Brainscape's Knowledge GenomeTM

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


See full index

IB Biology SL > Molecular Biology > Flashcards

Molecular Biology Flashcards

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

What is organic chemistry?

A

The study of the properties and structures of organic compounds

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

What is an organic compound? (2)

A
  1. Organic compound: A compound that contains carbon and is found in living things
  2. All organic compounds have carbon backbones, however not all carbon compounds are organic (Ex: CO2, urea)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the important properties of carbon? (4)

A
  1. Carbon-carbon bonds are strong and stable due to their covalent bond
  2. As a result, carbon can form an almost infinite number of compounds include long carbon chains.
  3. No other element can bond like this
  4. Therefore, carbon forms the basis of organic life due to its ability to form large and complex molecules via covalent bonding
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define metabolism

A

The web of all enzyme-catalyzed reactions in a cell or organism

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

Define anabolism

A

The synthesis of complex molecules from simpler units, it requires energy (formation of macromolecules from monomers)

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

Define catabolism

A

The breakdown of complex molecules into simpler units, it releases energy (formation of monomers from macromolecules)

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

What is the difference between condensation and hydrolysis reactions? (3)

A
  1. Carbon compounds can be formed using condensation, or broken using hydrolysis:
  2. Condensation makes bond, releases water and is an anabolic reaction
  3. Hydrolysis breaks bond, requires water, and is a catabolic reaction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What was the theory of vitalism and how was it disproved? (2)

A
  1. Vitalism was a belief that organic molecules can only be synthesized by living things
  2. However, in 1800 urea was produced from inorganic chemicals (ammonium cyanate) proving organic molecules don’t have to be synthesized by living things.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe how water is structured (3)

A
  1. Water (H2O) is composed of two hydrogen atoms covalently bonded to an oxygen atom
  2. The bond formed between the oxygen and hydrogen are referred to as a polar (unequal share of electrons) covalent bond
  3. The oxygen atom is slightly negative (δ-) while the hydrogen atoms are slightly positive (δ+) therefore the slightly charged regions of the water molecule can attract other polar or charged compounds and gives water special properties
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is cohesion? (4)

A
  1. An attraction between molecules of the same type
  2. This property occurs in water as a result of its polarity and its ability to form hydrogen bonds
  3. Even though hydrogen bonds are weak the large number of bonds present in water can give cohesive forces strength
  4. E.g: Surface tension allows some organisms to rest or move on top of water’s surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is adhesion? (4)

A
  1. An attraction between two unlike molecules
  2. This property occurs between water and other molecules as a result of waters polarity and its ability to form hydrogen bonds
  3. Individual hydrogen bonds are weak, but large number of bonds gives adhesive forces strength. Therefore, water molecules tend to stick to other molecules that are charged or polar just like cohesion
  4. Example: Water moves up the stems of plants because in addition to being attracted to itself (cohesion) it is also attracted to the side of the stem (adhesion). Water is so highly attracted to the sides of the stem that it pulls itself up against the force of gravity without any energy input from the plant - transpiration stream.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the solvent properties of water? (2)

A
  1. Water can dissolve any substance that contains charged particles (ions) or electronegative atoms (polarity)
  2. This occurs because the polar attraction of large quantities of water can sufficiently weaken intramolecular forces and result in the dissociation of the atoms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the thermal properties of water?

A
  1. Water has a high specific heat capacity - able to absorb a lot of energy before changing states e.g. sweat and cells
  2. This enables:
    o Aquatic organisms who can’t survive extreme temperature changes
    o Plants who have openings in their leaves called stomata to let vaporizing water out in order to cool down the left
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the differences in the thermal properties between methane and water? (3)

A
  1. The differences in thermal properties between water and methane arise from differences in polarity between the molecules
  2. While Water is polar and can form intermolecular hydrogen bonds which increases the amount of energy to break it, methane is non-polar and can only form weak dispersion forces between its molecules
  3. This means water absorbs more heat before changing state and so:
    o Boiling point of water is greater than methane
    o Melting point of water is greater than methane
    o Latent heat of vaporization of water is greater than methane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why is methane comparable to water? (2)

A
  1. Comparable size and weight (H2O = 18 dalton ; CH4 = 16 dalton)
  2. Comparable valence structures (both have tetrahedral orbital formations, but water is bent due to unbonded electron pairs)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Explain the use of water as a coolant in sweat

A
  1. The change of water from liquid to vapour (evaporation) requires an input of energy
  2. This energy comes from the surface of the skin when it is hot, therefore when the sweat evaporates the skin is cooled
  3. Because water has a high specific heat capacity, it absorbs a lot of thermal energy before it evaporates
    Thus water functions as a highly effective coolant, making it the principal component of sweat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the different classes of carbohydrates? (3)

A

Carbohydrate is another term for sugar. Carbohydrates can be classified into three classes depending on their complexity:

  1. Monosaccharides: Monomers of polysaccharides, the simplest carbohydrate e.g glucose, galactose and fructose
  2. Disaccharides: A molecule formed by condensation reactions between two monosaccharides e.g maltose, lactose and sucrose
  3. Polysaccharides: Polymers with more than 2 molecules linked together in different ways by condensation reactions e.g. glycogen, cellulose and starch.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the structure of a fatty acid? (3)

A
  1. Fatty acids consists of a straight chain of an even number of carbon atoms, with hydrogen atoms
  2. Fatty acids all have a methyl group (CH3) on one end and a carboxyl group (COOH) at the other end.
  3. CH3 ——-(CH2)n ——– C =====OOH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the three classes of lipids? (3)

A
  1. Phospholipids - they are made from a glycerol bonded to two fatty acids and one phosphate group. They are only partly hydrophobic and form the basis of membranes
  2. Steroids all have a similar structure of four fused rings in their molecules. Include cholesterol, progesterone, oestrogen and testosterone
  3. Triglycerides are the largest class of lipids and primarily function as a long-term energy storage. They are made from one glycerol bonded to three fatty acids glycerol by condensation reactions. E.g. fats and oils.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Compare the use of carbohydrate and lipids in energy storage

A
  1. Carbohydrates are usually used for short term storage whereas lipids are used for long term storage. 2. Carbohydrates are soluble in water unlike lipids. This makes carbohydrates easy to transport around the body (from and to the store).
  2. Carbohydrates are more easily and more rapidly digested so their energy is useful if the body requires energy fast. (aerobic and anaerobic respiration).
  3. Since lipids are insoluble they do not have an effect on osmosis which prevents problems within the cells in the body.
  4. Lipids also contain more energy per gram than carbohydrates which makes lipids a lighter store compared to a store of carbohydrates equivalent in energy. (Twice as much ATP per gram)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is BMI? (3)

A
  1. BMI is commonly used as a screening tool to identify potential weight problems
  2. BMI=(Weight (in kg))/(Height^2 (in m)) or use of nomogram
  3. However, BMI calculations should not solely be used as a diagnostic tool and should be used in conjunction with other measurements. Also BMI values are not a valid indicator for pregnant women
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How are blood cholesterol levels regulated? (6)

A
  1. Fats and cholesterol cannot dissolve in blood and are consequently packaged with proteins (to form lipoproteins) for transport:
    Low density lipoproteins (LDL) carry cholesterol from the liver to the rest of the body
    High density lipoproteins (HDL) scavenge excess cholesterol and carry it back to the liver for disposal
  2. Hence LDLs raise blood cholesterol levels while HDLs lower blood cholesterol levels
  3. Saturated fats increase LDL levels within the body, raising blood cholesterol levels
  4. Trans fats increase LDL levels and decrease HDL levels within the body, significantly raising blood cholesterol levels
  5. Unsaturated (cis) fats increase HDL levels within the body, lowering blood cholesterol levels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How do polypeptides differ from one another? (3)

A

o Their length (number of amino acids)
o Amino acids that are present
o Order of the amino acids - this is what gives each polypeptide its unique properties

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

What are peptide bonds? (4)

A
  1. Amino acids are linked together in proteins by a special kind of covalent bond known as a peptide bond or amid link
  2. Peptide bonds are formed by condensation reactions between the amino group of one amino acid and a carboxyl group of another amino acid
  3. A water molecule H2O is also formed
  4. Polypeptide chains can be broken down via hydrolysis reactions, which requires water to reverse the process
25
Q

Outline the 4 levels of protein structure (4)

A
  1. The primary structure refers to the sequence of amino acids in the polypeptide chain. This sequence is unique to that protein, and defines its structure and function
  2. The secondary structure of a protein refers to the folding of the polypeptide as a result of hydrogen bonding (Alpha-helix or beta-pleated sheets)
  3. The tertiary structure of a protein refers to the twisting and folding of the secondary structure to form a specific 3D shape (held together by interactions between the side chains (The R groups))
  4. The quaternary structure of proteins refers to the interactions between polypeptide chains
26
Q

What is denaturation? (3)

A
  1. A structural change of a protein that results in the loss of its biological properties
  2. Due to heat - Heat causes vibrations within protein molecules that break intramolecular bonds and cause the conformation to change. (Irreversible)
  3. Due to pH - pH changes causes intramolecular bonds to break
27
Q

What are enzymes?

