Chapter 2 - Cell Functions

Question 1

Prokaryotes

Answer 1

• Found in bacteria
• Lack of membrane bound organelles
• Contains free floating DNA
• Has a plasma membrane, cell wall, ribosomes and flagella/cilia
• No nucleus, mitochondrion, E.R, Golgi,
  Lysosomes or chloroplasts

Question 2

Eukaryotes

Answer 2

• Found in complex organisms (non-bacterial)
• Complex structure
• Have membrane bound organelles
• DNA found in nucleus

Question 3

Active Transport

Answer 3

The use of proteins powered by ATP to move molecules against a concentration gradient

Question 4

Apoptosis

Answer 4

Programmed and controlled series events which lead to cell death. Messenger molecules bind to receptors causing cascade of events within cell. Enzymes are triggered to break down cell components (many organelles unaffected) as cell begins into bleb into apoptic bodies encased in plasma membrane. Blebs are enveloped through phagocytosis.

Question 5

Carrier proteins

Answer 5

Proteins within the plasma membrane that assist with the

passage of other molecules across the membrane in

facilitated and active transport

Question 6

Channel proteins

Answer 6

Proteins that form channels within the plasma membrane to

allow for the passage of hydrophilic substances across the

membrane

Question 7

Chromatin

Answer 7

A complex of proteins and DNA in eukaryotic chromosomes

Question 8

Chromosome

Answer 8

Structure composed of DNA and protein that contains along its length linear arrays of genes carrying genetic information; prokaryotes have one circular chromosome whereas eukaryotes have a number of linear chromosomes

Question 9

Concentration Gradient

Answer 9

Difference in concentration across a boundary

Substances move from high to low

Question 10

Cytoskeleton

Answer 10

A network of filaments within a eukaryotic cell that provides structural support, anchorage, shape, motility and a capacity to move and arrange organelles within a cell

Question 11

Passive Diffusion

Answer 11

The movement of a dissolved substance from an area of high concentration to an area of low concentration; the process is
passive and does not require an input of energy

Question 12

Exocytosis

Answer 12

A fusion of a vesicle with the plasma membrane so that its

contents can be expelled or secreted from the cell

Question 13

Extra-cellular matrix (ECM)

Answer 13

Mixture of structural proteins and glycoproteins found in space between neighbouring cell that supports tissue structure

Question 14

Flagellum

Answer 14

(pl. flagella) whip-like organelle of cells that enable movement

Question 15

Golgi Apparatus

Answer 15

An organelle in eukaryotic cells that modifies proteins and lipids before exporting them inside vesicles from the cell.

Question 16

Isotonic

Answer 16

When the solution outside and inside the cell contains the same concentration of solute particles. There is no net
movement of water molecules.

Question 17

Lysosomes

Answer 17

A membrane-bound vesicle in eukaryotic cells containing enzymes which is involved in the breakdown and recycling of many types of molecules

Question 18

Organelle

Answer 18

Specialised structure or compartment in a eukaryotic cell that has a specific function

Question 19

Phagocytosis

Answer 19

A form of endocytosis in which solid material is engulfed by a plasma membrane and surrounded by a liposome within a cell.

Question 20

Pinocytosis

Answer 20

The process by which liquid and small molecules are engulfed and taken into the cell enclosed in a membrane-bound vacuole (endocytosis)

Question 21

Plasma Membrane

Answer 21

The insoluble boundary of the living cell that maintains the contents of the cell and regulates the movement of
substances in and out of the cell. All cells have a plasma membrane

Question 22

Plasmolysis

Answer 22

Occurs when the plasma membrane is drawn away from the cell wall in plants owing to the loss of water from the cell by osmosis

Question 23

Prokaryotic

Answer 23

Cell that lack a membrane bound nucleus and other membrane bound organelles; all bacteria are prokaryotic cells

Question 24

Ribosomes

Answer 24

The site of protein synthesis in all cells, this organelle is not
bound by a membrane; a ribosome consists of two rRNA (ribosomal RNA) subunits that lock onto a mRNA molecule; the ribosome moves along mRNA to translate its code and link amino acids. Forming a polypeptide

Question 25

Turgid

Answer 25

When water has entered plant cells by osmosis to the extent

that their swollen vacuole pushes the cell membrane against the cell wall

Question 26

Vacuole

Answer 26

A cavity inside a cell bounded by a membrane; it takes up most of the interior of a mature plant cell and contains dissolved materials for storage and waste; in animal cells, vacuole sacs are small and isolate materials, such as toxins and proenzymes, from the protoplasm

Question 27

Osmosis occurs in the direction

Answer 27

Low water concentration —> High

High solute concentration to low

Question 28

What determines whether a substance is permeable to a plasma membrane.
IN Vs OUT

Answer 28

Charge of molecule
size of molecule
IN: small polar and non polar molecules (non-polar more readily allowed through)
OUT; Ions and large molecules polar ones

Question 29

Simple diffusion Vs Passive Diffusion

Answer 29

Simple: Net movement of molecules down a concentration gradient without assistance of proteins
Passive: Net movement of molecules down a concentration gradient with or without assistance of proteins

Question 30

Facilitated diffusion

Answer 30

Net movement of molecules down a concentration gradient with the assistance of carrier and channel proteins.

Question 31

Active transport

Answer 31

Net movement of molecules through carrier proteins against concentration gradient using ATP to provide the energy.

Question 32

Isotonic

Answer 32

Surrounding fluid concentration equal to fluid inside the cell.

Question 33

Hypertonic:

Net water movement

Answer 33

The outside fluid is hypertonic to the cell if it has a higher concentration of solute than inside the cell.
Water moves out of cell

Question 34

Hypotonic:

Net water movement

Answer 34

The outside fluid is hypotonic to the cell if it has a lower concentration of solute than inside the cell.
water moves into cell

Question 35

What is bulk transport

Answer 35

Large macromolecules or clumps of molecules are transported across the plasma membrane in a vesicle.

Question 36

Endocytosis;

Name for solid and liquid endocytosis

Answer 36

Endocytosis: Plasma membrane sinks inwards, encloses particles within endocytic vesicle which transports them through the cytoplasm.
Solid: Phagocytosis
Liquid: pinocytisis

Question 37

Protein secretion pathway

Answer 37

1. ) Polypeptide chain synthesised from a bound ribosome
2. ) Protein enters lumen of rough ER and folds into 3D shape
3. ) Proteins leave ER in vesicle.
4. ) Vesicle received by Golgi apparatus (at the cis-face) where they are modified, often adding a carbohydrate group.
5. ) Proteins leave Golgi apparatus in liposome (from the trans-face) and are shipped to the cells membrane and exported from the cell in exocytosis.

Question 38

When are bound ribosomes used compared to free ribosomes?

Answer 38

Free ribosomes usually for proteins to be used within the cell.
Bound ribosomes: usually for proteins that will be secreted by the cell

Question 39

Identifying:
Rough ER
Smooth ER
Golgi apparatus

Answer 39

Rough ER: Interconnecting tubules with bumps (ribosomes)
Smooth ER: Interconnecting smooth tubules
Golgi apparatus: Looks like smooth ER but in shape of a C

Question 40

Purpose of smooth ER

Answer 40

involved in the production of lipids, including phospholipids and cholesterol

Question 41

Free ribosomes vs bound ribosomes purpose

Answer 41

Free ribosomes = synthesis of proteins that are to used in the cell
Bound ribosomes= synthesis of proteins that will be exported

Question 42

Sequence of protein synthesis to be exported

Answer 42

1. ) mRNA used to transcribe amino acid sequence on ribosome bound to the rough ER.
2. ) polypeptide sequence enter lumen of rough ER and is folded into its 3D functional shape
3. ) Protein exits rough ER in vesicle and enters Golgi apparatus through endocytosis.
4. ) here protein is introduced carbohydrate creating glycoproteins.
5. ) exits Golgi in vesicle and exocytoses out of the cell to be delivered around the body

Question 42

Purpose of rough endoplasmic reticulum

Answer 42

Polypeptide chain folded into 3D functional shape with aid of enzyme and is prepared for the addition of carbohydrates in the Golgi.

Question 43

Centriole

Answer 43

A pair of cylindrical structures that made up of several tubes that form spindle during cellular division.

Question 44

Cilia

Answer 44

Hair like projections on the surface on some cells.

Question 45

Peroxisomes

Answer 45

Contain enzymes that destroy toxic materials such as hydrogen peroxide.

Question 46

Difference between Plant and animal cells

Answer 46

Plant: Cell wall, Chloroplast, large vacuole
Animal: No cell wall, No Chloroplast, small vacuole

Question 47

Endosymbiotic theory and evidence

Answer 47

Mitochondria and Chloroplast were life forms of their own that were enveloped by a eukaryotic cell and utilised for energy production.
Evidence:
- Both have a double membrane, one of the prokaryote and one of the hosts.
- Both have unique circular DNA, allowing the, to pass on genetic info as independent organisms
- both contain small ribosomes indicating they make their own proteins.

Question 48

Discuss importance of membrane bound organelles

Answer 48

Allow for chemical environments which reactions can proceed with maximum efficiency. Allows cell to keep harmful reactions and substances contained

Question 49

Contractile vacuole

Answer 49

Contractile vacuoles absorb excess water and wastes from a microorganism’s cell and excrete them into the environment by contracting.