Biomolecules and cells

Question 1

Carbohydrates

Answer 1

Structure: Polymer made of monosaccharide. They are linked together by condensation to form polysaccharides.

Function: Energy storage, structural integrity

Examples: glucose, fructose, sucrose, lactose, starch, cellulose, chitin,…

Question 2

Lipids

Answer 2

Structure: (triglyceride) glucose + 3 fatty acids, (phospholipid) hydrophilic head + hydrophobic tail

Function: Energy storage, insulation, structure

Examples: steroid hormones, phospholipids, triglycerides

Question 3

Nucleic acids

Answer 3

Structure: (nucleotide) sugar, ribose or deoxyribose with 5C, phosphate and a base
Function: storage of genetic information, energy
Examples: DNA, RNA, ATP

Question 4

Proteins

Answer 4

Structure: (primary) arrangement of amino acids, (secondary) α helix or β sheet, (tertiary) further folding involved with extra bonding, (quaternary) arrangement of more than 1 stand-alone polypeptide chain

Function: cell structure, signalling, DNA transcription, enzymes, transport

Examples: hormones, enzymes, antibodies, collagen

Question 5

Cytoskeleton

Answer 5

microtubules (tubulin), intermediate filaments, microfilaments (actin)

Function: structure, transport, cell division
Maintains the 3D structure of the cell and its rigidity

Question 6

Microtubules (tubulin)

Answer 6

Grow out from the centrosome located close to the nucleus. contains a pair of centrioles

Question 7

Microfilaments (actin)

Answer 7

Built from actin (globular protein) aligned in a twisted double chain.
They bear tension by pulling force. They are formed on the outer cytoplasmic membrane. Responsible for the contraction of muscle cells and interact with myosin

Question 8

Intermediate filaments

Answer 8

Not in all cells, but specific animal cells. larger than microfilaments but smaller than microtubules. Nucleus often sits in a cage of intermediate filaments to fix its location

Question 9

Endomembrane system

Answer 9

regulates protein traffic and performs metabolic functions
(endoplasmic reticulum, golgi apparatus, lysosome, vacuole)

Question 10

plasmodesmata

Answer 10

plant cell wall perforated with connecting channels. Cytosol flows through

Question 11

tight junction

Answer 11

plasma membrane are pressed lightly together bound by proteins.

Question 12

desmosome

Answer 12

intermediate filament connect the desmosome to cytoplasme (muscule cell attached together)

Question 13

gap junction

Answer 13

cytoplasmic channels from cell to cell, small molecules can pass

Question 14

extracellular matrix (ECM) -> animal cell

Answer 14

Components: glycoproteins + sugar or other carbohydrate-containing molecules. Collagen is the most common glycoprotein.

Function: structure, communication between cell

Examples: (glycoprotein) collagen or fibronectin, (cell-surface receptor) integrins