2.2 Biological Molecules Flashcards Preview

A Level Biology > 2.2 Biological Molecules > Flashcards

Flashcards in 2.2 Biological Molecules Deck (46):
1

Describe the structure of a water molecule

•O δ- (attracts more electrons)
•H δ+ (O δ- makes H atoms slightly positive)
•Covalent bond

2

How is a Hydrogen bond formed in a water molecule?

There is a weak electrical attraction between a hydrogen molecule and an oxygen molecule. This happens because the δ- O bonds are attracted to the δ+ H bonds.

3

Describe the solvent properties of water

Solvent properties:
•Allows molecules and ions to be transported around living things whilst dissolved in water (as water is polar, the - and + parts are attracted to the + and - parts of the solvent)
•Molecules and ions can be transported around living things whilst dissolved in water

4

Describe the density+viscosity of water

•Ice is less dense than liquid water as when it goes from 4°C to freezing point the water molecules align themselves in a structure which is less dense (due to water's polar nature)
•Bodies of water are therefore insulated against cold due to layer of ice on top reducing rate of heat list from rest of pond
•This provides an ideal habitat for living things as is water was less dense, aquatic organisms would find it very difficult to float

5

Describe the cohesion+surface tension of water

•This makes a drop of water appear spherical because of the H bonding pulling the molecules together
•This explains why water molecules move together
•Allows some insects to walk across water
•Columns of water in plant vascular tissue are pulled up the xylem tissue together from the roots.

6

Describe the heat and temperature of water

•Water temp is a measure of the kinetic energy of the water molecules
•The amount of Heat Energy required to increase the kinetic energy and temperature is known as the specific heat capacity
•Means that water does not change temp easily
•Living things need a stable temp for enzyme-controlled reactions to take place properly
•Aquatic organisms need a stable environments to live in

7

What are the 2 different types of glucose?

α-glucose (isomer of glucose)
C6H12O6
•component of glycogen+starch (which act as energy stores) + energy source

β-glucose (isomer of glucose)
C6H12O6
•energy source, component of cellulose (which provides structural support in plant cell walls

8

What are triglycerides used for?

-energy source + store
-thermal insulator
-buoyancy
-protection
-an example of a macromolecule

9

How is a triglyceride formed?

-condensation reaction
-H2O molecule is removed
-forms an ester bond.
-left with 3 fatty acid chains joined to glycerol. fatty acids contain carboxyl group. glycerol contains hydroxyl group.

10

Is a triglyceride saturated or unsaturated?

Unsaturated

11

What are lipids?

•Biological molecules made of O, C and H
-fats, oils, cholesterol, steroids
-Animals-fats
-plants-oil
•soluble in alcohol rather than water
•not polar

12

Describe saturated and unsaturated fats

•Fatty acids can be saturated and unsaturated
•Saturated if the carbon atoms bond to many hydrogen atoms
•Unsaturated if one or more of the fatty acid chains contain C atoms which form a double bond with another C atom
•This means it can't bond with as many H atoms, forming a "kink" in the chain

13

Describe glycogen

•energy store in humans
•large polysaccharide molecule
•joined by condensation reactions
•glycosidic bonds between c1-4
•branches between c1-6

14

Describe cellulose

•found in plants, makes up cell walls
•not starch
•made of β-glucose
•glycosidic bonds c1-4
•not branched straight line not spiralled
•not soluble
•H bonds hold structure in place, stop it spiralling + give strength + stabilise molecules

15

What are polysaccharides?

Polysaccharides can be made by joining many monosaccharides together.

16

What is a carbohydrate?

Carbohydrates are organic compounds which comprise of only C, H and O.
•energy source
•energy store
•structural unit

17

What are monosaccharides

•simplest "simple sugars"
•same no. of C and O atoms
•have the general formula CnH2nOn
•white crystalline solids
•dissolve in water to form sweet tasting solutions

18

What are disaccharides

Monosaccharides can be joined together to form disaccharides, which dissolve in water and also taste sweet
•condensation reactions
•α1-4 glucose bond formed by hydrolysis

19

What is amylose?

•starch
•polysaccharide
•monomer: α-glucose
•α1-4 glycosidic bonds
•H bonds hold the spiral in place

20

What is amylopectin?

•starch
•polysaccharide
•made of α-glucose
• α1-4 bonds
• α1-6 glycosidic branches
•spiral shape held in place by H bonds with branches emerging from the spiral

21

What are phospholipids?

•molecule consisting of glycerol, 2 fatty acids and one phosphate group
-macromolecules

22

What is cholesterol and steroids?

•cholesterol is steroid alcohol helps maintain fluidity of cell membranes
•made of 4 C rings
•it is also small and hydrophobic, found in the tails of phospholipids
•cholesterol used to make steroids. many steroids are hormones

23

What are proteins?

Proteins contain C, H, O and N. some contain Sulphur.
•either structural or functional/chemical

24

What do amino acids make up

Amino acids make up proteins

25

How are dipeptide bonds formed

Condensation reaction between 2 amino acids.
Forms a bond

26

What is the first structural level of a protein?

(All proteins)
Polypeptide chain
-chains of amino acids
-formed by peptide bonds

27

What is the second structural level of a protein?

(All proteins)
Secondary structure
-Alpha helices and Beta pleated sheets (1 polypeptide chain)

28

What is the third structural level of a protein?

(All protein)
Tertiary structure
-stabilised polypeptide chain (1 chain)
-bonds have formed, protein is functional

29

What is the fourth structural level of a protein?

(Some proteins)
Quaternary structure
-made of more than 1 polypeptide chain

30

Describe insulin

•binds to glycoproteins receptors on the outside of muscle and fat cells (done to increase uptake of glucose from blood + to increase rate of consumption of glucose) (helps to regulate blood sugar levels)
•globular protein
•specific amino acid sequence
•quaternary structure
•chemical

31

Describe collagen

•fibrous + structural
•found in tendons, ligaments

32

Describe elastin

•structural + fibrous
•found in skin, bladder

33

Describe keratin

•found wherever a body part needs to be hard + strong e.g nails, hair
•fibrous + structural

34

Describe haemoglobin

•found in red blood cells
•specific sequences (2 a chains + 2 b chains)
•quaternary structure
•space within chain (haem groups which attracts the O because it has a 2+ charge)
•conjugated as it contains an iron ion
•globular

35

Describe pepsin

•enzyme that digests proteins in the stomach
•globular
•chemical
•specific amino acid sequence
•not a conjugated protein
•tertiary structure

36

What is the ionic formula of nitrate

NO3-

37

What is the ionic formula of hydrogencarbonate

HCO3-

38

What is the ionic formula of phosphate

PO4 3-

39

What is the formula used when doing thin layer chromatography

Rf (ratio of distance moved by solute ) = distance from pencil line to centre of spot of pigment / distance from pencil line to solvent front

40

What kind of monosaccharide is ribose

Pentose monosaccharide

41

What is the difference between a hexose and a pentose monosaccharide

Hexose - 6 carbon atoms
Pentose - 5 carbon atoms

42

Glucose structure makes it

Structure makes it soluble so it can be easily transported. Chemical bonds contain a lot of energy.

43

Sucrose

Disaccharide Formed when a-glucose and fructose join together

44

Lactose

Disaccharide formed by joining B-glucose and galactose

45

What kind of monosaccharide is glucose

Hexose monosaccharide

45

Maltose

Disaccharide 2x a-glucose