Ch3 Cell Structure

Question 1

What is Binary Fission?

Answer 1

The method of cell division used by prokaryotes involving the replication of the circular DNA and plasmid followed by cytoplasmic division

Question 2

What is the Cell Cycle?

Answer 2

The series of stages preparing the cell for division consisting of interphase and mitosis

Question 3

What is a Cell-surface Membrane

Answer 3

A phospholipid bilayer studded with proteins that surrounds cells and separates them from their environment

Question 4

What is a Cell Vacuole?

Answer 4

A membrane bound structure found in plant cells that contains cell sap

Question 5

What are Chloroplasts

Answer 5

An organelle found in plants and algae that is the site of photosynthesis

Question 6

What is Cytokinesis?

Answer 6

The division of the cytoplasm to produce 2 new cells

Question 7

What is a Flagella (Flagellum)?

Answer 7

A whip-like tail structure found on bacterial cells that is used for cell movement

Question 8

What is the Golgi Apparatus?

Answer 8

An organelle found in eukaryotic cells that is the site of aerobic respiration

Question 9

What are Lysosomes?

Answer 9

Membrane-bound vesicles found in the cytoplasm that contain a hydrolytic enzyme called Lysozyme

Question 10

What is a Lysozyme?

Answer 10

Digestive enzymes which digest material in the cell

Question 11

What is Magnification?

Answer 11

How much bigger an image appears compared to the original object calculated

Question 12

What is a Mitochondrion?

Answer 12

An organelle found in eukaryotic cells that is the site of aerobic respiration and releases energy for movement

Question 13

What is Mitosis?

Answer 13

The part of the cell cycle in which a eukaryotic cell divides to produce 2 daughter cells, each with identical copies of DNA

Question 14

What is a Nucleus?

Answer 14

An organelle found in eukaryotic cells that stores the genetic information of the cell as chromosomes and surrounded by a membrane called the nuclear envelope

Question 15

What are Plasmids?

Answer 15

A circular loop of DNA found in the cytoplasm of bacterial cells

Question 16

What is Resolution?

Answer 16

The minimum distance apart that 2 objects can be for them to appear as separate items

Question 17

What are Ribosomes?

Answer 17

Organelles found either free in the cytoplasm or membrane bund that are involved in the synthesis of proteins

Question 18

What is the Rough Endoplasmic Reticulum (RER)?

Answer 18

A membrane bound organelle that is involved in the synthesis and packaging of proteins

Question 19

What is the Smooth Endoplasmic Reticulum (SER)?

Answer 19

A membrane bound organelle involved in lipid synthesis

Question 20

How can the overall magnification of a light microscope be calculated?

Answer 20

Objective lens x eyepiece lens

Question 21

What is the formula for magnification?

Answer 21

Magnification - size of image / size of real object

Question 22

1mm = ? μm

Answer 22

1mm = 1000μm

Question 23

1μm = ? nm

Answer 23

1μm = 1000 nm

Question 24

Define magnification

Answer 24

How many times bigger the image is when compared to the object

Question 25

Define resolution

Answer 25

The minimum distance apart that two objects can be in order for them to appear as separate items

Question 26

What is the maximum resolution of a light microscope? What limits resolution?

Answer 26

0.2μm (wavelength of light)

Question 27

What is cell fractionation?

Answer 27

Cells are broken up and organelles are separated out

Question 28

List three steps involved in cell fractionation.

Answer 28

Homogenisation (breaking open cells), Filtration (removing unbroken cells and debris), Ultracentrifugation (spinning at increasing speeds to separate organelles by density)

Question 29

What is the heaviest organelle?

Answer 29

Nucleus

Question 30

What cell part is the last to be separated out?

Answer 30

Ribosomes

Question 31

What is the order which cells get separated out with?

Answer 31

Nucleus > chloroplasts > mitochondria > lysosomes > endoplasmic reticulum > ribosomes

Question 32

Why is an ice-cold solution used in cell fractionation?

Answer 32

To slow enzyme activity

Question 33

Why is an isotonic solution used in cell fractionation?

Answer 33

To prevent organelles bursting or shrinking due to osmotic gain or loss of water

Question 34

Why is a buffered solution used in cell fractionation?

Answer 34

To control pH which might otherwise alter the structure of membrane proteins

Question 35

What is the maximum resolution of an electron microscope? What limits resolution?

Answer 35

0.1nm (wavelength of electron beam)

Question 36

How do the TEM and SEM differ?

Answer 36

TEM beam of electrons passes through thin specimen producing a 2D image whereas SEM beam of electrons passes back and forth across surface of specimen forming a 3D image. SEM has a lower resolving power than TEM

Question 37

List limitations of electron microscopes

Answer 37

Must be in a vacuum therefore living samples cannot be observed, complex preparation required, specimen must be extremely thin in TEM, images may contain artefacts

Question 38

What is an artefact?

Answer 38

Structures viewed in the image that are not part of the specimen but result from the preparation of a sample

Question 39

What two pieces of equipment are needed to measure cells viewed under the microscope?

Answer 39

Eyepiece graticule calibrated against a stage micrometer

Question 40

What is the function of the nucleus?

Answer 40

Contains DNA, control's cell activities, produces mRNA, tRNA, and ribosomes

Question 41

What is the function of the nuclear envelope?

Answer 41

Double membrane surrounding nucleus, controls entry and exit, outer membrane has ribosomes and is continuous with ER. has pores to allow mRNA out of the nucleus

Question 42

What is the function of the nucleolus?

Answer 42

Makes ribosomal RNA and assembles ribosomes

Question 43

What is the function of the mitochondria?

Answer 43

Site of aerobic respiration (Krebs cycle and oxidative phosphorylation)

Question 44

Describe the structure of mitochondria

Answer 44

Double membrane, inner membrane folded into cristae providing a large surface area for the attachment of enzymes involved in respiration, matric contains proteins, lipids, ribosomes and DNA

Question 45

What is the function of the chloroplasts?

Answer 45

Photosynthesis (absorbing light and synthesizing sugars)

Question 46

Describe a structure of a chloroplast

Answer 46

Double membrane, grana (stacks of thylakoids), thylakoids contain chlorophyll, electron carriers and enzymes, stroma containing starch grains and enzymes for synthesis of sugars, contains DNA and ribosomes