out cells or organelles or digest food

Question 28

what are the two types of microscopes used?

Answer 28

light microscopes and electon microscope

Question 29

why do we stain specimens?

Answer 29

to enhance visualization of the cell or certain cellular components under a microscope. Cells may also be stained to highlight metabolic processes or to differentiate between live and dead cells in a sample.