Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology > M2 Biological Molecules > Flashcards

M2 Biological Molecules Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Role of calcium ions (Ca 2+)

A

Nerve impulse transmission
Muscle contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Role of sodium ions (Na 2+)

A

Nerve impulse transmission
Kidney function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Role of potassium ions (K +)

A

Nerve impulse transmission
Stomata opening

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Role of hydrogen ions (H +)

A

Catalysis of reactions
pH determination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Role of ammonium ions (NH4 +)

A

Production of nítrate ions by bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Role of nitrate ions (NO3 -)

A

Nitrogen supply to plants for amino acrid and protein formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Role of hydrogen carbonate ions (HCO3 -)

A

Maintenance of blood pH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Role of chloride ions (Cl-)

A

Balance positive charge of sodium and potassium ions in cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Role of phosphate ions (PO4 3-)

A

Cell membrane formation
Nucleic acid and ATP formation
Bone formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Role of hydroxide ions (OH-)

A

Catalysis of reactions
pH determination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What elements make up carbohydrates?

A

Carbon, hydrogen and oxygen
Usually in ratio C x (H2O) x

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What elements make up lipids?

A

Carbon, hydrogen and oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What elements make up proteins?

A

Carbon, hydrogen, oxygen, nitrogen and sulfur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What elements make up nucleic acids?

A

Carbon, hydrogen, oxygen, nitrogen and phosphorus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe polymers

A

Biological molecules are often polymers
Polymers are long-chain molecules made by the linking of multiple individual molecules called monomers in a repeating pattern

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the structure of water

A

A molecule of water is one atom of oxygen, joined to two atoms of hydrogen shared by electrons
The shared negative hydrogen electrons are pulled towards the oxygen atom, the other side of each hydrogen atom is left with a slight positive charge
The unshared negative electrons on the oxygen atom give it a slight negative charge
This makes water a polar molecule - it has a partial negative charge on one side and a partial positive charge on the other
The slightly negatively charged oxygen atoms attract the slightly positively charged hydrogen atoms of other water molecules
This attraction is called hydrogen bonding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why does water have a high specific heat capacity?

A

Hydrogen bonds between water molecules can absorb a lot of energy, so water has a high specific heat capacity as it takes a lot of energy to heat up
Therefore water doesn’t experience rapid temperature changes
This makes water a good habitat for organisms such as fish, as the temperature does not very providing a consistent habitat
Water also helps buffer temperature changes during chemical reactions in prokaryotic and eukaryotic cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why is ice less dense than liquid water?

A

Below 4° Celsius water molecules are held further apart in ice as each water molecule forms four hydrogen bonds to other water molecules making a lattice shape
This makes ice less dense than liquid water, meaning that it floats
This means ice forms on the top of ponds and lakes, forming an insulating layer above the water below
This allows aquatic organisms to survive freezing temperatures, and their whole habitat does not freeze

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why is water cohesive?

A

Cohesion is the attraction between molecules of the same type. Water molecules are cohesive as they are polar molecules.
Water has cohesive properties, it moves as one mass as the molecules are attracted to each other.
This allows plants to draw water up through their roots in the transpiration stream.
This also makes water an efficient transport median within living things. Adhesion occurs between water molecules and other polar molecules and surfaces resulting in water exhibiting a capillary action, allowing water to rise up a narrow tube against gravity.
Water molecules are more strongly cohesive to each other than they are to air, resulting in water having a ‘skin’ of surface tension, which supports small insects such as pond skaters.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why is water a good solvent?

A

Because it is a polar molecule, water acts as a solvent in which many of the solutes in an organism can be dissolved.
The positive end of the water molecule will be attracted to the negative ion, and the negative end of a water molecule will be attracted to the positive ion. The ions will be totally surrounded by water molecules and will dissolve.
Water acts as a medium for chemical reactions and helps transport dissolved compounds into and out of cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are proteins made up from?

