Chapter 3

Question 1

What is the structure and function of the cell membrane?

Answer 1

• made from lipids and proteins
• regulates movement of substances in/out of cell
• receptor cells recognise and allow cells to respond to chemical signals like hormones

Question 2

What are the properties of the nucleus?

Answer 2

• contains DNA and chromosomes
• site of DNA replication
• contains 1 or more nucleoli - to synthesise ribosomes
• surrounded in nuclear enevelope

Question 3

What is the structure and function of the mitochondira?@

Answer 3

• site of aerobic respiration
• provides energy
• doubles membrane for larger DA for respiration

Question 4

What is the structure and function of the chloroplasts?

Answer 4

PLANTS

- site of photosynthesis = in thylakoid membrance and grana

Question 5

What is the structure and function of the golgi body?

Answer 5

• flattened sacs that produce vessicles (vessels that remove things from cell)
• processes and packages substances made by rough and smooth ER

Question 6

What is the structure and function of lysosomes?

Answer 6

• types of golgi body

- produces digestive enzyme lysozymes to digest cells

Question 7

What is the structure and function of the ribosomes?

Answer 7

• tiny organelles that float in cytoplasm and attach to rough ER
• where proteins are synthesised

Question 8

What is the structure and function of the endoplasmic reticulum?

Answer 8

• membrane folds connected to nuclear enevelope
• spaces between folds filled with fluid to transport substances around cell
• SMOOTH = synthesise and process lipids
• ROUGH = studded in ribosomes to synthesise and transport proteins

Question 9

What is the structure and function of the cell wall?

Answer 9

PLANTS

• made from cellulose
• supports plasma membrane
• maintains structure of plant cell

Question 10

What is the structure and function of the vacuole?

Answer 10

PLANTS

• mature plants = larger
• filled with water, pigments and waste
• turgid = keeps cell supported

Question 11

How are cells specialised?

Answer 11

• Cells specialised to become tissues
• tissues work together to perform function and make an organ
• organs work togther to produce organ systems

Question 12

Give an example of specialised cells.

Answer 12

• Epithelial cells become epithelial tissues
• epithelial tissues work with glandular and muscular tissues to form stomach
• stomach part of digestive system

Question 13

What is the structures in prokaryotes?

Answer 13

• plasmids
• flagella
• capsule
• small ribosomes
• no nucleus = circular DNA floats around cell
• cytoplasm = no membrane bound organelles
• cell wall = contains muren (glycoprotein)

Question 14

What are the properties of an optical microscope?

Answer 14

• uses light to form an image
• max resolution of 0.2 micrometers
• max magnification of x1500

Question 15

What are the properties of an electron microscope?

Answer 15

• uses electrons to form an image so higher res that optical
• max resolution of 0.0002 micrometers
• max magnification of x1500000

Question 16

What is the formula for magnification?

Answer 16

magnification = size of observed image/size of real

Question 17

What is the difference between resolution and magnification?

Answer 17

resolution = how detailed the image produced is -how microscope differentiates between to points close together 
magnification = how much bigger the object is made

Question 18

How would you convert 1 micrometer to 1 mm?

Answer 18

divide the micrometer by 1000

Question 19

What is the process of cell fractionation?

Answer 19

• put cut up tissue in cold, buffered, isotonic solution
• homogenise (blend)
• filter homogenate to remove debris
• put in centrifuge machine at low speed
• remove supernatant, decant and re-centrifuge at higher speed until desired organelle removed

Question 20

What are the properties of a scanning electron microscope?

Answer 20

• scan a beam of electrons at specimen to knock of its own electrons which are gathered in a cathode ray to form an image
• shows surface of specimen
• used on thick specimen
• lower resolution that TEMs

Question 21

What are the properties of transmission electron microscopes?

Answer 21

• uses electromagnets yo focus a beam of electrons which are transmitted through specimen
• denser parts absorb more electrons = darker
• higher resolution
• only used on thin specimens

Question 22

What is the fluid mosaic model?

Answer 22

• called phosopholipid bilayer
• contains cholesterol to keep structure and stop membrane being too fluid
• glycoproteins and glycolipids recognise own/foreign cells
• small, non-polar pass easily
• large or polar molecules go through carrier/ channel proteins

Question 23

What does isotonic mean?

Answer 23

same amount of water in and out of cell so no osmosis

Question 24

What does hypertonic mean?

Answer 24

more water inside cell than out so water moves out = cell shrivels

Question 25

What does hypotonic mean?

Answer 25

more water outside cell than in so water moves in = cell bursts

Question 26

What is facilitated diffusion?

Answer 26

• passive process moves substances down a conc. gradient
• involves carrier and channel proteins
• molecules attach - proteins change shape - molecules release other side
• channel form pores in membrane

Question 27

What is osmosis?

Answer 27

the movement of water across a partially permeable membrane from an area of less negative water potential to an area of more

• pure water = 0 water potential
• impure = more negative

Question 28

What is diffusion?

Answer 28

passive -
the net movement of substances down a concentration gradient from an area of high concentration to an area of low concentration
- polar = facilitated diffusion - channel proteins
- non-polar =pass easily

Question 29

What is active transport?

Answer 29

• uses energy (ATP) to move substances against a concentration gradient
• carrier proteins = molecules attach, ATP provides energy, protein changes shape, molecule released other side

Question 30

Why does the solution the tissue is put in during cell fracturation have to be

• buffered
• ice cold
• isotonic?

Answer 30

• buffered = maintains pH
• ice cold = reduce enzyme activity that breaks down organelles
• isotonic = same conc of chemicals so no osmosis can occur that will damage the organelles