A1.1 B1.1 A1.2 B1.2 Flashcards
1
Q
What physical and chemical properties of water make it essential for life?
A
Polarity and Hydrogen Bonding:
High Heat Capacity:
Cohesion and Adhesion:
Density Anomaly:
Universal Solvent:
2
Q
What are the challenges and opportunities of water as a habitat?
A
Challenges: Limited oxygen availability, temperature fluctuations, pollution, and high pressure in deep waters.
Opportunities: Stability in temperature, abundant nutrients, and buoyancy that supports large organisms.
3
Q
What is water?
A
Water is the medium for life. It is a metabolite. It is a temperature buffer.
4
Q
Where did the first cells originate?
A
In water
5
Q
What are the two types of water reactions?
A
Condensation reaction: When water is formed as one of the products when two molecules join together.
Hydrolysis Reaction: When water reacts with a chemical to break it into smaller molecules.
6
Q
How is water a temperature buffer?
A
it buffers temperature changes in cells because of its relatively high specific heat capacity.
7
Q
How does water contribute to the formation of cell membranes?
A
Phospholipid heads interact with water, while the tails try to avoid water. Thus, they spontaneously form bilayers. with heads out and tails in.
8
Q
How does water impact the folding of proteins?
A
Water drives the folding of amino acid chains as different amino acids seek and avoid interacting with water. Without proper shape, they could not perform function. (does this because of polarity of molecule)
9
Q
How does water help with structure of double heliX of DNA?
A
THE PHOSPHATE, SUGAR BACKBONE IS POLAR AND THE NITROGENOUS BASE IS NON POLAR.
10
Q
What is a non-polar covalent bond?
A
When two atoms are equal in size, electrons are shared equally.
11
Q
What is a polar covalent bond?
A
Electrons are shared unequally between a large and a small atom. The electrons spend more time around the large atom. These atoms have a partial dipole/ partially charged.
12
Q
What is a hydrogen bond?
A
Attraction between two polar molecules. A weak bond between hydrogen and something else.
13
Q
Why do hydrogen bonds form between water molecules?
A
Because of the difference in charge between the oxygen and hydrogen atoms in a water molecule
14
Q
How do water molecules transport in plants under pressure?
A
There is greater water potential in the ground and roots and less in the leaves and atmosphere so water is brought through the plant.
15
Q
In chemistry what does organic mean?
A
Contains carbon, synthesized by living organisms
16
Q
Why is carbon so diversifiable?
A
It is able to form 4 covalent bonds, which are strong bonds. Because of the stability, large molecules with many bonds can be formed.
17
Q
What can be special about the structure of carbon molecules?
A
Different bonds can lead to different structures (double and single, tripple) these create different carbon compounds
18
Q
What is a hydrocarbon?
A
Molecules with only carbon and hydrogen. ex. ribose is a five carbon sugar in RNA.
19
Q
What are isomers? and 3 types
A
Molecules with the same molecular formula but different structures and properties. Structural, Geometric, Enantiomers.
20
Q
How many bonds will a carbon atom have?
A
Always 4
21
Q
What is a functional group?
A
A chemical group with distinct properties that behave differently in chemical reactions. Differences in one functional group may have significant effects on properties of molecule.
22
Q
Why is cholesterol significant?
A
Cholesterol is the backbone of testosterone, estrogen, is synthesized in the sER.
23
Q
7 functional groups to know
A
Hydroxyl > (C-OH) ex. Alcohol
Carbonyl > (C=O)
Carboxyl > (-COOH)
Amino > (-NH2)
Sulfhydryl > (-SH)
Methyl > (—OPO32−)
Phosphate > (—CH3)
24
Q
What type of chemical reaction allows molecules to combine and form a single molecule?
A
Condensation, usually with the loss of a small molecule such as water.
25
What is the opposite of condensation?
Hydrolysis needs water to make reaction. or when a chemical compound is broken down by reaction with water.
26
What is a phosphodiester bond?
C - O - P - O - C with two ester bonds. Bonds in DNA + RNA backbones
27
What are the emergent properties of water, and why are they important?
1. Cohesion/adhesion (water transport in plants),
2. high surface tension (habitats for insects),
3. high specific heat capacity (temperature stability),
4. high heat of vaporization (cooling via sweating),
5. unique density (ice floats, insulating water bodies), 6.universal solvent (dissolves substances),
7. buffering capacity (pH regulation), 8.hydrophilic/hydrophobic interactions (cell membranes),
9. hydrogen bonding (key to properties).
28
How do hydrogen bonds in water help biological processes?
Hydrogen bonds enable cohesion (water sticks to itself), adhesion (water sticks to other surfaces), and surface tension, supporting water transport in plants, blood flow in animals, and cellular membrane stability.
29
What is the importance of water as a universal solvent?
Water dissolves nutrients and waste, enabling transport in systems like blood and plant sap. It helps regulate pH and supports homeostasis by moving ions and molecules efficiently.
30
Why is water a polar molecule?
Oxygen pulls shared electrons closer, giving it a partial negative charge (δ-), while hydrogen becomes slightly positive (δ+). This polarity enables hydrogen bonding between water molecules.
31
How do hydrogen bonds contribute to cohesion and adhesion?
Cohesion allows water molecules to stick together, aiding plant water transport. Adhesion helps water stick to surfaces, enabling capillary action in plants and nutrient movement.
32
How does water support metabolic processes in organisms?
Hydrophilic molecules dissolve in water for reactions. Hydrophobic molecules like lipids form cell membranes, controlling what enters and exits cells.
33
How do water’s physical properties benefit aquatic life?
Buoyancy supports organisms; high heat capacity stabilizes temperatures; and surface tension provides habitats for small organisms like insects.
34
Why is water significant in the search for extraterrestrial life?
Water supports life on Earth, so finding it on other planets suggests potential habitability. Planets in the "Goldilocks zone" may have liquid water, vital for life.
35
What allows water to support capillary action in plants?
Water's adhesion to polar surfaces and cohesion between molecules enable it to move against gravity through plant vessels, aiding nutrient and water transport.
36
How does water's high specific heat capacity benefit organisms and ecosystems?
It stabilizes temperatures in water bodies, creating a consistent environment for aquatic life and moderating climate patterns.
37
Why does water's unique density matter for aquatic ecosystems?
Ice floats because water is less dense in its solid form, insulating water below and allowing aquatic life to survive in winter.
38
How does hydrogen bonding influence water's surface tension?
It creates a strong cohesive force, allowing organisms like insects to move or rest on water surfaces.
39
How do hydrophilic and hydrophobic interactions affect cellular structures?
Hydrophilic molecules dissolve in water, facilitating reactions, while hydrophobic molecules form cell membranes, maintaining structure and function.
40
How does water facilitate the transport of dissolved minerals in plants?
Water dissolves nutrients in soil, enabling their uptake by roots and transport to other plant parts via vascular tissues.
41
How do water's thermal properties support life in extreme climates?
Water’s high heat of vaporization cools organisms through evaporation (e.g., sweating) and its heat capacity buffers temperature fluctuations.
42
How does water's viscosity impact aquatic animals?
Its low viscosity allows animals to move easily through water, conserving energy for swimming and hunting.
43
How does water regulate pH in biological systems?
Water acts as a buffer, dissolving acidic or basic substances to maintain a stable pH essential for enzyme activity and cellular function.
44
Why is water's retention on Earth crucial for life?
Gravity and favorable temperatures allowed water to condense and persist, creating conditions for the evolution and sustainability of life.
45
How does water's high heat of vaporization help organisms?
It allows water to absorb significant heat before evaporating, aiding in thermoregulation through processes like sweating and transpiration.
46
What makes water a universal solvent?