A

Amino acids are monomers in proteins
A dipeptide is formed when two amino acids join together
A polypeptide is formed when more than two amino acids join together
Proteins are made up of one or more polypeptides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the general structure of an amino acid

A

R
|
H2N - C - COOH
|
H

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Describe the synthesis of peptides

A

Amino acids join when the amine and carboxylic acid groups connected to the central carbon atom react
The hydroxyl in the carboxylic acid group of one amino acid reacts with a hydrogen in the amine group of another amino acid
A peptide bond is formed between the amino acids and water is produced (condensation reaction) resulting in a dipeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe the primary structure of proteins

A
  • The number, type and sequence of amino acids that make up this linear chain together with the peptide bonds that hold them together.
  • Different proteins have different primary structures. The particular amino acids in the sequence will influence how te polypeptide folds to give the proteins final shape, which determines its function. The only bonds in the primary structure are peptide bonds.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Describe the secondary structure of proteins

A

The arrangement of the atoms that form the backbone or linear chain of the protein.
The amino acid chain can coil into an alpha helix, or form a beta pleated sheet.
The helix and beta pleated sheet shapes are secondary structures of proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Describe the alpha helix secondary structure of proteins

A

The amino acid chain coils into a right-handed helix and hydrogen bonds form between oxygen and hydrogen atoms that have been brought into close proximity.
These hydrogen bonds help to stabilise this secondary structure.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Describe the beta pleated sheet secondary structure of proteins

A

The amino acid chain folds back upon itself many times forming anti-parallel chains. The oxygen and hydrogen atoms that have been brought into close proximity form hydrogen bonds.
The hydrogen bonds help to stabilise the secondary structure.

28
Q

Describe the tertiary structure of proteins

A

The folding of a protein into its final shape, it often includes sections of secondary structure.
The coiling or folding of sections of proteins into their secondary structure brings R-groups of different amino acids closer together so they are close enough to interact and further folding of these sections will occur.
The following interactions occur between the R groups:
- hydrophobic and hydrophilic interactions (weak interactions between polar and non-polar R-groups)
- hydrogen bonds (the weakest of the bonds formed)
- ionic bonds (stronger than hydrogen bonds and form between oppositely charged R-groups)
- disulfide bonds (covalent bonds that form between R-groups that contain sulfur atoms, strongest of the bonds)

29
Q

Describe the quaternary structure of proteins

A

A level of structure displayed by proteins that consist of more than one polypeptide chain.

30
Q

Describe the structure and function of globular proteins

A

Globular proteins are compact, soluble and roughly spherical.
They are formed when proteins fold into their tertiary structures in such a way that the hydrophobic R-groups on the amino acids are kept away from the aqueous environment.
The hydrophilic R-groups are kept on the outside of the protein, meaning the proteins are soluble in water.
This solubility is important for the functions of globular proteins. They are essential for regulating many of the processes necessary to life eg. chemical reactions, immunity and muscle contractions
The secondary structure forms an alpha helix

31
Q

Function of insulin

A

Insulin is a globular protein
It is a hormone involved in the regulation of blood glucose concentration.
Hormones are transported in the blood stream so need to be soluble.
Hormones also have to fit into specific receptors on cell-surface membranes to have their effect and therefore need to have a precise shape.

32
Q

Describe the structure and function of conjugated proteins

A

Conjugated proteins are globular proteins that contain a non-protein component called a prosthetic group.
Proteins without prosthetic groups are called simple proteins.
There are different types of prosthetic groups, haem groups are examples of prosthetic groups. They contain an iron ii ion (Fe 2+). Catalase and haemoglobin both contain haem groups.

33
Q

Describe the structure and function of haemoglobin

A

Haemoglobin is the red, oxygen-carrying pigment found in red blood cells.
It is a quaternary (4Y) protein made from four polypeptide chains, two alpha and two beta subunits.
Each subunit contains a prosthetic group (it is a conjugated protein).
The iron (ii) ions present in the haem group are able to combine reversibly with an oxygen molecule (associates with oxygen), enabling haemoglobin to transport oxygen by picking it up in the lungs and transporting it to cells that need it, where it is released.

