Molecular Biology Wk 3

Question 1

what is molecular biology

Answer 1

field of science concerned with studying the chemical structures and processes of biological phenomena that involve the basic units of life, molecules. The field of molecular biology is focused especially on nucleic acids (e.g., DNA and RNA) and proteins—macromolecules that are essential to life processes—and how these molecules interact and behave within cells.

Question 2

what are biochemicals

Answer 2

The compounds produced by living organisms - The chemistry of life centers around the chemistry of the carbon atom. The small and large carbon compounds made by cells are called organic molecules. Carbon-containing backbones may be linear, branched, or cyclic.

Question 3

what are functional groups

Answer 3

groupings of atoms that often behave as a unit and give organic molecules their physical properties, chemical reactivity, and solubility in aqueous solution

hydroxl- carbs
carbonyl- lipids
carboxyl- proteins
amino- proteins
phosphate- DNA and ATP

Question 4

examples of functional groups

Answer 4

hydroxyl
carbonyl
caboxyl
amino

Question 5

how are biological molecules classified by function

Answer 5

macromolecules
the building blocks of macromlecules
metabolic intermediates
molecules of miscellaneous function

Question 6

what are the major characteristics of macromolecules

Answer 6

can be divided into four major categories: proteins, nucleic acids, polysaccharides, and certain lipids.

Question 7

how are macromolecules produced

Answer 7

polymerisation- constructed by their monomers

dehydrating
water is lost

Question 8

how are macromolecules diassembled

Answer 8

by hydrolysis of the bonds that join the monomers together. Hydrolysis is the splitting of a bond by water. All of these reactions are catalyzed by specific enzymes.

Question 9

which macromolecules are localized in cellular structures- nucleus, plasma membrane, ribosomes, mitochondria

Answer 9

chromatin in the nucleus- DNA and protein
plasma membrane- carbs and lipids
ribosome- protein and rna
mitochondrion- DNA and lipid
microtubules- protein
starch grain in chloroplast- carbohydrates
cell wall- carbs

Question 10

what are the building blocks of macromolecules

Answer 10

Sugars, which are the precursors of polysaccharides;
Amino acids, which are the precursors of proteins;
Nucleotides, which are the precursors of nucleic acids;
Fatty acids, which are incorporated into lipids.

Question 11

types of amino acids

Answer 11

essential
non essential
semi essential

Question 12

types of nucleotides

Answer 12

A,U,T,C,G

Question 13

what are metabolic intermediates

Answer 13

In the cell, each series of chemical reactions is termed a metabolic pathway

The compounds formed along the pathways leading to the end products might have no function per se and are called metabolic intermediates .

Question 14

what are molecules of miscellaneous function

Answer 14

include such substances as vitamins, which function primarily as materials to proteins; certain steroid or amino acid hormones; molecules involved in energy storage, such as ATP; regulatory molecules such as cyclic AMP; and metabolic waste products such as urea.

Question 15

what are carbohydrates

Answer 15

include simple sugars (or monosaccharides ) and all
larger molecules constructed of sugar building blocks. Carbohydrates function primarily as stores of chemical energy and as durable building materials for biological construction. Most sugars have the general formula (CH2O)n . The sugars of importance in cellular metabolism have values of n that range from 3 to 7.

Question 16

what is bernards hypothesis

Answer 16

the balance between glycogen formation and glycogen breakdown in the liver was the prime determinant in maintaining the relatively constant homeostatic level of glucose in the blood

Question 17

what bonds do sugars join by

Answer 17

can be joined to one another by covalent glycosidic bonds to form larger molecules. Glycosidic bonds form by reaction between carbon atom C1 of one sugar and the hydroxyl group of another sugar, generating a
-C- O- C- linkage between the two sugars.

Sugars may also be linked together to form small chains called oligosaccharides ( oligo = few). Most often such chains are found covalently attached to lipids and proteins, converting them into glycolipids and glycoproteins, respectively. Oligosaccharides are particularly important on the glycolipids and glycoproteins of the plasma membrane, where they project from the cell surface.

Question 18

name some disaccharides

Answer 18

Sucrose and lactose are two of the most common disaccharides. Sucrose is composed of glucose and fructose joined by an α (1 → 2) linkage, whereas lactose is composed of glucose and
galactose joined by a β (1 → 4) linkage.

Question 19

what are the common properties of lipids

Answer 19

ability to dissolve in organic solvents, such as chloroform or benzene;

Question 20

lipids of importance in cellular function

Answer 20

Fats

Question 21

what do fats consist of

Answer 21

Glycerol molecule Three fatty acids
The composite molecule is termed a triacylglycerol (FIGURE ), also known as a triglyceride.

Question 22

what is the function of fats

Answer 22

Carbohydrates function primarily as a shortterm, rapidly available energy source, whereas fat reserves store energy on a long-term basis.

Question 23

where are fats stored

Answer 23

Fats are extremely insoluble in water /lack polar groups/ and are stored in cells in the form of dry lipid droplets. Fats are stored in special cells ( adipocytes ) whose cytoplasm is filled with one or a few large lipid droplets. Adipocytes exhibit a remarkable ability to change their volume to accommodate varying quantities of fat

Question 24

what are steroids

Answer 24

Steroids are built around a characteristic four-ringed hydrocarbon skeleton.
Cholesterol - a component of animal cell membranes and a precursor for the synthesis of a number of steroid hormones, such as testosterone, progesterone and estrogen.

Question 25

what are phospholipids

Answer 25

fat (triacylglycerol), but has only two fatty acid chains rather than three; it is a diacylglycerol .

Question 26

Phospholipids contain two ends that have very different properties:

Answer 26

The end containing the phosphate group has hydrophilic character;

Question 27

The phospholipid phosphatidylcholine.

Answer 27

The molecule consists of a glycerol backbone whose hydroxyl groups are covalently bonded to two fatty acids and a phosphate group.

Question 28

what are the many functions of proteins

Answer 28

structural- collagen in tendons and cartilage
keratin in skin and hair

contractile- the movement of muscles
myosin and actin contract muscle fibres

transport - Hb transports oxgen
lipoproteins transport lipids

storage- casein stores protein in the milk
ferritin stores iron in the spleen and liver

hormone- insulin regulates BGL

enzyme- sucrase catalyses the hydrolysis of sucrose

Protection- immunoglobins- stimulate immune responses

Question 29

all amino acids have two groups

Answer 29

carboxyl and amino group

Question 30

how many types of radicals (r groups) can there be

Answer 30

20

Question 31

describe the structure of an amino acid

Answer 31

During the process of protein synthesis, each amino acid becomes joined to two other amino acids, forming a long, continuous, unbranched polymer called a polypeptide chain . The amino acids that make up a polypeptide chain are joined by peptide bonds that result from the linkage of the carboxyl group of one amino acid to the amino group of its neighbor, with the elimination of a molecule of water

Question 32

what groups are amino acids classified as

Answer 32

Essential amino acids- isoleucine, leucine, lysine

Question 33

what are nucleic acids

Answer 33

Nucleic acids are macromolecules out of long chains of monomers called nucleotides

There are two types of nucleic acids found in living organisms, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Nucleic acids function primarily in the storage and transmission of genetic information, but they may also have structural or catalytic roles.

Question 34

what three parts of RNA are there

Answer 34

a five-carbon sugar, ribose;
a nitrogenous base (so called because nitrogen atoms form part of the rings of the molecule); (3) a phosphate group.

Question 35

what is a nucleoside

Answer 35

The sugar and nitrogenous base together

Question 36

differences between RNA and DNA

Answer 36

The nucleotides of RNA contain the sugar ribose, which has a hydroxyl group bonded to the second carbon atom. In contrast, the nucleotides of DNA contain the sugar deoxyribose, which has a hydrogen atom rather than a hydroxyl group attached to the second carbon atom.

Question 37

A strand of RNA (or DNA) contains four different types of nucleotides distinguished by their
nitrogenous base:

Answer 37

Pyrimidines- cytosine, thymine and uracil

Question 38

what is a ribozyme

Answer 38

catalytic RNA molecules rRna and large part of ribosome

Question 39

main types of RNA and their functions

Answer 39

mRNA- provides a plan for polypeptide synthesis

tRNA- translates nucleotides to amino acids

rRNA- produced and synthesised in the nucleolus and provides a platform for protein synthesis

Question 40

function of GTP and ATP

Answer 40

energy is accumulated in bonds

activates the G proeins

Question 41

what are nucleotides

Answer 41

Nucleotides are not only important as building blocks of nucleic acids, they also have important functions in their
own right.