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Biology > Topic 1.2 - More Biological Molecules > Flashcards

Topic 1.2 - More Biological Molecules Flashcards

1
Q

What is DNA and RNA?
Where are they found?

A
  • Types of nucleic acids
  • Found in all living cells
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2
Q

What is DNA and RNA a polymer of?

A

Nucleotides

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3
Q

Structure of a nucleotide

A
  • Pentose sugar
  • Phosphate group
  • Nitrogen containing base
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4
Q

What does the condensation of nucleotides form?

A

Polynucleotide chains

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5
Q

Define phophodiester bond and what does it consist of?

A

Bond between two nucleotides between one phosphate group and pentose sugar

Consists of:
- 1 phosphate group
- 2 ester bonds

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6
Q

What does DNA stand for?

A

deoxyribonucleic acid

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7
Q

What is the structure of DNA?

A
  • Sugar phosphate backbone + DNA bases
  • Tightly coiled double helix
  • Compact to fit into nucleus
  • 2 polynucleotide strands (held together by hydrogen bonds between complementary base pairs)
  • Long molecule
  • Contains hydrogen and phosphodiester bonds
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8
Q

What are the two complementary base pairs in DNA?

A
  • Adenine + Thymine
  • Guanine + Cytosine
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9
Q

What is the DNA nucleotide structure?

A
  • Deoxyribose sugar
  • Phosphate group
  • 1 of 4 nitrogen containing base
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10
Q

How are the polynucleotide strands in DNA arranged?

A
  • Anti-parallel (run in opposite directions)
  • 5’ (phosphate group) > 3’ (hydroxyl group)
  • Allows DNA to twist into a double helix
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11
Q

What does RNA stand for?

A

Ribonucleic acid

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12
Q

What is the structure of RNA?

A
  • Single polypeptide chain
  • Sugar phosphate backbone + RNA bases
  • Relatively short molecule
  • Contains phosphodiester bonds
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13
Q

What are the two complementary base pairs in RNA?

A
  • Adenine + Uracil
  • Guanine + Cytosine
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14
Q

What is the RNA nucleotide structure?

A
  • Ribose sugar
  • Phosphate group
  • 1 of 4 nitrogen containing bases
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15
Q

Define purines and give examples

A

Two carbon nitrogen ring bases
- Adenine
- Guanine

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16
Q

Define pyrimidines and give examples

A

One carbon nitrogen ring bases
- Thymine
- Cytosine
- Uracil

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17
Q

Define semi-conservative replication

A

Replication of DNA in which one strand in each new molecule is from the original DNA molecule.
Genetic continuity between generations of cells

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18
Q

What is the process of semi-conservative replication?

A

1) DNA helicase breaks hydrogen bonds between the complementary bases
2) Double helix unwinds creating two separate nucleotide strands
3) Each strand acts as a template strand for two new strands
4) Free DNA nucleotides are attracted to exposed complementary bases on template strands
5) DNA polymerase joins nucleotides forming phosphodiester bonds in a sugar phosphate backbone
6) Hydrogen bonds form between complementary bases on opposing strands
7) Each new DNA molecule consists of one original template strand and one new strand

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19
Q

Where does DNA polymerase bind on DNA molecule?
Give an explanation

A
  • Complementary to 3’ end of newly forming DNA strand
  • Only adds nucleotides to end of 3’ strand
  • Moves down the template strand in a 3’ to 5’ direction (anti-parallel)
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20
Q

What did Watson and Crick discover?

A
  • Determined DNA structure (carried genetic information
  • Theorised semi-conservative replication
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21
Q

What did Meselson and Stahl discover?

A

Validated semi-conservative replication (Experiments used sample of bacteria)

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22
Q

Describe Meselson’s and Stahl’s experiment

A

1) A sample of DNA is taken from two batches of of bacteria and spun in a centrifuge
2) N15 (heavy) containing DNA = settled lower in centrifuge tube
N14 (light) containing DNA = settled higher in centrifuge tube
3) Bacteria cultured in N15 was then put into broth containing only N14
4) DNA replication one round. Sample removed and spun in centrifuge
5) Semi-conservative replication took place.
New DNA molecules (lined in the middle) contained one old strand of DNA (heavy) and one new strand of DNA (light)

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23
Q

What does ATP stand for and what is its definition?

A
  • Adenine Triphosphate
  • An immediate source of energy in a cell that is used to fuel biological processes
  • A nucleotide derivative
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24
Q

What is the structure of ATP?