34
Q

Describe the structure and functions of catalase

A

Catalase is an enzyme that catalyse’s reactions, meaning they increase reaction rates, and each enzyme is specific to a particular reaction.
Catalase is a quaternary (4Y) protein containing four haem prosthetic groups (a conjugated protein).
The presence of iron (ii) ions in the prosthetic group allow catalase to interact with hydrogen peroxide and speed up its breakdown.
Hydrogen peroxide is a common product of metabolism, but is damaging to cells and cell components if allowed to accumulate. Catalase makes sure this doesn’t happen.

35
Q

Describe the structure and functions of fibrous proteins

A

Fibrous proteins are formed from long, insoluble molecules due to the presence of a high proportion of amino acids in the hydrophobic R-group in their primary structures.
They contain a limited range of amino acids, usually with small R-groups.
The amino acid sequence in the primary structure is usually quite repetitive.
This leads to very organised structures reflected in the roles fibrous proteins often have.
Fibrous proteins tend to make strong, long molecules which are not folded into 3d shapes like globular proteins.
Fibrous proteins have a beta pleated sheet in their secondary structure.

36
Q

Describe the structure and functions of keratin

A

Keratin is a group of fibrous proteins present in hair, skin and nails.
It has a large proportion of sulfur-containing amino acid: cysteine.
This results in many strong disulfide bonds forming strong, inflexible and insoluble materials.
The degree of disulfide bonds determines the flexibility - hair contains fewer bonds making it more flexible than nails, which contains more bonds.

37
Q

Describe the structure and function of elastin

A

Elastin is a fibrous protein found in elastic fibres (along with small protein fibres).
Elastic fibres are present in the walls of blood vessels and in the alveoli of the lungs, they have these structures the flexibility to expand when needed, but also to recoil to their normal size.
Elastin is a quaternary (4Y) protein made from many stretchy molecules called tropoelastin.

38
Q

Describe the structure and functions of collagen

A

Collagen is a fibrous protein that is a connective tissue (made of tropocollagen) in skin, tendons, ligaments and the nervous system.
There are a number of different forms but all are made up of three polypeptides wound together in a long and strong rope-like structure. Like rope, collagen has flexibility.
Every third amino acid in the chain is glycine.

39
Q

What are carbohydrates?

A
  • Carbohydrates are a group of substances used as both energy sources and structural materials in organisms.
  • All carbohydrates contain carbon, hydrogen and oxygen and have the general formula Cx(H2O)y
40
Q

What are the three main groups of carbohydrates?

A
  • Monosaccharides: a single sugar unit eg. glucose, fructose and ribose
  • Disaccharides: double sugars, formed from two monosaccharides eg. lactose and sucrose
  • Polysaccharides: large molecules formed from many monosaccharides eg. glycogen, cellulose and starch
41
Q

Describe glucose

A
  • Glucose is an abundant and very important monosaccharide, it is the building blocks of some biologically important carbohydrates.
  • Glucose contains six carbon atoms, so it is a hexose monosaccharide (hexose sugar). It’s general formula is C6H12O6.
  • Glucose is a major energy source for most cells. Glucose molecules are polar and highly soluble in water, and is the main form in which carbohydrates are transported around the body of animals.
  • Glucose is polar and soluble due to the hydrogen bonds that form between the hydroxyl groups and water molecules. Solubility is important as glucose is dissolved in the cytosol of the cell.
42
Q

What are the two different structures of glucose?

A
  • Glucose exists in different forms called structural isomers, two common isomers are alpha glucose and beta glucose.
  • The difference between these two isomers is in alpha glucose the -OH group attached to carbon 1 is below the carbon, and in beta glucose the -OH group is above the carbon atom.
43
Q

How are disaccharides formed?

