Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Progression Exam ~ Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

(48 cards)

Start Studying
1
Q

Monosaccharide

A

A single sugar molecule.

  • The simplest carbohydrate which only contain carbon , hydrogen and oxygen.
  • Soluble in water ~ have a large number of OH (hydroxyl) groups which can form hydrogen bonds with water molecules.

Examples :
- Glucose
- Galactose
- Fructose

hexose sugar ~ six carbon atoms
pentose sugars ~ five carbon atoms
triose sugars ~ three carbon atoms

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

ISOMERS and the two forms of glucose

A

Isomer ~ molecules with the same formula , but whose atoms are arranged differently in space.

Glucose ~ C6H12O6

Beta glucose ~ Carbon 1 hydroxyl points ABOVE the ring.

Alpha glucose ~ Carbon 1 hydroxyl points BELOW the ring.

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

Disaccharides

A

Form when two monosaccharides chemically react together, contain TWO saccharide molecules.

Examples:
Maltose ~ (a glucose + a glucose)
Sucrose ~ (a glucose + fructose)
Lactose ~ (B glucose + galactose)

Maltose:

  • GLYCOSIDIC BOND between carbon 1 and carbon 4 .
  • WATER MOLECULE is formed from a hydrogen atom from one of the monosaccharides and a hydroxyl group from another ~ CONDENSATION REACTION.
  • OXYGEN atom acts as a link between the two monosaccharide units
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Hydrolysis Reaction Vs Condensation Reaction

A

HYDROLYSIS REACTION:

  • SPLITTING APART two molecules
  • ADDITION of a water molecule

CONDENSATION:

  • JOINING two molecules together
  • REMOVAL of a water molecule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Polysaccharide

A
  • Polysaccharides are POLYMERS of monosaccharides.
  • made of hundreds or thousands of monosaccharide monomers bonded together.

HOMOpolysaccharide ~made solely of one kind of monosaccharide.

HETERpolysaccharide ~ made of more than one monomer.

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

The energy source : GLUCOSE

A
  • Produced in plant cells using light energy trapped during photosynthesis.
  • A store of chemical energy which can be released during respiration.
  • The energy released is used to make ATP , which is the energy currency of the cell.

SOLUBLE IN WATER:

  • HYDROXYL groups are POLAR:
  • small negative charge on oxygen
  • small positive charge on the hydrogen
  • Able to form HYDROGEN BONDS with water

PROBLEM ~ allows water to move into the cell by osmosis.

SOLUTION ~ plant cells store glucose as STARCH in starch grains.

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

The energy store : STARCH

A

Consists of TWO types of polysaccharides:
- Amylose
- Amylopectin

Amylose and amylopectin are POLYMERS:
They are too large to diffuse through the cell membrane and pass out of the cell.

Insoluble in water :
Starch does not cause water to enter the cell by osmosis.

ENZYMES:
Used when the cell needs glucose to break the glycosidic bond in starch. Water is used as is known as a hydrolysis reaction.

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

Amylose

A

A polymer of ALPHA glucose molecules.

  • Glycosidic bonds between 1 and 4.

Spiral / HELIX shape:
- makes starch COMPACT ~ large amounts of glucose can be stored for its size.

HYDROGEN BONDS form between glucose molecules along the chain , hold the helix in place.

HYDROXYL GROUPS situated on carbon 2 are located on the inside of the coil making the molecule LESS soluble in water.

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

AMYLOPECTIN

A

A polymer of alpha glucose molecules.

BRANCHES:
- every 25-30 glucose molecules.

  • simply another chain of alpha glucose molecules joined by a 1, 4 glycosidic bond.
  • The branch is joined to the main chain by a 1, 6 glycosidic bond
  • Provide a large number of ends to allow ENZYMES to break down starch rapidly.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

GLYCOGEN

A
  • Storage form of glucose in ANIMALS
  • Major stores ~ liver &muscle cells.
  • A polymer of ALPHA glucose molecules
  • joined together by 1,4 glycosidic bonds.
  • BRANCHES ~ joined to main chain by 1,6 glycosidic bonds.

