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biology > BIOLOGICAL MOLECULES > Flashcards

BIOLOGICAL MOLECULES Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a monomer?

A

smaller units which can create large molecules

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2
Q

What is a polymer?

A

made from lots of monomers bonded together

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3
Q

Name 3 monosaccahrides

A

Glucose
Fructose
Galactose

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4
Q

Alpha glucose

A

H on top then OH

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5
Q

Beta glucose

A

OH on top then H

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6
Q

What is a disaccharide?

A

made of two monosaccharides which are joined by a glycosidic bond and formed via a condensation reaction

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7
Q

What are the condensation reactions that form disaccharides?

A

glucose + glucose –> maltose + water
glucose + galactose –> lactose + water
glucose + fructose –> sucrose + water

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8
Q

Define a condensation reaction

A

joining two molecules together by removing water

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9
Q

Define a hydrolysis reaction

A

splitting apart molecules through addition of water

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10
Q

Formation of polysaccharides and name the 3

A

3 = starch, cellulose, glycogen
Created by condensation reactions between many glucose monomers

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11
Q

Info about starch

A

MONOMERS = alpha glucose
BOND BETWEEN MONOMERS = 1-5 in amylose and 1-4 & 1-6 in amylopectin
FUNCTION = store of glucose
LOCATION = plant cells
STRUCTURE = 2 polymers. Amylose is and unbranched helix. Amylopectin is a branched molecule
EXPLANATION OF HOW STRUCTURE LEADS TO FUNCTION:
- Helix can compact to fit a lot of glucose in a small space
- Branched structure increases surface area for rapid hydrolysis back to glucose
- Insoluble so won’t affect water potential

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12
Q

Info about cellulose

A

MONOMERS = beta glucose
BOND BETWEEN MONOMERS = 1-4 glycosidic bonds
FUNCTION = structure strength for cell wall
LOCATION = plant cell - cell wall
STRUCTURE = Polymer forms long straight chains which are held in parallel by many hydrogen bonds to form fibrils
EXPLANATION OF HOW STRUCTURE LEADS TO FUNCTION:
- Many hydrogen bonds provide collective strength
- Insoluble so won’t affect water potential

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13
Q

Info about glycogen

A

MONOMERS = alpha glucose
BOND BETWEEN MONOMERS = 1-4 and 1-6 glycosidic bonds
FUNCTION = store of glucose
LOCATION = animals (mainly in liver and muscle cells)
STRUCTURE = a highly branched molecule
EXPLANATION OF HOW STRUCTURE LEADS TO FUNCTION:
- Branched structure increases surface area for rapid hydrolysis back to glucose
- Insoluble won’t affect water potential.

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14
Q

What do lipids contain and what are the main groups?

A

Contain : Carbon, Hydrogen, Oxygen
Main groups = triglycerides and phospholipids.

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15
Q

Formation and structure of triglycerides

A

They are made of one glycerol molecule and 3 fatty acids (RCOOH)
Join together in a condensation which forms 3 ester bonds (broken in hydrolysis)

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16
Q

Properties of triglycerides

A
  1. Energy storage = Large ratio of energy storing carbon- hydrgoen bonds compared to the number of carbon atoms, a lot of energy is stored in the molecule
  2. Metabolic water source = high ratio of hydrogen to oxygen atoms. Can also release water if oxidised. Essential for camels
  3. Don’t affect water potential = Large and hydrophobic so insoluble to water
  4. Low mass= Lots can be stores without increasing mass
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17
Q

Define saturated

A

R group can be saturated or unsaturated
Only contain C-C single bonds -such as those found in animal fats

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18
Q

Define unsaturated

A

Contains one or more C=C double bonds
- slight kink in the chain which is why they can form oils

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19
Q

Structure of phospholipid

A

One glycerol
Two fatty acids
Phosphate
Hydrophilic head and hydrophobic tail - results in them forming a micelle/bilayer when they are in contact with water and so they are polar.