A
  • A condensation reaction between two monosaccharides forming a 1 - 4 glycosidic bond, releasing a molecule of water (formed between carbon 1 and carbon 4)
  • When two alpha glucose molecules are side my side, the two hydroxyl groups interact, forming the glycosidic bond.
44
Q

Describe pentose (carbohydrate)

A
  • Pentose monosaccharides contain 5 carbon atoms which form a ring.
  • Two pentose sugars are important components of biological molecules ribose (sugar present in RNA nucleotides) and deoxyribose (sugar present in DNA nucleotides)
45
Q

Describe maltose (carbohydrate)

A

Formed from two glucose molecules by an alpha 1-4 glycosidic bond

46
Q

Describe sucrose (carbohydrate)

A

Formed from glucose and fructose by an alpha 1-4 glycosidic bond

47
Q

Describe lactose (carbohydrates)

A

Formed from galactose and glucose by a beta 1-4 glycosidic bond

48
Q

What are polysaccharides?

A
  • Polymers containing many monosaccharides linked by glycosidic bonds, formed by condensation reactions.
  • Polysaccharides are mainly used as an energy store and as structural components of cells.
  • The major polysaccharides are starch and cellulose in plants, and glycogen in animals.
49
Q

Describe starch

A
  • Starch is a polysaccharide made of many alpha glucose molecules joined by glycosidic bonds to form two different polysaccharides (amylose and amylopectin) known collectively as starch.
  • Starch is the major carbohydrate storage molecule in plants. It is usually stored as intracellular starch grains in organelles called plastids.
  • Plastids include green chloroplasts and colourless amyloplasts.
  • Starch is produced from glucose made during photosynthesis, it is broken down during respiration to provide energy and is a source of carbon for producing other molecules.
50
Q

Describe amylose (polysaccharide in starch)

A
  • Amylose is formed by alpha glucose molecules joined together by 1-4 glycosidic bonds.
  • The angle of the bond means this long chain of glucose twists to form a helix which is further stabilised by hydrogen bonding within the molecule, making the polysaccharide more compact and less soluble than the glucose molecules used to make it.
51
Q

Describe amylopectin (polysaccharide of starch)

A
  • Amylopectin is also made by 1-4 glycosidic bonds between alpha glucose molecules, but there are also some glycosidic bonds formed by condensation reactions between carbon 1 and carbon 6 in two glucose molecules.
  • This means that amylopectin has a branched structure with the 1-6 branching points occurring once every 25 glucose subunits.
52
Q

Describe glycogen

A
  • Animals do not store carbohydrates as starch but as glycogen.
  • Glycogen has a similar structure to amylopectin, containing many alpha 1-6 glycosidic bonds that produce an even more branched structure, meaning it is more compact and less space is needed to store it, which is important as animals are mobile.
  • The branching of polysaccharides also means there are many free ends where glucose molecules can be added or removed, which speeds up the process of storing or releasing glucose molecules required by the cell.
  • Glycogen is stored as small granules, particularly in muscles and liver.
  • Glycogen is less dense and more soluble than starch, and is broken down more rapidly, which indicates the higher metabolic requirements of animals compared with plants.
53
Q

Describe cellulose

A
  • Cellulose is another polysaccharide and is the main component of plant cell walls, it is the most organic polymer.
  • When a polysaccharide is formed from beta glucose molecules, it is unable to coil or form branches. A straight chain molecule is formed called cellulose.
  • Cellulose consists of long chains of beta glucose molecules joined by beta 1-4 glycosidic bonds.
  • Cellulose molecules make hydrogen bonds with each other forming microfibrils. These microfibrils join together forming macrofibres, which combine to produce fibres. These fibres are strong, insoluble and used to make cell walls. Cellulose is an important part of our diet, it is hard to break down and forms the ‘roughage’ necessary for a healthy digestive system.
54
Q

What are lipids?

A
  • Lipids (fats and oils) are molecules containing carbon, hydrogen and oxygen.
  • They are non-polar molecules therefore are not soluble in water.
  • Lipids are large complex molecules known as macromolecules.
55
Q

Describe triglycerides (lipids)

A
  • A triglyceride is make by combining one glycerol molecule with three fatty acids. Glycerol is a member of the alcohols group. Fatty acids belong to a group of molecules called carboxylic acids, they consist of a carboxyl group (-COOH) with a hydrocarbon chain attached.
  • The hydroxyl groups interact leading to the formation of three water molecules and bonds between the fatty acids and the glycerol molecule. These are ester bonds, which are formed in a condensation reaction.
  • When triglycerides are broken down, three water molecules are needed to be supplied to reverse the reaction.
56
Q

Describe saturated triglycerides

A

Fatty acid chains that have no double bonds present between the carbon atoms, because all of the carbon atoms form the maximum number of bonds with hydrogen atoms.

57
Q

Describe unsaturated triglycerides

A

A fatty acid chain with a double bond between some of the carbon atoms. The presence of double bonds causes the molecule to bend, and they therefore cannot pack so closely together, making them liquid at room temperature.

58
Q

Describe phospholipids

A
  • Phospholipids are modified triglycerides and contain the element phosphorus, along with carbon, hydrogen and oxygen. One of the fatty acid chains in a triglyceride molecule is replaced with a phosphate group to make a phospholipid.
  • Phospholipids have a non-polar end (tail) and a charged end (head). The non-polar tails are repelled by water (hydrophobic), but the charged heads are attracted to water (hydrophilic).
  • As a result of this they will form a layer on the surface of the water with the phosphate heads in the water and the fatty tails sticking out of the water, meaning they are surface active agents.
  • They also form structures based on a two-layered sheet formation (bilayer) with all of the hydrophobic tails pointing towards the centre, due to this they separate an aqueous environment in which cells exist from the aqueous cytosol in cells (cell membrane).
59
Q

Describe sterols (lipids)

A
  • Sterols (steroid alcohols) are a type of lipid found in cells. They are complex molecules based on a four carbon ring structure with a hydroxyl (OH) group at one end. The hydroxyl group is polar, therefore hydrophilic, and the rest of the molecule is hydrophobic.
  • Cholesterol is a sterol, it has an important role in the formation of cell membranes, adding stability and regulates their fluidity by keeping membrane fluid at low temperatures.
60
Q

Role of lipids

A

Due to their non-polar structure, lipids have many biological roles including:
- membrane formation and the creation of hydrophobic barriers
- hormone production
- electrical insulation necessary for impulse transmission
- waterproofing

In particular triglycerides, have an important role as a long-term energy storage. They are stored under the skin and around vital organs where they provide:
- thermal insulation to reduce heat loss eg. adipose tissue under the skin in mammals
- protection, adipose tissue around vital organs acts as a cushion against impacts
- buoyancy for aquatic animals like whales

61
Q

Describe the test for lipids

A

Emulsion test:
- Grind any solid foods and add to a test tube
- Add ethanol and shake to dissolve lipids.
- Add an equal volume of water and mix.
- If a white emulsion forms as a layer on top of the solution a lipid is present.

62
Q

Describe the test for reducing sugars

A

Reducing sugars (all monosaccharides and some disaccharides) can donate electrons, or reduce another molecule/chemical.
- Add the sample to a test tube, if not liquid grind it in water.
- Add an equal volume of Benedicts reagent (equal to volume of sample) and heat in a water bath for 5 minutes.
- The starting colour/negative result is blue, the closer to brick-red the more reducing sugars present: green - yellow - brown - brick-red

63
Q

Describe the test for non-reducing sugars

A
  • Add a known volume of sample to a test tube and add the same volume of hydrochloride acid.
  • Heat the sample for 3 minutes to hydrolyse the glycosidic bond. (now a reducing sugar)
  • Add sodium hydrogen carbonate to neutralise the solution.
  • Add the same known volume of Benedicts reagent, the closer to brick red the more non-reducing sugars present: blue - green - yellow - brown - brick-red
64
Q

Describe the test for proteins

A

Biuret test for proteins:
- A liquid solution is treated with sodium or potassium hydroxide to make the solution alkaline.
- Add a few drops of copper (II) sulfate solution (blue)
- If a colour change is observed from blue to lilac/purple, it is a positive result and proteins are present. No colour change is a negative result.

65
Q

Describe the test for starch

A

Iodine test for starch:
- A few drops of iodine dissolved in potassium iodide solution are mixed with a sample.
- If the solution changes colour from yellow-brown to blue-black if starch is present, no colour change indicates a negative result.

Biology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions