2 - Basic components of living systems

Question 1

Light microscopes

Answer 1

• lower magnification and resolution than electron microscopes
• uses light
• used to look at whole cells/tissues.
• max magnification x1500
• alive

Question 2

laser scanning confocal microscopes

Answer 2

• laser beams are used
• resolution is higher than an light microscope.
• used to look at objects at different depths and thick specimens.

Question 3

Transmission electron microscopes

Answer 3

• beam of electrons transmitted through a specimen.
• x1 000 000
• high resolution 0.5nm
• dead

Question 4

Scanning electron microscope

Answer 4

• beam of electrons
• resolution 3-10nm
  3d images produced.
• false coloured
• x500000
• dead

Question 5

How is a microscope slide prepared?

Answer 5

• dry mount
• wet mount
• smear slides
• squash slides.

Question 6

what stains are used in light microscopy and why?

Answer 6

• methylene blue
• different cell components take up stains to different degrees.
• the contrast makes the different parts show up.

Question 7

dry mount microscope slide how?

Answer 7

• use tweezers to put thin specimen on middle of clean slide.
• put a cover slip on top.

Question 8

wet mount microscope slide how?

Answer 8

• pipette a small amount of water onto the slide
• use tweezers to place specimen on top of water drop.
• place cover slip at an angle.

Question 9

under light microscope, gram-negative bacteria appear…

Answer 9

red

Question 10

under light microscope, gram-positive bacteria appear…

Answer 10

blue

Question 11

How do you use a light microscope?

Answer 11

• clip slide onto the stage
• select lowest powered objective lens
• use coarse adjustment knob for rough focusing
• use fine adjustment knob for finer focusing for a clearer image.
• switch to a higher powered objective lens to see the specimen with a higher magnification.

Question 12

1 division on the stage micrometre is?

Answer 12

0.1mm

Question 13

formula linking image size, actual size, magnification?

Answer 13

image size = actual size x magnification.

Question 14

What is magnification?

Answer 14

how much bigger the image is than the specimen

Question 15

What is resolution?

Answer 15

The ability to be able to distinguish between two distinct points on an image.

Question 16

cell surface membrane?

Answer 16

• regulates the movement of substances into and out of cells.
• has receptor molecules which respond to chemicals eg hormones

Question 17

nucleus

Answer 17

• controls activity of the cell

- where genetic information is stored, replicated, copied into RNA

Question 18

nucleolus

Answer 18

makes ribosomes

Question 19

nuclear envelope

Answer 19

protective double layer with nuclear pores.

Question 20

lysosome

Answer 20

• contain powerful hydrolytic enzymes called lysozymes

- breaks down worn out cell components or digest invading cells.

Question 21

ribosome

Answer 21

• site of protein synthesis.

Question 22

rough endoplasmic reticulum

Answer 22

• folds and processes proteins made at the ribosomes.

Question 23

smooth endoplasmic reticulum

Answer 23

• site of lipid and carbohydrate synthesis

- storage

Question 24

vesicle

Answer 24

• transports substances in and out of the cell.

- formed by golgi apparatus, endoplasmic reticulum

Question 25

golgi apparatus

Answer 25

• receives proteins from rough ER
• modifies and processes molecules (e.g new lipids and proteins) and packages them into vesicles.
• makes lysosomes.

Question 26

mitochondrion

Answer 26

• site of aerobic respiration

- ATP is produced by them.

Question 27

chloroplast

Answer 27

• site of photosynthesis
• grana
• stroma

Question 28

centriole

Answer 28

• involved in separation of chromosomes in cell division

Question 29

cilia

Answer 29

• for locomotion
• waft substances along the cell surface.
• microtubules allow them to move

Question 30

flagellum

Answer 30

• enables cell mobility
• microtubules contract to make the flagellum move
• propels cells forwards

Question 31

what us the cytoskeleton composed of?

Answer 31

• microfilaments
• microtubules
• intermediate fibres

Question 32

cell wall

Answer 32

• gives plant cell structure mechanical support.
• gives plant cells their shape.
• cellulose

Question 33

what is the importance of the cytoskeleton?

Answer 33

• providing mechanical strength to cells
• aiding transport within cells (microtubules)
• enables cell movement.

Question 34

Interrelationship between organelles (protein production and secretion)

Answer 34

• DNA in the nucleus contains the gene to make protein.
• This gene is copied by mRNA and is taken out of the nucleus via nuclear pore and to the ribosome.
• protein is synthesised at the ribosome (bound to RER)
• protein passes into cisternae of RER and is packaged into a vesicle.
• vesicle moves to Golgi apparatus and fuses.
• Protein is structurally modified and processed.
• Golgi apparatus repackages the protein in a secretory vesicle.
• secretory vesicle travels along microtubules, and fuses with cell surface membrane.
• contents released by exocytosis.

Question 35

what is cisternae

Answer 35

rough ER has flattened stacks of membrane bound sacs which forms sheets called cisternae.

Question 36

Special features of prokaryotic cells?

Answer 36

• 70s ribosomes
• no nucleus
• no membrane bound organelles
• plasmids
• single strand of DNA free in cytoplasm
• cell wall
• sometimes have flagella
• bacteria
• circular DNA

Question 37

Special features of Eukaryotic cells?

Answer 37

• 80s ribosomes
• DNA enclosed in nucleus
• has membrane bound organelles.
• plant and animal cells
• linear DNA

Question 38

what type of microscope is needed to see bacterial cells?

Answer 38

electron microscopes.