GLYCOGEN OR AMYLOPECTIN?
Same structure ~ glycogen is MORE BRANCHED making it a very COMPACT molecule.

LARGE NUMBER OF BRANCHES:
- lots of free ends
- ENZYMES can convert glycogen back to glucose very rapidly .
- Important for animals as:
- HIGH rate of respiration
- ENERGY NEEDS of animals can change very quickly.

INSOLUBLE IN WATER:
Does not allow water into cells by OSMOSIS preventing the cell from bursting.

LARGE MOLECULE:
Glycogen cannot DIFFUSE out of the cell.

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

CELLULOSE

A
  • A major part of the CELL WALL found in plant cells.
  • Polymer of BETA glucose.
  • Hydroxyl group on carbon 1 points ABOVE the plane of the ring.
  • Every SECOND beta glucose rotates 180 degrees so a glycosidic bond can form between carbons 1 and 4.

STRAIGHT CHAINS WITH NO BRANCHES:
- Cellulose molecules to get close together.
- Many HYDROGEN BONDS form between neighbouring chains ~ STRENGTH

MICROFIBRILS:
- 60-70 cellulose chains group together

MACROFIBRILS:
- These group together to form large structures

CELULOSE FIBRES:
- These group together to form larger structures which forms the plant cell wall.

STRUCTURE:

  • Macrofibrils and microfibrils ~ very high TENSILE STRENGTH ~ glycosidic & hydrogen bonds
  • Macrofibrils CRISS CROSS the wall for extra strength.
  • Difficult to DIGEST ~ the glycosidic bonds are less easy to break.

PLANT CELL WALL FUNCTION:
- Strength and support ~ plants do not have a rigid skeleton.
- Permeable ~ SPACES between macrofibrils allow water and mineral ions to pass on their way in and out of the cell.

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

PROTEINS

A

Large polymers compromised of long chains of AMINO ACIDS.

Functions:
- blood clotting
- enzymes
- transport
- hormones
- motors
- toxins
- lubrication
- antibodies

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

AMINO ACIDS

A
  • There are TWENTY different amino acids found in biology.
  • Contain the elements carbon, hydrogen, nitrogen , oxygen and sometimes sulfur .

Consist of :
- Amine group NH2
- Carboxyl group COOH
- R group varies with each amino acid

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

Peptide bond

A
  • A bond that forms between TWO amino acids
  • HYDROXYL GROUP lost from one amino acid
  • HYDROGEN is lost from the other.
  • WATER MOLECULE is formed ~ CONDENSATION REACTION.
  • When two amino acids join together ~ DIPEPTIDE.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Polypeptide & hydrolysis reaction

A
  • When THREE or more amino acids are joined.
  • ONE molecule of water is form for EVERY peptide bond.
  • Polypeptides often consist of HUNDREDS of amino acids joined.

HYDROLYSIS REACTION:
If we add a molecule of water, we REVERSE the reaction and break the polypeptide bond.

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

Primary structure

A
  • The SEQUENCE of amino acids in a polypeptide chain.
  • Helps determine the 3D shape of a protein.
  • The SHAPE of a protein is critical for its FUNCTION.
  • Even changing A SINGLE amino acid in the primary structure can change the final shape of the protein.
  • The primary structure is determined by the DNA SEQUENCE of the GENE which encodes that polypeptide.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

SECONDARY STRUCTURE

A
  • HYDROGEN BONDS form between amino acids all along the polypeptide chain.
  • Cause polypeptide chain to TWIST and FOLD into shape

Hydrogen bonds are form between:
- C=O of carboxyl group of one amino acid
- H of amine group of another amino acid

  • Type of secondary structure formed, depends on the primary structure in that region. It is either:

ALPHA HELIX ~ helical shaped

BETA PLEATED SHEET~ flat & sheet like

Both of these contain HYDROGEN BONDS that hold the shape in place.

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

Tertiary structure

A
  • The OVERALL 3D shape of the polypeptide chain.
  • Critical for how a protein FUNCTIONS.

BONDS form between the amino acids to hold the precise shape in place:
- Hydrophobic & hydrophilic
- hydrogen
- ionic
- disulfide

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

Quaternary structure

A
  • A protein made up of MORE THAN ONE polypeptide chain each called SUBUNITS
  • Shows how the individual subunits are ARRANGED to form a LARGER 3D SHAPE.

PROSETHIC GROUPS:

  • Found in some proteins
  • Non-protein molecules
  • Help carry out the proteins function
  • These proteins are known as
    CONJUGATED proteins
  • Their POSITION is shown in the quaternary structure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Hydrogen bonding

Study These Flashcards
A
  • Form due to the slight + and - charges present on the hydroxyl
  • WEAK BONDS ~ are easily broken by high temperature and PH changes
21
Q

Hydrophobic & Hydrophilic interactions

Study These Flashcards
A

Hydrophobic:
- NOT attracted to water
- Located in the CENTRE of proteins

Hydrophilic:
- ATTRACTED to water
- Located on the SURFACE of proteins

22
Q

Ionic bonding

Study These Flashcards
A
  • Found between amino acids with OPPOSITELY CHARGE R groups.
  • Broken with PH changes ~ why enzymes denature in acidic and alkaline conditions.
23
Q

Disulfide bonding

Study These Flashcards
A
  • When two atoms form a covalent bond
  • Usually occurs in the sulfur containing amino acid CYSTEINE.
  • STRONG BOND ~ not broken by high temperatures or PH changes.
24
Q

GLOBULAR proteins

Study These Flashcards
A
  • Approximate spherical shape
  • FUNCTIONAL proteins
  • SPECIFIC shape - helps them to take up roles as enzymes, hormones & haemoglobin.
  • More sensitive to changes in heat and PH.

SOLUBLE in water:
-Hydrophilic amino acids ~ outer surface.
- Hydrophobic amino acids ~ deep in the centre, away from any water molecules.
- Allows the hydrophilic R group can INTERACT with water molecules.

25
Globular protein : HAEMOGLOBIN
QUATERNARY STRUCTURE: - made up of FOUR polypeptide subunits - TWO alpha & TWO beta BINDS TO OXYGEN: - Red blood cells - Lungs ~ releasing it in body tissues HAEM: - Prosthetic group - Found in each subunit - Each haem group contains the Fe2+ ion where oxygen binds - ONE haemoglobin molecule binds to FOUR oxygen molecules. WHEN OXYGEN ATTACHES: - Quaternary structure slightly changes - EASIER for oxygen to attach CONJUGATED PROTEIN ~ contains a prosthetic group
26
Globular protein : INSULIN
- HORMONE carried in the bloodstream - Role in BLOOD GLUCOSE regulation. - TWO polypeptide chains (alpha and beta) - These FOLD into tertiary structure then linked by DISULFIDE BONDS. - Bind to SPECIFIC RECEPTOR molecules. - Receptors are PROTEINS found on the CELL MEMBRANE of target cells. - The SHAPES of protein hormones are CRITICAL for how they BIND to their receptors and carry out their EFFECTS.
27
Globular proteins : ENZYMES
- Only react with a SPECIFIC SUBSTRATE molecule. - This specificity is due to the STRUCTURE of the enzyme. - ACTIVE SITE of an enzyme is COMPLEMENATARY to the SUBSTRATE LYSOZYME: - Found in SALIVA and TEARS. - made up of a single polypeptide chain - the chain fold to form the active site. - the shape of the active site means that it fits perfectly to the substrate molecule in the BACTERIAL CELL WALL. Some amino acids HOLD the substrate in place, whilst others CATALYSE the reaction
28
Fibrous proteins
- Have a REGULAR, repetitive sequence of amino acids - UNREACTIVE - Play a STRUCTURAL role. - Form LONG, ROPE-LIKE molecules INSOLUBLE in water: - have a large proportion of amino acids with HYDROPHOBIC R groups
29
Fibrous protein : COLLAGEN
FOUND IN: Tendons ~ connecting muscles to bone Ligaments ~ connect bones to each other Artery walls ~ prevents bursting from high pressure of blood. Provides MECHANICAL STRENGTH due to its STRUCTURE: - Polypeptide chains, wrap tightly together to form a TRIPLE HELIX. GLYCINE: - Every third amino acid - Has the smallest R group ( HYDROGEN) - Allow polypeptides to wrap tightly around each other HYDROGEN BONDS: - form between the polypeptide chains - Stabilise the quaternary structure of the protein. - STRONG CROSSLINKS join the polypeptide chains.
30
Fibrous protein : KERATIN
FOUND IN: - Hair - Fingernails - Outer surface of skin CYSTEINE: - High proportion found in keratin - Form DISULIDE BONDS - Contributes to STRENGTH - IMPERMEABLE BARRIER to infection . - WATERPROOF ~prevents the entry of water-borne pollutants.
31
Fibrous protein : ELASTIN
FOUND IN: Skin Walls of arteries lungs bladder This is because elastin can STRETCH and RECOIL allowing MOVEMENT or STORAGE. ELASTIC: - Elastin molecules are stretched - Strands move apart but remain ATTACHED at the crosslinks. - After stretching , the elastin molecules REASSOCIATE springing back together.
32
Hydrogen bonding in water
- ONE OXYGEN ATOM ~ slight negative charge - TWO HYDROGEN ATOMS ~ slight positive charge - COVALENTLY bonded together - These charges make water POLAR - OPPOSITE charges allow water molecules to be ATTRACTED to each other ~ HYDROGEN bonds: - WEAK but even a SMALL volume of water contains a LARGE NUMBER of hydrogen bonds - Have a large effect on the properties of water.
33
Property 1 : HIGH SHC
- We have to put in or take out a large amount of energy to change the temperature of water. - When we heat water , the heat energy goes towards WEAKENING or BREAKING the hydrogen bonds rather than increasing the kinetic energy of the water molecules. - This means the temperature of water tends not to change rapidly. - This allows water to act as a HABITAT for AQUATIC organisms.
34
Property 2 : LESS DENSE IN SOLID FORM THAN LIQUID FORM
- This allows ICE to FLOAT on water. - This can act as a HABITAT for a number of organisms such as POLAR BEARS. - This ice INSULATES the water below and PREVENTS it from freezing. - This means organisms can continue to live in the water under the ice.
35
Property 3 : HIGH LATENT HEAT OF VAPOURISATION
- Takes a LARGE amount of heat energy to EVPORATE water. -This allows organisms to COOL themselves without losing a great deal of water. - SWEATING ~ heat energy is used to evaporate water from the surface of the skin and this transfer of heat energy allows organisms to cool down.
36
Property 4 : SOLVENTS