Its polarity enables it to dissolve many substances, including ions and polar molecules, facilitating metabolic reactions and nutrient transport.
47
Why is water essential for enzymatic reactions?
Most enzymes function in aqueous solutions where water dissolves substrates and enables the catalytic process.
48
How does water's buoyancy benefit aquatic life?
Buoyancy reduces the energy required for organisms to move, allowing efficient locomotion and stability in water.
49
What is the "Goldilocks zone," and why is it important for life?
It’s the region around a star where conditions are suitable for liquid water, making it critical for the potential development of life.
50
How does water's polarity affect its role in biological systems?
Polarity creates hydrogen bonds, enabling cohesion, adhesion, and solvent properties essential for biological processes.
51
Why are water's high boiling and freezing points biologically significant?
They allow water to remain liquid across a wide temperature range, supporting life in diverse environments.
52
How do hydrogen bonds support life at a molecular level?
They stabilize structures like DNA and proteins and facilitate the unique properties of water that support life.
53
How does water’s high thermal conductivity influence aquatic ecosystems?
It distributes heat efficiently, maintaining stable temperatures that support diverse aquatic life forms.
54
What is the primary difference between organic and inorganic compounds?
Organic compounds contain carbon-hydrogen bonds and include biomolecules like carbohydrates and proteins, while inorganic compounds lack these bonds and include salts, metals, and nonmetals.
55
How does carbon's atomic structure allow it to form diverse compounds?
Carbon’s four valence electrons enable it to form covalent bonds with other atoms, creating a variety of compounds.
56
What is carbon's tetravalency, and why is it important?
Carbon's tetravalency allows it to form up to four covalent bonds, enabling complex molecules like chains, branches, and rings.
57
What are the monomers of the four types of organic compounds?
Carbohydrates: Monosaccharides
Lipids: Fatty acids and glycerol
Proteins: Amino acids
Nucleic acids: Nucleotides
58
Define metabolism, catabolism, and anabolism.
Metabolism: All chemical reactions in an organism.
Catabolism: Breakdown of molecules, releasing energy.
Anabolism: Synthesis of molecules, requiring energy.
59
What is a condensation reaction?
It’s a reaction where two molecules combine, forming a covalent bond and releasing water.
60
Give an example of a condensation reaction.
Glucose + Fructose → Sucrose + Water (C6H12O6 + C6H12O6 → C12H22O11 + H2O).
61
What is a hydrolysis reaction?
A reaction where water breaks a compound into smaller molecules, such as sucrose + water → glucose + fructose.
62
Name three key 6-carbon monosaccharides.
Glucose, fructose, and galactose.
63
What is the general molecular formula of monosaccharides?
(CH2O)n, typically with n between 3 and 7.
64
How do cellulose, starch, and glycogen differ?
Cellulose: Linear, β-1,4 bonds, structural in plants.
Starch: Includes amylose (straight) and amylopectin (branched), energy storage in plants.
Glycogen: Highly branched, α-1,4 and α-1,6 bonds, energy storage in animals.
65
What are the colors representing atoms in a glucose molecule in models?
Carbon: Grey, Hydrogen: White, Oxygen: Red.
66
What are glycoproteins, and how are they formed?
Glycoproteins are proteins with carbohydrates attached to their polypeptide chains. They form in the endoplasmic reticulum and Golgi apparatus during protein synthesis.
67
What roles do glycoproteins play in immune response and antigen recognition?
Glycoproteins help immune cells distinguish between self and non-self cells and recognize pathogens, triggering immune reactions.
68
Name examples of glycoproteins involved in cell-cell recognition and their functions.
Blood group antigens: Determine blood compatibility.
MHC molecules: Aid immune response.
Selectins: Mediate cell adhesion during inflammation.
69
How do lipid structures contribute to their hydrophobic nature?
Long nonpolar hydrocarbon chains and rings in lipids prevent them from mixing with water, making them hydrophobic.
70
What is a triglyceride, and how is it formed?
A triglyceride is a lipid formed from one glycerol and three fatty acids through a condensation reaction, creating ester bonds and releasing water.
71
Define "saturated" fatty acids and describe their properties.
Saturated fatty acids have no double bonds in their hydrocarbon chains, are straight, solid at room temperature, and found in animal fats.
72
What is the difference between saturated, monounsaturated, and polyunsaturated fatty acids?
Saturated: No double bonds.
Monounsaturated: One double bond, creating a kink.
Polyunsaturated: Multiple double bonds, highly flexible.
73
Why are lipids used for long-term energy storage?
1. High energy density.
2. Minimal water content.
3. Slow metabolism for sustained energy.
4. Lightweight storage.
74
What is "amphipathic"?
A molecule with both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions, like phospholipids.
75
How do phospholipids contribute to cell membrane structure?
Their hydrophilic heads and hydrophobic tails form bilayers that selectively allow passage of substances.
76
How do non-polar steroids cross cell membranes?
Non-polar steroids diffuse directly through the lipid bilayer due to their hydrophobic nature.
77
Name examples of non-polar steroid hormones and their action.
Examples: Cortisol, estrogen, testosterone.
Action: Bind intracellular receptors to influence gene expression.
78
Why is glycogen preferred over lipids for immediate energy?
Glycogen breaks down quickly into glucose for immediate use in cellular respiration.
79
Where is glycogen stored in animals, and what are its functions?
Stored in the liver (to regulate blood sugar) and muscles (for local energy needs).
80
Why are triglycerides important in hibernating animals?
They provide long-term energy during extended periods of metabolic inactivity in cold climates.
81
What is DNA, and where is it found in cells?
DNA (deoxyribonucleic acid) is a molecule that carries genetic instructions for an organism's development, functioning, growth, and reproduction. It is primarily found in the nucleus of eukaryotic cells and in the nucleoid region of prokaryotic cells.
82
Do all organisms use DNA as genetic material?
Most organisms use DNA, but some viruses (such as retroviruses like HIV) use RNA as their genetic material.
83
How does DNA store genetic information?
DNA stores genetic information in the sequence of four nitrogenous bases: adenine (A), cytosine (C), guanine (G), and thymine (T).
84
What makes up a single nucleotide in DNA?
A single nucleotide consists of a phosphate group, a pentose sugar (deoxyribose in DNA), and a nitrogenous base (A, T, C, or G).
85
What is the sugar-phosphate backbone in DNA and RNA?
The sugar-phosphate backbone consists of alternating sugar molecules and phosphate groups that form the structural framework of DNA and RNA.
86
How are the sugar and phosphate molecules connected in the backbone?
They are connected by phosphodiester bonds, where the phosphate group of one nucleotide links to the sugar of the next nucleotide.
87
What are the four nitrogenous bases in nucleic acids?
In DNA: adenine (A), cytosine (C), guanine (G), and thymine (T). In RNA: adenine (A), cytosine (C), guanine (G), and uracil (U).
88
How does the structure of RNA differ from DNA?
RNA is single-stranded, whereas DNA is double-stranded. RNA contains ribose as the sugar, and uracil (U) replaces thymine (T).
89
What is the role of condensation in RNA formation?
Condensation removes a water molecule to bond nucleotides together, forming the RNA polymer through phosphodiester bonds.
90
How do the bases pair in DNA?
In DNA, adenine pairs with thymine (A-T), and guanine pairs with cytosine (G-C), held together by hydrogen bonds.
91
Why is complementary base pairing important?
It ensures accurate replication and transcription of genetic information, preserving genetic fidelity across generations.
92
How does DNA replication rely on complementary base pairing?
During DNA replication, each strand serves as a template for creating a complementary strand, ensuring the accurate copying of genetic material.
93
What is the significance of DNA's base sequence diversity?
The vast diversity of DNA sequences allows for the encoding of extensive genetic information, supporting the variety of traits and functions in organisms.
94
How does DNA store vast amounts of genetic information?
DNA's length and the combination of its four nitrogenous bases allow for the storage of a large amount of information, which is passed on to offspring.
95
What makes any length of DNA sequence and any base sequence possible?
The four nitrogenous bases (A, C, G, T) can be arranged in any order, allowing for an infinite variety of DNA sequences of varying lengths.
96
How many unique DNA sequences are possible for a given length N?
For a sequence of length N, there are 4^N possible unique DNA sequences, since each position can be filled by any of the four bases.
97
What does the diversity of DNA sequences allow for?
The vast number of possible DNA sequences allows DNA to encode a huge amount of genetic information, supporting the wide range of traits and functions in organisms.
98
How does DNA’s information storage capacity enable inheritance?
DNA carries genetic information from parent to offspring, ensuring that traits and characteristics are passed down through generations.
99
What is the genetic code?
The genetic code is a set of rules that dictates how sequences of nucleotides in DNA and RNA correspond to sequences of amino acids in proteins.
100
Why is the conservation of the genetic code across organisms important?
The conservation of the genetic code supports the idea of a shared evolutionary history and common ancestry among organisms.
101
How is the genetic code conserved across organisms with significant differences?
Despite genetic diversity, the basic rules of the genetic code remain consistent across all organisms, from bacteria to plants to animals.
102
What does "5' to 3'" directionality mean?
It refers to the direction in which nucleotides are added to a nucleic acid strand. The 5' end is where the phosphate group is attached, and the 3' end has a hydroxyl group.
103
How do 5' to 3' directionality rules affect processes like replication, transcription, and translation?
These processes occur in a 5' to 3' direction, with DNA or RNA being synthesized in this direction, ensuring accurate copying and transcription of genetic material.
104
What are purines and pyrimidines in DNA?
Purines (adenine and guanine) and pyrimidines (cytosine and thymine) are types of nitrogenous bases that pair to form the DNA structure.
105
How does purine-to-pyrimidine bonding contribute to DNA stability?
Purine-pyrimidine base pairing (A-T, G-C) ensures the DNA helix maintains a stable, consistent structure, crucial for its function.
106
What is a nucleosome?
A nucleosome consists of DNA wrapped around a core of eight histone proteins, with an additional histone protein attaching to linker DNA.
107
How do histone proteins and DNA interact in a nucleosome?
Histones, with their positive charges, attract the negatively charged DNA, enabling the formation of a tightly packed structure that helps organize DNA.
108
Why did Hershey and Chase use T2 bacteriophage for their experiment?
T2 bacteriophage was used because it has both a protein coat and DNA core, allowing scientists to track which part enters the bacteria during infection.
109
What did the Hershey-Chase experiment prove about DNA?
The experiment showed that DNA, not protein, is the genetic/hereditary material passed down from one generation to the next.
110
What did Chargaff’s data reveal about DNA base composition?
Chargaff's data showed that adenine (A) pairs with and is equal in amount to thymine (T), and cytosine (C) pairs with and is equal in amount to guanine (G), a critical observation for understanding DNA structure.
111
What was the tetranucleotide hypothesis and how did Chargaff's data disprove it?
The tetranucleotide hypothesis suggested a repeating base sequence in DNA. Chargaff’s data contradicted this by showing unequal ratios of adenine to thymine and cytosine to guanine.
112
What is an essential amino acid?
Phenylalanine
113
What is the general structure of an amino acid?
An amino acid has an alpha carbon atom attached to an amine group (-NH₂), a carboxyl group (-COOH), a hydrogen atom, and an R-group (side chain).
114
How many standard amino acids exist, and how many are synthesized by ribosomes?
There are 20 standard amino acids, all of which are synthesized by ribosomes.
115
Name three amino acids synthesized by ribosomes.
Alanine (Ala), Glycine (Gly), Leucine (Leu).
116
What is a condensation reaction in the context of amino acids?
A reaction where amino acids join to form dipeptides or polypeptides, producing water as a byproduct.
117
What structure mediates polypeptide formation, and what else is needed?
Ribosomes mediate this, requiring ATP, tRNA, and enzymes like aminoacyl-tRNA synthetases.
118
Define essential and non-essential amino acids.
Essential: Cannot be synthesized and must come from the diet. Non-Essential: Can be synthesized by the body.
119
What is a complete protein source?
A protein that provides all nine essential amino acids in sufficient amounts, like meat, soy, or quinoa.
120
What are the four levels of protein structure?
Primary (sequence of amino acids), Secondary (alpha-helices/beta-sheets), Tertiary (3D folding), Quaternary (multiple polypeptide chains).
121
What three factors contribute to the diversity of polypeptides?
20 amino acids, sequence variability, and varying chain lengths.
122
How many different polypeptides can be formed with a sequence of 5 amino acids?
20
5
=3,200,000.
123
What is the longest known polypeptide, and how many amino acids does it contain?
Titin, with approximately 38,138 amino acids.
124
What is denaturation, and what causes it?
Loss of a protein's structure and function due to heat, pH changes, ionic strength, chemicals, or mechanical agitation.
125
In what environment does pepsin work best?
Acidic.
126
What is the optimum pH for trypsin?
Around 8.
127
Can either pepsin or trypsin function at a pH of 5?
No, neither enzyme works at a pH of 5.
128
What determines the properties of assembled polypeptides?
The R-groups of amino acids.
129
List the properties that R-groups of amino acids can possess.
Hydrophobic, hydrophilic, charged, and polar.
130
How do hydrophobic R-groups contribute to protein folding?
They cluster inside the protein to avoid water, stabilizing the structure.
131
How does the chemical diversity of R-groups allow specific protein functions?
It enables unique interactions and structural arrangements, like histidine in hemoglobin stabilizing oxygen binding.
132
What is the primary structure of a protein?
The sequence of amino acids in a polypeptide chain.
133
What are the 4 R groups?
Polar, Non-Polar, Acidic, Basic
134
How does the primary structure affect protein conformation?
It dictates folding and the final three-dimensional shape, determining function.
135
What forms the secondary structure of proteins?
Alpha-helices and beta-sheets stabilized by hydrogen bonds.
136
What types of bonds maintain tertiary structure?
Hydrogen bonds, ionic bonds, disulfide covalent bonds, and hydrophobic interactions.
137
What are disulfide bonds?
Covalent bonds between cysteine residues, stabilizing tertiary structure.
138
Describe the quaternary structure of proteins.
The arrangement of multiple protein subunits into a functional complex.
139
Give an example of a conjugated and a non-conjugated protein.
Conjugated: Hemoglobin. Non-conjugated: Collagen.
140
What is the difference between fibrous and globular proteins?
Fibrous proteins are long and structural, while globular proteins are compact and functional.
141
How do polar and non-polar amino acids influence solubility?
Polar amino acids on the surface increase solubility; non-polar amino acids form hydrophobic cores, reducing solubility.
142
What are alpha-helices and beta-pleated sheets?
Alpha-Helix: A coiled structure formed by hydrogen bonds between the carbonyl oxygen and amide hydrogen of amino acids four residues apart. It creates a spiral shape.
Beta-Pleated Sheet: A sheet-like structure formed by hydrogen bonds between adjacent polypeptide chains or segments, arranged in parallel or antiparallel directions.
143
What stabilizes Alpha Helix and Beta Pleated sheet structures?
Hydrogen bonds between the backbone atoms of amino acids.
144
What is significant about insulin?
After transcription and translation insulin is left with a quaternary structure which is stored in a hexamer.
145
What is the collagen structure?
three alpha helixes essentially braiding together.
146
