Biology

Question 1

How do Proteins function and operate?

Answer 1

Proteins fold to give distinct structures and they require the correct folding to function . They operate in vivo as catalysts (enzymes), structural molecules (cytoskelaton, collagen), receptors (membrane protein), and transporters.

Question 2

Proteins structures and its stability

Answer 2

Protein structure is stabilized by:

H bond

salt bridge

hydrophobic effect

metal ion binding

disulfide bridge

Question 3

Amino Acids

Answer 3

Amino Acids are classified as

non polar (hydrophobic)

polar charged

polar uncharged

depeding on the basis of the nature of side chain

Question 4

isoelectric point

Answer 4

amino acids and proteins are insoluble at that pt

net charge zero

no migration to electric field

Question 5

Acid base titration of amino acid (Lys)

Answer 5

Question 6

Carbohydrates

General formula

there two forms

Answer 6

General formula (CH2O)n

monosacharides 3 to 6 C atoms

there two forms linear and cyclic forms

Question 7

Hemiacetal and Hemiketal

Answer 7

Hemiacetal aldose sugar and Hemiketal ketose sugar

Question 8

Glucose

Answer 8

different polymers of glucose differ in their connectivity:

carbon centers connected via oxygen

configuration of anomic center

Question 9

polysacharides

Answer 9

they are polymers of monosacharides which can be linear or branched

Question 10

Enzyme

Answer 10

are biological catalysts that increase the rate of the metabolic reaction. the active site of an enzyme acts as a catalyst. The substrate turns into the product when a rxn involves an enzyme.

Question 11

Cofactor

Answer 11

Cofactors are small molecules or ions that associate with (bind to) proteins to provide them with chemical activity (e.g. oxidation, reduction, methylation) that is not available from the standard repertoire of amino acids.

They generally comprise an active chemical functional group, plus additional segments that are used for binding to the active site of a protein.

Question 12

Metabolism

Answer 12

is the chemical process that takes place in a living cell that provides energy for vital processess and for synthesizing organic material.

Question 13

Metabolic pathways

Answer 13

a sequence of chemical steps that converts starting materials into products.

Question 14

where does a metabolic pathway occurs

Answer 14

A metabolic pathway usually occurs in a specific location within the cell (compartment/organelle).

Question 15

Catabolic pathway

Answer 15

Metabolic pathways that involve ‘breaking down’ complex molecules into smaller ones, with the release of energy, are termed catabolic.

Question 16

anabolic pathway

Answer 16

Metabolic pathways that involve ‘building up’ complex molecules, with the consumption of energy, are termed anabolic.

Question 17

Metabolites

Answer 17

Metabolites are small molecules that are formed in cells and organisms by the catalytic activity of enzymes as part of a metabolic pathway

Question 18

receptors

Answer 18

It is an organ or a specialized cell that can detect the change that is causing the stimulus

Question 19

cellulose structure

Answer 19

Question 20

Amylose structure

Answer 20

Question 21

Carbohydrates role

Answer 21

to supply the body with energy

Question 22

Lipids structure

Answer 22

Lipids are amphipathic – (relatively) small hydrophilic headgroup and (relatively) large hydrophobic fatty acyl chains.

Because of this amphipathicity, they spontaneously form bilayers in water, diameter (headgroup to headgroup) 4–8 nm.

Question 23

Lipids role

Answer 23

Store energy

structural componen of cell membranes

Question 24

Fatty acids

Answer 24

Fatty acids: long chain carboxylic acids. Can be saturated (no alkene groups) or unsaturated (one or more alkenes, normally in cis configuration).

(Note numbering of fatty acyl chains: n system is 1 at carbonyl etc. In italics is bond position from carbonyl; ω system – 1st C of C=C from end of chain).

Question 25

Headgroups

Answer 25

Headgroups: choline (PC), ethanolamine (PE), inositol (PI), serine (PS), glycerol (PG), no additional group (PA).

PC and PE are neutral lipids (no net charge) at physiological pH (7.4). PG, PS, PI and PA are negatively charged.

Question 26

Glycerophospholipids structure

Answer 26

Glycerophospholipids – based on glycerol. Phosphate + headgroup at one position (3), fatty acyl groups at other 2 positions.

Question 27

Sterols structure

Answer 27

Cholesterol has a large hydrophobic tetracyclic hydrocarbon group, and a small polar headgroup and therefore readily inserts into bilayer.

Question 28

Archidonic linoleic and oleic acid

Answer 28

Question 29

Nucleoside

Answer 29

Nucleoside = base + sugar (ribose or deoxyribose).

Question 30

Nucleotide

Answer 30

Question 31

DNA bases structure

Answer 31

Question 32

DNA

Answer 32

In DNA, there are 2 chains, running antiparallel in a double helix.

Bases pair in centre of double helix: A-T (2 H-bonds); C-G (3 H-bonds).

DNA carries genetic information.

Question 33

RNA

Answer 33

RNA rarely forms double helices. Intrastrand base pairing forms hairpins (stems + loops), and bulges. RNA forms more complex 3° structures than DNA.

RNA is used to process this information (transcription and translation)

Question 34

Prokaryote

dimension

component genetic material

Answer 34

Question 35

Eukaryote

dimension

component genetic material

Answer 35

Question 36

Cytosol (cytoplasm):

Answer 36

Cytosol (cytoplasm): fluid filled (aqueous) inner compartment of cells

Question 37

Rough ER

Answer 37

Rough ER: double membrane sheets, continuous with the outer envelope of the nucleus. Studded with ribosomes (the particles visible in EM)

Question 38

Smooth ER:

Answer 38

Smooth ER: membrane tubules connected to the nuclear envelope. protein synthesis (30-50 nm)

Question 39

Nucleus

Answer 39

Nucleus: store of genetic information in eukaryotes. Has a double membrane. (contains DNA and Protein)

Question 40

Nucleolus

Answer 40

Nucleolus: site of ribosome assembly

Question 41

Golgi apparatus

Answer 41

Golgi apparatus: membrane stacks. Protein sorting, e.g. for secretion or transport to the membrane. Not continuous with the ER. (2-5 micro m)

Question 42

Vesicle/Vacuole

Answer 42

Vesicle/Vacuole: particle with an fluid-filled (aqueous) interior and a single membrane. Vesicles small (< 200 nm), vacuoles large (> 200 nm) {ball park numbers}

Lysosomes and Secretory Vesicles are examples in animal cells. Plants also usually contain a large central vacuole.

Question 43

Cell (plasma) membrane

Answer 43

Cell (plasma) membrane: not really an organelle, but crucial to the structural integrity of the cell and its organelles. Formed of a double layer of lipids.