A

Enzymes are (globular) proteins that act as biological catalysts, increasing reaction rates of biological processes without being used up in the process

28
Q

List some examples of proteins and their functions (8)

A

Collagen - Used in skin to prevent tearing, in bones to prevent fractures, and ligaments to give tensile strength
Spider silk - Used to make webs for catching prey and lifelines on which spiders suspend themselves. It has very high tensile strength and becomes stronger when stretched
Insulin - Is carried dissolved in blood and binds specifically and reversibly to insulin receptors in the membranes of body cells, causing the cells to absorb glucose and lower glucose concentration
Immunoglobulins - Antibodies that bind to antigens on pathogens
Haemoglobin - A protein found in red blood cells that is responsible for the transport of oxygen
Cytochrome - A group of proteins located in the mitochondria involved in electron transport chain
Rhodopsin - A pigment in the photoreceptor cells of the retina that is responsible for the detection of light
Rubisco - An enzyme involved in the light independent stage of photosynthesis

29
Q

Explain the differences between the lock and key theory and the induced- fit model (4)

A
  1. Enzymes are extremely particular, and each enzyme only binds with one particular substrate
  2. The induced-fit model is based on the lock-and-key model. The lock-and-key model states that the substrate acts as a “key” to the “lock” of the active site
  3. The induced-fit model is a theory that says the active site will change shape to enfold a substrate molecule
  4. Instead of the active site and substrate being perfect matches, the substrate induces a change of shape in the enzyme
30
Q

Outline the different factors affecting the enzymes (3)

A
  1. Temperature
    Increasing temperature increases enzyme activity since
    collisions between substrate and active site happen more frequently due to faster molecular motion at higher temperatures. However, at high temperature the enzymes will become denatured and stop working.
  2. pH levels
    Increasing pH increases enzyme activity to an optimum point. Increasing pH beyond this optimum point will reduce enzyme activity due to denaturation
  3. Concentration
    Increasing substrate concentration increases enzyme activity. This is because random collisions between substrate and active site happens more frequently with higher substrate concentrations. However, at high substrate concentrations the active site of the enzyme is saturated therefore raising the substrate concentration has little effect on enzyme activity.
31
Q

What are immobilized enzymes? (2)

A
  1. An immobilized enzyme is an enzyme attached to an inert, insoluble material.
  2. Enzyme immobilization therefore involves restricting enzyme mobility in a fixed space
32
Q

Advantages and disadvantages of immobilized enzymes

A

Advantages:
Enzymes can be reused
Enzymes are more stable and less likely to denature because they are binded to a surface
There will be no enzyme left in the product as enzymes are immobilized. Thus, purification is not necessary

Disadvantages:
Requires extra time, equipment and work
May be a reaction in reaction rates if enzymes cannot mix freely with the substrate
Immobilized enzymes cannot be used if one of the substrate is insoluble

33
Q

Advantages of lactose free dairy products (3)

A

o As a source of dairy for lactose-intolerant individuals
o As a means of increasing sweetness in the absence of artificial sweeteners
o To reduce crystallization of ice creams

34
Q

What is the structure of nucleic acids

A

Nucleic acids are composed of nucleotide monomers which are linked into a single strand via condensation reactions

35
Q

What are the differences between DNA and RNA nucleotides? (2)

A
  1. The type of pentose is ribose in RNA but deoxyribose in DNA
  2. In both DNA and RNA there are four possible bases. There of these are the same. However the fourth base is thymine in DNA but uracil in RNA
36
Q

Watson and Crick

A

Watson and Crick were able to assemble a DNA that showed that:

  1. DNA strands are antiparallel and form a double helix
  2. DNA strands pair via complementary base pairing
  3. However, their first model showed that DNA had a triple helix
  4. The final construction of a correct DNA molecule owed heavily to the X-ray crystallography data generated by Franklin
37
Q

Explain the importance of DNA helicase (3)

A
  1. DNA helicase separates the two polynucleotide strands of DNA by breaking the hydrogen bonds between complementary base pairs
  2. ATP is needed by helicase to both move along the DNA molecule and to break the hydrogen bond
  3. The two separated strands become parent/template strands for the replication process. There are now a bunch of free nucleotides present in the nucleus
38
Q

Explain the importance of DNA polymerase (3)

A
  1. DNA polymerase links nucleotides together to form a new strand, using the pre-existing strand as a template
  2. DNA polymerase moves in a 5’ to 3’ direction
  3. There are very few mistakes because A can only bond with T and G with C, therefore it ensures that the new strand is complementary to the parent strand, and therefore identical to the other original parent strand
39
Q

Semi-conservative (4)

A
  1. DNA replication is said to be semi-conservative, because each strand contains one original and one new strand
  2. The original DNA strands are split into two and each half is used as a template to make the complementary strand (the other half). The complementary strands are made using free nucleotides that are floating around the nucleus.
  3. This was proven by the Meselson-Stahl experiment in 1958. Meselson and Stahl used radioactive isotopes of nitrogen. • Nitrogen is a key component of DNA and can exist as a heavier 15N or a lighter 14N. DNA samples were then separated via centrifugation to determine the composition of DNA in the replicated molecules. After one division DNA molecules were found to contain a mix of either nitrogen isotopes disproving the conservative model. After two divisions, some molecules of DNA were found to consist solely of 14N
  4. Conservative model: An entirely new molecule is synthesized from a DNA template (which remains unaltered)
    Semi conservative model: Each new molecule consists of one newly synthesized strand and one template strand
    Dispersive mode: New molecules are made of segments of new and old DNA
40
Q

What are the three main types of RNA? (3)

A
  1. MRNA (messenger RNA): Serves as a temporary copy of DNA and carries the DNA codes from the nucleus to the ribosome
  2. rRNA (ribosomal RNA): Makes up the ribosome
  3. tRNA (transfer RNA): Carries a specific amino acid to the ribosome and adds it to the growing polypeptide chain
41
Q

What is transcription? (5)

A
  1. Transcription is the synthesis of mRNA copied from the DNA base sequences by RNA polymerase
  2. This process occurs in the nucleus and results in a molecule of mRNA
  3. However, transcription is not used for long-term storage (temporary copy) and can freely exist only in the nucleus
  4. The two nucleotides are temporarily separated in transcription opposed to translation where they would be permanently separated
  5. Transcription uses an enzyme called RNA polymerase and a number of necessary proteins called transcription factors
42
Q

Describe the process of transcription (4)

A
  1. RNA polymerase separates the DNA strands and synthesizes a complementary RNA copy from one of the DNA strands
  2. When the DNA strands are separated, ribonucleotide triphosphates align opposite their exposed complementary base partner
  3. RNA polymerase removes the additional phosphate groups and uses the energy from this cleavage the covalently join the nucleotide to the growing sequence
  4. Once the RNA sequence has been synthesizes, RNA polymerase detaches from the DNA Molecule and the double helix reforms
43
Q

What is translation?

A
  1. Translation is the process of converting a sequence of mRNA nucleotides to a sequence of amino acids
  2. This process occurs in the cytoplasm and results in a polypeptide chain (protein)
  3. Groups of three letters on DNA are called triplets; Groups of three letters on mRNA are called codons; Groups of three letters on tRNA has anticodons
44
Q

Describe the process of translation

A
  1. Ribosomes bind to mRNA in the cytoplasm and move along the molecule in a 5’ – 3’ direction until it reaches a start codon (AUG)
  2. Anticodons on tRNA molecules align opposite appropriate codons according to complementary base pairing (e.g. AUG = UAC)
  3. These two form a hydrogen bond together. Another transfer RNA molecule then bonds since two tRNA molecules can bind at once.
  4. Each tRNA molecule carries a specific amino acid (according to the genetic code)
    Ribosomes catalyse the formation of peptide bonds between adjacent amino acids (via condensation reactions)
  5. The ribosome moves along the mRNA molecule synthesising a polypeptide chain until it reaches a stop codon
  6. At this point translation ceases and the polypeptide chain is released
45
Q

What are the uses of ATP (3)

A

o Synthesis of macromolecules. This include DNA, RNA and proteins
o Active transport
o All movements in the cell, such as muscle contraction, endocytosis, exocytosis, etc

46
Q

Outline aerobic respiration

A

If oxygen is available, the pyruvate is taken up into the mitochondria and is broken down into carbon dioxide and water. It also produces
A large yield of ATP(~34 – 36 molecules)

47
Q

Outline anaerobic respiration

A
  1. Starts with glucose (6 carbons)
  2. An enzyme modifies to make it unstable
  3. A series of reactions splits the glucose into 2 molecules of pyruvate (3 carbons each)
  4. The energy from the bond that are broken in this process are used to generate 2 ATP molecules
48
Q

What is fermentation? (2)

A
  1. The breakdown of organic molecules for ATP production anaerobically
  2. takes place in the cytoplasm as it is anaerobic
49
Q

Use of yeast in industry (3)

A
  1. Yeast is used in baking bread. It is mixed into the dough before baking
  2. The yeast rapidly uses up all oxygen present in the dough and then produces ethanol and carbon dioxide by anaerobic cell respiration. The carbon dioxide forms bubbles making the dough rise
  3. Yeast can be used to produce ethanol by fermentation. The yeast is cultured in a liquid containing sugar and other nutrients, but not oxygen so its respires anaerobically
50
Q

Outline aerobic respiration (3)

A

If there is oxygen present organisms will undergo aerobic respiration in the mitochondria:
1. Pyruvate (from glycolysis) and oxygen enter the mitochondria
2. The pyruvate is completely broken down during reactions called the Krebs cycle and electron transport chain
3. Water, carbon dioxide and ATP are generated (along with heat)
• This produces 36ATP

51
Q

What is photosynthesis?

A
  1. The synthesis of energy rich molecules (like glucose) from carbon dioxide and water using light energy/ production of carbon compounds in cells using light energy.
  2. 6CO2 + 6H2O → C6H12O6 + 6O2
  3. Requires a photosynthetic pigment (chlorophyll) a
  4. Is a two step process: light dependent (light-> ATP) and light independent (ATP-> carbon compounds)
52
Q

What factors affect photosynthesis? (3)

A

CO2 Levels
• Increasing CO2 concentration increases the rate of photosynthesis, until the photosynthetic enzymes involved in the cycle reach their saturation point and can no longer increase reaction rates

Temperature
• At low temperatures the enzymes involved in photosynthesis reactions work very slowly. The rate of reaction increases steadily as temperature increases until reaching an optimum point when all enzymes are working at a high rate. When the temperature surpasses this optimal point enzymes can be denatured once again decreasing photosynthetic rate

Light intensity
• At low light intensities, rate of photosynthesis is limited. Photolysis which requires the absorption of light waves slow down, and thus so does oxygen and ATP production. The graph levels off once all the enzymes and reactions are occurring at the highest speed possible

53
Q

What is chlorophyll?

A

1.Chlorophyll is a green pigment found in photosynthetic organisms that is responsible from light absorption
2. It is found in thylakoid membranes
3. Chlorophyll absorbs blue and red light
light most strongly but reflects green

54
Q

Visible light

A

Visible light has a range of wavelengths with violet the shortest wavelength and red the longest. (between 400 and 700 nanometres)

55
Q

How can rates of photosynthesis be measured?

A

Measuring CO2 uptake
• Carbon dioxide uptake can be measured by placing leaf tissue in an enclosed space with water. Data logger.

Measuring O2 uptake
• Oxygen production can be measured by submerging a plant in an enclosed water filled space attached to a sealed gas syringe

Measuring Biomass (Indirect)
•	Glucose production can be indirectly measured by a change in the plant’s biomass (weight)
•	This requires the plant tissue to be completely dehydrated prior to weighing to ensure the change in biomass represents organic matter and not water content
•	An alternative method for measuring glucose production is to determine the change in starch levels (glucose is stored as starch)
•	Starch can be identified via iodine staining (turns starch solution purple) and quantitated using a colorimeter
56
Q

What is the electromagnetic spectrum?

A
  • The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation
  • The shorter the wavelength the greater the energy and vice versa
  • Photosynthesis with other wavelengths should be possible, as long as it contains energy
57
Q

What is photolysis?

A

When photons (light) are used to split (lysis). The reason for this reaction is because some plants need some e- and H+ during photosynthesis, thus they split water and produce oxygen as a waste product
• Photolysis occurs in the thylakoid
• The equation: 2H2O -> 4e- + 4H+ + o2
• ATP is also produced as a product
• Oxygen is produced as a waste product of photosynthesis

58
Q

What is an absorption/Action Spectrum?

A
  • The absorption spectrum indicates the wavelengths of light absorbed by each pigment
  • The action spectrum indicates the overall rate of photosynthesis at each wavelength of light
  • As you can see from the absorption spectrum green is reflected while blue and red are absorbed the most, with blue having a shortest wavelength

IB Biology SL (7 decks)

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