A
  • Ribose sugar
  • Adenine base
  • 3 phosphate groups
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26
What is the structure of water?
- 1 Oxygen atom - 2 Hydrogen atoms - Partially negative and partially positive charge - Polar molecule (shared electrons are pulled towards the oxygen atom)
27
Where is energy stored in ATP?
Energy is stored in the high energy bonds between phosphate groups
28
What are the 5 important properties of water?
1) Metabolite (e.g. condensation and hydrolysis reactions) as they are reactive 2) Important solvent as metabolic reactions occur faster when substances are dissolved, making a solution. This means substances are easily transported around the organism 3) Relatively high specific heat capacity due to hydrogen bonds as lots of energy is needed to break hydrogen bonds. This means less energy is available to increase temperature of water. This also means water can buffer (resist) changes in temperature. 4) Relatively high latent heat if vaporisation. This provides a cooling effect. Water molecules on surface evaporate and escape as a gas. This means little water is lost through evaporation. As evaporation carries away heat energy from surface, this lowers the temperature 5) Cohesive. Due to polarity, water molecules stick together. This rams water can flow (transportation). This creates a high surface tension which means small organisms can walk on water.
29
How are water molecules held together?
Held together by hydrogen bonds. This is due to the partial charges on the oxygen atom and the hydrogen atoms
30
What is a cation?
Positively charged because of a loss of electrons
31
What is an anion?
Negatively charged because of a gain of electrons
32
Define an inorganic ion
An ion that doesn’t usually contain carbon
33
Where are inorganic ions found?
- Found in solutions: Cytoplasm of cells Tissue fluid (interstitial fluid) Blood Lymph Kidney fluids - Each have a specific role depending on their properties - Role determines whether it is found in high or low concentrations
34
What are the types of inorganic ions? (3)
- Iron (Fe 2+) - Phosphate ions (PO4 3-) - Sodium ions (Na +)
35
What is the function of Fe 2+ ? What is its structure?
Carries oxygen around the body in red blood cells → 4 polypeptide chains → each with iron ion centre → Fe 2+ + 02 (oxyheemoglobin) → Fe 2+ temporarily becomes Fe 3+ until oxygen is released
36
What is the function of PO4 3-?
When attached to another molecule, it becomes a phosphate group
37
What is the function of Na+ ?
- Involved in co-transport - Process by which two molecules are simultaneously transported across a membrane using a carrier protein e.g. absorption of glucose and amino acids in the ileum
38
What is the function of H+ ?
Concentration of hydrogen ions determine pH in an environment - More H+ present = lower pH - pH = -log[H+]
39
Define ion
Atom/ group of atoms with an electric charge by doing or gaining electrons
39
Define digestion
The process by which large, biological molecules are hydrolysed to smaller molecules that can be absorbed across cell membranes
40
When carbohydrates are digested, what is produced
Carbohydrates > disaccharides > monosaccharides
41
What enzymes help digest carbohydrates into 1) disaccharides 2) monosaccharides ?
1) Amylase 2) Membrane bound disaccharides
42
How does amylase help digest carbohydrates into disaccharides?
- Carbohydrates > disaccharides - Digestive enzymes that catalyses the breakdown of starch - Produces by: salivary glands > secreted into the mouth Pancreas > secreted into small intestine
43
How do membrane bound disaccharides help digest carbohydrates into monosaccharides?
- Disaccharides > monosaccharides - Enzymes bound to the membrane of epithelial cells lining to the ileum
44
What do amylase and membrane bound organelles hydrolyse?
Glycosidic bonds
45
What disaccharidase hydrolyses sucrose? What are the products?
Sucrase hydrolyses sucrose into glucose and fructose
46
What disaccharidase hydrolyses maltose? What are the products?
Maltese hydrolyses maltose into glucose
47
What disaccharidase hydrolyses lactose? What are the products?
Lactase hydrolyses lactose into glucose and galactose
48
What does the digestion of lipids produce?
Digestion of lipids produces fatty acids and monoglycerides
49
What are lipase enzymes? Where are they produced?
- Digestive enzymes that catalyses the breakdown of lipids - Produced by the pancreas and secreted into the small intestine
50
What do bile salts do? Where are they produced?
- Emulsify lipids into small droplets - Produced by the liver
51
When lipids are hydrolysed, what do the monoglycerides and fatty acids bind to? What do they form?
Bind with bile salts to form micelles
52
What are micelles?
Aid the absorption of monoglycerides and fatty acids
53
What do lipase enzymes hydrolyse?
Ester binds
54
What are proteins digested into?
Amino acids
55
What are peptidases/proteases?
Digestive enzymes that catalyse the breakdown of proteins
56
What are the three types of peptidases/proteases?
- Endopeptidases - Exopeptidases - Dipeptidases
57
What do endopeptidases do? Give examples
Hydrolyse peptide bonds within a polypeptide chain to create shorter polypeptide fragments E.g. Trypsin = produced in pancreas and secreted into small intestine Pepsin = produced in the stomach
58
What do exopeptidases do?
Hydrolyse peptide bonds at the ends of polypeptide chain (removes single amino acids)
59
What do dipeptidases do
Separate two amino acids that make up a dipeptide Often membrane bound to epithelial cells of the ileum
60
What do all peptidases hydrolyse?
Peptide bonds
61
What are the three parts of the small intestine?
Duodenum Jejenum Ileum
62
Where are products for digestion absorbed into?
Absorbed across ileum epithelium into the bloodstream
63
What are the products of digestion (3) ?
Monosaccharides Monoglycerides/fatty acids Amino acids
64
How are monosaccharides absorbed after being produced by digestion?
- Glucose/galactose = absorbed by active transport via a co-transport protein - Fructose = absorbed by facilitated diffusion via a transporter protein
65
How are monoglycerides/fatty acids absorbed after being produced by digestion?
- Micelles help move monoglycerides and fatty acids towards the epithelium (allows them to be absorbed) - Monoglycerides and fatty acids are lipid soluble - Diffuse directly across the epithelial cell membrane
66
How are amino acids absorbed after being produced by digestion?
Carried by sodium ions into epithelial cells
67
How does the sodium potassium pump work?
1) Sodium ions are actively transported out of the epithelial cells, through the ileum and into the blood by the sodium potassium pump 2) Now there is a higher concentration of sodium ions into the lumen of the ileum than the inside of the epithelial cell 3) This causes sodium ions to diffuse from the liken of the ileum into the epithelial cell down their concentration gradient using a sodium glucose transporter protein 4) As co-transporter brings in sodium (down its concentration gradient) it also transports glucose (against concentration gradient) for the liken into the cell 5) The concentration of glucose inside the epithelial cell increases 6) Glucose diffuses out of the epithelial cell into the blood down its concentration gradient through a channel protein by facilitated diffusion
68
Why is there a high quantity of mitochondria in epithelial cells?
For a high production of ATP from respiration

Biology (6 decks)

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