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Biology HL IB Flashcards > Unit 2: Molecules > Flashcards

Unit 2: Molecules Flashcards

(53 cards)

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1
Q

What are the SI Units Prefixes?

A

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2
Q

Explain why carbon is the most suited for being the backbone of everything

A

Carbon:
- Since it has 4 valence electrons, It can form 4 single bonds and is thus suited for being the backbone due to its stability
- It allows carbs, lipids, proteins, and nucleic acids to form

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3
Q

What is a monomer and polymer + in the context of carbohydrates?

A

Monomer:
- Molecules that join to other similar molecules to form a polymer OR one unit of something
EX: DNA’s monomers are nucleotides + Polymer = DNA
Carbohydrates:
- Their monomers are monosaccharides + polymer = carbs

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4
Q

How are polypeptides formed?

A

Process:
- Polypeptides are made via condensation reactions which release a water molecule
- The OH/hydroxyl group is from both of the monosaccharide leaves. Leaving the molecule w one oxygen between them
- Bonds are usually formed between 1 and 4 prime carbon of diff. monosaccharides

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5
Q

What is a monosaccharide

A

Monosaccharides:
- Defined as a single sugar molecule
- Atoms C,H,O are always in a 1:2:1 ratio EX: C6H12O6
- hydrogen to oxygen ratio is 2:1

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6
Q

Carbohydrates are also broken down in digestion. What is the process?

A

Carbs:
- are broken via hydrolysis reactions
- Are defined by an addition of water to split apart the bond of a large molecule

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7
Q

How are carbohydrates classified?

A

Classification:
- is classified based on the # of sugar molecules
- one sugar are called monosaccharide, two are disaccharides, and many are polysaccharides + poly are the energy for organisms

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8
Q

Define hexose sugars and pentose sugars

A

Hexose:
- are monosaccharides with 6 carbon
EX: Glucose, galactose, fructose
Pentose:
- monosaccharide w 5 carbons
EX: deoxyribose and ribose

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9
Q

What are alpha and beta glucose and its differences

A

Glucose:
- are types of glucose and hexose sugars
- alpha: at the one prime carbon, the hydroxyl group is pointed up
-Beta: at the one prime carbon, the hydroxyl group is going down

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10
Q

Outline 3 properties of glucosej

A

Glucose:
1. is Soluble in water because it’s polar and can be dissolved in a polar solvent such as water
2. can be easily transported EX: in the bloodstream
3. relatively stable compound and doesn’t degrade as its being transported cause strong cov bonds 4. Yields a great amount of energy when the covalent bonds break

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11
Q

What are the energy sources in plants and it’s structure

A

Starch:
- Starch is made of amylose amylopectin
- Amylose: long chains of alpha glucose molecules
- Amylopectin: long chains of alpha glucose + branching of alpha glucose
- Starch is not soluble in water due to the size which allows for compact storage of starch grains w out affecting osmotic pressure
- After 20 glucose units, amylopectin has a branch
- They are bonded w glycosidic bonds
- are compact due to branching and coiling
Note: Starch is made of glucose molecules

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12
Q

What is the energy source for animals:?

A

Glycogen:
- is defined as a polysaccharide for short-term energy
- has cov bonds between 1 + 4 carbon and has branches of alpha glucose bonding to 6 prime carbon
- Its insoluble, and compact due to branches and coiling
Note: Glycogen is made of glucose molecules

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13
Q

What is the polysaccharide found in the cell wall of plants?

A

Cell wall:
- cellulose has long chains of beta glucose molecules which are unbranched
- molecules bonded between 1 + 4 carbon
- every second beta glucose molecule is flipped resulting in a straight chain
- Cellulose forms groups called microfibrils held together by hydrogen bonds
- Microfibrils have high tensile strength to maintain the structural integrity of cell wall

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14
Q

What are the different types of fatty acids and their composition?

A

Fatty acids:
- Contain a carboxyl group (-COOH) and a methyl group (-CH3)
- can be saturated: only contains single bonds between hydrocarbon chain
- can be unsaturated which means they have double bonds that are bent and are called kinks
- Amongst unsaturated, it can be monounsaturated or polyunsaturated meaning one or many double bonds

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15
Q

How does carbohydrate assist with membrane proteins ?

A

Mem proteins:
- glycoproteins have a carbohydrate chain
- the carb has a specific shape that can act as an antigen: the molecule that binds to a receptor on a cell surface for cell to cell communication (ID card)

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16
Q

Outline the roles of glycoproteins

A

Glycoproteins:
- cell to cell adhesion: interact with other glycoproteins to form tissue
- receptors: when hormones bind = changes metabolism in cell
- cell-cell communication: neurotransmitters bind to glycoproteins
- immune response: act as markers on cells allowing the immune system to distinguish outside cells
- act as an antigen which simulates an immune response = production of antibodies to remove pathogens

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17
Q

Outline the differences in fats and oils

A

Fats:
- fats are triglycerides which are solid at room temperature
- they have a higher MP and are usually saturated
- used by animals
Oils:
- oils are triglycerides that are liquid at room temperature w a lower MP
- fatty acids are unsaturated because the kinks mean they are more spread out so they turn liquid
- Oils are used by plants and fish

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18
Q

Outline the composition of triglycerides and phospholipids

A

Triglycerides:
- made of one glycerol molecule (a sugar) and 3 fatty acids

Phospholipids:
- made of one glycerol molecule + 2 fatty acids + one phosphate

  • both are formed via condensation reactions
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19
Q

Explain how triglycerides are good insulators

A
  • triglycerides are good insulators cause they have a low thermal conductivity
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20
Q

Outline the composition of steroids + whether they can diffuse across cell mem + examples

A

Steroids:
- they are lipids with 4 carbon rings +. a hydrocarbon chain
- They can diffuse through the cell mem cause they dissolve in fatty acid tail
EX: Oestradiol and testosterone

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21
Q

Outline the properties of water + give some examples of whr water can be found

A

Water:
- is polar, covalent, w weak charges at poles
- is dense as a liquid than a solid EX: ice floats in water
- can bond with 4 other water molecules

Examples:
- water makes up the cyto and is also found between cells as interstitail fluid because metabolic processes work best in an aqueous environment

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22
Q

What is electronegativity + explain why water is polar

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A

Electronegativity:
- the strength of attraction between an atom and its valence electrons

Water:
- oxygen has a more positive nucleus than hydrogen atoms and has greater attraction for the elctrons
- So electrons are shared unequally
- the hydrogen bonds of water are weak

23
Q

Explain why water is a good solvent

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A

Water:
- it dissolves stuff well EX: anyt polar will dissolve
- water forms hydrogen bonds with anything polar and pulls it apart

24
Q

What is the xylem in plants

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A

Xylem:
- a thin narrow tube that transports water and the nutrients in the water from the roots of the plant to the leaves
- This is due to capillary action: the ability of water to flow against gravity in a narrow space + the co/adhesion of water
- water sticks to the plant and also to other water molecules

25
Define cohesion, adhesion, and surface tension
Cohesion: - attraction between the same kind of molecules Adhesion: - Attraction between different kinds of molecules Surface tension: - property allowing liquid to resist external forces
26
Define buoyancy, viscosity, thermal conductivity, and specific heat capacity with examples in nature
Physical properties of water: Buoyancy: - defined as the upward force exerted by a fluid on something in the fluid - since liquid water is less dense than air, aquatic animals have more buoyancy in water and float easier - animal fat gives the animal more buoyancy Viscosity: - defined as a measure of a fluid's resistance to flow - Since water has a higher viscosity than air, many animals have a streamlined body to move more smoothly through the water Thermal conductivity: - the rate at which heat passes through the material and will vary based on the collision of particles - since water has a higher TC than air, animals in water lose heat faster - animals have adapted to the rapid heat loss in water such as no dorsal fin Specific heat capacity: - is defined as the energy required to raise the temp of 1g of a substance by 1 Celsius - water has a high heat cap of 4.186 j/g Celsius cause it has lots of hydrogen bonds to break - animal cells are resistant to temp change so it maintain body temp - metals can change temp quickly causing low heat cap cause they're better conductors - large bodies of water have high heat caps which is ideal for organisms that thrive in a range of temp
27
Discuss why ice was not present during pre-biotic earth + how water came to earth
Water: - water as ice was not present because the temp was too high + any gas water were moved by solar winds - water formed outside of solar system due to low temp - earth's water came from asteroids or carbonaceous chondrites from the "Late Heavy Bombardment"
28
What is the Goldilocks zone
Zone: - planets are in a goldilocks zone where their orbit around stars allows for liquid water - not too far from the sun and not too close - earth's temp is suitable for water cycle and for life
29
Describe the composition of DNA and RNA + how does nucleotides form
Comp: - made of a deoxyribose (sugar) + nitrogenous bases and a phosphate group - same for RNA except the sugar is ribose - These are called nucleotides which are formed via condensation reactions
30
Outline differences between RNA and DNA
RNA: - Single Stranded - Has AUCG bases (AU + CG) - has ribose sugar - has an extra oxygen off 3 prime carbon - relatively shorter DNA: - double-stranded or double helix - is anti-parallel - has ATCG bases (CG + AT)
31
What is the composition of a nucleotide + the comp of pentose sugars
Nucleotide: - Is defined as an organic molecule or pentose sugar, nitrogenous bases, and a phosphate group - pentose sugars have 5 carbon called primes - the fifth carbon is not on the molecule but instead bonded to a phosphate group. - oxygen takes the last spot
32
Define transcrption and translation
Transcription: - DNA code is transcribed to mRNA code - in nucleus Translation: - mRNA code is translated by ribosomes into a polypeptide sequence - in ribosomes
33
How many chromosomes does human usually have
Chromo: - 23 pairs
34
Define genes
sequences of nitrogenous bases which is a code for specific protein and determines amino acid sequence
35
What is a codon
3 nitrogenous bases
36
What are purines and pyrimidines
Purines: - bases w 2-ringed structure EX: A and G Pyrimidines: - bases w 1 ring structure EX: U, T, and C - pyrimidines bond with purines
37
What is the tetranucleotide hypothesis and how was it debunked
Tetranucleotide Hypothesis: - hypothesis that DNA had 4 strands and the DNA sequence is always TACG a - this was disproved by looking at the % of bases - since the % of bases within the sample is diff, then it can't always be TACG - the conc of A and T are relatively equal + vice versa
38
What is Chargaff's rule
Chargaff: - % of A = T and C=G are the same - A bonds with T and creates 2 hydrogen bonds - C and G bonds and creates 3 hydrogen bonds
39
Describe the discovery of DNA
DIscovery: - Watson and crick figured out the bases unions - Rosalind Franklin generated DNA crystal and shot x rays through which produced a double helix
40
What are nucleosomes
Nucleosome: - is defined as negatively charge DNA wrapped twice around a core of 8 histones proteins + another linker histone protein to hold nucleosome tgt
41
Explain the Hershey-Chase experiment
Experiment: - The purpose of this experiment is to find out whether protein or DNA was the genetic information - They let bacteriophages (which are viruses that infect bacteria with their genetic info) infect e coli - This particular bacteriophage had a DNA core and a protein coat - They labelled one w radioactive phosphorus and one w radioactive Sulfer because DNA contains phosphors and vice-versa - The bacteriophage infected the bacteria - They put the bacteria into a centrifuge to separate the heavy bacteria to come as a pellet - fhey checked if it had radioactivity and found it in the dna sample or phosphorus radioactive - This revealed that the bacteriophage injected DNA inside thus DNA must be the genetic information. Note: the substance in the centrifuge that isn't the pellet is called the supernatant
42
Outline the composition of an amino acid
Amino acid: - its made of an amine group, a central carbon or alpha carbon, and a carboxyl group + a side chain
43
What is the importance of the R side chain
R Side Chain: - R side chain determines the chemical characteristics of amino acids of an assembled polypeptide - can be categorized as hydrophilic or hydrophobic
44
How many types of amino acids are there
20 and all living organims share it
45
How do polypeptides form+ how are they bonded + How are they classified
Form: - Amino acids undergo condensation reactions to form polypeptides in the ribosome during translation - they are bonded with peptide bonds which is a type of covalent bond Classified: - 1 = peptide, 2 = dipeptide, 20 = Oligopeptide, 20+ = polypeptide or a protein
46
What is the difference between essential and nonessential amino acids + what are complete proteins
Essential: - are amino acids that need to be obtained via diet Non-essential: - are amino acids that the body are able to synthesize Complete: - complete proteins contain 9 essential amino acids EX: meat
47
Define denaturation + causes of denaturation
Denaturation: - is defined as a conformational change in the shape of a molecule such as protein that results in loss of function - when heated, the molecules vibrate a lot thus causing for the hydrogen bonds to break and ionic bonds break Causes: - could be due to pH or temp change - it breaks that hydrogen bonds
48
Describe the primary structure in protein folding
Primary: - the primary structure simply establishes the sequence of amino acids - they are formed via condensation reactions and bonded w peptide bonds - Theres always a free amine group and a carboxyl group at the end as well
49
Describe the secondary structure
Secondary: - the protein starts to fold - its held tgt with hydrogen bonds between oxygen of carboxyl and the hydrogen of amino group - they can either be folded into a alpha helix or a beta pletaed sheet
50
Describe the tertiary structure
Tertiary: - further folding of proteins due to the R-group interactions - interactions include covalnet, ionic, and hydrogen bonds forming - an example of cov bond are disulfide bridges between cysteine - in this stage, the hydrophobic amino acids will be in the globular proteins while the hydrophilic will be on the outside
51
Describe quaternary
Quaternary: - different polypeptides come tgt and r group from diff polypeptides are keeping them tgt - r group interactions are the same as tertiary
52
What are conjugated proteins + Non conjugated proteins
Conjugated: - a conjugated protein is a protein attached to a non-polypeptide group which is called a prosthetic group EX: hemoglobin Non Conjugated: - non-conjugated proteins are composed of only polypeptides EX: insulin
53
Describe the structure of collagen and insulin + their uses
Collagen: - is a fibrous protein composed of 3 polypeptide chains that are tightly coiled tgt in a triple helix structure - main structural protein in connective tissue + provides structural support - bonded together by disulfide bonds Insulin: - is a globular protein that is composed of two polypeptide chain that are inked by 2 disulfide bridges - helps with blood regulation as it causes the liver to remove glucose from blood - bonded together w hydrogen bonds Note: we can use cryogenic microscopy to observe protein structure

Biology HL IB Flashcards (4 decks)

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