20
Q

Properties of phospholipids

A

1.in an aqueous environment being polar means a bilayer can be formed.
2.The hydrophilic heads of the phospholipids can be used to hold at the surface of the cell
surface membrane.
3.Form glycolipds with carbohydrates which are important on the
cell surface membrane for cell recognition.

21
Q

What monomers are proteins made from?

A

Amino acids

22
Q

Formation and structure of amino acids

A

Structure : amino group (NH2), carboxylic acid group (-COOH) and a variable R group (one of 20 amino acids)
Formation : joined by peptide bonds formed in condensation reactions.
* Dipeptides are formed by the condensation of two amino
acids.
* Polypeptides are formed by the condensation of many amino
acids

23
Q

Primary structure of protein

A

The sequence of the amino acids in the polypeptide chain

24
Q

Secondary structure of protein

A

The sequence of amino acids causes part of a protein molecule to bend into a alpha helix or fold into beta pleated sheets - hydrogen bonds hold the secondary structure
- Hydrogen bonds for between -COOH and -NH2 of adjacent amino acids

25
Q

Tertiary structure of protein

A
  • the further folding of the secondary structure to form a unique 3D shape which is held in place by ionic, hydrogen and disulphide bonds.
  • Ionic and disulphide form between R groups of amino acids but in disulphide there must be a sulphur present
26
Q

Quaternary structure of protein

A

Multiple polypeptide chains bonded together and each chain is held together in a precise structure e.g. haemoglobin.

27
Q

What is an enzyme and describes it function

A

Increase rate of reaction by lowering the activation energy without being used up
They are 3D globular proteins with its shape determined by the primary sequence of amino acids

28
Q

What is the induced fit model?

A

When the active site of an enzyme comes in contact with the substrate the enzyme will attempt to mould itself around the substrate to form an enzyme-substrate complex and a conformational shape change takes place
This puts stress on the bonds in the substrate and so lowers the activation energy

29
Q

Which 5 factors affect the rate of enzyme-controlled reaction and how do they do this?

A
  1. TEMPERATURE = up to optimum the rate of reaction increases as Ek of enzyme increases. Above optimum it decreases due to being denature
  2. PH = low pH means low rate as acidity breaks bonds maintaining tertiary structure so active site denatures. High ph is the same but alkalinity instead of acidity. Optimum is high rate due to lots of enzyme substrate collisions
  3. ENZYME CONCENTRATION = rate of reaction increases as enzyme concentration increase as there are more active sites for substrate to bind too. Too much increase no longer has an effect due to there being more active sites than substrates
  4. SUBSTRATE CONCENTRATION = same as enzyme but in terms of substrate
  5. INHIBITORS
30
Q

Describe competitive inhibitors

A

Bind to active site of enzyme
- Molecular shape similar to substrate so also binds to active site (cause competition)
If substrate conc is increased than the effect of the inhibitor reduces.
The inhibitor doesn’t permanently bond to the active site

31
Q

Describe non competitive inhibitors

A

Bind to the enzyme at a position other than the active site
- When attached to allosteric site the inhibitor alters the shape of the enzyme and thus its active site so enzyme cant function
- Increase in substrate doesn’t decrease the effect of the inhibitor as they aren’t competing for the same site

32
Q

Similarites between DNA and RNA

A

Both DNA and RNA are polymers of nucleotides. Each nucleotide is formed from a pentose, a nitrogen-containing organic base and a phosphate group:

A condensation reaction between two nucleotides forms a phosphodiester bond.

33
Q

Describe RNA

A

RNA transfers genetic information from DNA to the ribosomes.

Ribosomes are formed from RNA and proteins.

34
Q

Differences between DNA and RNA

A

DNA is a double helix with two polynucleotide chains held together by hydrogen bonds between specific complementary base pairs whilst an RNA molecule is a relatively short polynucleotide chain.

The components of a DNA nucleotide are deoxyribose, a phosphate group and one of the organic bases adenine, cytosine, guanine or thymine. whilst the components of an RNA nucleotide are ribose, a phosphate group and one of the organic bases adenine, cytosine, guanine or uracil.

35
Q

What does DNA replication ensure?

A

The semi-conservative replication of DNA ensures genetic continuity between generations of cells.

36
Q

What are the steps of DNA replication

A
  1. DNA helicase causes the two strands of DNA to separate breaking the hydrogen bonds between the complementary bases
  2. One of the strands is used as the template and complementary base pairing occurs between the template strand and free nucleotides
  3. Once activated nucleotides are bound by the enzyme DNA polymerase joins adjacent nucleotides together through a condensation reaction and forms phosphodiester bonds. Result is that 2 identical strands of DNA are formed
37
Q

Work of Meselson and Stahl

A
  • Bacteria are grown in a broth containing the heavy (15N) nitrogen isotope
  • A sample of DNA from the 15N culture of bacteria was extracted and spun in a centrifuge - heavy nitrogen settled near the bottom of the centrifuge tube
  • 15N containing bacteria’s DNA was taken out of the 15N broth and added to a broth containing only the lighter 14N nitrogen. Bacteria then left for one round of replication and then centrifuged.
    Meselson and Stahl confirmed that the bacterial DNA had undergone semi-conservative replication as the DNA from this centrifugation settled in the middle of the tube, showing that each DNA molecule contained a mixture of the heavier and lighter nitrogen isotopes

This experiment proved Watson and Crick’s theory correct

38
Q

What is ATP?

A

Adenosine triphosphate is a nucleotide derivative and consists of ribose, adenine and three phosphate groups

39
Q

ATP hydrolysis

A

Energy is released when ATP is hydrolysed to form ADP and a phosphate molecule
- Process is catalysed by ATP hydrolase and energy comes from bonds between the phosphate molecules.
- This is because these bonds are very unstable and have low ea so breaking these is quick and releases energy

40
Q

ATP : importance of inorganic phosphate

A

Inorganic phosphate can be used to phosphorylate other compounds - as a result makes the more reactive

41
Q

Resynthesis of ATP

A

ATP is resynthesised by the condensation of ADP and Pi.
Reaction is catalysed by the enzyme ATP synthase during photosynthesis, or during respiration.

42
Q

ATP properties

A
  1. Immediate source of energy - more desirable to use than glucose as ATP can be broken down in a single step to release a manageable quantity of energy
  2. Isn’t stored in large quantities as it can easily be reformed from ADP in seconds
  3. Used in a variety of ways - metabolic processes, movement, active transport, secretion and activation of molecules
43
Q

two ways in which the hydrolysis of ATP is used in cells

A
  1. energy for active transport
  2. Add phosphate to other substances and make them change their shape
44
Q

Importance of water’s properties

A
  1. METABOLITE - in many metabolic reactions, including condensation and hydrolysis reactions
  2. SOLVENT - is an important solvent in which metabolic reactions occur
  3. HIGH HEAT CAPACITY - buffering changes in temperature
  4. LARGE LATENT HEAT OF VAPORISATION - providing a cooling effect with little loss of water through evaporation
  5. STRONG COHESION BETWEEN WATER MOLECULES -supports columns of water in the tube-like transport cells of plants and produces surface tension where water meets air.
45
Q

What are inorganic ions? where do they occur

A

Occur in solution in the cytoplasm and body fluid of organisms, some in high concentration and others in very low concentrations

46
Q

Essential inorganic ions

A

HYDROGEN IONS : determine the pH of substances such as blood - the higher the concentration of hydrogen ions the lower the pH
IRON IONS - a component of haemoglobin which is an oxygen carrying molecule in red blood cells
SODIUM IONS - involved in co-transport of glucose and amino cids
PHOSPHATE IONS - component of DNA and ATP

biology (4 decks)

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