- Lots of substances can dissolve in water - Water molecules are POLAR ~ enables them to solute molecules - Both EUKARYOTIC and PROKARYOTIC cells contain a large amount of dissolved substances. EXAMPLES: - Chemicals involved in metabolic reactions such as respiration. - Enzymes needed to carry out these reactions. - Ponds and rivers contain dissolved OXYGEN and this is used by organisms living in the water to carry out respiration , making water an excellent HABITAT for organisms. A GOOD TRANSPORT MEDIUM: Blood plasma ~ contains a large number of dissolved substances such as CO2 and mineral ions. Xylem vessels of plants ~ mineral ions pass into the plant roots from the soil and transported in the xylem to the leaves.
37
Property 5 : COHESION
- Water molecules tend to STICK together due to the HYDROGEN BONDS between water molecules. - Allows LONG COLUMNS of water to travel in the XYLEM TUBES. - This makes water an ideal transport medium in plants. - Also causes SURFACE TENSION where water meets air. - This is useful as it allows the surface of water to act as a HABITAT for organisms such as the insect PONDSKATERS.
38
Property 6 : METABOLIC REACTIONS
REACTANT: - Hydrolysis reactions - Photosynthesis PRODUCT: - Condensation reactions - Aerobic respiration
39
Lipids ~ Features & Uses
- Fats and oils FEATURES: - More carbon-carbon bonds / carbon-hydrogen bonds - Energy rich / contain more energy per molecule - More energy stored in less space - Insoluble ~ do not affect water potential of cell Uses: - Energy SOURCE e.g in human diet - Energy STORE e.g Adipose tissue - Protection e.g delicate organs - Thermal and electrical INSULATOR - Waterproofing - Major part of the structure of membranes e.g in cells and mitochondria
40
Triglyceride
- A type of LIPID General formula: - A molecule of GLYEROL C3H8O3 - Bonded to 3 FATTY ACIDS NON POLAR : - hydrophobic - waterproofing - do not affect water potential TRANSFER ENERGY - LARGE ratio of C and H bonds compared to number of carbon atoms - A great deal of energy can be RELEASED METABOLIC WATER SOURCE: - Release water if they are oxidised
41
Fatty acids
- Have a CARBOXYL GROUP at the end which plays an important role when forming triglycerides. - The rest of the molecule consists of a long chain of C atoms bonded to H atoms. SATURATED fatty acids ~ contain SINGLE C-C bonds only. UNSATURATED fatty acids ~ have at least one DOUBLE C=C bond. MONO unsaturated ~ contains only ONE double C=C bond. POLY unsaturated ~ contains MORE THAN ONE double C=C bond.
42
Formation of a triglyceride
- OH is lost from the glycerol - H is lost from the fatty acid - An OXYGEN links the two molecules together forming and ESTER BOND. - This process is known as ESTERFICATION. - Forms WATER so is known as a CONDENSATION REACTION. - When THREE bonds are formed this is known as a TRIGLYCERIDE.
43
HYDROLYSIS REACTION in triglycerides
- In the digestive system, lipase breaks the ester bonds. - This releases the glycerol and fatty acids. - This reaction requires THREE water molecules.
44
Phospholipids
- ONE glycerol - TWO fatty acids - PHOSPHATE GROUP : -Negatively charged making this part of the molecule POLAR. -This means the phosphate group is HYDROPHILIC ( it attracts water molecules).
45
The phospholipid bilayer
HEAD - the polar , hydrophilic part of the molecule. TAIL - represents the two fatty acid molecules which are non-polar and hydrophobic. This means phospholipids contain both a hydrophilic and a hydrophobic region. IN WATER: - position themselves so that the hydrophilic head groups can interact with the water molecules. - The hydrophobic tails CLUSTER together, well away from water molecules. This is known as a PHOSPHOLIPID BILAYER. USEFUL ~ allows phospholipids to form the membranes that we find both AROUND & WITHIN cells
46
Cholesterol
- Part of a family of lipids called STEROLS. - The HYDROXYL GROUP is hydrophilic where as the rest of the molecule is hydrophobic. - This means cholesterol can INSERT into CELL MEMBRANES.
47
The interaction of cholesterol and phospholipids
- The HYDROPHILIC hydroxyl group on the cholesterol molecule can interact with the HEAD groups of phospholipids. - The rest of the cholesterol molecule can interact with the HYDROPHOBIC fatty acid tails.
48
ROLES of cholesterol
Controlling the FLUIDITY of cell membranes: - HIGH temperatures ~ reduces fluidity - LOW temperatures ~ increases fluidity - Used as the starting point of a range of HORMONES : Oestrogen and testosterone can pass through the cell membrane and interact with their RECEPTORS inside the cell - Used in the body to make VITAMIN D: This takes place in the SKIN in response to UV light .Vitamin D is important for the proper development of BONES. - Used in the LIVER to produce BILE which increases the rate of digestion of lipids by the enzyme lipase.

Progression Exam ~ Biology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions