U1 biological molecules

Question 1

what is an atom

Answer 1

• smallest particle of matter

- nucleus surrounded by electrons

Question 2

What is a molecule

Answer 2

• formed by two or more atoms

- atoms bond together to create a molecule

Question 3

What is an ion

Answer 3

-electrically charged particle produced by adding or removing an electron

Question 4

what is a covalent bond

Answer 4

• electrons are shared between two or more non-metallic atoms
• polar, non-polar

Question 5

what is an ionic bond

Answer 5

• metal and non-metal ions are held together by electrical attraction
• donates and receives electrons

Question 6

what is a hydrogen bond

Answer 6

-electrical attraction between slightly positive and slightly negative hydrogen atoms in another molecule

Question 7

What functions does water have in the body

Answer 7

• lubricant (saliva, eyeballs, prevent friction in organs)
• solvent (blood, cytoplasm, water dissolves almost all molecules in the body)
• temperature regulator (absorbs excess heat)

Question 8

Why is water a universal solvent?

Answer 8

-dissolves more than any other substance because of its polar nature, compounds are pulled apart in water to form ions that are attracted to the poles of the water molecule

Question 9

What does water being a polar molecule mean

Answer 9

-Each molecule of water contains one atom of oxygen
covalently bonded to two hydrogen atoms. The oxygen atom has a greater affinity for the shared electrons, and so tends to be slightly more negative than the hydrogen atoms.

Question 10

why does being a polar molecule affect water’s relationship with other molecules

Answer 10

-creates a polarity, with the oxygen end of the molecule being slightly negative and the hydrogen end of the molecule slightly positive. Hydrogen bonds form
between water molecules because these positive and negative poles are attracted to each other.

Question 11

difference between acids and bases?

Answer 11

-Acids are molecules that break apart in water to release hydrogen ions (H + ). Bases are molecules that break apart in water to release hydroxide ions (OH - )

Question 12

What are buffers and how do they work?

Answer 12

Buffers are chemicals that absorb excess quantities of hydrogen and hydroxide ions in solution,
the result is a constant pH regardless of whether acids or bases are added

Question 13

what is a molecule that is a polymer

Answer 13

A polymer is a large molecule made up of repeated subunits attached together with covalent
bonds.

Question 14

what is the process of dehydration synthesis

Answer 14

-chemical reaction in which two monomers are joined together
-Both monomers must contain hydroxide (OH) groups in their chemical structure.
-A hydrogen atom from one monomer and a hydroxide molecule from the other monomer are broken off.
-form a new covalent bond with the remaining oxygen atom of the first monomer, and the
release of a molecule of water.

Question 15

what is the process of hydrolysis

Answer 15

• breaks apart two monomers in a polymer

- water is broken down into OH and H and added to the two resulting monomers

Question 16

what are the three groups of lipids and where in the body

Answer 16

neutral fats - stored in adipose, tissues
phospholipids - form cellular membrane that surrounds every cell
steroids - found throughout body in cholesterol, and hormones like estrogen

Question 17

functions of lipids?

Answer 17

neutral fats- form portion of body’s energy storage. cushion organs, and insulate body.
phospholipids- form outer double layer of a cells outer membrane
steroids- form cholesterol

Question 18

What is the basic structure of a neutral fat?

Answer 18

glycerol group bonded to three fatty acids

Question 19

how is phosphoric different from a neutral fat?

Answer 19

• they contain a phosphate group in the position of the third fatty acid in a triglyceride.
• phosphate group can ionize to become polar
• a molecule with a polar ‘head’ that can be dissolved in water, and non-polar ‘tails’ that do not dissolve in water.

Question 20

contrast saturated and unsaturated fats

Answer 20

saturated: carbon atoms are bonded to as many hydrogen atoms possible
- produced by animals
- solid at room temp
unsaturated: carbon atoms can form double bonds with carbon atoms and do not contain hydrogen atoms
- produced by plants
- liquid at room temp

Question 21

what are the functions of carbohydrates in the human body?

Answer 21

-Carbohydrates provide the human body with energy, because glucose is used by the
mitochondria to make molecules of ATP.

Question 22

three groups of carbohydrates?

Answer 22

• monosaccharides
• disaccharides
• polysaccharides

Question 23

chemical formula for carbohydrate?

Answer 23

C6H12O6

Question 24

what is a disaccharide sugar?

Answer 24

• “double sugar” contains two monosaccharides

- sucrose (glucose and fructose), lactose (glucose and galactose)

Question 25

what is a polysaccharide

Answer 25

-polymer of more than two monosaccharide monomers

Question 26

Difference between main three polysaccharides?

Answer 26

Starch: simple branched chain of glucose with few branches
-stores glucose in plants, and provides nutrition
glycogen: branched chain with shorter and more frequent branches
-store glucose in animals
cellulose: straight long chain of glucose
-forms cell wall in plants
-

Question 27

glycogen is found where in the human body

Answer 27

muscles, liver

Question 28

what are the functions of proteins?

Answer 28

enzymes – speed up chemical reactions.
e.g. pepsin
membrane proteins – move molecules and
ions in and out of the cell. e.g. Na/K pump
structural proteins – make up part of the
body. e.g. keratin in hair and nails
hormones – signalling between body
organs. e.g. insulin

Question 29

what is the primary structure of a protein?

Answer 29

The primary structure of a protein is the sequence of amino acids that make up the
polypeptide.

Question 30

what is the secondary structure of a protein?

Answer 30

• three-dimensional shape assumed by the amino acid
  strand. Common shapes include the α (alpha) helix and β (beta) pleated sheet.
• These shapes result from hydrogen bonding between the R groups of amino acids.

Question 31

what is the tertiary structure of a protein

Answer 31

-the complex folding and twisting of the secondary
structure to form the protein’s final shape.
- held together by covalent bonds between
amino acid R groups

Question 32

what is the quaternary structure of a protein ?

Answer 32

-combination of more than one polypeptide chain
to form one large protein.
-Haemoglobin is a combination of four polypeptides, each of which contains an iron atom that allows it to carry oxygen.

Question 33

what is a polypeptide

Answer 33

-three or more amino acids bonded together
-amino acid sequence folds on itself to form a
large, globular structure
-final shape of the folded polypeptide
determines its function

Question 34

what is a dipeptide

Answer 34

-pair of amino acids bonded together
-they form by dehydration synthesis, and are
broken by hydrolysis in the normal way

Question 35

how is a peptide bond formed?

Answer 35

• form through dehydration synthesis: the OH from the carboxyl group of one amino acid and the H from the amine group of the other amino acid are broken off
• new covalent bond forms between the C of the carboxyl group and the N of the amino group.

Question 36

functions of nucleic acids?

Answer 36

DNA: stores the information for creation of protein and when copied allows that information to be passed on to offspring.
RNA: acts as an intermediate between DNA and protein, carrying the information stored in DNA (a sequence of amino acids) out of the nucleus to where proteins are
assembled.

Question 37

for nitrogenous bases in DNA?

Answer 37

cytosine, guanine, thymine, adenine

Question 38

complementary base pairings in DNA?

Answer 38

A and T, C and G

Question 39

what is the structure of DNA

Answer 39

-double helix shape,
-two twisted strands of nucleotides joined
together by the hydrogen bonding between complementary base pairs.

Question 40

nitrogenous bases in RNA?

Answer 40

cytosine, guanine, uracil, adenine

Question 41

structure of RNA?

Answer 41

single strand in shape

Question 42

What is the molecular structure of ATP?

Answer 42

an adenine RNA nucleotide with three phosphate groups

instead of one.

Question 43

How is ATP related to its role as the cell’s “energy

currency”?

Answer 43

The bonds between the extra phosphate groups store chemical energy, and this energy can be released to perform work within the cell by breaking the bonds.