Test 2 Unit 1

Question 1

What are the organelles that are unique to plants?

Answer 1

Chloroplasts, amyoplasts and chromoplasts, central vacuoles, cell walls (cellulose)

Question 2

What are the functions of the plastids?

Answer 2

Chloroplast: site of photosynthesis in plants, contains chlorophyll, a green pigment that absobs light
Amyoplast: store starch in roots and tubers
Chromoplasts: red and yellow pigments for ripening

Question 3

What is the function of the central vacuole?

Answer 3

The pressure within the central vacuole supports the cells. Roles in Storage, Structural Support, and Cell Growth.
Store salts, organic acids, sugars, storage proteins, pigments, and, in some cells, waste products.
sometimes contain enzymes to break down molecules.

Question 4

What is the function of the cell wall?

Answer 4

Contains cellulose fibers, which give tensile strength to the walls. Are perforated by minute channels, the plasmodesmata, which allows ions and small molecules to move directly from one cell to another through the connecting cytosol.

Question 5

Explain the context of appearance of plastids?

Answer 5

By endosymbiosis, where a host cell engulfed a prokaryotic cell capable of photosynthesis like the chloroplast and other plastids originated.

Question 6

Explain how the vacuole regulates the water/solute balance inside the cytoplasm.

Answer 6

The tonoplast, the membrane that surrounds the central vacuole, contains transport proteins that move substances into and out of the vacuole when they are in excess or needed. Diffusion and osmosis.

Question 7

Function of plasmodesmata? Compare it to cell junctions in animal cells.

Answer 7

Allow ions and small molecules to move directly from one cell to another without having to penetrate the plasma membrane or cell walls. Anchoring junctions and tight junctions are in the plasma membrane. gap junctions allow ions to flow between cytoplasms or adjacent cells.

Question 8

Differences between animal and plant cells?

Answer 8

Chloropasts, cell wall and central vacuole. Photosynthesis.

Question 9

Similarities between animal and plant cells?

Answer 9

Nuclei and cytoskeleton, cell membrane, nuclear pore complex, ribosomes, rough ER and smooth ER, golgi apparatus, cytoplasm, mithochondrion.

Question 10

How do nuclear pores regulate what comes in and out of the nucleus?

Answer 10

It exchanges components between the nucleus and cytoplasm and prevents the transport of material not meant to cross the nuclear membrane by the means of the protein-lined channels. Allows necessary proteins to enter the nucleus from the cytoplasm if the proteins have special sequences that indicate they belong in the nucleus.

Question 11

Explain how the RER, the cytoskeleton and Golgi apparatus work together in the exocytosis or endocytosis process.

Answer 11

The proteins synthesized from ribosomes are released in the (RER) endoplasmic reticulum lumen, where they are folded in their 3D conformation by proteins called chaperones. They are then carried to the Golgi complex by transport molecules, where they might go through additional post-translational modifications. The proteins are then carried to the cell membrane in secretory vesicles.

1. Upon merging of the secretory vesicle with the cell membrane, the proteins are released outside of the cell.(exocytosis)
2. A portion of the cell membrane folds in on itself, encircling extracellular fluid and various molecules or microorganisms. The resulting vesicle breaks off and is transported within the cell.(endocytosis).

Question 12

Explain how the Golgi apparatus and lysosomes work together to digest the contents of endocytic vesicles.

Answer 12

Lysosomes budding from Golgi membrane contain enzymes that digest damaged organelles or fuse with endocytic vesicles that form at the plasma membrane and move into the cytoplasm. (endocytosis).

Question 13

Describe the functions of the cytoskeleton.

Answer 13

Contains structural elements of three major types: microtubules (involved in cellular division), intermediate filaments (anchoring junctions between cells), and microfilaments (movement and muscle contration).

Question 14

What the 4 major types of macromolecules and an example of each?

Answer 14

1. Carbohydrates; glucose
2. Lipids; testosterone
3. Proteins; insuline
4. Nucleic acids; cytosine

Question 15

What is the difference between alpha and beta polysaccharides by structure and function?

Answer 15

Alpha: an OH group pointing below the plane of the ring, alpha linkage is flat and easy to break

Beta: an OH group pointing above the plane of the ring, beta linkage is angle (almost 90°) and very difficult to break, so used in cellulose and chitin (cell wall) = rigidity.

Question 16

Explain the relationship between the structure of sugars and their solubility in water or lipids

Answer 16

WATER: They contain OH and H which makes for a high solubility in water because they are very polar.
LIPIDS: no soluble because lipids are nonpolar and hydrophobic.

Question 17

What is the difference between structural isomers from enantiomers

Answer 17

Isomers is the larger category (same chemical formula but different molecular structures) that englobes enantiomers which are isomers that are MIRROR IMAGES.

Question 18

What is the function of plant starches?

Answer 18

Energy storage of plants.

Question 19

What is the function of glycogen?

Answer 19

Energy storage of animals.

Question 20

What is the function of cellulose?

Answer 20

Makes up the cell wall of plants and gives it rigidity.

Question 21

What are the components of triglycerides?

Answer 21

• Glycerol (backbone with 3 binding spots)

- 3 Fatty acids (with carboxyl group)

Question 22

Explain the properties of lipids in regards to their function.

Answer 22

Water insoluble because they are non-polar because of the big CH chains. Lipids make up membranes which function to separate individual cells from their environments and to compartmentalize the cell interior into structures that carry out special functions. So the dual solubility of lipids with having a polar tail and nonpolar head is what makes membranes work.

Question 23

Explain the formation of a cell membrane with phospholipids and cholesterol

Answer 23

1. The lipib bilayer, made of phospholipids because of their dual solubility, arranges with the tails inside and the heads out in contact with the environment.
2. Then some cholesterol molecules are inserted between the phospholipids. Cholesterol functions to immobilise the outer surface of the membrane, reducing fluidity. It makes the membrane less permeable to very small water-soluble molecules that would otherwise freely cross. It functions to separate phospholipid tails and so prevent crystallisation of the membrane.

Question 24

Enumerate different protein functions with examples.

Answer 24

• support: a and b-tubulin
• ↑ rates of reactions: DNA polymerases
• ↑ movements of substances across membranes: ion/glucose transporters, aquaporins
• Carry regulatory signals ↔ cells: insulin
• Defense: antibodies
• Produce cellular movements: myosin, dynein
• Promote/inhibit activity of cell molecules: protein kinases, cyclins (cellular checkpoints)
• Bind molecules: hormone receptors

Question 25

How do amino acid properties influence the function of proteins?

Answer 25

a.a can be nonpolar, uncharged polar, + charged polar or - charged polar. They determine the function of the gene because of their polarity/solubility which causes the polypeptide to assume a particular shape. The shape of a protein determines its specific function.

Question 26

What is the role of the 1° structure?

Answer 26

Determines the sequence of a.a (determined by the coding region of the corresponding gene)

Question 27

What is the role of the 2° structure?

Answer 27

Determines the shape of the a.a chain (twists and turns) by the h-bonds ↔ atoms of the backbone of the protein.

Question 28

What is the role of the 3° structure?

Answer 28

Determines how the a.a chain will fold into its 3D shape. This is done by

• ioninc bonds
• h-bonds
• hydrophobic interactions
• disulfide bridges

Question 29

What is the role of the 4° structure?

Answer 29

not always present Determines the arrangement of the polypeptide chains when there is MORE THAN 1 chain.

Question 30

Difference between the 4 protein structures?

Answer 30

1° regards a sequence of a.a, whereas 2° and 3° regards 1 polypeptide chain and 4° regards 2+ polypeptide chains.

Question 31

What are the possible consequences of amino acid substitutions on the structure of a protein?

Answer 31

1. Look if the substitution changed the polarity group of the a.a.
2. If not, and the a.a are similar, little to no change
3. If yes, change in the function of the protein that may now be more/less polar. It might break the protein, or the compromise the structure, therefore the protein might lose its function.

Question 32

What are the different components of a nucleoside

Answer 32

1.A nitrogenous base formed from rings of carbon and nitrogen atoms
2.A 5-carbon, ring-shaped sugar
(add a phosphate group to make nucleotide)